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  • permission denied to move files

    - by James
    i want to clear space on my computer in order to download drivers for my internet, so i tried moving files to a different location, unfortunately i dont have permission to do this, how do i change this, i should point out that i am not logged in, i think im a guest or something because if i log in i can not gain access to the internet to download the drivers that i need, so im using the cd and using the try ubunt feature to try achieve downloading the drivers. this is very frustrating for me as im new and have not got a clue how to do this

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  • OBIA on Teradata - Part 3 Stats

    - by Mohan Ramanuja
    Statements to run table stats on W_Party_Per_DS and W_Party_Per_DCOLLECT STATISTICS ON W_PARTY_PER_DS COLUMN ("DEPARTMENT_NAME");COLLECT STATISTICS ON W_PARTY_PER_DS COLUMN ("CONTACT_ID");COLLECT STATISTICS ON W_PARTY_PER_DS COLUMN ("CITY");COLLECT STATISTICS ON W_PARTY_PER_D COLUMN ("ACCNT_FLG");COLLECT STATISTICS ON W_PARTY_PER_D COLUMN ("SUPPLIER_FLG");help statistics w_party_per_d; Date Time    Unique Values    Column Names10/06/02    15:37:47  5,002,185        ROW_WID10/06/21    14:02:55  0     VIS_PR_POS_ID10/06/02    15:37:48  2     CREATED_BY_WID10/06/02    15:37:49  2     CHANGED_BY_WID10/06/02    15:37:50  2     SRC_EFF_FROM_DT10/06/02    15:37:51  1     SRC_EFF_TO_DT10/06/02    15:37:52  2     EFFECTIVE_FROM_DT10/06/02    15:37:53  2     EFFECTIVE_TO_DT10/06/02    15:37:57  1     DELETE_FLG10/06/21    14:02:54  0     CURRENT_FLG10/06/02    15:37:59  2     DATASOURCE_NUM_ID10/06/02    15:38:02  1     ETL_PROC_WID10/06/10    18:27:21  1,000     INTEGRATION_ID select top 10 * from DBC.TableSize; VprocDataBaseName AccountName     TableName     CurrentPerm PeakPerm 0    T21_ETL_TEMP_ENT         IM IT/IM IT Enterprise region  RZ_PENDD_FCLTY_CLM_STG   1024     0 0    SSB_RDS                  IM IT/IM IT ENTERPRISE REGION  RDS_RESP_997_TLR         1024     0 0    T17_EDL                  IM IT/IM IT Enterprise region  SPCMN_ACTN               1024     0 0    T20_ETL_CAPTR_DATA_ENT   IM IT/IM IT Enterprise region  HZ_CS90_VSGPNTE_S9MGNT14 2048     0 0    T5_ETL_DATA_PBM          IM IT/IM IT Enterprise region  PRCG_OVRD_BY_RX_NM       1536     0 0    PIP_DB                   $H&D&H                         PIPTRGENTSRC             1024     0 0    STest5_ADW0              sysadmin                       PROV_RGSTRTN             59904     0 0    AEDWSTG1                 NEIM/NEIM                      MEMBERSHIP_LKUP_ETL      1024     0 0    AEDWTST5                 dbc                            cptn_agrmt_xwlk          1024     0 0    VAL_LAG_TEMP             $H1$&D&HDBA                    clm_lag_stg              347136     0 select vproc, CurrentPerm from DBC.TableSize where databasename = 'PRJ_CRM_STGC' and tablename='w_party_per_d' ORDER BY 2 DESC;Vproc    DataBaseName    AccountName TableName        CurrentPerm    PeakPerm0        PRJ_CRM_STGC    DBA/DBA      W_PARTY_PER_D    8704.00        841728.003        PRJ_CRM_STGC    DBA/DBA      W_PARTY_PER_D    8704.00        782848.00

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  • Load previous (last) scene used in unity3d

    - by user3666251
    Im making a 2D game for android and I made over 200 levels/scenes.I also made a game over scene that opens when the players collides with an obscale.In the GameOver scene I added a retry button which I wanna make it so it opens the last level played.Im new in Unity and scripting.I've read other similar questions but none of them fixed my issue.Anyone has any idea that could help ? Im doing this because I don't wanna create over 200 game over scenes and edit each obscale in game. Thank you. Edit : Im using javascript.

