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• Embed external images for use in HTML canvas?

  - by Philipp Lenssen

  I'm using JavaScript to load an image into my Canvas element in Firefox. This works fine for local images, but throws a security exception for external images. Is there any way to avoid this security exception, one that does not involve my server having to act as proxy to load the image locally (because that would stress my server)? PS: The current code is similar to this: var img = new Image(); var contextSource = canvasSource.getContext('2d'); contextSource.drawImage(img, 0, 0); // get image data to do stuff with pixels var imageDataSource = contextSource.getImageData(0, 0, width - 1, height - 1);

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• Side effects of reordering columns in PostgreSQL

  - by Summer

  I sometimes re-order the columns in my Postgres DB. Since Postgres can only add columns at the end of tables, I end up re-ordering by adding new columns at the end of the table, setting them equal to existing columns, and then dropping the original columns. My question is: what does PostgreSQL do with the memory that's freed by dropped columns? Does it automatically re-use the memory, so a single record consumes the same amount of space as it did beforehand? But that would require a re-write of the whole table, so to avoid that, does it just keep a bunch of blank space around in each record? Thanks! ~S

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• Avoiding "variable might not have been initialized"

  - by Mason Wheeler

  I recently ran across a routine that looks something like this: procedure TMyForm.DoSomething(list: TList<TMyObject>; const flag: boolean); var local: integer; begin if flag then //do something else local := ExpensiveFunctionCallThatCalculatesSomething; //do something else for i := 0 to list.Count do if flag then //do something else if list[i].IntValue > local then //WARNING HERE //do something else end; This gives Variable 'local' might not have been initialized even though you can tell by reading the code that you won't hit that line unless the code branch that initializes it has run. Now, I could get rid of this warning by adding a useless local := 0; at the top of the procedure, but I wonder if there might not be a better way to structure this to avoid the issue. Anyone have any ideas?

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• Is it OK to mixed NumberLong and normal integers in the same field in MongoDB?

  - by Nicholas Tolley Cottrell

  I have been using Morphia to persistent objects from Java. I have also been running some batch processes from the console. I just realised that some values are now stored as NumberLong and number as plain Javascript numbers. I have an index on this field. Everything seems to be ok, but if I query: {f: 100} from the console it still returns the object even if it actually contains {f: NumberLong(100)} Is this true of all the drivers? It is best practice to avoid NumberLong is I can fit the value inside 32-bit? Will I save a lot of data and index space if I convert all NumberLongs to basic numbers?

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• Is *not* using the asp.net membership provider a bad idea?

  - by EJB

  Is it generally a really bad idea to not use the built-in asp.net membership provider? I've always rolled my own for my asp.net apps (public facing), and really have not had any problems in doing so. It works, and seems to avoid a layer of complexity. My needs are pretty basic: once setup, the user must use email address and password to login, if they forget it, it will be emailed back to them (a new one). After setup there is little that needs to be done to each user account, but I do need to store several extra fields with each user (full name, telephone and a few other fields etc). The number of users that required login credentials are small (usually just the administrator and a few backups), and everyone else uses the site unauthenticated. What are the big advantages that I might be missing out on by skipping the asp.net membership provider functionality?

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• Controlling LaTeX column flow

  - by hdhermans

  What I'm trying to do: I have a page that consists of pairs of two sentences each. The pairs are separated by a whole line break. My problem is that when I have an odd number of pairs, the second sentence will automatically be placed on the next column. How can I use LaTeX to make block structures that multicol does not ignore, to keep the two sentences together? If there's better code to solve this problem, or a better column implementation (though I don't believe I can use \twocolumn in the document declaration), please post it. My current code: \documentclass{article} \usepackage{fullpage} \usepackage{multicol} \setlength{\parindent}{0pt} \setlength{\parskip}{\baselineskip} \newcommand{\pair}[2]{ \emph{#1}\\* #2 } \begin{document} \begin{multicols}{2} \pair{Sentence 1.}{Sentence 2.} \pair{Sentence 2 (pair 2).}{Sentence 2 (pair 2).} \pair{The last pair, first sentence.}{Last sentence.} \end{multicols} \end{document} This generates: http://img541.imageshack.us/img541/3444/columns.png . The second pair is what I am trying to avoid.

