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  • Wandering CGAffineTransformMakeRotation

    - by Joe
    Okay this is about to make me insane -- any help would be appreciated. I have two images which are part of a timer application. One is the needle/hand and the other is a little hub which is styled to look like the needle base. I'm using a CGAffineTransformMakeRotation to rotate the needle and the base stays stationary. The problem: there is like a 1-2px 'wander' to the needle's rotation which makes it look like it's moving off center in relation to the base. I have worked the base and needle image over in PS extensively, and both are dead center pixel wise -- seriously. My method to rotate the hand: -(IBAction) rotateSteamArrow{ CGAffineTransform rotate = CGAffineTransformMakeRotation( degreesSteam / 180.0 * 3.14159265); degreesSteam = degreesSteam + 1.5; if (degreesSteam <= 180) { [steamNeedle setTransform:rotate]; } else { [self handleSteamTimer]; [self toggleButton:(id)timerButton]; [self switchSound]; } }

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  • putpixel with pyglet

    - by pts
    I'm new to pyglet. I'd like to change a pixel from black to white at each on_draw iteration. So after 1000 iterations, there should be exactly 1000 white pixels in the window. However, I'd like to avoid calling 1000 draw operations in on_draw for that. So I'd like to create an image, do an RGB putpixel on the image, and blit the image to the screen. How can I do that? The pyglet documentation, the examples and the source code aren't too helpful on this.

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  • UISearchBar and UINavigationController

    - by Calvin L
    I have an .xib file connected to a ViewController, which is init'ed as the root controller of an instance of UINavigationController in my appDelegate. In that view, I have a UISearchBar and a UITableView below it. When the view loads up, there's a navigationBar at the top, followed by a ~20 pixel gap, and then the UISearchBar, and the table beneath it: My problem is that when I enter the UISearchBar to type something, the navigation bar disappears (which is fine), but the search box is all screwy: I'm pretty new to this (a couple of weeks), so I'm not quite sure what's going on. Can anyone help me shed some light on this?

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  • Matlab - plot multiple data sets on a scatter plot

    - by Mark
    Hey all, I have 2 sets of data (Ax, Ay; Bx, By) - I'd like to plot both of these data sets on a scatter plot with different colors, but can't seem to get it to work because it seems scatter() does not work like plot(). Is it possible to do this? I've tried... scatter(Ax, Ay, 'g', Bx, By, 'b') And scatter(Ax, Ay, 'g') scatter(Bx, By, 'b') The first way returns an error. The latter only plots the Bx/By data. Many thanks!

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  • Using NHibernate with an EAV data model

    - by devonlazarus
    I'm trying to leverage NH to map to a data model that is a loose interpretation of the EAV/CR data model. I have most of it working but am struggling with mapping the Entity.Attributes collection. Here are the tables in question: -------------------- | Entities | -------------------- | EntityId PK |-| | EntityType | | -------------------- | ------------- | V -------------------- | EntityAttributes | ------------------ --------------------------- -------------------- | Attributes | | StringAttributes | | EntityId PK,FK | ------------------ --------------------------- | AttributeId FK | -> | AttributeId PK | -> | StringAttributeId PK,FK | | AttributeValue | | AttributeType | | AttributeName | -------------------- ------------------ --------------------------- The AttributeValue column is implemented as an sql_variant column and I've implemented an NHibernate.UserTypes.IUserType for it. I can create an EntityAttribute entity and persist it directly so that part of the hierarchy is working. I'm just not sure how to map the EntityAttributes collection to the Entity entity. Note the EntityAttributes table could (and does) contain multiple rows for a given EntityId/AttributeId combination: EntityId AttributeId AttributeValue -------- ----------- -------------- 1 1 Blue 1 1 Green StringAttributes row looks like this for this example: StringAttributeId AttributeName ----------------- -------------- 1 FavoriteColor How can I effectively map this data model to my Entity domain such that Entity.Attributes("FavoriteColors") returns a collection of favorite colors? Typed as System.String?