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  • android shut-down errors / thread problems

    - by iQue
    Im starting to deal with some stuff in my game that I thought were "minor problems" and one of these are that I get an error every time I shut down my game that looks like this: 09-05 21:40:58.320: E/AndroidRuntime(30401): FATAL EXCEPTION: Thread-4898 09-05 21:40:58.320: E/AndroidRuntime(30401): java.lang.NullPointerException 09-05 21:40:58.320: E/AndroidRuntime(30401): at nielsen.happy.shooter.MainGamePanel.render(MainGamePanel.java:94) 09-05 21:40:58.320: E/AndroidRuntime(30401): at nielsen.happy.shooter.MainThread.run(MainThread.java:101) on these lines is my GameViews rendering-method and the line in my Thread that calls my GameViews rendering-method. Im guessing Something in my surfaceDestroyed(SurfaceHolder holder) is wrong, or maybe Im not ending the tread in the right place. My surfaceDestroyed-method: public void surfaceDestroyed(SurfaceHolder holder) { Log.d(TAG, "Surface is being destroyed"); boolean retry = true; ((MainThread)thread).setRunning(false); while (retry) { try { ((MainThread)thread).join(); retry = false; } catch (InterruptedException e) { } } Log.d(TAG, "Thread was shut down cleanly"); } Also, In my activity for this View my onPaus, onDestoy and onStop are empty, do I maybe need to add something there? The crash occurs when I press my home-button on the phone, or any other button that makes the game stop. But as I understand it the onPaus is called when you press the Home-button.. This is really new territory for me so Im sorry if im missing something obvious or something really big. adding my surfaceCreated method asweel since that is where I start this thread: public void surfaceCreated(SurfaceHolder holder) { controls = new GameControls(this); setOnTouchListener(controls); timer1.schedule(new Task(this), 0, delay1); thread.setRunning(true); thread.start(); } and aslong as this is running, my game is rendering and updating.

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  • Rails backend: debugging [closed]

    - by banditKing
    I have a rails -API app with Rabl. Im trying to build a photo sharing app. Im getting status 500 codes when my client communicates with the server. Im trying to find out how to debug this. The client is an iOS app I wrote. Where should I begin the debugging process and what are the best tools for debugging rails-api backend apps. Im new to server development so trying to learn the tricks of the trade. Any help would be appreciated. Thanks

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  • Visual sitemap generater

    - by rugbert
    Im looking for a something to visually create a sitemap for one of my websites. Id like something in a tree structure, so I have the hierarchical view of my site. A couple requirements I have tho, the ability to map password protected pages, and (not REALLY a requirement) the ability to integrate google analytics data. Im trying a evaluation version of powermapper, but the version that includes analytics integration is like $300 so Im looking for something cheaper.

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  • Online DATAFILE MOVE in Oracle Database 12c

    - by Ulrike Schwinn (DBA Community)
    Einige Operationen im Datenbankumfeld können nicht nur offline sondern auch online durchgeführt werden. Ein wichtiges Kennzeichen einer Online Operation ist dabei, dass Abfragen und DML Operationen während des Ablaufs der Operation (beispielsweise einer Reorganisation) ohne Unterbrechung weiter laufen können. Je nach einplanbarer Maintenance Zeit ist es daher durchaus wünschenswert, gewisse Operationen online durchzuführen. Generell gibt es in jedem Datenbankrelease einige Erweiterungen im Umfeld von Online Operationen. Besonders im aktuellen Release 12c gibt es eine Vielzahl neuer Operationen zu diesem Thema.Während der ersten 12c Veranstaltungen fand besonders das Kommando "DATAFILE ONLINE MOVE" besondere Aufmerksamkeit bei vielen Kunden. Aus diesem Grund wird im aktuellen Tipp dazu eine kleine Einführung gegeben.  Mehr dazu erfahren Sie hier. 

