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  • Make winform run away from the mouse.

    - by JACK IN THE CRACK
    Okay so I'm trying to make a little gag program that will "run away" from the mouse. So, to get the mouse coordinates for the whole screen and not just the form control I had to create a little helper: static class MouseHelper { [DllImport("user32.dll")] [return: MarshalAs(UnmanagedType.Bool)] internal static extern bool GetCursorPos(ref Point pt); public static Point GetPosition() { Point w32Mouse = new Point(); GetCursorPos(ref w32Mouse); return w32Mouse; } } Now I thought I was going to use the MouseMove event... but that doesn't work for outside the form control either so I have an auto-enabled timer on a 10ms loop called timerMouseMove. public partial class Form1 : Form { public Form1() { InitializeComponent(); } private bool CollisionCheck() { Point win32Mouse = MouseHelper.GetPosition(); if (win32Mouse.X <= Location.X || win32Mouse.X >= (Location.X + Width)) return false; if (win32Mouse.Y <= Location.Y || win32Mouse.Y >= (Location.Y + Height)) return false; return true; } private void timerMouseMove_Tick(object sender, EventArgs e) { if (CollisionCheck()) Location = new Point(Location.X + 1, Location.Y + 1); } } So this works out nicely, at least I have the collision checking working and whatnot. But now, how should I go about figuring which side of the form the mouse has collided with, so that I can update its location to move in the opposite direction the mouse collides with it? And such halp

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  • jQueryUI Tabs: how to keep them on a single line?

    - by Andi
    Hi all, Maybe my question is wired: is there a way to prevent jQueryUI tabs from floating if browser window is too small? Explanation: I have a simple horizontal tab using CSS only. The content is floating but not the tabs. Important: there is no width set manually, the current width is taken automatically. Here is the code: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <style type="text/css"> #tabs ul { white-space: nowrap; } #tabs ul li { display: inline; white-space: nowrap; } </style> <title>Tabs-CSS</title> </head> <body> <div class="demo"> <div id="tabs"> <ul> <li><a href="#tabs-1">Preloaded</a></li> <li><a href="ajax/content1.html">Tab 1</a></li> <li><a href="ajax/content2.html">Tab 2</a></li> <li><a href="ajax/content3-slow.php">Tab 3 (slow)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> </ul> <div id="tabs-1"> <p>Proin elit arcu, rutrum commodo, vehicula tempus, commodo a, risus. Curabitur nec arcu. Donec sollicitudin mi sit amet mauris. Nam elementum quam ullamcorper ante. Etiam aliquet massa et lorem. Mauris dapibus lacus auctor risus. Aenean tempor ullamcorper leo. Vivamus sed magna quis ligula eleifend adipiscing. Duis orci. Aliquam sodales tortor vitae ipsum. Aliquam nulla. Duis aliquam molestie erat. Ut et mauris vel pede varius sollicitudin. Sed ut dolor nec orci tincidunt interdum. Phasellus ipsum. Nunc tristique tempus lectus.</p> </div> </div> </div> </body> </html> This is exactly what I want. Next step: add jQueryUI Tab as unobtrusive Javascript. For example like this: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js" type="text/javascript"></script> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.1/jquery-ui.min.js"></script> <link type="text/css" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.7.2/themes/ui-lightness/jquery-ui.css" rel="stylesheet"/> <style type="text/css"> #tabs ul { white-space: nowrap; } #tabs ul li { display: inline; white-space: nowrap; } </style> <title>Tabs-CSS</title> </head> <body> <div class="demo"> <div id="tabs"> <ul> <li><a href="#tabs-1">Preloaded</a></li> <li><a href="ajax/content1.html">Tab 1</a></li> <li><a href="ajax/content2.html">Tab 2</a></li> <li><a href="ajax/content3-slow.php">Tab 3 (slow)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> </ul> <div id="tabs-1"> <p>Proin elit arcu, rutrum commodo, vehicula tempus, commodo a, risus. Curabitur nec arcu. Donec sollicitudin mi sit amet mauris. Nam elementum quam ullamcorper ante. Etiam aliquet massa et lorem. Mauris dapibus lacus auctor risus. Aenean tempor ullamcorper leo. Vivamus sed magna quis ligula eleifend adipiscing. Duis orci. Aliquam sodales tortor vitae ipsum. Aliquam nulla. Duis aliquam molestie erat. Ut et mauris vel pede varius sollicitudin. Sed ut dolor nec orci tincidunt interdum. Phasellus ipsum. Nunc tristique tempus lectus.</p> </div> </div> </div> <script type="text/javascript"> //<![CDATA[ $(function() { $("#tabs").tabs({ ajaxOptions: { error: function(xhr, status, index, anchor) { $(anchor.hash).html("Couldn't load this tab. We'll try to fix this as soon as possible. If this wouldn't be a demo."); }, } }); }); $(function() { $("#innertabs").tabs({ ajaxOptions: { error: function(xhr, status, index, anchor) { $(anchor.hash).html("Couldn't load this tab. We'll try to fix this as soon as possible. If this wouldn't be a demo."); } } }); }); //]]> </script> </body> </html> Now I can see that the tabbar floats on minimizing the browser window. And there are some ugly effect with the tabs jumping around. My main questions is: can I avoid floating the tabbar and keep all tabs on one single line? Kind regards, Andi

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  • jQueryUI Tabs: how too keep them on a single line?

    - by Andi
    Hi all, Maybe my question is wired: is there a way to prevent jQueryUI tabs from floating if browser window is too small? Explanation: I have a simple horizontal tab using CSS only. The content is floating but not the tabs. Important: there is no width set manually, the current width is taken automatically. Here is the code: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <style type="text/css"> #tabs ul { white-space: nowrap; } #tabs ul li { display: inline; white-space: nowrap; } </style> <title>Tabs-CSS</title> </head> <body> <div class="demo"> <div id="tabs"> <ul> <li><a href="#tabs-1">Preloaded</a></li> <li><a href="ajax/content1.html">Tab 1</a></li> <li><a href="ajax/content2.html">Tab 2</a></li> <li><a href="ajax/content3-slow.php">Tab 3 (slow)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> </ul> <div id="tabs-1"> <p>Proin elit arcu, rutrum commodo, vehicula tempus, commodo a, risus. Curabitur nec arcu. Donec sollicitudin mi sit amet mauris. Nam elementum quam ullamcorper ante. Etiam aliquet massa et lorem. Mauris dapibus lacus auctor risus. Aenean tempor ullamcorper leo. Vivamus sed magna quis ligula eleifend adipiscing. Duis orci. Aliquam sodales tortor vitae ipsum. Aliquam nulla. Duis aliquam molestie erat. Ut et mauris vel pede varius sollicitudin. Sed ut dolor nec orci tincidunt interdum. Phasellus ipsum. Nunc tristique tempus lectus.</p> </div> </div> </div> </body> </html> This is exactly what I want. Next step: add jQueryUI Tab as unobtrusive Javascript. For example like this: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js" type="text/javascript"></script> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.1/jquery-ui.min.js"></script> <link type="text/css" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.7.2/themes/ui-lightness/jquery-ui.css" rel="stylesheet"/> <style type="text/css"> #tabs ul { white-space: nowrap; } #tabs ul li { display: inline; white-space: nowrap; } </style> <title>Tabs-CSS</title> </head> <body> <div class="demo"> <div id="tabs"> <ul> <li><a href="#tabs-1">Preloaded</a></li> <li><a href="ajax/content1.html">Tab 1</a></li> <li><a href="ajax/content2.html">Tab 2</a></li> <li><a href="ajax/content3-slow.php">Tab 3 (slow)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> </ul> <div id="tabs-1"> <p>Proin elit arcu, rutrum commodo, vehicula tempus, commodo a, risus. Curabitur nec arcu. Donec sollicitudin mi sit amet mauris. Nam elementum quam ullamcorper ante. Etiam aliquet massa et lorem. Mauris dapibus lacus auctor risus. Aenean tempor ullamcorper leo. Vivamus sed magna quis ligula eleifend adipiscing. Duis orci. Aliquam sodales tortor vitae ipsum. Aliquam nulla. Duis aliquam molestie erat. Ut et mauris vel pede varius sollicitudin. Sed ut dolor nec orci tincidunt interdum. Phasellus ipsum. Nunc tristique tempus lectus.</p> </div> </div> </div> <script type="text/javascript"> //<![CDATA[ $(function() { $("#tabs").tabs({ ajaxOptions: { error: function(xhr, status, index, anchor) { $(anchor.hash).html("Couldn't load this tab. We'll try to fix this as soon as possible. If this wouldn't be a demo."); }, } }); }); $(function() { $("#innertabs").tabs({ ajaxOptions: { error: function(xhr, status, index, anchor) { $(anchor.hash).html("Couldn't load this tab. We'll try to fix this as soon as possible. If this wouldn't be a demo."); } } }); }); //]]> </script> </body> </html> Now I can see that the tabbar floats on minimizing the browser window. And there are some ugly effect with the tabs jumping around. My main questions is: can I avoid floating the tabbar and keep all tabs on one single line? Kind regards, Andi

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  • Implementing Model-level caching

    - by Byron
    I was posting some comments in a related question about MVC caching and some questions about actual implementation came up. How does one implement a Model-level cache that works transparently without the developer needing to manually cache, yet still remains efficient? I would keep my caching responsibilities firmly within the model. It is none of the controller's or view's business where the model is getting data. All they care about is that when data is requested, data is provided - this is how the MVC paradigm is supposed to work. (Source: Post by Jarrod) The reason I am skeptical is because caching should usually not be done unless there is a real need, and shouldn't be done for things like search results. So somehow the Model itself has to know whether or not the SELECT statement being issued to it worthy of being cached. Wouldn't the Model have to be astronomically smart, and/or store statistics of what is being most often queried over a long period of time in order to accurately make a decision? And wouldn't the overhead of all this make the caching useless anyway? Also, how would you uniquely identify a query from another query (or more accurately, a resultset from another resultset)? What about if you're using prepared statements, with only the parameters changing according to user input? Another poster said this: I would suggest using the md5 hash of your query combined with a serialized version of your input arguments. This would require twice the number of serialization options. I was under the impression that serialization was quite expensive, and for large inputs this might be even worse than just re-querying. And is the minuscule chance of collision worth worrying about? Conceptually, caching in the Model seems like a good idea to me, but it seems in practicality the developer should have direct control over caching and write it into the controller. Thoughts/ideas? Edit: I'm using PHP and MySQL if that helps to narrow your focus.