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• Deadlock between select and truncate (postgresql)

  - by valodzka

  Table output_values_center1 (and some other) inherits output_values. Periodically I truncate table output_values_center1 and load new data (in one transaction). In that time user can request some data and he got error message. Why it ever happens (select query requests only one record) and how to avoid such problem: 2010-05-19 14:43:17 UTC ERROR: deadlock detected 2010-05-19 14:43:17 UTC DETAIL: Process 25972 waits for AccessShareLock on relation 2495092 of database 16385; blocked by process 26102. Process 26102 waits for AccessExclusiveLock on relation 2494865 of database 16385; blocked by process 25972. Process 25972: SELECT * FROM "output_values" WHERE ("output_values".id = 122312) LIMIT 1 Process 26102: TRUNCATE TABLE "output_values_center1"

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• Position elements without overlap

  - by eWolf

  I have a number of rectangular elements that I want to position in a 2D space. I calculate an ideal position for each element. Now my problem is that many elements overlap as very often the ideal positions are concentrated in one region. I want to avoid overlap as much as possible (doesn't have to be perfect, though). How can I do this? I've heard physics simulations are suitable for this - is that correct? And can anyone provide an example/tutorial? By the way: I'm using XNA, if you know any .NET library that does exactly this job - tell me!

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• Best approach to create a security environment in Java

  - by Tom Brito

  I need to create a desktop application that will run third party code, and I need to avoid the third party code from export by any way (web, clipboard, file io) informations from the application. Somethig like: public class MyClass { private String protectedData; public void doThirdPartyTask() { String unprotedtedData = unprotect(protectedData); ThirdPartyClass.doTask(unprotectedData); } private String unprotect(String data) { // ... } } class ThirdPartyClass { public static void doTask(String unprotectedData) { // Do task using unprotected data. // Malicious code may try to externalize the data. } } I'm reading about SecurityManager and AccessControler, but I'm still not sure what's the best approach to handle this. What should I read about to do this implementation?

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• Show friendly message on ASP.NET Ajax error

  - by balexandre

  You all know how annoying is this: I do have a log system and the correct error is well explicit there, but I want to give a better message to the user. I keep trying several ways but I'm using Telerik components and well jQuery and I ended up using both ASP.NET Ajax methods and jQuery, so I use function pageLoad() { try { var manager = Sys.WebForms.PageRequestManager.getInstance(); manager.add_endRequest(endRequest); manager.add_beginRequest(OnBeginRequest); manager } catch (err) { alert(err); } } as well $(document).ready(function() { ... } that alert(err) is never fired even upon OnClick events what's the best approach to avoid this message errors and provide a cleaner way? all this happens in <asp:UpdatePanel> as I use that when I didn't know better (3 years ago!) and I really don't want to mess up and build all again from scratch :( Any help is greatly appreciated Updated with more error windows after volpav solution

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• Is there such a thing as a converter from php to html?

  - by 0plus1

  Don't think that I'm mad, I understand how php works! That being said. I develop personal website and I usually take advantage of php to avoid repetion during the development phase nothing truly dynamic, only includes for the menus, a couple of foreach and the likes. When the development phase ends I need to give the website in html files to the client. Is there a tool (crawler?) that can do this for me instead of visiting each page and saving the interpreted html?

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• Locking a file to verify a single execution of a service. How reliable?

  - by Camilo Díaz

  Hello, I am deploying a little service to an UNIX(AIX) system. I want to check if there is no active instance of that service running when starting it. How reliable is to implement that check like this? Try to acquire a lock on a file (w/ FileChannel) If succeeds, keep lock and continue execution If fails, exit and refuse to run the main body I am aware of software like the Tanuki wrapper, however, I'm longing for a simpler(maybe not portable) solution. Regarding PIDFILE(s): I want to avoid using them if possible, as I don't have administrative rights on the machine, neither knowledge in AIX's shell programming.