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  • Objective-C RGB to HSB

    - by Johannes Jensen
    Let's say I've got the colour FF0000, which is red. Finding a darker colour is easy, I just type maybe CC instead of the FF, but let's say I've got the colour AE83FC, which is a complicated colour, how the heck would I find a lighter or darker version of it automatically? I figured the easy way to do this is to convert my RGB to HSB [Hue, Saturation, Brightness] How would I do that in Objective-C? Let's say I've got a RGB which is: 1.0, 0.0, 0.0. That's red. CGFloat r = 1.0; CGFloat g = 0.0; CGfloat b = 0.0; How would I convert that to HSB and then transform the colors and make it go back to RGB to I can use CGContextRGBSetFillColor? Are there any HSB functions? Please help. :)

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  • CGBitmapContextCreate: unsupported parameter combination

    - by tarmes
    I'm getting this error when creating a bitmap context: CGBitmapContextCreate: unsupported parameter combination: 8 integer bits/component; 24 bits/pixel; 3-component color space; kCGImageAlphaNone; 7936 bytes/row. Here's the code (note that the context is based on the parameters of an existing CGImage: context = CGBitmapContextCreate(NULL, (int)pi.bufferSizeRequired.width, (int)pi.bufferSizeRequired.height, CGImageGetBitsPerComponent(imageRef), 0, CGImageGetColorSpace(imageRef), CGImageGetBitmapInfo(imageRef)); Width is 2626, height is 3981. I've leaving bytesPerRow at zero so that it gets calculated automatically for me, and it's chosen 7936 of its own accord. So, where on Earth is the inconsistency? It's driving me nuts.

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  • Jpeg calculating max size

    - by Doodle
    I have to say the I don't know much about how file formats work. My question is say I have a jpeg file that is 200 px by 200 px, how can one calculate what the maximum size that file could be in terms of megabytes/bytes? I think that the reasoning that led to the question will help some one answer me. I have a Java Applet the uploads Images that people draw with it to my server. I need to know what the max size that this file can conceivably reach. It is always going to be 200x200. It sounds dumb but are there colors that take more byte size then others and if so what is the most expensive one?

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  • glTexImage2D behavior on iPhone and other OpenGL ES platforms

    - by spurserh
    Hello, I am doing some work which involves drawing video frames in real time in OpenGL ES. Right now I am using glTexImage2D to transfer the data, in the absence of Pixel Buffer Objects and the like. I suspect that the use of glTexImage2D with one or two frames of look-ahead, that is, using several textures so that the glTexImage2D call can be initiated a frame or two ahead, will allow for sufficient parallelism to play in real time if the system is capable of it at all. Is my assumption true that the driver will handle the actual data transfer to the hardware asynchronously after glTexImage2D returns, assuming I don't try to use the texture or call glFinish/glFlush? Is there a better way to do this with OpenGL ES? Thank you very much, Sean

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  • How create UIImage from bytes ?

    - by Sergey
    Hello, all! I need in UIImage created from my colors (for example, i need in image 1x1 pixel with black color). I've got array: unsigned char *color[] = {0, 0, 0, 1}; How can i create UIImage from this array ? I've try unsigned char *bytes[4] = {0,0,0,1}; NSData *data = [NSData dataWithBytes:bytes length:4]; UIImage *img = [UIImage imageWithData:data]; but this method has no result...

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  • Why Does .Hide()ing and .Show()ing Panels in wxPython Result in the Sizer Changing the Layout?