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  • How to do cleanup reliably in python?

    - by Cheery
    I have some ctypes bindings, and for each body.New I should call body.Free. The library I'm binding doesn't have allocation routines insulated out from the rest of the code (they can be called about anywhere there), and to use couple of useful features I need to make cyclic references. I think It'd solve if I'd find a reliable way to hook destructor to an object. (weakrefs would help if they'd give me the callback just before the data is dropped. So obviously this code megafails when I put in velocity_func: class Body(object): def __init__(self, mass, inertia): self._body = body.New(mass, inertia) def __del__(self): print '__del__ %r' % self if body: body.Free(self._body) ... def set_velocity_func(self, func): self._body.contents.velocity_func = ctypes_wrapping(func) I also tried to solve it through weakrefs, with those the things seem getting just worse, just only largely more unpredictable. Even if I don't put in the velocity_func, there will appear cycles at least then when I do this: class Toy(object): def __init__(self, body): self.body.owner = self ... def collision(a, b, contacts): whatever(a.body.owner) So how to make sure Structures will get garbage collected, even if they are allocated/freed by the shared library? There's repository if you are interested about more details: http://bitbucket.org/cheery/ctypes-chipmunk/

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  • Qt MOC Filename Collisions using multiple .pri files

    - by Skinniest Man
    In order to keep my Qt project somewhat organized (using Qt Creator), I've got one .pro file and multiple .pri files. Just recently I added a class to one of my .pri files that has the same filename as a class that already existed in a separate .pri file. The file structure and makefiles generated by qmake appear to be oblivious to the filename collision that ensues. The generated moc_* files all get thrown into the same subdirectory (either release or debug, depending) and one ends up overwriting the other. When I try to make the project, I get several warnings that look like this: Makefile.Release:318: warning: overriding commands for target `release/moc_file.cpp` And the project fails to link. Here is a simple example of what I'm talking about. Directory structure: + project_dir | + subdir1 | | - file.h | | - file.cpp | + subdir2 | | - file.h | | - file.cpp | - main.cpp | - project.pro | - subdir1.pri | - subdir2.pri Contents of project.pro: TARGET = project TEMPLATE = app include(subdir1.pri) include(subdir2.pri) SOURCES += main.cpp Contents of subdir1.pri: HEADERS += subdir1/file.h SOURCES += subdir1/file.cpp Contents of subdir2.pri: HEADERS += subdir2/file.h SOURCES += subdir2/file.cpp Is there a way to tell qmake to generate a system that puts the moc_* files from separate .pri files into separate subdirectories?

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  • no more hitcollision at 1 life

    - by user1449547
    So I finally got my implementation of lives fixed, and it works. Now however when I collide with a ghost when I am at 1 life, nothing happens. I can fall to my death enough times for a game over. from what i can tell the problem is that hit collision is not longer working, because it does not detect a hit, I do not fall. the question is why? update if i kill myself fast enough it works, but if i play for like 30 seconds, it stops the hit collision detection on my ghosts. platforms and springs still work. public class World { public interface WorldListener { public void jump(); public void highJump(); public void hit(); public void coin(); public void dying(); } public static final float WORLD_WIDTH = 10; public static final float WORLD_HEIGHT = 15 * 20; public static final int WORLD_STATE_RUNNING = 0; public static final int WORLD_STATE_NEXT_LEVEL = 1; public static final int WORLD_STATE_GAME_OVER = 2; public static final Vector2 gravity = new Vector2(0, -12); public Hero hero; public final List<Platform> platforms; public final List<Spring> springs; public final List<Ghost> ghosts; public final List<Coin> coins; public Castle castle; public final WorldListener listener; public final Random rand; public float heightSoFar; public int score; public int state; public int lives=3; public World(WorldListener listener) { this.hero = new Hero(5, 1); this.platforms = new ArrayList<Platform>(); this.springs = new ArrayList<Spring>(); this.ghosts = new ArrayList<Ghost>(); this.coins = new ArrayList<Coin>(); this.listener = listener; rand = new Random(); generateLevel(); this.heightSoFar = 0; this.score = 0; this.state = WORLD_STATE_RUNNING; } private void generateLevel() { float y = Platform.PLATFORM_HEIGHT / 2; float maxJumpHeight = Hero.hero_JUMP_VELOCITY * Hero.hero_JUMP_VELOCITY / (2 * -gravity.y); while (y < WORLD_HEIGHT - WORLD_WIDTH / 2) { int type = rand.nextFloat() > 0.8f ? Platform.PLATFORM_TYPE_MOVING : Platform.PLATFORM_TYPE_STATIC; float x = rand.nextFloat() * (WORLD_WIDTH - Platform.PLATFORM_WIDTH) + Platform.PLATFORM_WIDTH / 2; Platform platform = new Platform(type, x, y); platforms.add(platform); if (rand.nextFloat() > 0.9f && type != Platform.PLATFORM_TYPE_MOVING) { Spring spring = new Spring(platform.position.x, platform.position.y + Platform.PLATFORM_HEIGHT / 2 + Spring.SPRING_HEIGHT / 2); springs.add(spring); } if (rand.nextFloat() > 0.7f) { Ghost ghost = new Ghost(platform.position.x + rand.nextFloat(), platform.position.y + Ghost.GHOST_HEIGHT + rand.nextFloat() * 3); ghosts.add(ghost); } if (rand.nextFloat() > 0.6f) { Coin coin = new Coin(platform.position.x + rand.nextFloat(), platform.position.y + Coin.COIN_HEIGHT + rand.nextFloat() * 3); coins.add(coin); } y += (maxJumpHeight - 0.5f); y -= rand.nextFloat() * (maxJumpHeight / 3); } castle = new Castle(WORLD_WIDTH / 2, y); } public void update(float deltaTime, float accelX) { updatehero(deltaTime, accelX); updatePlatforms(deltaTime); updateGhosts(deltaTime); updateCoins(deltaTime); if (hero.state != Hero.hero_STATE_HIT) checkCollisions(); checkGameOver(); checkFall(); } private void updatehero(float deltaTime, float accelX) { if (hero.state != Hero.hero_STATE_HIT && hero.position.y <= 0.5f) hero.hitPlatform(); if (hero.state != Hero.hero_STATE_HIT) hero.velocity.x = -accelX / 10 * Hero.hero_MOVE_VELOCITY; hero.update(deltaTime); heightSoFar = Math.max(hero.position.y, heightSoFar); } private void updatePlatforms(float deltaTime) { int len = platforms.size(); for (int i = 0; i < len; i++) { Platform platform = platforms.get(i); platform.update(deltaTime); if (platform.state == Platform.PLATFORM_STATE_PULVERIZING && platform.stateTime > Platform.PLATFORM_PULVERIZE_TIME) { platforms.remove(platform); len = platforms.size(); } } } private void updateGhosts(float deltaTime) { int len = ghosts.size(); for (int i = 0; i < len; i++) { Ghost ghost = ghosts.get(i); ghost.update(deltaTime); if (ghost.state == Ghost.GHOST_STATE_DYING && ghost.stateTime > Ghost.GHOST_DYING_TIME) { ghosts.remove(ghost); len = ghosts.size(); } } } private void updateCoins(float deltaTime) { int len = coins.size(); for (int i = 0; i < len; i++) { Coin coin = coins.get(i); coin.update(deltaTime); } } private void checkCollisions() { checkPlatformCollisions(); checkGhostCollisions(); checkItemCollisions(); checkCastleCollisions(); } private void checkPlatformCollisions() { if (hero.velocity.y > 0) return; int len = platforms.size(); for (int i = 0; i < len; i++) { Platform platform = platforms.get(i); if (hero.position.y > platform.position.y) { if (OverlapTester .overlapRectangles(hero.bounds, platform.bounds)) { hero.hitPlatform(); listener.jump(); if (rand.nextFloat() > 0.5f) { platform.pulverize(); } break; } } } } private void checkGhostCollisions() { int len = ghosts.size(); for (int i = 0; i < len; i++) { Ghost ghost = ghosts.get(i); if (hero.position.y < ghost.position.y) { if (OverlapTester.overlapRectangles(ghost.bounds, hero.bounds)){ hero.hitGhost(); listener.hit(); } break; } else { if(hero.position.y > ghost.position.y) { if (OverlapTester.overlapRectangles(hero.bounds, ghost.bounds)){ hero.hitGhostJump(); listener.jump(); ghost.dying(); score += Ghost.GHOST_SCORE; } break; } } } } private void checkItemCollisions() { int len = coins.size(); for (int i = 0; i < len; i++) { Coin coin = coins.get(i); if (OverlapTester.overlapRectangles(hero.bounds, coin.bounds)) { coins.remove(coin); len = coins.size(); listener.coin(); score += Coin.COIN_SCORE; } } if (hero.velocity.y > 0) return; len = springs.size(); for (int i = 0; i < len; i++) { Spring spring = springs.get(i); if (hero.position.y > spring.position.y) { if (OverlapTester.overlapRectangles(hero.bounds, spring.bounds)) { hero.hitSpring(); listener.highJump(); } } } } private void checkCastleCollisions() { if (OverlapTester.overlapRectangles(castle.bounds, hero.bounds)) { state = WORLD_STATE_NEXT_LEVEL; } } private void checkFall() { if (heightSoFar - 7.5f > hero.position.y) { --lives; hero.hitSpring(); listener.highJump(); } } private void checkGameOver() { if (lives<=0) { state = WORLD_STATE_GAME_OVER; } } }