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  • Hilfreiche Linemode Skripte

    - by Ulrike Schwinn (DBA Community)
    Die mitgelieferten Skripte im Verzeichnis $ORACLE_HOME/rdbms/admin bieten schon seit jeher DBAs und Entwickler eine zusätzliche Unterstützung bei ihrer Arbeit. Sie stehen automatisch nach jeder Installation im Verzeichnis rdbms/admin zur weiteren Verwendung zur Verfügung. Nur wie findet man genau das Skript, das einem die richtige Unterstützung bietet? Eine Dokumentation aller Skripte existiert nicht. Man kann sich an den Namen der Skripte orientieren, da sie mit sprechenden Namen aufgelistet sind und kann die Kurzeinleitung im Skript nachlesen. Das ist mühselig und kostet Zeit. Daher wird im neuen Tipp ein Überblick über wichtige Skripte einschließlich einer Kurzbeschreibung gegeben. Mehr dazu hier

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  • how to share a folder in the same pc for ubuntu and windows

    - by AdanJosue
    i need to know if its possible to share a folder, so that i can open the files in it from ubuntu and windows at the time im using windows but im planning to move back to ubuntu but my problem would be losing some compatibility that windows offers me when im doing college work, and that can be a pain, so my plan is to dual boot and have both OS. but i dont want to be loging in and out of each OS in order to work or share files so is ther a way to share folders or files between, lets say, ubuntu 14.0 and windows 7?

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  • How well does ubuntu run on the asus Eee tablet? please read details before answering

    - by Const
    Im considering buying an Asus Eee transformer prime, i mainly want it so I can do some light web coding on the go, I commute a lot, most of my time is spent on the trains unfortunately. I know that it is possible to install ubuntu on the transformer prime, im also aware that it is not stable since its something new. Im wondering if anyone has tried it, how responsive/ fast is it? Does the batter die quickly?

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  • Improving Performance on this Image Creation function

    - by Abs
    Hello all, I am making use of GD2 and the image functions to take in a string and then convert that into an image using different fonts at different sizes. The function I use is below. Currently, its pretty quick but not quick enough. The function gets called about 20 times per user and the images generated are always new ones (different) so caching isn't going to help! I was hoping to get some ideas on how to make this function faster. Maybe supply more RAM to the script running? Anything else that is specific to this PHP function? Anything else that I can do to tweak performance of this function? function generate_image($save_path, $text, $font_path, $font_size){ $font = $font_path; /* * I have simplifed the line below, its actually a function that works out the size of the box * that is need for each image as the image size is different based on font type, font size etc */ $measure = array('width' => 300, 'height'=> 120); if($measure['width'] > 900){ $measure['width'] = 900; } $im = imagecreatetruecolor($measure['width'], $measure['height']); $white = imagecolorallocate($im, 255, 255, 255); $black = imagecolorallocate($im, 0, 0, 0); imagefilledrectangle($im, 0, 0, $measure['width'], $measure['height'], $white); imagettftext($im, $font_size, 0, $measure['left'], $measure['top'], $black, $font, ' '.$text); if(imagepng($im, $save_path)){ $status = true; }else{ $status = false; } imagedestroy($im); return $status; } Thanks all for any help

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  • Using PHP GD to create image form text with different fonts.

    - by Meredith
    I have been using this simple script to generate images from text: <?php header('Content-type: image/png'); $color = RgbfromHex($_GET['color']); $text = urldecode($_GET['text']); $font = 'arial.ttf'; $im = imagecreatetruecolor(400, 30); $bg_color = imagecolorallocate($im, 255, 255, 255); $font_color = imagecolorallocate($im, $color[0], $color[1], $color[2]); imagefilledrectangle($im, 0, 0, 399, 29, $bg_color); imagettftext($im, 20, 0, 10, 20, $font_color, $font, $text); imagepng($im); imagedestroy($im); function RgbfromHex($hexValue) { if(strlen(trim($hexValue))==6) { return array( hexdec(substr($hexValue,0,2)), // R hexdec(substr($hexValue,2,4)), // G hexdec(substr($hexValue,4,6)) // B ); } else return array(0, 0, 0); } ?> I call the script with file.php?text=testing script&color=000000 Now I'd like to know how could I generate text with normal and bold fonts mixed in the same image, something like file.php?text=testing <b>script</b>&color=000000