    - by MetaHyperBolic
    As referenced in my previous question, I am trying to make something slightly wizard-like in function. I have settled on a single frame with a sizer added to it. I build panels for each of the screens I would like users to see, add them to the frame's sizer, then switch between panels by .Hide()ing one panel, then calling a custom .ShowYourself() on the next panel. Obviously, I would like the buttons to remain in the same place as the user progresses through the process. I have linked together two panels in an infinite loop by their "Back" and "Next" buttons so you can see what is going on. The first panel looks great; tom10's code worked on that level, as it eschewed my initial, over-fancy attempt with borders flying every which way. And then the second panel seems to have shrunk down to the bare minimum. As we return to the first panel, the shrinkage has occurred here as well. Why does it look fine on the first panel, but not after I return there? Why is calling .Fit() necessary if I do not want a 10 pixel by 10 pixel wad of grey? And if it is necessary, why does .Fit() give inconsistent results? This infinite loop seems to characterize my experience with this: I fix the layout on a panel, only to find that switching ruins the layout for other panels. I fix that problem, by using sizer_h.Add(self.panel1, 0) instead of sizer_h.Add(self.panel1, 1, wx.EXPAND), and now my layouts are off again. So far, my "solution" is to add a mastersizer.SetMinSize((475, 592)) to each panel's master sizer (commented out in the code below). This is a cruddy solution because 1) I have had to find the numbers that work by trial and error (-5 pixels for the width, -28 pixels for the height). 2) I don't understand why the underlying issue still happens. What's the correct, non-ugly solution? Instead of adding all of the panels to the frame's sizer at once, should switching panels involve .Detach()ing that panel from the frame's sizer and then .Add()ing the next panel to the frame's sizer? Is there a .JustMakeThisFillThePanel() method hiding somewhere I have missed in both the wxWidgets and the wxPython documents online? I'm obviously missing something in my mental model of layout. Here's a TinyURL link, if I can't manage to embed the . Minimalist code pasted below. import wx import sys class My_App(wx.App): def OnInit(self): self.frame = My_Frame(None) self.frame.Show() self.SetTopWindow(self.frame) return True def OnExit(self): print 'Dying ...' class My_Frame(wx.Frame): def __init__(self, image, parent=None,id=-1, title='Generic Title', pos=wx.DefaultPosition, style=wx.CAPTION | wx.STAY_ON_TOP): size = (480, 620) wx.Frame.__init__(self, parent, id, 'Program Title', pos, size, style) sizer_h = wx.BoxSizer(wx.HORIZONTAL) self.panel0 = User_Interaction0(self) sizer_h.Add(self.panel0, 1, wx.EXPAND) self.panel1 = User_Interaction1(self) sizer_h.Add(self.panel1, 1, wx.EXPAND) self.SetSizer(sizer_h) self.panel0.ShowYourself() def ShutDown(self): self.Destroy() class User_Interaction0(wx.Panel): def __init__(self, parent, id=-1): wx.Panel.__init__(self, parent, id) # master sizer for the whole panel mastersizer = wx.BoxSizer(wx.VERTICAL) #mastersizer.SetMinSize((475, 592)) mastersizer.AddSpacer(15) # build the top row txtHeader = wx.StaticText(self, -1, 'Welcome to This Boring\nProgram', (0, 0)) font = wx.Font(16, wx.DEFAULT, wx.NORMAL, wx.BOLD) txtHeader.SetFont(font) txtOutOf = wx.StaticText(self, -1, '1 out of 7', (0, 0)) rowtopsizer = wx.BoxSizer(wx.HORIZONTAL) rowtopsizer.Add(txtHeader, 3, wx.ALIGN_LEFT) rowtopsizer.Add((0,0), 1) rowtopsizer.Add(txtOutOf, 0, wx.ALIGN_RIGHT) mastersizer.Add(rowtopsizer, 0, flag=wx.EXPAND | wx.LEFT | wx.RIGHT, border=15) # build the middle row text = 'PANEL 0\n\n' text = text + 'This could be a giant blob of explanatory text.