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  • Effective communication in a component-based system

    - by Tesserex
    Yes, this is another question about my game engine, which is coming along very nicely, with much thanks to you guys. So, if you watched the video (or didn't), the objects in the game are composed of various components for things like position, sprites, movement, collision, sounds, health, etc. I have several message types defined for "tell" type communication between entities and components, but this only goes so far. There are plenty of times when I just need to ask for something, for example an entity's position. There are dozens of lines in my code that look like this: SomeComponent comp = (SomeComponent)entity.GetComponent(typeof(SomeComponent)); if (comp != null) comp.GetSomething(); I know this is very ugly, and I know that casting smells of improper OO design. But as complex as things are, there doesn't seem to be a better way. I could of course "hard-code" my component types and just have SomeComponent comp = entity.GetSomeComponent(); but that seems like a cop-out, and a bad one. I literally JUST REALIZED, while writing this, after having my code this way for months with no solution, that a generic will help me. SomeComponent comp = entity.GetComponent<SomeComponent>(); Amazing how that works. Anyway, this is still only a semantic improvement. My questions remain. Is this actually that bad? What's a better alternative?

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  • How can I define an irregular area of the screen and find the closest point to the mouse in that area?

    - by JonathonG
    I'm looking for a method to define an area of the screen that the mouse cannot leave. I have been directed by rob mayoff, the answerer of this question, that I can use a Quartz Event Tap to detect mouse events. This puts me part of the way to the solution to THIS question. I need to define an irregular area of the screen, not just a rectangle, that the mouse cannot leave. I have been researching this and the only idea I can come up with is using a bitmap to define the irregular area, as it will be very oddly shaped. However, I am open to solutions other than using a bitmap. Since this must be done on a Mac, I've determined that I will have to use objective C / Cocoa . I need to know how to define the area and, equally importantly, how to find the closest point in the area to the mouse (so that I can move the mouse to it if the mouse tries to move outside of the area). This is similar to what the restricted area will look like: [edit:] Okay, I've come up with part of the answer to this. If I can do a basic (light-weight) point collision detection on the image mask, I can use a simple algorithm to detect the closest point to the mouse on the black area of the image. I could do this by calculating distance between a pre-defined point (P) inside the black area of the image and the target mouse position (T), taking the midpoint (M), then checking if the midpoint is inside or outside of the shape (black or white, respectively). If M is inside the shape, then move the P to M, otherwise move T to the M, continuously recalculate this until the distance between T and P is 1 pixel or less, then move the mouse to the final calculated position. All of that being said, I still need some way to test the position of the mouse against that same position on the bitmap (assume the bitmap is the same resolution as the monitor), and check if that point is black or white. All of this needs to be done in the background, without this application actually having focus, or the bitmap being visible... is this possible?

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  • Scalable way to store files on server (PHP)?

    - by Nathaniel Bennett
    I'm creating my first web application - a really simplistic online text editor. What I need to do is find the best way to store text based files - a lot of them. These text files can be past 10,000 words in size (text words not computer words.) in essence I want the text documents to be limitless in size. I was thinking about storing the text files in my MySQL database - but thought there was a better way. Instead I'm planing on storing the text files in XML based format in a directory on my server. The rows in the database define the name of the xml based text file and the user who created the text along with basic metadata. An ID is generated using a V4 GUID generator , which gives the text an id and stores the text in the "/store" directory on my server. The text definitions in my server contain this id, and the android app I'm developing gets the contents of the text file by retrieving the text definition and then downloading the text to the local device using the GUID in the text definition. I just think this is a botch job? how can I improve this system? There has been cases of GUID colliding. I don't want this to happen. A "slim" possibility isn't good enough - I need to make sure there is absolutely no chance in a GUID collision. I was planning on checking the database for texts that have the same id before storing the text with a particular id - I however believe with over 20,000 pieces of text in my database this would take an long time and produce unneeded stress on the server. How can I make GUID safe? What happens when a GUID collides? The server backend is going to be written in PHP.

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  • How to implement a Linked List in Java?

    - by nbarraille
    Hello! I am trying to implement a simple HashTable in Java that uses a Linked List for collision resolution, which is pretty easy to do in C, but I don't know how to do it in Java, as you can't use pointers... First, I know that those structures are already implemented in Java, I'm not planning on using it, just training here... So I created an element, which is a string and a pointer to the next Element: public class Element{ private String s; private Element next; public Element(String s){ this.s = s; this.next = null; } public void setNext(Element e){ this.next = e; } public String getString(){ return this.s; } public Element getNext(){ return this.next; } @Override public String toString() { return "[" + s + "] => "; } } Of course, my HashTable has an array of Element to stock the data: public class CustomHashTable { private Element[] data; Here is my problem: For example I want to implement a method that adds an element AT THE END of the linked List (I know it would have been simpler and more efficient to insert the element at the beginning of the list, but again, this is only for training purposes). How do I do that without pointer? Here is my code (which could work if e was a pointer...): public void add(String s){ int index = hash(s) % data.length; System.out.println("Adding at index: " + index); Element e = this.data[index]; while(e != null){ e = e.getNext(); } e = new Element(s); } Thanks!

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  • SQL SERVER – History of SQL Server Database Encryption

    - by pinaldave
    I recently met Michael Coles and Rodeney Landrum the author of one of the kind book Expert SQL Server 2008 Encryption at SQLPASS in Seattle. During the conversation we ended up how Microsoft is evolving encryption technology. The same discussion lead to talking about history of encryption tools in SQL Server. Michale pointed me to page 18 of his book of encryption. He explicitly give me permission to re-produce relevant part of history from his book. Encryption in SQL Server 2000 Built-in cryptographic encryption functionality was nonexistent in SQL Server 2000 and prior versions. In order to get server-side encryption in SQL Server you had to resort to purchasing or creating your own SQL Server XPs. Creating your own cryptographic XPs could be a daunting task owing to the fact that XPs had to be compiled as native DLLs (using a language like C or C++) and the XP application programming interface (API) was poorly documented. In addition there were always concerns around creating wellbehaved XPs that “played nicely” with the SQL Server process. Encryption in SQL Server 2005 Prior to the release of SQL Server 2005 there was a flurry of regulatory activity in response to accounting scandals and attacks on repositories of confidential consumer data. Much of this regulation centered onthe need for protecting and controlling access to sensitive financial and consumer information. With the release of SQL Server 2005 Microsoft responded to the increasing demand for built-in encryption byproviding the necessary tools to encrypt data at the column level. This functionality prominently featured the following: Support for column-level encryption of data using symmetric keys or passphrases. Built-in access to a variety of symmetric and asymmetric encryption algorithms, including AES, DES, Triple DES, RC2, RC4, and RSA. Capability to create and manage symmetric keys. Key creation and management. Ability to generate asymmetric keys and self-signed certificates, or to install external asymmetric keys and certificates. Implementation of hierarchical model for encryption key management, similar to the ANSI X9.17 standard model. SQL functions to generate one-way hash codes and digital signatures, including SHA-1 and MD5 hashes. Additional SQL functions to encrypt and decrypt data. Extensions to the SQL language to support creation, use, and administration of encryption keys and certificates. SQL CLR extensions that provide access to .NET-based encryption functionality. Encryption in SQL Server 2008 Encryption demands have increased over the past few years. For instance, there has been a demand for the ability to store encryption keys “off-the-box,” physically separate from the database and the data it contains. Also there is a recognized requirement for legacy databases and applications to take advantage of encryption without changing the existing code base. To address these needs SQL Server 2008 adds the following features to its encryption arsenal: Transparent Data Encryption (TDE): Allows you to encrypt an entire database, including log files and the tempdb database, in such a way that it is transparent to client applications. Extensible Key Management (EKM): Allows you to store and manage your encryption keys on an external device known as a hardware security module (HSM). Cryptographic random number generation functionality. Additional cryptography-related catalog views and dynamic management views. SQL language extensions to support the new encryption functionality. The encryption book covers all the tools in its various chapter in one simple story. If you are interested how encryption evolved and reached to the stage where it is today, this book is must for everyone. You can read my earlier review of the book over here. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Book Review, SQLAuthority News, T SQL, Technology Tagged: Encryption, SQL Server Encryption, SQLPASS