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• DatabaseName.bak File Transfer Problem

  - by Jordon

  I have downloaded databasename.bak file from my hosting company, when i tried to restore that DB file in SQL server 2008 it is keep on giving me following error. The media family on device 'C:\go4sharepoint_1384_8481.bak' is incorrectly formed. SQL Server cannot process this media family. RESTORE HEADERONLY is terminating abnormally. (Microsoft SQL Server, Error: 3241) According to this error and from following link http://www.sqlcoffee.com/Troubleshooting047.htm Later when I tried to restore file on server it was restored correctly, but when I tried to transfer same file using FTP Software FileZila and tried to restore that downloaded file it was giving above error. That is file is getting corrupted on the way to tranfer using FTP. Any Idea how can i avoid that file to get courrupt? Note: File is downloaded using FileZila - TransferType as Binary. Thank you.

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• How do I use dependencies in a makefile without calling a target?

  - by rassie

  I'm using makefiles to convert an internal file format to an XML file which is sent to other colleagues. They would make changes to the XML file and send it back to us (Don't ask, this needs to be this way ;)). I'd like to use my makefile to update the internal files when this XML changes. So I have these rules: %.internal: $(DATAFILES) # Read changes from XML if any # Create internal representation here %.xml: %.internal # Convert to XML here Now the XML could change because of the workflow described above. But since no data files have changed, make would tell me that file.internal is up-to-date. I would like to avoid making %.internal target phony and a circular dependency on %.xml obviously doesn't work. Any other way I could force make to check for changes in the XML file and re-build %.internal?

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• Applying styles for custom TextArea in ActionScript 3

  - by Vijay Dev

  I have the following code to create and apply a few styles for a custom TextArea in ActionScript 3. public class MyCustomTextArea extends TextArea { override protected function createChildren():void { super.createChildren(); this.styleSheet.setStyle("sup", { display: "inline", fontFamily: "ArialSup", fontSize:"12"}); this.styleSheet.setStyle("sub", { display: "inline", fontFamily: "ArialSub", fontSize:"12"}); this.setStyle("fontFamily", "Arial"); } } I have two problems with this code. this.styleSheet is always null when I create an instance of the class. If this.styleSheet is initialized to new StyleSheet() to avoid this issue, then the TextArea instance does not seem to recognize any of the HTML tags that can be used with the htmlText property. Can anyone help in fixing these two issues? Thanks.

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• Caurina Tweener and Alpha

  - by Jk_

  Hi guys, Usually I work with TweenLite but I had to modify the code of someone else who worked with Caurina Tweener. I have a basic problem with it! On my scene, I have a simple movie clip filled with black. Into this movieclip a bitmap file (jpg). When I make a tween on the alpha of my mc, it seems that there is a delay (in the alpha) between this the black background and the image. Tweener.addTween(thisMc, { _autoAlpha:0, time:1 } ); I'm sure there is an easy way to avoid this problem but I can't find it out! Cheers, Jk_

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• Android Paypal One time Payment

  - by Ameya

  Hi All, Does any one know, or is it possible to do one time payment, with paypal in android ? Consider the senario. Buyer purchases installs free application. Clicks on paypal module and makes in-app payment, purchases feature successfully. Buyer deletes application. All information including the feature purchase enty in database is deleted. Buyer reinstalls the application. Here is the catch, if he wants to use the feature he will have to do a re-purchase. Which I wann to avoid in my application. This is taken care in iPhoen in-app purchase. That is if a buyer has already purchased an feture or in-app item, and if he trys to repurchase it (item has been set to one time payment) , the in-app purchase transaction will succeed without the user actually having to repay for the item. Is there an solution for this can anyone help.

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• ASP.NET auto submits form with only one textbox

  - by MartinHN

  Hi, look at this code: <%@ Page Language="C#" AutoEventWireup="true" CodeFile="test.aspx.cs" Inherits="test" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title>Untitled Page</title> </head> <body> <form id="form1" runat="server"> <input type="text" /> </form> </body> </html> When I hit the enter key, when the input box has focus - the form submits. If I add another input box it doesn't submit. How can I avoid the auto submit when there's only one input box?

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• Doing arithmetic with up to two decimal places in Python?

  - by user248237

  I have two floats in Python that I'd like to subtract, i.e. v1 = float(value1) v2 = float(value2) diff = v1 - v2 I want "diff" to be computed up to two decimal places, that is compute it using %.2f of v1 and %.2f of v2. How can I do this? I know how to print v1 and v2 up to two decimals, but not how to do arithmetic like that. The particular issue I am trying to avoid is this. Suppose that: v1 = 0.982769777778 v2 = 0.985980444444 diff = v1 - v2 and then I print to file the following: myfile.write("%.2f\t%.2f\t%.2f\n" %(v1, v2, diff)) then I will get the output: 0.98 0.99 0.00, suggesting that there's no difference between v1 and v2, even though the printed result suggests there's a 0.01 difference. How can I get around this? thanks.