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  • How to achieve interaction between GUI class with logic class

    - by volting
    Im new to GUI programming, and haven't done much OOP. Im working on a basic calculator app to help me learn GUI design and to brush up on OOP. I understand that anything GUI related should be kept seperate from the logic, but Im unsure how to implement interaction between logic an GUI classes when needed i.e. basically passing variables back and forth... Im using TKinter and when I pass a tkinter variable to my logic it only seems to hold the string PY_VAR0. def on_equal_btn_click(self): self.entryVariable.set(self.entryVariable.get() + "=") calculator = Calc(self.entryVariable) self.entryVariable.set(calculator.calculate()) Im sure that im probably doing something fundamentally wrong and probabaly really stupid, I spent a considerable amount of time experimenting (and searching for answers online) but Im getting no where. Any help would be appreciated. Thanks, V The Full Program (well just enough to show the structure..) import Tkinter class Gui(Tkinter.Tk): def __init__(self,parent): Tkinter.Tk.__init__(self,parent) self.parent = parent self.initialize() def initialize(self): self.grid() self.create_widgets() """ grid config """ #self.grid_columnconfigure(0,weight=1,pad=0) self.resizable(False, False) def create_widgets(self): """row 0 of grid""" """Create Text Entry Box""" self.entryVariable = Tkinter.StringVar() self.entry = Tkinter.Entry(self,width=30,textvariable=self.entryVariable) self.entry.grid(column=0,row=0, columnspan = 3 ) self.entry.bind("<Return>", self.on_press_enter) """create equal button""" equal_btn = Tkinter.Button(self,text="=",width=4,command=self.on_equal_btn_click) equal_btn.grid(column=3, row=0) """row 1 of grid""" """create number 1 button""" number1_btn = Tkinter.Button(self,text="1",width=8,command=self.on_number1_btn_click) number1_btn.grid(column=0, row=1) . . . def on_equal_btn_click(self): self.entryVariable.set(self.entryVariable.get() + "=") calculator = Calc(self.entryVariable) self.entryVariable.set(calculator.calculate()) class Calc(): def __init__(self, equation): self.equation = equation def calculate(self): #TODO: parse string and calculate... return self.equation if __name__ == "__main__": app = Gui(None) app.title('Calculator') app.mainloop()

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  • httpd.conf variables : What is the difference between ${var} and %{var}?

    - by 108.im
    What is the difference between ${var} and %{var} in httpd.conf? How and when would one use ${} and %{}? http://httpd.apache.org/docs/2.4/configuring.html mentions : The values of variables defined with the Define of or shell environment variables can be used in configuration file lines using the syntax ${VAR}. http://httpd.apache.org/docs/2.4/mod/mod_rewrite.html mentions: Server-Variables:These are variables of the form %{ NAME_OF_VARIABLE } and RewriteMap expansions:These are expansions of the form ${mapname:key|default}. Will ${VAR} be used everywhere in httpd.conf, except in mod_rewrite directive's (like RewriteCond, RewriteRule but except for RewriteMap expansions which use ${} as in RewriteRule ^/ex/(.*) ${examplemap:$1} ) Would a variable set in httpd.conf using SetEnvIf Directive, for use in same httpd.conf, be used as ${var} except when the variable is used with mod_rewrite directive's, where the variable would be used as %{var}?

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  • Need help to configure file:default on apache2