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  • XNA Notes 006

    - by George Clingerman
    If you used to think the XNA community was small and inactive, hopefully these XNA Notes are opening your eyes. And I honestly feel like I’m still only catching the tail end of everything that’s going on. It’s a large and active community and you can be so mired down in one part of it you miss all sorts of cool stuff another part is doing. XNA is many things to a lot of people and that makes for a lot of really awesome things going on. So here’s what I saw going on this last week! Time Critical XNA New: XNA Team - Peer Review now closes for XNA 3.1 games http://blogs.msdn.com/b/xna/archive/2011/02/08/peer-review-pipeline-closed-for-new-xna-gs-3-1-games-or-updates-on-app-hub.aspx http://twitter.com/XNACommunity/statuses/34649816529256448 The XNA Team posts about a meet up with Microsoft for Creator’s going to be at GDC, March 3rd at the Lobby Bar http://on.fb.me/fZungJ XNA Team: @mklucher is busying playing the the bubblegum on WP7 made by a member of the XNA team (although reportedly made in Silverlight? Crazy! ;) ) http://twitter.com/mklucher/statuses/34645662737895426 http://bubblegum.me Shawn Hargreaves posts multiple posts (is this a sign that something new is coming from the XNA team? Usually when Shawn has time to post, something has just wrapped up…) Random Shuffle http://blogs.msdn.com/b/shawnhar/archive/2011/02/09/random-shuffle.aspx Doing the right thing: resume, rewind or skip ahead http://blogs.msdn.com/b/shawnhar/archive/2011/02/10/doing-the-right-thing-resume-rewind-or-skip-ahead.aspx XNA Developers: Andrew Russel was on .NET Rocks recently talking with Carl and Richard about developing games for Xbox, iPhone and Android http://www.dotnetrocks.com/default.aspx?ShowNum=635 Eric W. releases the Fishing Girl source code into the wild http://ericw.ca/blog/posts/fishing-girl-now-open-source/ http://forums.create.msdn.com/forums/p/74642/454512.aspx#454512 BinaryTweedDeej reminds that XNA community that Indie City wants you involved http://twitter.com/BinaryTweedDeej/statuses/34596114028044288 http://www.indiecity.com Mike McLaughlin (@mikebmcl) releases his first two XNA articles on the TechNet wiki http://social.technet.microsoft.com/wiki/contents/articles/xna-framework-overview.aspx http://social.technet.microsoft.com/wiki/contents/articles/content-pipeline-overview.aspx John Watte plays around with the Content Pipeline and Music Visualization exploring just what can be done. http://www.enchantedage.com/xna-content-pipeline-fft-song-analysis http://www.enchantedage.com/fft-in-xna-content-pipeline-for-beat-detection-for-the-win Simon Stevens writes up his talk on Vector Collision Physics http://www.simonpstevens.com/News/VectorCollisionPhysics @domipheus puts together an XNA Task Manager http://www.flickr.com/photos/domipheus/5405603197/ MadNinjaSkillz releases his fork of Nick's Easy Storage component on CodePlex http://twitter.com/MadNinjaSkillz/statuses/34739039068229634 http://ezstorage.codeplex.com @ActiveNick was interviewed by Rob Cameron and discusses Windows Phone 7, Bing Maps and XNA http://twitter.com/ActiveNick/statuses/35348548526546944 http://msdn.microsoft.com/en-us/cc537546 Radiangames (Luke Schneider) posts about converting his games from XNA to Unity http://radiangames.com/?p=592 UberMonkey (@ElementCy) posts about a new project in the works, CubeTest a Minecraft style terrain http://www.ubergamermonkey.com/personal-projects/new-project-in-the-works/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+Ubergamermonkey+%28UberGamerMonkey%29 Xbox LIVE Indie Games (XBLIG): VideoGamer Rob review Bonded Realities http://videogamerrob.wordpress.com/2011/02/05/xblig-review-bonded-realities/ XBLIG Round Up on Gamergeddon http://www.gamergeddon.com/2011/02/06/xbox-indie-game-round-up-february-6th/ Are gamers still rating Indie Games after the Xbox Dashboard update? http://www.gamemarx.com/news/2011/02/06/are-gamers-still-rating-indie-games-after-the-xbox-dashboard-update.aspx Joystiq - Xbox Live Indie Gems: Corrupted http://www.joystiq.com/2011/02/04/xbox-live-indie-gems-corrupted/ Raymond Matthews of DarkStarMatryx reviews (Almost) Total Mayhem and Aban Hawkins & the 1000 Spikes http://www.darkstarmatryx.com/?p=225 http://www.darkstarmatryx.com/?p=229 8 Bit Horse reviews Aban Hawkins & the 1000 spikes http://8bithorse.blogspot.com/2011/01/aban-hawkins-1000-spikes-xbl-indie.html 2010 wrap-up for FunInfused Games http://www.krissteele.net/blogdetails.aspx?id=245 NeoGaf roundup of January's XBLIGs http://www.neogaf.com/forum/showthread.php?t=420528 Armless Ocotopus interviews Michael Ventnor creator of Bonded Realities http://www.armlessoctopus.com/2011/02/07/interview-michael-ventnor-of-red-crest-studios/ @recharge_media posts about the new city music for Woodvale in Sin Rising http://rechargemedia.com/2011/02/08/new-city-theme-woodvale/ @DrMisty posts some footage of YoYoYo in action http://www.mstargames.co.uk/mistryblogmain/54-yoyoyoblogs/184-video-update.html Xona Games - Decimation X3 on Reviews on the Run http://video.citytv.com/video/detail/782443063001.000000/reviews-on-the-run--february-8-2011/g4/ @benkane gives an early peek at his action RPG coming to XBLIG http://www.youtube.com/watch?v=bDF_PrvtwU8 Rock, Paper Shotgun talks to Zeboyd games about bringing Cthulhu Saves the World to PC http://www.rockpapershotgun.com/2011/02/11/summoning-cthulhu-natter-with-zeboyd/ Xbox LIVE Indieverse interviews the creator of Bonded Realities http://xbl-indieverse.blogspot.com/2011/02/xbl-indieverse-interview-red-crest.html XNA Game Development: Dream-In-Code posts about an upcoming XNA Challenge/Coding contest http://www.dreamincode.net/forums/blog/1385/entry-3192-xna-challengecontest/ Sgt.Conker covers Fishing Girl and IndieFreaks Game Framework release http://www.sgtconker.com/2011/02/fishing-girl-did-not-sell-a-single-copy/ http://www.sgtconker.com/2011/02/indiefreaks-game-framework-v0-2-0-0/ @slyprid releases Transmute v0.40a with lots of new features and fixes http://twitter.com/slyprid/statuses/34125423067533312 http://twitter.com/slyprid/statuses/35326876243337216 http://forgottenstarstudios.com/ Jeff Brown writes an XNA 4.0 tutorial on Saving/Loading on the Xbox 360 http://www.robotfootgames.com/xna-tutorials/92-xna-tutorial-savingloading-on-xbox-360-40 XNA for Silverlight Developers: Part 3- Animation http://www.silverlightshow.net/items/XNA-for-Silverlight-developers-Part-3-Animation-transforms.aspx?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+xna-connection-twitter-specific-stream+%28XNA+Connection%27s+Twitter+specific+stream%29 The news from Nokia is definitely something XNA developers will want to keep their eye on http://blogs.forum.nokia.com/blog/nokia-developer-news/2011/02/11/letter-to-developers?sf1066337=1

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  • Distinctly LINQ &ndash; Getting a Distinct List of Objects

    - by David Totzke
    Let’s say that you have a list of objects that contains duplicate items and you want to extract a subset of distinct items.  This is pretty straight forward in the trivial case where the duplicate objects are considered the same such as in the following example: List<int> ages = new List<int> { 21, 46, 46, 55, 17, 21, 55, 55 }; IEnumerable<int> distinctAges = ages.Distinct(); Console.WriteLine("Distinct ages:"); foreach (int age in distinctAges) { Console.WriteLine(age); } /* This code produces the following output: Distinct ages: 21 46 55 17 */ What if you are working with reference types instead?  Imagine a list of search results where items in the results, while unique in and of themselves, also point to a parent.  We’d like to be able to select a bunch of items in the list but then see only a distinct list of parents.  Distinct isn’t going to help us much on its own as all of the items are distinct already.  Perhaps we can create a class with just the information we are interested in like the Id and Name of the parents.  public class SelectedItem { public int ItemID { get; set; } public string DisplayName { get; set; } } We can then use LINQ to populate a list containing objects with just the information we are interested in and then get rid of the duplicates. IEnumerable<SelectedItem> list = (from item in ResultView.SelectedRows.OfType<Contract.ReceiptSelectResults>() select new SelectedItem { ItemID = item.ParentId, DisplayName = item.ParentName }) .Distinct(); Most of you will have guessed that this didn’t work.  Even though some of our objects are now duplicates, because we are working with reference types, it doesn’t matter that their properties are the same, they’re still considered unique.  What we need is a way to define equality for the Distinct() extension method. IEqualityComparer<T> Looking at the Distinct method we see that there is an overload that accepts an IEqualityComparer<T>.  We can simply create a class that implements this interface and that allows us to define equality for our SelectedItem class. public class SelectedItemComparer : IEqualityComparer<SelectedItem> { public new bool Equals(SelectedItem abc, SelectedItem def) { return abc.ItemID == def.ItemID && abc.DisplayName == def.DisplayName; } public int GetHashCode(SelectedItem obj) { string code = obj.DisplayName + obj.ItemID.ToString(); return code.GetHashCode(); } } In the Equals method we simply do whatever comparisons are necessary to determine equality and then return true or false.  Take note of the implementation of the GetHashCode method.  GetHashCode must return the same value for two different objects if our Equals method says they are equal.  Get this wrong and your comparer won’t work .  Even though the Equals method returns true, mismatched hash codes will cause the comparison to fail.  For our example, we simply build a string from the properties of the object and then call GetHashCode() on that. Now all we have to do is pass an instance of our IEqualitlyComarer<T> to Distinct and all will be well: IEnumerable<SelectedItem> list =     (from item in ResultView.SelectedRows.OfType<Contract.ReceiptSelectResults>()         select new SelectedItem { ItemID = item.dahfkp, DisplayName = item.document_code })                         .Distinct(new SelectedItemComparer());   Enjoy. Dave Just because I can… Technorati Tags: LINQ,C#

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  • C# 4.0: Named And Optional Arguments