\n' txtBasic = wx.StaticText(self, -1, text) font = wx.Font(11, wx.DEFAULT, wx.NORMAL, wx.NORMAL) txtBasic.SetFont(font) mastersizer.Add(txtBasic, 1, flag=wx.EXPAND | wx.LEFT | wx.RIGHT, border=15) # build the bottom row btnBack = wx.Button(self, -1, 'Back') self.Bind(wx.EVT_BUTTON, self.OnBack, id=btnBack.GetId()) btnNext = wx.Button(self, -1, 'Next') self.Bind(wx.EVT_BUTTON, self.OnNext, id=btnNext.GetId()) btnCancelExit = wx.Button(self, -1, 'Cancel and Exit') self.Bind(wx.EVT_BUTTON, self.OnCancelAndExit, id=btnCancelExit.GetId()) rowbottomsizer = wx.BoxSizer(wx.HORIZONTAL) rowbottomsizer.Add(btnBack, 0, wx.ALIGN_LEFT) rowbottomsizer.AddSpacer(5) rowbottomsizer.Add(btnNext, 0) rowbottomsizer.AddSpacer(5) rowbottomsizer.AddStretchSpacer(1) rowbottomsizer.Add(btnCancelExit, 0, wx.ALIGN_RIGHT) mastersizer.Add(rowbottomsizer, flag=wx.EXPAND | wx.LEFT | wx.RIGHT, border=15) # finish master sizer mastersizer.AddSpacer(15) self.SetSizer(mastersizer) self.Raise() self.SetPosition((0,0)) self.Fit() self.Hide() def ShowYourself(self): self.Raise() self.SetPosition((0,0)) self.Fit() self.Show() def OnBack(self, event): self.Hide() self.GetParent().panel1.ShowYourself() def OnNext(self, event): self.Hide() self.GetParent().panel1.ShowYourself() def OnCancelAndExit(self, event): self.GetParent().ShutDown() class User_Interaction1(wx.Panel): def __init__(self, parent, id=-1): wx.Panel.__init__(self, parent, id) # master sizer for the whole panel mastersizer = wx.BoxSizer(wx.VERTICAL) #mastersizer.SetMinSize((475, 592)) mastersizer.AddSpacer(15) # build the top row txtHeader = wx.StaticText(self, -1, 'Read about This Boring\nProgram', (0, 0)) font = wx.Font(16, wx.DEFAULT, wx.NORMAL, wx.BOLD) txtHeader.SetFont(font) txtOutOf = wx.StaticText(self, -1, '2 out of 7', (0, 0)) rowtopsizer = wx.BoxSizer(wx.HORIZONTAL) rowtopsizer.Add(txtHeader, 3, wx.ALIGN_LEFT) rowtopsizer.Add((0,0), 1) rowtopsizer.Add(txtOutOf, 0, wx.ALIGN_RIGHT) mastersizer.Add(rowtopsizer, 0, flag=wx.EXPAND | wx.LEFT | wx.RIGHT, border=15) # build the middle row text = 'PANEL 1\n\n' text = text + 'This could be a giant blob of boring text.\n' txtBasic = wx.StaticText(self, -1, text) font = wx.Font(11, wx.DEFAULT, wx.NORMAL, wx.NORMAL) txtBasic.SetFont(font) mastersizer.Add(txtBasic, 1, flag=wx.EXPAND | wx.LEFT | wx.RIGHT, border=15) # build the bottom row btnBack = wx.Button(self, -1, 'Back') self.Bind(wx.EVT_BUTTON, self.OnBack, id=btnBack.GetId()) btnNext = wx.Button(self, -1, 'Next') self.Bind(wx.EVT_BUTTON, self.OnNext, id=btnNext.GetId()) btnCancelExit = wx.Button(self, -1, 'Cancel and Exit') self.Bind(wx.EVT_BUTTON, self.OnCancelAndExit, id=btnCancelExit.GetId()) rowbottomsizer = wx.BoxSizer(wx.HORIZONTAL) rowbottomsizer.Add(btnBack, 0, wx.ALIGN_LEFT) rowbottomsizer.AddSpacer(5) rowbottomsizer.Add(btnNext, 0) rowbottomsizer.AddSpacer(5) rowbottomsizer.AddStretchSpacer(1) rowbottomsizer.Add(btnCancelExit, 0, wx.ALIGN_RIGHT) mastersizer.Add(rowbottomsizer, flag=wx.EXPAND | wx.LEFT | wx.RIGHT, border=15) # finish master sizer mastersizer.AddSpacer(15) self.SetSizer(mastersizer) self.Raise() self.SetPosition((0,0)) self.Fit() self.Hide() def ShowYourself(self): self.Raise() self.SetPosition((0,0)) self.Fit() self.Show() def OnBack(self, event): self.Hide() self.GetParent().panel0.ShowYourself() def OnNext(self, event): self.Hide() self.GetParent().panel0.ShowYourself() def OnCancelAndExit(self, event): self.GetParent().ShutDown() def main(): app = My_App(redirect = False) app.MainLoop() if __name__ == '__main__': main()