    - by turk182
    hi all!! im trying to use xen on ubuntu 8.04 hardy heron, because it is a project that assign to me in my new job, i have already installed xen and im running the virtual machines. according to the guide that they give me, i have to configure de file: default, from apache2 directory, like this: vi /etc/apache2/sites-available/default inside of this file i have to write the next information: NameVirtualHost * VirtualHost * ServerName "www".ejemplo.com ServerAlias ejemplo.com DocumentRoot /var/www/ ProxyRequests Off Proxy * Order deny,allow Allow from all /Proxy ProxyPass /balancer-manager ! ProxyPass / balancer://mycluster/ stickysession=BALANCEID nofailover=On ProxyPassReverse / "http"://http1.ejemplo.com/ ProxyPassReverse / "http"://http2.ejemplo.com/ Proxy balancer://mycluster BalancerMember "http://10.10.2.101:8080 loadfactor=1 BalancerMember "http://10.10.2.102:8080 loadfactor=2 ProxySet lbmethod=byrequests /Proxy Location /balancer-manager SetHandler balancer-manager Order deny,allow Allow from all /Location /VirtualHost in the section of balancermember im using the ip of the virtual machine: virtual machine 1 has ip 10.10.2.101 and virtual machine 2 has ip 10.10.2.102 then i have to install apache2 on each virtual machine and restart apache2 the question is what i hace to do to verify if all of this works allegedly i have to open a browser and write "www.ejemplo.com" and suppost show something thats the reason that im ask for help cause i dont know what to do, im looking for on the web and i cant find nothing related with this... ill appreciatte your help. THXS!!! pd. i closed "www" and "HTTP" in quotes by rules of this sites cause im a new user

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  • What are the general strategies for the server of an FPS multiplayer game to update its clients?

    - by Hooray Im Helping
    A friend and I were having a discussion about how a FPS server updates the clients connected to it. We watched a video of a guy cheating in Battlefield: Bad Company 2 and saw how it highlighted the position of enemies on the screen and it got us thinking. His contention was that the server only updates the client with information that is immediately relevant to the client. I.e. the server won't send information about enemy players if they are too far away from the client or out of the client's line of sight for reasons of efficiency. He was unsure though - he brought up the example of someone hiding behind a rock, not able to see anyone. If the player were suddenly to pop up where he had three players in his line of sight, there would be a 50ms delay before they were rendered on his screen while the server transmitted the necessary information. My contention was the opposite: that the server sends the client all the information about every player and lets the client sort out what is allowed and what isn't. I figured it would actually be less expensive computationally for the server to just send everything to the client and let the client do the heavy lifting, so to speak. I also figured this is how cheat programs work - they intercept the server packets, get the location of enemies, then show them on the client's view. So the question: What are some general policies or strategies a modern first person shooter server employs to keep its clients updated?

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  • Jquery history, inspect the history stack

    - by nickmorss
    Im using this history jquery plugin http://www.mikage.to/jquery/jquery_history.html and im trying to inspect the back stack. I can call this $.historyCurrentHash to return the current hash, but im trying to figure out how to look one step back in the stack. if i try calling this $.historyBackStack, but i just get an 'undefined'. anyone got any ideas? I can see that its not a public variable, but im wondering if i need to modify the library or just call it in a different way

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  • Dynamically populating an ExtJS HTML editor

    - by sean.mcgary
    So Im using ExtJS for a job Im working and Im trying to dynamically populate the textarea associated with the HTML editor with data based on what a user selects from a combo box. From what Ive found, I can load the HTML editor with text using the defaultValue property. So if Im going to populate it after the page loads, can I give it something like a datastore or is there a method I can call to set the text?

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  • Refresh text shown in a Gtk Widget

    - by paultop6
    Hi Guys, Being resonably new to using GTK, im not fully aware of all its functionality. Basically, i have a GtkTreeView widget that has 4 Columns. I need to update the text displayed in the 4 columns every couple of seconds, but im not aware how to do this in GTK. Im aware that i could flush the data using gtk_tree_store_clear, but im not sure how to repopulate the columns and have the top level window refresh to show this new data. Any ideas? Regards Paul

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  • com.mysql.jdbc.Driver classnotfoundException

    - by Mohammed_Q
    Im getting classnotfountexception on Class.forname("com.mysql.jdbc.Driver") im using: windows vista 64-bit, Eclipse Galileo, GWT framework i downloaded (mysql-connector-java-5.1.6-bin), but what the exact path i should add to. im getting this exception while im in gwt-projects, but normal projects working good, any idea how that should be done???...thanks

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  • Little (Employee - Shift) SQL Database help