    - by Paulo Morgado
    As part of the co-evolution effort of C# and Visual Basic, C# 4.0 introduces Named and Optional Arguments. First of all, let’s clarify what are arguments and parameters: Method definition parameters are the input variables of the method. Method call arguments are the values provided to the method parameters. In fact, the C# Language Specification states the following on §7.5: The argument list (§7.5.1) of a function member invocation provides actual values or variable references for the parameters of the function member. Given the above definitions, we can state that: Parameters have always been named and still are. Parameters have never been optional and still aren’t. Named Arguments Until now, the way the C# compiler matched method call definition arguments with method parameters was by position. The first argument provides the value for the first parameter, the second argument provides the value for the second parameter, and so on and so on, regardless of the name of the parameters. If a parameter was missing a corresponding argument to provide its value, the compiler would emit a compilation error. For this call: Greeting("Mr.", "Morgado", 42); this method: public void Greeting(string title, string name, int age) will receive as parameters: title: “Mr.” name: “Morgado” age: 42 What this new feature allows is to use the names of the parameters to identify the corresponding arguments in the form: name:value Not all arguments in the argument list must be named. However, all named arguments must be at the end of the argument list. The matching between arguments (and the evaluation of its value) and parameters will be done first by name for the named arguments and than by position for the unnamed arguments. This means that, for this method definition: public static void Method(int first, int second, int third) this call declaration: int i = 0; Method(i, third: i++, second: ++i); will have this code generated by the compiler: int i = 0; int CS$0$0000 = i++; int CS$0$0001 = ++i; Method(i, CS$0$0001, CS$0$0000); which will give the method the following parameter values: first: 2 second: 2 third: 0 Notice the variable names. Although invalid being invalid C# identifiers, they are valid .NET identifiers and thus avoiding collision between user written and compiler generated code. Besides allowing to re-order of the argument list, this feature is very useful for auto-documenting the code, for example, when the argument list is very long or not clear, from the call site, what the arguments are. Optional Arguments Parameters can now have default values: public static void Method(int first, int second = 2, int third = 3) Parameters with default values must be the last in the parameter list and its value is used as the value of the parameter if the corresponding argument is missing from the method call declaration. For this call declaration: int i = 0; Method(i, third: ++i); will have this code generated by the compiler: int i = 0; int CS$0$0000 = ++i; Method(i, 2, CS$0$0000); which will give the method the following parameter values: first: 1 second: 2 third: 1 Because, when method parameters have default values, arguments can be omitted from the call declaration, this might seem like method overloading or a good replacement for it, but it isn’t. Although methods like this: public static StreamReader OpenTextFile( string path, Encoding encoding = null, bool detectEncoding = true, int bufferSize = 1024) allow to have its calls written like this: OpenTextFile("foo.txt", Encoding.UTF8); OpenTextFile("foo.txt", Encoding.UTF8, bufferSize: 4096); OpenTextFile( bufferSize: 4096, path: "foo.txt", detectEncoding: false); The complier handles default values like constant fields taking the value and useing it instead of a reference to the value. So, like with constant fields, methods with parameters with default values are exposed publicly (and remember that internal members might be publicly accessible – InternalsVisibleToAttribute). If such methods are publicly accessible and used by another assembly, those values will be hard coded in the calling code and, if the called assembly has its default values changed, they won’t be assumed by already compiled code. At the first glance, I though that using optional arguments for “bad” written code was great, but the ability to write code like that was just pure evil. But than I realized that, since I use private constant fields, it’s OK to use default parameter values on privately accessed methods.

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  • WEB203 &ndash; Jump into Silverlight!&hellip; and Become Effective Immediately with Tim Huckaby, Fou

    - by Robert Burger
    Getting ready for the good stuff. Definitely wish there were more Silverlight and WCF RIA sessions, but this is a start.  Was lucky to get a coveted power-enabled seat.  Luckily, due to my trustily slow Verizon data card, I can get these notes out amidst a total Internet outage here.  This is the second breakout session of the day, and is by far standing-room only.  I stepped out before the session started to get a cool Diet COKE and wouldn’t have gotten back in if I didn’t already have a seat. Tim says this is an intro session and that he’s been begging for intro sessions at TechEd for years and that by looking at this audience, he thinks the demand is there.  Admittedly, I didn’t know this was an intro session, or I might have gone elsewhere.  But, it was the very first Silverlight session, so I had to be here. Tim says he will be providing a very good comprehensive reference application at the end of the presentation.  He has just demoed it, and it is a full CRUD-based Sales Manager application based on…  AdventureWorks! Session Agenda What it is / How to get started Declarative Programming Layout and Controls, Events and Commands Working with Data Adding Style to Your Application   Silverlight…  “WPF Light” Why is the download 4.2MB?  Because the direct competitor is a 4.2MB download.  There is no technical reason it is not the entire framework.  It is purely to “be competitive”.   Getting Started Get all of the following downloads from www.silverlight.net/getstarted Install VS2010 or Visual Web Developer Express 2010 Install Silverlight 4 Tools for VS2010 Install Expression Blend 4 Install the Silverlight 4 Toolkit   Reference Application Features Uses MVVM pattern – a way to move data access code that would normally be inline within the UI and placing it in nice data access libraries Images loaded dynamically from the database, converting GIF to PNG because Silverlight does not support GIF. LINQ to SQL is the data access model WCF is the data provider and is using binary message encoding   Declarative Programming XAML replaces code for UI representation Attributes control Layout and Style Event handlers wired-up in XAML Declarative Data Binding   Layout Overview Content rendering flows inside of parent Fixed positioning (Canvas) is seldom used Panels are used to house content Margins and Padding over fixed size   Panels StackPanel – Arranges child elements into a single line oriented horizontally or vertically Grid – A flexible grid are that consists of rows and columns Canvas – An are where positions are specifically fixed WrapPanel (in Toolkit) – Positions child elements in sequential position left to right and top to bottom. DockPanel (in Toolkit) – Positions child controls within a dockable area   Positioning Horizontal and Vertical Alignment Margin – Separates an element from neighboring elements Padding – Enlarges the effective size of an element by a thickness   Controls Overview Not all controls created equal Silverlight, as a subset of WPF, so many WPF controls do not exist in the core Siverlight release Silverlight Toolkit continues to add controls, but are released in different quality bands Plenty of good 3rd party controls to fill the gaps Windows Phone 7 is to have 95% of controls available in Silverlight Core and Toolkit.   Events and Commands Standard .NET Events Routed Events Commands – based on the ICommand interface – logical action that can be invoked in several ways   Adding Style to Your Application Resource Dictionaries – Contains a hash table of key/value pairs.  Silverlight can only use Static Resources whereas WPF can also use Dynamic Resources Visual State Manager Silverlight 4 supports Implicit styles ResourceDictionary.MergedDictionaries combines many different file-based resources   Downloads

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  • Day 4 - Game Sprites In Action

    - by dapostolov
    Yesterday I drew an image on the screen. Most exciting, but ... I spent more time blogging about it then actual coding. So this next little while I'm going to streamline my game and research and simply post key notes. Quick notes on the last session: The most important thing I wanted to point out were the following methods:           spriteBatch.Begin(SpriteBlendMode.AlphaBlend);           spriteBatch.Draw(sprite, position, Color.White);           spriteBatch.End(); The spriteBatch object is used to draw Textures and a 2D texture is called a Sprite A texture is generally an image, which is called an Asset in XNA The Draw Method in the Game1.cs is looped (until exit) and utilises the spriteBatch object to draw a Scene To begin drawing a Scene you call the Begin Method. To end a Scene you call the End Method. And to place an image on the Scene you call the Draw method. The most simple implementation of the draw method is:           spriteBatch.Draw(sprite, position, Color.White); 1) sprite - the 2D texture you loaded to draw 2) position - the 2d vector, a set of x & y coordinates 3) Color.White - the tint to apply to the texture, in this case, white light = nothing, nada, no tint. Game Sprites In Action! Today, I played around with Draw methods to get comfortable with their "quirks". The following is an example of the above draw method, but with more parameters available for us to use. Let's investigate!             spriteBatch.Draw(sprite, position2, null, Color.White, MathHelper.ToRadians(45.0f), new Vector2(sprite.Width / 2, sprite.Height / 2), 1.0F, SpriteEffects.None, 0.0F); The parameters (in order): 1) sprite  the texture to display 2) position2 the position on the screen / scene this can also be a rectangle 3) null the portion of the image to display within an image null = display full image this is generally used for animation strips / grids (more on this below) 4) Color.White Texture tinting White = no tint 5) MathHelper.ToRadians(45.0f) rotation of the object, in this case 45 degrees rotates from the set plotting point. 6) new Vector(0,0) the plotting point in this case the top left corner the image will rotate from the top left of the texture in the code above, the point is set to the middle of the image. 7) 1.0f Image scaling (1x) 8) SpriteEffects.None you can flip the image horizontally or vertically 9) 0.0f The z index of the image. 0 = closer, 1 behind? And playing around with different combinations I was able to come up with the following whacky display:   Checking off Yesterdays Intention List: learn game development terminology (in progress) - We learned sprite, scene, texture, and asset. how to place and position (rotate) a static image on the screen (completed) - The thing to note was, it's was in radians and I found a cool helper method to convert degrees into radians. Also, the image rotates from it's specified point. how to layer static images on the screen (completed) - I couldn't seem to get the zIndex working, but one things for sure, the order you draw the image in also determines how it is rendered on the screen. understand image scaling (in progress) - I'm not sure I have this fully covered, but for the most part plug a number in the scaling field and the image grows / shrinks accordingly. can we reuse images? (completed) - yes, I loaded one image and plotted the bugger all over the screen. understand how framerate is handled in XNA (in progress) - I hacked together some code to display the framerate each second. A framerate of 60 appears to be the standard. Interesting to note, the GameTime object does provide you with some cool timing capabilities, such as...is the game running slow? Need to investigate this down the road. how to display text , basic shapes, and colors on the screen (in progress) - i got text rendered on the screen, and i understand containing rectangles. However, I didn't display "shapes" & "colors" how to interact with an image (collision of user input?) (todo) how to animate an image and understand basic animation techniques (in progress) - I was able to create a stripe animation of numbers ranging from 1 - 4, each block was 40 x 40 pixles for a total stripe size of 160 x 40. Using the portion (source Rectangle) parameter, i limited this display to each section at varying intervals. It was interesting to note my first implementation animated at rocket speed. I then tried to create a smoother animation by limiting the redraw capacity, which seemed to work. I guess a little more research will have to be put into this for animating characters / scenes. how to detect colliding images or screen edges (todo) - but the rectangle object can detect collisions I believe. how to manipulate the image, lets say colors, stretching (in progress) - I haven't figured out how to modify a specific color to be another color, but the tinting parameter definately could be used. As for stretching, use the rectangle object as the positioning and the image will stretch to fit! how to focus on a segment of an image...like only displaying a frame on a film reel (completed) - as per basic animation techniques what's the best way to manage images (compression, storage, location, prevent artwork theft, etc.) (todo) Tomorrows Intention Tomorrow I am going to take a stab at rendering a game menu and from there I'm going to investigate how I can improve upon the code and techniques. Intention List: Render a menu, fancy or not Show the mouse cursor Hook up click event A basic animation of somesort Investigate image / menu techniques D.