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  • Format of compiled directx9 shader files?

    - by JB
    Is the format of compiled pixel and vertex shader object files as produced by fxc.exe documented anywhere either officially or unofficially? I'd like to be able to read the constant name to register assignments from the shader files. I know that the effects framework in D3DX can do this, but I need to avoid using D3DX as it may not be installed on user's machines and I don't need it for anything else so I want to avoid them having to run the directx update. If the effects framework can do it, then so can I if I can find out the file format but I can' seem to find it documented anywhere.

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  • OpenCL or OpenGL – which one to use?

    - by Malte Schledjewski
    My Problem involves a black and white image with a black area in the middle. I never worked with OpenGL or OpenCL before so I do not know which one to chose. I want to put some white circles over the area and check at the end whether the whole image is white. I will try many combinations so I want to use the GPU because of its parallelism. Should I use OpenGL and create the circle as a texture and put it on top of the image or should I write some OpenCL kernels which work on the pixel/entries in the matrix?

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  • XHTML / CSS help?

    - by Chris Leah
    Basically on GunChester my project I have an few pixel wide gap between #login_top (top image holder) and the 3 CSS col's below, #login_left, #login_centre and #login_right so that my first question why? and how can I fix this, this is in FF, Chrome and IE. Secondly the BG image seems to be overlaying twice as in its stretched at the top then the full picture does display as it should. I did have it working but when trying to fix the pixel gap I must of messed something up but no idea what, so it is now going pear shape, lease help with both these situations :)? Css below: @charset "utf-8"; /* Autoher: Chris Leah Date: 20/04/2010 (C) GunChester.net / Chris Leah HTML and Body CSS */ html, body { background-image: url(../images/home/bg.png); background-repeat: repeat-x; background-color: #070a12; text-align: center; /* for IE */ font-family: Verdana, Tahoma, Arial, sans-serif, Helvetica; } /* Wrapper div */ #wrapper { margin: 0 auto; /* align for good browsers */ text-align: left; /* counter the body center */ height: auto; width: 932px; margin-top:100px; } /* Logo div inside wrapper div */ #wrapper #logo { position: relative; height: auto; width: auto; text-align: center; } /* Wrapper login top div */ #wrapper #login_top { position: relative; height: auto; width: auto; float: left; } /* Wrapper login left div */ #wrapper #login_left { float: left; width: 259px; position: relative; } /* Wrapper login centre div */ #wrapper #login_centre { height: 152px; width: 385px; float: left; background-color: #181F37; background-image: url(../images/home/login_area.png); } /* Wrapper login right div */ #wrapper #login_right { float: right; width: 277px; position: relative; margin-right: 11px; } HTML for page below... <!DOCTYPE html> <html> <head> <!-- Meta Info --> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <!-- Page title --> <title>GunChester - Free Online Gangster RPG!</title> <!-- Link in CSS and JS files --> <link href="../css/home.css" rel="stylesheet" type="text/css" /> </head> <body> <!-- Content wrapper div layer --> <div id="wrapper"> <!-- Logo div layer --> <div id="logo"> <img src="../images/home/header.png" width="799" height="256" /> </div> <!-- Login top image div layer --> <div id="login_top"> <img src="../images/home/login_top.png" width="932" height="68" alt="Login Box Top Image" /> </div> <div id="login_left"> <img src="../images/home/login_left.png" width="259" height="152" alt="Login Left Image" /> </div> <!-- Login centre div layer --> <div id="login_centre"> test </div> <!-- Login right image div layer --> <div id="login_right"> <img src="../images/home/login_right.png" width="277" height="152" alt="Login Right Image" /> </div> </div> </body> </html>

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  • Customize VisualStudio syntax highlighting even more

    - by Alex K
    Hi everybody, I am wondering if it is possible to set VisualStudio IDE so it highlights private/protected/public variables of the class differently as well as change formatting on locals (i.e. variables that are either passed in or declared inside a function, like this). I did not find any such options in the normal Fonts and Colors menu of VS. Also a search on SO reveals that (at least as of 2 years ago) only add-ons provide such features. But is there a way to manually edit some file? Just because we don't get a nice UI to edit, doesn't mean underlying framework automatically doesn't support it. I mean add-ons have to plug into something to do their magic in the editor. Any insights into this issue? Thanks!

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  • Interface Photoshop size for iPhone app

    - by Sorin M
    Hello, I am building an iPhone app interface and I know the dpi has to be 163, but when it comes to the size of the file, I was looking through all the recommendations and found 2 different answers... Does anyone know what size should i set the Photoshop file at? The answers I have so far are: "The screen on the iPhone is 480×320, minus the 20-pixel status bar (making a 460×320 working screen size). The screen shots on the App Store should not include the status bar." "400 x 320 or 960 x 640 (iPhone 4) You must also consider the landscape mode (320 x 400 and 640 x 960)" I would really appreciate the answer. Thanks!

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  • Set text highlight colour of Blackberry RichTextField

    - by DaveJohnston
    Does anyone know how to set the background colour of just a section of text within a RichTextField on the Blackberry? I already use the offsets, attributes and fonts arrays to make changes to the appearance of certain sections of the text, but I would like to add a highlight colour to the background of one section too. I know there is a protected method called getBackgroundColors that returns an array of colors to be used, which I can overwrite. But I have tried this and that method never seems to get called in my code, I don't actually know how and when the underlying implementation of the RichTextField actually use this method. Any ideas?

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  • Distance by sea calculator, intermediate coordinates?