    - by latinunit-net
    Hi Guys, Im creating a little database that has employee, emp_shift, shift, tables now im suppose to be able to calculate at the end of the month which employee has done the most number of shifts. Ive created the SQL creation, insert statements for the tables, and a little diagram to explain what im trying to acomplish, im a beginner and this is a homework ive been trying to do for the last 4 days. Diagram: http://latinunit.net/emp_shift.jpg SQL: latinunit.net/emp_shift.txt can you please guys check it, deadline is 2 days and this is just a part of the whole database

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  • Uploadify Minimum Image Width And Height

    - by Richard Knop
    So I am using the Uplodify plugin to allow users to upload multiple images at once. The problem is I need to set a minimum width and height for images. Let's say 150x150px is the smallest image users can upload. How can I set this limitation in the Uploadify plugin? When user tries to upload smaller picture, I would like to display some error message as well. Here is the PHP file that is called bu the plugin to upload images: <?php define('BASE_PATH', substr(dirname(dirname(__FILE__)), 0, -22)); // set the include path set_include_path(BASE_PATH . '/../library' . PATH_SEPARATOR . BASE_PATH . '/library' . PATH_SEPARATOR . get_include_path()); // autoload classes from the library function __autoload($class) { include str_replace('_', '/', $class) . '.php'; } $configuration = new Zend_Config_Ini(BASE_PATH . '/application' . '/configs/application.ini', 'development'); $dbAdapter = Zend_Db::factory($configuration->database); Zend_Db_Table_Abstract::setDefaultAdapter($dbAdapter); function _getTable($table) { include BASE_PATH . '/application/modules/default/models/' . $table . '.php'; return new $table(); } $albums = _getTable('Albums'); $media = _getTable('Media'); if (false === empty($_FILES)) { $tempFile = $_FILES['Filedata']['tmp_name']; $extension = end(explode('.', $_FILES['Filedata']['name'])); // insert temporary row into the database $data = array(); $data['type'] = 'photo'; $data['type2'] = 'public'; $data['status'] = 'temporary'; $data['user_id'] = $_REQUEST['user_id']; $paths = $media->add($data, $extension, $dbAdapter); // save the photo move_uploaded_file($tempFile, BASE_PATH . '/public/' . $paths[0]); // create a thumbnail include BASE_PATH . '/library/My/PHPThumbnailer/ThumbLib.inc.php'; $thumb = PhpThumbFactory::create(BASE_PATH . '/public/' . $paths[0]); $thumb->adaptiveResize(85, 85); $thumb->save(BASE_PATH . '/public/' . $paths[1]); // add watermark to the bottom right corner $pathToFullImage = BASE_PATH . '/public/' . $paths[0]; $size = getimagesize($pathToFullImage); switch ($extension) { case 'gif': $im = imagecreatefromgif($pathToFullImage); break; case 'jpg': $im = imagecreatefromjpeg($pathToFullImage); break; case 'png': $im = imagecreatefrompng($pathToFullImage); break; } if (false !== $im) { $white = imagecolorallocate($im, 255, 255, 255); $font = BASE_PATH . '/public/fonts/arial.ttf'; imagefttext($im, 13, // font size 0, // angle $size[0] - 132, // x axis (top left is [0, 0]) $size[1] - 13, // y axis $white, $font, 'HunnyHive.com'); switch ($extension) { case 'gif': imagegif($im, $pathToFullImage); break; case 'jpg': imagejpeg($im, $pathToFullImage, 100); break; case 'png': imagepng($im, $pathToFullImage, 0); break; } imagedestroy($im); } echo "1"; } And here's the javascript: $(document).ready(function() { $('#photo').uploadify({ 'uploader' : '/flash-uploader/scripts/uploadify.swf', 'script' : '/flash-uploader/scripts/upload-public-photo.php', 'cancelImg' : '/flash-uploader/cancel.png', 'scriptData' : {'user_id' : 'USER_ID'}, 'queueID' : 'fileQueue', 'auto' : true, 'multi' : true, 'sizeLimit' : 2097152, 'fileExt' : '*.jpg;*.jpeg;*.gif;*.png', 'wmode' : 'transparent', 'onComplete' : function() { $.get('/my-account/temporary-public-photos', function(data) { $('#temporaryPhotos').html(data); }); } }); $('#upload_public_photo').hover(function() { var titles = '{'; $('.title').each(function() { var title = $(this).val(); if ('Title...' != title) { var id = $(this).attr('name'); id = id.substr(5); title = jQuery.trim(title); if (titles.length > 1) { titles += ','; } titles += '"' + id + '"' + ':"' + title + '"'; } }); titles += '}'; $('#titles').val(titles); }); }); Now bear in mind that I know how to check images dimensions in the PHP file. But I'm not sure how to modify the javascript so it won't upload images with very small dimensions.