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  • New Management Console in Java SE Advanced 8u20

    - by Erik Costlow-Oracle
    Java SE 8 update 20 is a new feature release designed to provide desktop administrators with better control of their managed systems. The release notes for 8u20 are available from the public JDK release notes page. This release is not a Critical Patch Update (CPU). I would like to call attention to two noteworthy features of Oracle Java SE Advanced, the commercially supported version of Java SE for enterprises that require both support and specialized tools. The new Advanced Management Console provides a way to monitor and understand client systems at scale. It allows organizations to track usage and more easily create and manage client configuration like Deployment Rule Sets (DRS). DRS can control execution of tracked applications as well as specify compatibility of which application should use which Java SE installation. The new MSI Installer integrates into various desktop management tools, making it easier to customize and roll out different Java SE versions. Advanced Management Console The Advanced Management Console is part of Java SE Advanced designed for desktop administrators, whose users need to run many different Java applications. It provides usage tracking for those Applet & Web Start applications to help identify them for guided DRS creation. DRS can then be verified against the tracked data, to ensure that end-users can run their application against the appropriate Java version with no prompts. Usage tracking also has a different definition for Java SE than it does for most software applications. Unlike most applications where usage can be determined by a simple run-count, Java is a platform used for launching other applications. This means that usage tracking must answer both "how often is this Java SE version used" and "what applications are launched by it." Usage Tracking One piece of Java SE Advanced is a centralized usage tracker. Simply placing a properties file on the client informs systems to report information to this usage tracker, so that the desktop administrator can better understand usage. Information is sent via UDP to prevent any delay on the client. The usage tracking server resides at a central location on the intranet to collect information from those clients. The information is stored in a normalized database for performance, meaning that a single usage tracker can handle a large number of clients. Guided Deployment Rule Sets Deployment Rule Sets were introduced in Java 7 update 40 (September 2013) in order to help administrators control security prompts and guide compatibility. A previous post, Deployment Rule Sets by Example, explains how to configure a rule set so that most applications run against the most secure version but a specific applet may run against the Java version that was current several years ago. There are a different set of questions that can be asked by a desktop administrator in a large or distributed firm: Where are the Java RIAs that our users need? Which RIA needs which Java version? Which users need which Java versions? How do I verify these answers once I have them? The guided deployment rule set creation uses usage tracker data to identify applications both by certificate hash and location. After creating the rules, a comparison tool exists to verify them against the tracked data: If you intend to run an RIA, is it green? If something specific should be blocked, is it red? This makes user-testing easier. MSI Installer The Windows Installer format (MSI) provides a number of benefits for desktop administrators that customize or manage software at scale. Unlike the basic installer that most users obtain from Java.com or OTN, this installer is built around customization and integration with various desktop management products like SCCM. Desktop administrators using the MSI installer can use every feature provided by the format, such as silent installs/upgrades, low-privileged installations, or self-repair capabilities Customers looking for Java SE Advanced can download the MSI installer through their My Oracle Support (MOS) account. Java SE Advanced The new features in Java SE Advanced make it easier for desktop administrators to identify and control client installations at scale. Administrators at organizations that want either the tools or associated commercial support should consider Java SE Advanced.

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  • Serial plans: Threshold / Parallel_degree_limit = 1

    - by jean-pierre.dijcks
    As a very short follow up on the previous post. So here is some more on getting a serial plan and why that happens Another reason - compared to the auto DOP is not on as we looked at in the earlier post - and often more prevalent to get a serial plan is if the plan simply does not take long enough to consider a parallel path. The resulting plan and note looks like this (note that this is a serial plan!): explain plan for select count(1) from sales; SELECT PLAN_TABLE_OUTPUT FROM TABLE(DBMS_XPLAN.DISPLAY()); PLAN_TABLE_OUTPUT -------------------------------------------------------------------------------- Plan hash value: 672559287 -------------------------------------------------------------------------------------- | Id  | Operation            | Name  | Rows  | Cost (%CPU)| Time     | Pstart| Pstop | -------------------------------------------------------------------------------------- PLAN_TABLE_OUTPUT -------------------------------------------------------------------------------- |   0 | SELECT STATEMENT     |       |     1 |     5   (0)| 00:00:01 |       |     | |   1 |  SORT AGGREGATE      |       |     1 |            |          |       |     | |   2 |   PARTITION RANGE ALL|       |   960 |     5   (0)| 00:00:01 |     1 |  16 | |   3 |    TABLE ACCESS FULL | SALES |   960 |     5   (0)| 00:00:01 |     1 |  16 | Note -----    - automatic DOP: Computed Degree of Parallelism is 1 because of parallel threshold 14 rows selected. The parallel threshold is referring to parallel_min_time_threshold and since I did not change the default (10s) the plan is not being considered for a parallel degree computation and is therefore staying with the serial execution. Now we go into the land of crazy: Assume I do want this DOP=1 to happen, I could set the parameter in the init.ora, but to highlight it in this case I changed it on the session: alter session set parallel_degree_limit = 1; The result I get is: ERROR: ORA-02097: parameter cannot be modified because specified value is invalid ORA-00096: invalid value 1 for parameter parallel_degree_limit, must be from among CPU IO AUTO INTEGER>=2 Which of course makes perfect sense...

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  • Surviving MATLAB and R as a Hardcore Programmer

    - by dsimcha
    I love programming in languages that seem geared towards hardcore programmers. (My favorites are Python and D.) MATLAB is geared towards engineers and R is geared towards statisticians, and it seems like these languages were designed by people who aren't hardcore programmers and don't think like hardcore programmers. I always find them somewhat awkward to use, and to some extent I can't put my finger on why. Here are some issues I have managed to identify: (Both): The extreme emphasis on vectors and matrices to the extent that there are no true primitives. (Both): The difficulty of basic string manipulation. (Both): Lack of or awkwardness in support for basic data structures like hash tables and "real", i.e. type-parametric and nestable, arrays. (Both): They're really, really slow even by interpreted language standards, unless you bend over backwards to vectorize your code. (Both): They seem to not be designed to interact with the outside world. For example, both are fairly bulky programs that take a while to launch and seem to not be designed to make simple text filter programs easy to write. Furthermore, the lack of good string processing makes file I/O in anything but very standard forms near impossible. (Both): Object orientation seems to have a very bolted-on feel. Yes, you can do it, but it doesn't feel much more idiomatic than OO in C. (Both): No obvious, simple way to get a reference type. No pointers or class references. For example, I have no idea how you roll your own linked list in either of these languages. (MATLAB): You can't put multiple top level functions in a single file, encouraging very long functions and cut-and-paste coding. (MATLAB): Integers apparently don't exist as a first class type. (R): The basic builtin data structures seem way too high level and poorly documented, and never seem to do quite what I expect given my experience with similar but lower level data structures. (R): The documentation is spread all over the place and virtually impossible to browse or search. Even D, which is often knocked for bad documentation and is still fairly alpha-ish, is substantially better as far as I can tell. (R): At least as far as I'm aware, there's no good IDE for it. Again, even D, a fairly alpha-ish language with a small community, does better. In general, I also feel like MATLAB and R could be easily replaced by plain old libraries in more general-purpose langauges, if sufficiently comprehensive libraries existed. This is especially true in newer general purpose languages that include lots of features for library writers. Why do R and MATLAB seem so weird to me? Are there any other major issues that you've noticed that may make these languages come off as strange to hardcore programmers? When their use is necessary, what are some good survival tips? Edit: I'm seeing one issue from some of the answers I've gotten. I have a strong personal preference, when I analyze data, to have one script that incorporates the whole pipeline. This implies that a general purpose language needs to be used. I hate having to write a script to "clean up" the data and spit it out, then another to read it back in a completely different environment, etc. I find the friction of using MATLAB/R for some of my work and a completely different language with a completely different address space and way of thinking for the rest to be a huge source of friction. Furthermore, I know there are glue layers that exist, but they always seem to be horribly complicated and a source of friction.