    - by Lucian2k
    How do I calculate distance between 2 coordinates by sea? I also want to be able to draw a route between the two coordinates. Only solution I found so far is to split a map into pixels, identify each pixel as LAND or SEA and then try to find the path using A* algorithm. Then transform pixels to relative coordinates. There are some software packages I could buy but none have online extensions. A service that calculates distances between sea ports and plots the path on a map is searates.com

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  • Visual Studio HTML Cursor-within-HTML-Element Syntax-highlighting color

    - by David Murdoch
    I can't, for the life of me, figure out how to change grey highlight color in the screenshot below to something that will make the text a little more legible. Does anyone know what the "Display Item" name is that I need to change? To get to the "theme editor" select Tools = Options = Environment = Fonts and Colors. I can't find what to edit. I've also looked through Tools = Options = Text Editor = HTML = Formatting to no avail. In case you are wondering the theme is a slightly modified Coding Instinct Theme

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  • box-shadow : is there a "box-shadow-color" ?

    - by Epaga
    Note: CSS novice here. Be gentle. ;-) I have the following CSS: ... -webkit-box-shadow: inset 0px 0px 2px #a00; -moz-box-shadow: inset 0px 0px 2px #a00; ... Now I am trying to extract that color to make the page colors "skinnable". Is there any way of doing this? Simply removing the color, and then using the same key again later overwrites the original rule. There doesn't seem to be a -webkit-box-shadow-color, at least Google turns nothing up.

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  • Image Application in WPF and Perfomance.

    - by Harsha
    Hello All, I am planning to build Image processing application using WPF. Brightness /Contrast and Histogram are main operation of this application. I have downloaded the application " Foundations: Bitmaps and Pixel Bits" from http://msdn.microsoft.com/en-us/magazine/cc534995.aspx . But when I tried to open the images which are more than 1200x1600, It is very slow. How to increase the performance. Is any one worked on Image processing in WPF. Please suggest me how to solve this perfomance issue in WPF for image(more than 1600x1200) operation. Thanks you, Harsha

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  • Android color picker - updating color array

    - by zorglub76
    Hi all, I'm trying to create a color picker for Android that looks like a minimalistic version of Gimp's. So, it has a hue slider and a rectangle with saturation/value variants of a color chosen in hue slider. Question: what is the best way to create the rectangle? Right now, I'm creating an 200x200 array of pixels, but it takes ~5sec to create and display rectangle with that array. And I need colors in rectangle to change whenever I change the value in hue slider... Rectangle is bitmap, btw. Can I use color matrices on that and how? Any examples? Thanks in advance!

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  • WinForms button position - not aligned as it should

    - by Zka
    Adding some gui modifications and I want to have a button which is 10pixels away from the forms left and right border. With this code the right border of the button is around 20-30 pixel outside the form window. Why is that? How can I position my button to be exactly 10pixels away from the form borders ? int margin = 10; meny1 = new Button(); meny1.Top = 50; meny1.Left = margin; meny1.Size = new Size(this.Width - (2*margin), 30);

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  • Java code optimization on matrix windowing computes in more time