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  • LINQ und ArcObjects

    - by Marko Apfel
    LINQ und ArcObjects Motivation LINQ1 (language integrated query) ist eine Komponente des Microsoft .NET Frameworks seit der Version 3.5. Es erlaubt eine SQL-ähnliche Abfrage zu verschiedenen Datenquellen wie SQL, XML u.v.m. Wie SQL auch, bietet LINQ dazu eine deklarative Notation der Problemlösung - d.h. man muss nicht im Detail beschreiben wie eine Aufgabe, sondern was überhaupt zu lösen ist. Das befreit den Entwickler abfrageseitig von fehleranfälligen Iterator-Konstrukten. Ideal wäre es natürlich auf diese Möglichkeiten auch in der ArcObjects-Programmierung mit Features zugreifen zu können. Denkbar wäre dann folgendes Konstrukt: var largeFeatures = from feature in features where (feature.GetValue("SHAPE_Area").ToDouble() > 3000) select feature; bzw. dessen Äquivalent als Lambda-Expression: var largeFeatures = features.Where(feature => (feature.GetValue("SHAPE_Area").ToDouble() > 3000)); Dazu muss ein entsprechender Provider zu Verfügung stehen, der die entsprechende Iterator-Logik managt. Dies ist leichter als man auf den ersten Blick denkt - man muss nur die gewünschten Entitäten als IEnumerable<IFeature> liefern. (Anm.: nicht wundern - die Methoden GetValue() und ToDouble() habe ich nebenbei als Erweiterungsmethoden deklariert.) Im Hintergrund baut LINQ selbständig eine Zustandsmaschine (state machine)2 auf deren Ausführung verzögert ist (deferred execution)3 - d.h. dass erst beim tatsächlichen Anfordern von Entitäten (foreach, Count(), ToList(), ..) eine Instanziierung und Verarbeitung stattfindet, obwohl die Zuweisung schon an ganz anderer Stelle erfolgte. Insbesondere bei mehrfacher Iteration durch die Entitäten reibt man sich bei den ersten Debuggings verwundert die Augen wenn der Ausführungszeiger wie von Geisterhand wieder in die Iterator-Logik springt. Realisierung Eine ganz knappe Logik zum Konstruieren von IEnumerable<IFeature> lässt sich mittels Durchlaufen eines IFeatureCursor realisieren. Dazu werden die einzelnen Feature mit yield ausgegeben. Der einfachen Verwendung wegen, habe ich die Logik in eine Erweiterungsmethode GetFeatures() für IFeatureClass aufgenommen: public static IEnumerable GetFeatures(this IFeatureClass featureClass, IQueryFilter queryFilter, RecyclingPolicy policy) { IFeatureCursor featureCursor = featureClass.Search(queryFilter, RecyclingPolicy.Recycle == policy); IFeature feature; while (null != (feature = featureCursor.NextFeature())) { yield return feature; } //this is skipped in unit tests with cursor-mock if (Marshal.IsComObject(featureCursor)) { Marshal.ReleaseComObject(featureCursor); } } Damit kann man sich nun ganz einfach die IEnumerable<IFeature> erzeugen lassen: IEnumerable features = _featureClass.GetFeatures(RecyclingPolicy.DoNotRecycle); Etwas aufpassen muss man bei der Verwendung des "Recycling-Cursors". Nach einer verzögerten Ausführung darf im selben Kontext nicht erneut über die Features iteriert werden. In diesem Fall wird nämlich nur noch der Inhalt des letzten (recycelten) Features geliefert und alle Features sind innerhalb der Menge gleich. Kritisch würde daher das Konstrukt largeFeatures.ToList(). ForEach(feature => Debug.WriteLine(feature.OID)); weil ToList() schon einmal durch die Liste iteriert und der Cursor somit einmal durch die Features bewegt wurde. Die Erweiterungsmethode ForEach liefert dann immer dasselbe Feature. In derartigen Situationen darf also kein Cursor mit Recycling verwendet