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  • Project Euler 17: (Iron)Python

    - by Ben Griswold
    In my attempt to learn (Iron)Python out in the open, here’s my solution for Project Euler Problem 17.  As always, any feedback is welcome. # Euler 17 # http://projecteuler.net/index.php?section=problems&id=17 # If the numbers 1 to 5 are written out in words: # one, two, three, four, five, then there are # 3 + 3 + 5 + 4 + 4 = 19 letters used in total. # If all the numbers from 1 to 1000 (one thousand) # inclusive were written out in words, how many letters # would be used? # # NOTE: Do not count spaces or hyphens. For example, 342 # (three hundred and forty-two) contains 23 letters and # 115 (one hundred and fifteen) contains 20 letters. The # use of "and" when writing out numbers is in compliance # with British usage. import time start = time.time() def to_word(n): h = { 1 : "one", 2 : "two", 3 : "three", 4 : "four", 5 : "five", 6 : "six", 7 : "seven", 8 : "eight", 9 : "nine", 10 : "ten", 11 : "eleven", 12 : "twelve", 13 : "thirteen", 14 : "fourteen", 15 : "fifteen", 16 : "sixteen", 17 : "seventeen", 18 : "eighteen", 19 : "nineteen", 20 : "twenty", 30 : "thirty", 40 : "forty", 50 : "fifty", 60 : "sixty", 70 : "seventy", 80 : "eighty", 90 : "ninety", 100 : "hundred", 1000 : "thousand" } word = "" # Reverse the numbers so position (ones, tens, # hundreds,...) can be easily determined a = [int(x) for x in str(n)[::-1]] # Thousands position if (len(a) == 4 and a[3] != 0): # This can only be one thousand based # on the problem/method constraints word = h[a[3]] + " thousand " # Hundreds position if (len(a) >= 3 and a[2] != 0): word += h[a[2]] + " hundred" # Add "and" string if the tens or ones # position is occupied with a non-zero value. # Note: routine is broken up this way for [my] clarity. if (len(a) >= 2 and a[1] != 0): # catch 10 - 99 word += " and" elif len(a) >= 1 and a[0] != 0: # catch 1 - 9 word += " and" # Tens and ones position tens_position_value = 99 if (len(a) >= 2 and a[1] != 0): # Calculate the tens position value per the # first and second element in array # e.g. (8 * 10) + 1 = 81 tens_position_value = int(a[1]) * 10 + a[0] if tens_position_value <= 20: # If the tens position value is 20 or less # there's an entry in the hash. Use it and there's # no need to consider the ones position word += " " + h[tens_position_value] else: # Determine the tens position word by # dividing by 10 first. E.g. 8 * 10 = h[80] # We will pick up the ones position word later in # the next part of the routine word += " " + h[(a[1] * 10)] if (len(a) >= 1 and a[0] != 0 and tens_position_value > 20): # Deal with ones position where tens position is # greater than 20 or we have a single digit number word += " " + h[a[0]] # Trim the empty spaces off both ends of the string return word.replace(" ","") def to_word_length(n): return len(to_word(n)) print sum([to_word_length(i) for i in xrange(1,1001)]) print "Elapsed Time:", (time.time() - start) * 1000, "millisecs" a=raw_input('Press return to continue')

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  • How to Make the Gnome Panels in Ubuntu Totally Transparent

    - by The Geek
    We all love transparency, since it makes your desktop so beautiful and lovely—so today we’re going to show you how to apply transparency to the panels in your Ubuntu Gnome setup. It’s an easy process, and here’s how to do it. This article is the first part of a multi-part series on how to customize the Ubuntu desktop, written by How-To Geek reader and ubergeek, Omar Hafiz. Making the Gnome Panels Transparent Of course we all love transparency, It makes your desktop so beautiful and lovely. So you go for enabling transparency in your panels , you right click on your panel, choose properties, go to the Background tab and make your panel transparent. Easy right? But instead of getting a lovely transparent panel, you often get a cluttered, ugly panel like this: Fortunately it can be easily fixed, all we need to do is to edit the theme files. If your theme is one of those themes that came with Ubuntu like Ambiance then you’ll have to copy it from /usr/share/themes to your own .themes directory in your Home Folder. You can do so by typing the following command in the terminal cp /usr/share/themes/theme_name ~/.themes Note: don’t forget to substitute theme_name with the theme name you want to fix. But if your theme is one you downloaded then it is already in your .themes folder. Now open your file manager and navigate to your home folder then do to .themes folder. If you can’t see it then you probably have disabled the “View hidden files” option. Press Ctrl+H to enable it. Now in .themes you’ll find your previously copied theme folder there, enter it then go to gtk-2.0 folder. There you may find a file named “panel.rc”, which is a configuration file that tells your panel how it should look like. If you find it there then rename it to “panel.rc.bak”. If you don’t find don’t panic! There’s nothing wrong with your system, it’s just that your theme decided to put the panel configurations in the “gtkrc” file. Open this file with your favorite text editor and at the end of the file there is line that looks like this “include “apps/gnome-panel.rc””. Comment out this line by putting a hash mark # in front of it. Now it should look like this “# include “apps/gnome-panel.rc”” Save and exit the text editor. Now change your theme to any other one then switch back to the one you edited. Now your panel should look like this: Stay tuned for the second part in the series, where we’ll cover how to change the color and fonts on your panels. Latest Features How-To Geek ETC How To Remove People and Objects From Photographs In Photoshop Ask How-To Geek: How Can I Monitor My Bandwidth Usage? Internet Explorer 9 RC Now Available: Here’s the Most Interesting New Stuff Here’s a Super Simple Trick to Defeating Fake Anti-Virus Malware How to Change the Default Application for Android Tasks Stop Believing TV’s Lies: The Real Truth About "Enhancing" Images The Legend of Zelda – 1980s High School Style [Video] Suspended Sentence is a Free Cross-Platform Point and Click Game Build a Batman-Style Hidden Bust Switch Make Your Clock Creates a Custom Clock for your Android Homescreen Download the Anime Angels Theme for Windows 7 CyanogenMod Updates; Rolls out Android 2.3 to the Less Fortunate

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  • JavaOne Latin America Opening Keynotes

    - by Tori Wieldt
    Originally published on blogs.oracle.com/javaone It was a great first day at JavaOne Brazil, which included the Java Strategy and Java Technical keynotes. Henrik Stahl, Senior Director, Product Management for Java opened the keynotes by saying that this is the third year for JavaOne Latin America. He explained, "You know what they say, the first time doesn't count, the second time is a habit and the third time it's a tradition!" He mentioned that he was thrilled that this is largest JavaOne in Brazil to date, and he wants next year to be larger. He said that Oracle knows Latin America is an important hub for development.  "We continually come back to Latin America because of the dedication the community has with driving the continued innovation for Java," he said. Stahl explained that Oracle and the Java community must continue to innovate and Make the Future Java together. The success of Java depends on three important factors: technological innovation, Oracle as a strong steward of Java, and community participation. "The Latin American Java Community (especially in Brazil) is a shining example of how to be positive contributor to Java," Stahl said. Next, George Saab, VP software dev, Java Platform Group at Oracle, discussed some of the recent and upcoming changes to Java. "In addition to the incremental improvements to Java 7, we have also increased the set of platforms supported by Oracle from Linux, Windows, and Solaris to now also include Mac OS X and Linux/ARM for ARM-based PCs such as the Raspberry Pi and emerging ARM based microservers."  Saab announced that EA builds for Linux ARM Hard Float ABI will be available by the end of the year.  Staffan Friberg, Product Manager, Java Platform Group, provided an overview of some of the language coming in Java 8, including Lambda, remove of PermGen, improved data and time APIs and improved security, Java 8 development is moving along. He reminded the audience that they can go to OpenJDK to see this development being done in real-time, and that there are weekly early access builds of OracleJDK 8 that developers can download and try today. Judson Althoff, Senior Vice President, Worldwide Alliances and Channels and Embedded Sales, was invited to the stage, and the audience was told that "even though he is wearing a suit, he is still pretty technical." Althoff started off with a bang: "The Internet of Things is on a collision course with big data and this is a huge opportunity for developers."  For example, Althoff said, today cars are more a data device than a mechanical device. A car embedded with sensors for fuel efficiency, temperature, tire pressure, etc. can generate a petabyte of data A DAY. There are similar examples in healthcare (patient monitoring and privacy requirements creates a complex data problem) and transportation management (sending a package around the world with sensors for humidity, temperature and light). Althoff then brought on stage representatives from three companies that are successful with Java today, first Axel Hansmann, VP Strategy & Marketing Communications, Cinterion. Mr. Hansmann explained that Cinterion, a market leader in Latin America, enables M2M services with Java. At JavaOne San Francisco, Cinterion launched the EHS5, the smallest 3g solderable module, with Java installed on it. This provides Original Equipment Manufacturers (OEMs) with a cost effective, flexible platform for bringing advanced M2M technology to market.Next, Steve Nelson, Director of Marketing for the Americas, at Freescale explained that Freescale is #1 in Embedded Processors in Wired and Wireless Communications, and #1 in Automotive Semiconductors in the Americas. He said that Java provides a mature, proven platform that is uniquely suited to meet the requirements of almost any type of embedded device. He encouraged University students to get involved in the Freescale Cup, a global competition where student teams build, program, and race a model car around a track for speed.Roberto Franco, SBTVD Forum President, SBTVD, talked about Ginga, a Java-based standard for television in Brazil. He said there are 4 million Ginga TV sets in Brazil, and they expect over 20 million TV sets to be sold by the end of 2014. Ginga is also being adopted in other 11 countries in Latin America. Ginga brings interactive services not only at TV set, but also on other devices such as tablets,  PCs or smartphones, as the main or second screen. "Interactive services is already a reality," he said, ' but in a near future, we foresee interactivity enhanced TV content, convergence with OTT services and a big participation from the audience,  all integrated on TV, tablets, smartphones and second screen devices."Before he left the stage, Nandini Ramani thanked Judson for being part of the Java community and invited him to the next Geek Bike Ride in Brazil. She presented him an official geek bike ride jersey.For the Technical Keynote, a "blue screen of death" appeared. With mock concern, Stephin Chin asked the rest of the presenters if they could go on without slides. What followed was a interesting collection of demos, including JavaFX on a tablet, a look at Project Easel in NetBeans, and even Simon Ritter controlling legos with his brainwaves! Stay tuned for more dispatches.