    - by rano
    I have a matrix which represents an image and I need to cycle over each pixel and for each one of those I have to compute the sum of all its neighbors, ie the pixels that belong to a window of radius rad centered on the pixel. I came up with three alternatives: The simplest way, the one that recomputes the window for each pixel The more optimized way that uses a queue to store the sums of the window columns and cycling through the columns of the matrix updates this queue by adding a new element and removing the oldes The even more optimized way that does not need to recompute the queue for each row but incrementally adjusts a previously saved one I implemented them in c++ using a queue for the second method and a combination of deques for the third (I need to iterate through their elements without destructing them) and scored their times to see if there was an actual improvement. it appears that the third method is indeed faster. Then I tried to port the code to Java (and I must admit that I'm not very comfortable with it). I used ArrayDeque for the second method and LinkedLists for the third resulting in the third being inefficient in time. Here is the simplest method in C++ (I'm not posting the java version since it is almost identical): void normalWindowing(int mat[][MAX], int cols, int rows, int rad){ int i, j; int h = 0; for (i = 0; i < rows; ++i) { for (j = 0; j < cols; j++) { h = 0; for (int ry =- rad; ry <= rad; ry++) { int y = i + ry; if (y >= 0 && y < rows) { for (int rx =- rad; rx <= rad; rx++) { int x = j + rx; if (x >= 0 && x < cols) { h += mat[y][x]; } } } } } } } Here is the second method (the one optimized through columns) in C++: void opt1Windowing(int mat[][MAX], int cols, int rows, int rad){ int i, j, h, y, col; queue<int>* q = NULL; for (i = 0; i < rows; ++i) { if (q != NULL) delete(q); q = new queue<int>(); h = 0; for (int rx = 0; rx <= rad; rx++) { if (rx < cols) { int mem = 0; for (int ry =- rad; ry <= rad; ry++) { y = i + ry; if (y >= 0 && y < rows) { mem += mat[y][rx]; } } q->push(mem); h += mem; } } for (j = 1; j < cols; j++) { col = j + rad; if (j - rad > 0) { h -= q->front(); q->pop(); } if (j + rad < cols) { int mem = 0; for (int ry =- rad; ry <= rad; ry++) { y = i + ry; if (y >= 0 && y < rows) { mem += mat[y][col]; } } q->push(mem); h += mem; } } } } And here is the Java version: public static void opt1Windowing(int [][] mat, int rad){ int i, j = 0, h, y, col; int cols = mat[0].length; int rows = mat.length; ArrayDeque<Integer> q = null; for (i = 0; i < rows; ++i) { q = new ArrayDeque<Integer>(); h = 0; for (int rx = 0; rx <= rad; rx++) { if (rx < cols) { int mem = 0; for (int ry =- rad; ry <= rad; ry++) { y = i + ry; if (y >= 0 && y < rows) { mem += mat[y][rx]; } } q.addLast(mem); h += mem; } } j = 0; for (j = 1; j < cols; j++) { col = j + rad; if (j - rad > 0) { h -= q.peekFirst(); q.pop(); } if (j + rad < cols) { int mem = 0; for (int ry =- rad; ry <= rad; ry++) { y = i + ry; if (y >= 0 && y < rows) { mem += mat[y][col]; } } q.addLast(mem); h += mem; } } } } I recognize this post will be a wall of text. Here is the third method in C++: void opt2Windowing(int mat[][MAX], int cols, int rows, int rad){ int i = 0; int j = 0; int h = 0; int hh = 0; deque< deque<int> *> * M = new deque< deque<int> *>(); for (int ry = 0; ry <= rad; ry++) { if (ry < rows) { deque<int> * q = new deque<int>(); M->push_back(q); for (int rx = 0; rx <= rad; rx++) { if (rx < cols) { int val = mat[ry][rx]; q->push_back(val); h += val; } } } } deque<int> * C = new deque<int>(M->front()->size()); deque<int> * Q = new deque<int>(M->front()->size()); deque<int> * R = new deque<int>(M->size()); deque< deque<int> *>::iterator mit; deque< deque<int> *>::iterator mstart = M->begin(); deque< deque<int> *>::iterator mend = M->end(); deque<int>::iterator rit; deque<int>::iterator rstart = R->begin(); deque<int>::iterator rend = R->end(); deque<int>::iterator cit; deque<int>::iterator cstart = C->begin(); deque<int>::iterator cend = C->end(); for (mit = mstart, rit = rstart; mit != mend, rit != rend; ++mit, ++rit) { deque<int>::iterator pit; deque<int>::iterator pstart = (* mit)->begin(); deque<int>::iterator pend = (* mit)->end(); for(cit = cstart, pit = pstart; cit != cend && pit != pend; ++cit, ++pit) { (* cit) += (* pit); (* rit) += (* pit); } } for (i = 0; i < rows; ++i) { j = 0; if (i - rad > 0) { deque<int>::iterator cit; deque<int>::iterator cstart = C->begin(); deque<int>::iterator cend = C->end(); deque<int>::iterator pit; deque<int>::iterator pstart = (M->front())->begin(); deque<int>::iterator