werden. Ein mehrfaches Ausführen von foreach ist hingegen kein Problem weil dafür jedes Mal die Zustandsmaschine neu instanziiert wird und somit der Cursor neu durchlaufen wird – das ist die oben schon erwähnte Magie. Ausblick Nun kann man auch einen Schritt weiter gehen und ganz eigene Implementierungen für die Schnittstelle IEnumerable<IFeature> in Angriff nehmen. Dazu müssen nur die Methode und das Property zum Zugriff auf den Enumerator ausprogrammiert werden. Im Enumerator selbst veranlasst man in der Reset()-Methode das erneute Ausführen der Suche – dazu übergibt man beispielsweise ein entsprechendes Delegate in den Konstruktur: new FeatureEnumerator( _featureClass, featureClass => featureClass.Search(_filter, isRecyclingCursor)); und ruft dieses beim Reset auf: public void Reset() {     _featureCursor = _resetCursor(_t); } Auf diese Art und Weise können Enumeratoren für völlig verschiedene Szenarien implementiert werden, die clientseitig restlos identisch nach obigen Schema verwendet werden. Damit verschmelzen Cursors, SelectionSets u.s.w. zu einer einzigen Materie und die Wiederverwendbarkeit von Code steigt immens. Obendrein lässt sich ein IEnumerable in automatisierten Unit-Tests sehr einfach mocken - ein großer Schritt in Richtung höherer Software-Qualität.4 Fazit Nichtsdestotrotz ist Vorsicht mit diesen Konstrukten in performance-relevante Abfragen geboten. Dadurch dass im Hintergrund eine Zustandsmaschine verwalten wird, entsteht einiges an Overhead dessen Verarbeitung zusätzliche Zeit kostet - ca. 20 bis 100 Prozent. Darüber hinaus ist auch das Arbeiten ohne Recycling schnell ein Performance-Gap. Allerdings ist deklarativer LINQ-Code viel eleganter, fehlerfreier und wartungsfreundlicher als das manuelle Iterieren, Vergleichen und Aufbauen einer Ergebnisliste. Der Code-Umfang verringert sich erfahrungsgemäß im Schnitt um 75 bis 90 Prozent! Dafür warte ich gerne ein paar Millisekunden länger. Wie so oft muss abgewogen werden zwischen Wartbarkeit und Performance - wobei für mich Wartbarkeit zunehmend an Priorität gewinnt. Zumeist ist sowieso nicht der Code sondern der Anwender die Bremse im Prozess. Demo-Quellcode support.esri.de   [1] Wikipedia: LINQ http://de.wikipedia.org/wiki/LINQ [2] Wikipedia: Zustandsmaschine http://de.wikipedia.org/wiki/Endlicher_Automat [3] Charlie Calverts Blog: LINQ and Deferred Execution http://blogs.msdn.com/b/charlie/archive/2007/12/09/deferred-execution.aspx [4] Clean Code Developer - gelber Grad/Automatisierte Unit Tests http://www.clean-code-developer.de/Gelber-Grad.ashx#Automatisierte_Unit_Tests_8

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  • Lucene numDocs and doqFreq on custom similarity class

    - by David A
    Hi All, im doing an aplication with Lucene (im a noob with it) and im facing some problems. My aplication uses the Lucene 2.4.0 library with a custom similaraty implementation (the jar is imported) In my app im calculating doqFreq and numDocs manually (im adding the values of all indexes and then i calculate a global value in order to use it on every query) and i want to use that values on a custom similarity implementation in order to calculate a new IDF. The problem is that I dont know how to use (or send) the new doqFreq and numDocs values from my app on that new similarty implementation as I dont want to change lucene´s code apart from this extra class. Any suggestions or examples? I read the docs but i dont now how to aproach this :s Thanks

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