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  • JavaOne Latin America Opening Keynotes

    - by Tori Wieldt
    It was a great first day at JavaOne Brazil, which included the Java Strategy and Java Technical keynotes. Henrik Stahl, Senior Director, Product Management for Java opened the keynotes by saying that this is the third year for JavaOne Latin America. He explained, "You know what they say, the first time doesn't count, the second time is a habit and the third time it's a tradition!" He mentioned that he was thrilled that this is largest JavaOne in Brazil to date, and he wants next year to be larger. He said that Oracle knows Latin America is an important hub for development.  "We continually come back to Latin America because of the dedication the community has with driving the continued innovation for Java," he said. Stahl explained that Oracle and the Java community must continue to innovate and Make the Future Java together. The success of Java depends on three important factors: technological innovation, Oracle as a strong steward of Java, and community participation. "The Latin American Java Community (especially in Brazil) is a shining example of how to be positive contributor to Java," Stahl said. Next, George Saab, VP software dev, Java Platform Group at Oracle, discussed some of the recent and upcoming changes to Java. "In addition to the incremental improvements to Java 7, we have also increased the set of platforms supported by Oracle from Linux, Windows, and Solaris to now also include Mac OS X and Linux/ARM for ARM-based PCs such as the Raspberry Pi and emerging ARM based microservers."  Saab announced that EA builds for Linux ARM Hard Float ABI will be available by the end of the year.  Staffan Friberg, Product Manager, Java Platform Group, provided an overview of some of the language coming in Java 8, including Lambda, remove of PermGen, improved data and time APIs and improved security, Java 8 development is moving along. He reminded the audience that they can go to OpenJDK to see this development being done in real-time, and that there are weekly early access builds of OracleJDK 8 that developers can download and try today. Judson Althoff, Senior Vice President, Worldwide Alliances and Channels and Embedded Sales, was invited to the stage, and the audience was told that "even though he is wearing a suit, he is still pretty technical." Althoff started off with a bang: "The Internet of Things is on a collision course with big data and this is a huge opportunity for developers."  For example, Althoff said, today cars are more a data device than a mechanical device. A car embedded with sensors for fuel efficiency, temperature, tire pressure, etc. can generate a petabyte of data A DAY. There are similar examples in healthcare (patient monitoring and privacy requirements creates a complex data problem) and transportation management (sending a package around the world with sensors for humidity, temperature and light). Althoff then brought on stage representatives from three companies that are successful with Java today, first Axel Hansmann, VP Strategy & Marketing Communications, Cinterion. Mr. Hansmann explained that Cinterion, a market leader in Latin America, enables M2M services with Java. At JavaOne San Francisco, Cinterion launched the EHS5, the smallest 3g solderable module, with Java installed on it. This provides Original Equipment Manufacturers (OEMs) with a cost effective, flexible platform for bringing advanced M2M technology to market.Next, Steve Nelson, Director of Marketing for the Americas, at Freescale explained that Freescale is #1 in Embedded Processors in Wired and Wireless Communications, and #1 in Automotive Semiconductors in the Americas. He said that Java provides a mature, proven platform that is uniquely suited to meet the requirements of almost any type of embedded device. He encouraged University students to get involved in the Freescale Cup, a global competition where student teams build, program, and race a model car around a track for speed.Roberto Franco, SBTVD Forum President, SBTVD, talked about Ginga, a Java-based standard for television in Brazil. He said there are 4 million Ginga TV sets in Brazil, and they expect over 20 million TV sets to be sold by the end of 2014. Ginga is also being adopted in other 11 countries in Latin America. Ginga brings interactive services not only at TV set, but also on other devices such as tablets,  PCs or smartphones, as the main or second screen. "Interactive services is already a reality," he said, ' but in a near future, we foresee interactivity enhanced TV content, convergence with OTT services and a big participation from the audience,  all integrated on TV, tablets, smartphones and second screen devices."Before he left the stage, Nandini Ramani thanked Judson for being part of the Java community and invited him to the next Geek Bike Ride in Brazil. She presented him an official geek bike ride jersey.For the Technical Keynote, a "blue screen of death" appeared. With mock concern, Stephin Chin asked the rest of the presenters if they could go on without slides. What followed was a interesting collection of demos, including JavaFX on a tablet, a look at Project Easel in NetBeans, and even Simon Ritter controlling legos with his brainwaves! Stay tuned for more dispatches.

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  • Computer Networks UNISA - Chap 8 &ndash; Wireless Networking

    - by MarkPearl
    After reading this section you should be able to Explain how nodes exchange wireless signals Identify potential obstacles to successful transmission and their repercussions, such as interference and reflection Understand WLAN architecture Specify the characteristics of popular WLAN transmission methods including 802.11 a/b/g/n Install and configure wireless access points and their clients Describe wireless MAN and WAN technologies, including 802.16 and satellite communications The Wireless Spectrum All wireless signals are carried through the air by electromagnetic waves. The wireless spectrum is a continuum of the electromagnetic waves used for data and voice communication. The wireless spectrum falls between 9KHZ and 300 GHZ. Characteristics of Wireless Transmission Antennas Each type of wireless service requires an antenna specifically designed for that service. The service’s specification determine the antenna’s power output, frequency, and radiation pattern. A directional antenna issues wireless signals along a single direction. An omnidirectional antenna issues and receives wireless signals with equal strength and clarity in all directions The geographical area that an antenna or wireless system can reach is known as its range Signal Propagation LOS (line of sight) uses the least amount of energy and results in the reception of the clearest possible signal. When there is an obstacle in the way, the signal may… pass through the object or be obsrobed by the object or may be subject to reflection, diffraction or scattering. Reflection – waves encounter an object and bounces off it. Diffraction – signal splits into secondary waves when it encounters an obstruction Scattering – is the diffusion or the reflection in multiple different directions of a signal Signal Degradation Fading occurs as a signal hits various objects. Because of fading, the strength of the signal that reaches the receiver is lower than the transmitted signal strength. The further a signal moves from its source, the weaker it gets (this is called attenuation) Signals are also affected by noise – the electromagnetic interference) Interference can distort and weaken a wireless signal in the same way that noise distorts and weakens a wired signal. Frequency Ranges Older wireless devices used the 2.4 GHZ band to send and receive signals. This had 11 communication channels that are unlicensed. Newer wireless devices can also use the 5 GHZ band which has 24 unlicensed bands Narrowband, Broadband, and Spread Spectrum Signals Narrowband – a transmitter concentrates the signal energy at a single frequency or in a very small range of frequencies Broadband – uses a relatively wide band of the wireless spectrum and offers higher throughputs than narrowband technologies The use of multiple frequencies to transmit a signal is known as spread-spectrum technology. In other words a signal never stays continuously within one frequency range during its transmission. One specific implementation of spread spectrum is FHSS (frequency hoping spread spectrum). Another type is known as DSS (direct sequence spread spectrum) Fixed vs. Mobile Each type of wireless communication falls into one of two categories Fixed – the location of the transmitted and receiver do not move (results in energy saved because weaker signal strength is possible with directional antennas) Mobile – the location can change WLAN (Wireless LAN) Architecture There are two main types of arrangements Adhoc – data is sent directly between devices – good for small local devices Infrastructure mode – a wireless access point is placed centrally, that all devices connect with 802.11 WLANs The most popular wireless standards used on contemporary LANs are those developed by IEEE’s 802.11 committee. Over the years several distinct standards related to wireless networking have been released. Four of the best known standards are also referred to as Wi-Fi. They are…. 802.11b 802.11a 802.11g 802.11n These four standards share many characteristics. i.e. All 4 use half duplex signalling Follow the same access method Access Method 802.11 standards specify the use of CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) to access a shared medium. Using CSMA/CA before a station begins to send data on an 802.11 network, it checks for existing wireless transmissions. If the source node detects no transmission activity on the network, it waits a brief period of time and then sends its transmission. If the source does detect activity, it waits a brief period of time before checking again. The destination node receives the transmission and, after verifying its accuracy, issues an acknowledgement (ACT) packet to the source. If the source receives the ACK it assumes the transmission was successful, – if it does not receive an ACK it assumes the transmission failed and sends it again. Association Two types of scanning… Active – station transmits a special frame, known as a prove, on all available channels within its frequency range. When an access point finds the probe frame, it issues a probe response. Passive – wireless station listens on all channels within its frequency range for a special signal, known as a beacon frame, issued from an access point – the beacon frame contains information necessary to connect to the point. Re-association occurs when a mobile user moves out of one access point’s range and into the range of another. Frames Read page 378 – 381 about frames and specific 802.11 protocols Bluetooth Networks Sony Ericson originally invented the Bluetooth technology in the early 1990s. In 1998 other manufacturers joined Ericsson in the Special Interest Group (SIG) whose aim was to refine and standardize the technology. Bluetooth was designed to be used on small networks composed of personal communications devices. It has become popular wireless technology for communicating among cellular telephones, phone headsets, etc. Wireless WANs and Internet Access Refer to pages 396 – 402 of the textbook for details.

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