pend = (M->front())->end(); for(cit = cstart, pit = pstart; cit != cend; ++cit, ++pit) { (* cit) -= (* pit); } deque<int> * k = M->front(); M->pop_front(); delete k; h -= R->front(); R->pop_front(); } int row = i + rad; if (row < rows && i > 0) { deque<int> * newQ = new deque<int>(); M->push_back(newQ); deque<int>::iterator cit; deque<int>::iterator cstart = C->begin(); deque<int>::iterator cend = C->end(); int rx; int tot = 0; for (rx = 0, cit = cstart; rx <= rad; rx++, ++cit) { if (rx < cols) { int val = mat[row][rx]; newQ->push_back(val); (* cit) += val; tot += val; } } R->push_back(tot); h += tot; } hh = h; copy(C->begin(), C->end(), Q->begin()); for (j = 1; j < cols; j++) { int col = j + rad; if (j - rad > 0) { hh -= Q->front(); Q->pop_front(); } if (j + rad < cols) { int val = 0; for (int ry =- rad; ry <= rad; ry++) { int y = i + ry; if (y >= 0 && y < rows) { val += mat[y][col]; } } hh += val; Q->push_back(val); } } } } And finally its Java version: public static void opt2Windowing(int [][] mat, int rad){ int cols = mat[0].length; int rows = mat.length; int i = 0; int j = 0; int h = 0; int hh = 0; LinkedList<LinkedList<Integer>> M = new LinkedList<LinkedList<Integer>>(); for (int ry = 0; ry <= rad; ry++) { if (ry < rows) { LinkedList<Integer> q = new LinkedList<Integer>(); M.addLast(q); for (int rx = 0; rx <= rad; rx++) { if (rx < cols) { int val = mat[ry][rx]; q.addLast(val); h += val; } } } } int firstSize = M.getFirst().size(); int mSize = M.size(); LinkedList<Integer> C = new LinkedList<Integer>(); LinkedList<Integer> Q = null; LinkedList<Integer> R = new LinkedList<Integer>(); for (int k = 0; k < firstSize; k++) { C.add(0); } for (int k = 0; k < mSize; k++) { R.add(0); } ListIterator<LinkedList<Integer>> mit; ListIterator<Integer> rit; ListIterator<Integer> cit; ListIterator<Integer> pit; for (mit = M.listIterator(), rit = R.listIterator(); mit.hasNext();) { Integer r = rit.next(); int rsum = 0; for (cit = C.listIterator(), pit = (mit.next()).listIterator(); cit.hasNext();) { Integer c = cit.next(); Integer p = pit.next(); rsum += p; cit.set(c + p); } rit.set(r + rsum); } for (i = 0; i < rows; ++i) { j = 0; if (i - rad > 0) { for(cit = C.listIterator(), pit = M.getFirst().listIterator(); cit.hasNext();) { Integer c = cit.next(); Integer p = pit.next(); cit.set(c - p); } M.removeFirst(); h -= R.getFirst(); R.removeFirst(); } int row = i + rad; if (row < rows && i > 0) { LinkedList<Integer> newQ = new LinkedList<Integer>(); M.addLast(newQ); int rx; int tot = 0; for (rx = 0, cit = C.listIterator(); rx <= rad; rx++) { if (rx < cols) { Integer c = cit.next(); int val = mat[row][rx]; newQ.addLast(val); cit.set(c + val); tot += val; } } R.addLast(tot); h += tot; } hh = h; Q = new LinkedList<Integer>(); Q.addAll(C); for (j = 1; j < cols; j++) { int col = j + rad; if (j - rad > 0) { hh -= Q.getFirst(); Q.pop(); } if (j + rad < cols) { int val = 0; for (int ry =- rad; ry <= rad; ry++) { int y = i + ry; if (y >= 0 && y < rows) { val += mat[y][col]; } } hh += val; Q.addLast(val); } } } } I guess that most is due to the poor choice of the LinkedList in Java and to the lack of an efficient (not shallow) copy method between two LinkedList. How can I improve the third Java method? Am I doing some conceptual error? As always, any criticisms is welcome. UPDATE Even if it does not solve the issue, using ArrayLists, as being suggested, instead of LinkedList improves the third method. The second one performs still better (but when the number of rows and columns of the matrix is lower than 300 and the window radius is small the first unoptimized method is the fastest in Java)

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  • Comparing (similar) images with Python/PIL

    - by Attila Oláh
    I'm trying to calculate the similarity (read: Levenshtein distance) of two images, using Python 2.6 and PIL. I plan to use the python-levenshtein library for fast comparison. Main question: What is a good strategy for comparing images? My idea is something like: Convert to RGB (transparent - white) (or maybe convert to monochrome?) Scale up the smaller one to the larger one's size Convert each channel (= the only channel, if converted to monochrome) to a sequence (item value = color value of the pixel) Calculate the Levenshtein distance between the two sequences Of course, this will not handle cases like mirrored images, cropped images, etc. But for basic comparison, this should be useful. Is there a better strategy documented somewhere?

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