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• Import module stored in a cStringIO data structure vs. physical disk file

  - by Malcolm

  Is there a way to import a Python module stored in a cStringIO data structure vs. physical disk file? It looks like "imp.load_compiled(name, pathname[, file])" is what I need, but the description of this method (and similar methods) has the following disclaimer: Quote: "The file argument is the byte-compiled code file, open for reading in binary mode, from the beginning. It must currently be a real file object, not a user-defined class emulating a file." [1] I tried using a cStringIO object vs. a real file object, but the help documentation is correct - only a real file object can be used. Any ideas on why these modules would impose such a restriction or is this just an historical artifact? Are there any techniques I can use to avoid this physical file requirement? Thanks, Malcolm [1] http://docs.python.org/library/imp.html#imp.load_module

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• Changing ylim (axis limits) drops data falling outside range. How can this be prevented?

  - by Alex Holcombe

  df <- data.frame(age=c(10,10,20,20,25,25,25),veg=c(0,1,0,1,1,0,1)) g=ggplot(data=df,aes(x=age,y=veg)) g=g+stat_summary(fun.y=mean,geom="point") Points reflect mean of veg at each age, which is what I expected and want to preserve after changing axis limits with the command below. g=g+ylim(0.2,1) Changing axis limits with the above command unfortunately causes veg==0 subset to be dropped from the data, yielding "Warning message: Removed 4 rows containing missing values (stat_summary)" This is bad because now the data plot (stat_summary mean) omits the veg==0 points. How can this be prevented? I simply want to avoid showing the empty part of the plot- the ordinate from 0 to .2, but not drop the associated data from the stat_summary calculation.

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• killing a separate thread having a socket

  - by user311906

  Hi All I have a separate thread ListenerThread having a socket listening to info broadcasted by some remote server. This is created at the constructor of one class I need to develop. Because of requirements, once the separate thread is started I need to avoid any blocking function on the main thread. Once it comes to the point of calling the destructor of my class I cannot perform a join on the listener thread so the only thing I can do is to KILL it. My questions are: what happens to the network resoruces allocated by the function passed to the thead? Is the socket closed properly or there might be something pending? ( most worried about this ) is this procedure fast enough i.e. is the thread killed so that interrupt immediately ? I am working with Linux ...what command or what can I check to ensure that there is no networking resource left pending or that something went wrong for the Operating system I thank you very much for your help Regards MNSTN NOTE: I am using boost::thread in C++

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• How to prevent UI from freezing during lengthy process?

  - by OverTheRainbow

  Hello, I need to write a VB.Net 2008 applet to go through all the fixed-drives looking for some files. If I put the code in ButtonClick(), the UI freezes until the code is done: Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click 'TODO Find way to avoid freezing UI while scanning fixed drives Dim drive As DriveInfo Dim filelist As Collections.ObjectModel.ReadOnlyCollection(Of String) Dim filepath As String For Each drive In DriveInfo.GetDrives() If drive.DriveType = DriveType.Fixed Then filelist = My.Computer.FileSystem.GetFiles(drive.ToString, FileIO.SearchOption.SearchAllSubDirectories, "MyFiles.*") For Each filepath In filelist 'Do stuff Next filepath End If Next drive End Sub Google returned information on a BackGroundWorker control: Is this the right/way to solve this issue? If not, what solution would you recommend, possibly with a really simple example? FWIW, I read that Application.DoEvents() is a left-over from VBClassic and should be avoided. Thank you.

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• problem when migrating from development into live server

  - by justjoe

  I'm facing problem when migrate my web app project from development server to live server. the reason is because i just realize that the live server has different PHP version and available memory lower then mine. i found this after client give me their ftp and cpanel access of their server, which is a shared host. so, how do we handle this situation ? and avoid similar problem in the future ? What is the most suitable configuration of a development server ? btw, i use xampp in windows. it's has apache and mysql.

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• Exception "Illegal attempt to associate a collection with two open sessions" when saving object

  - by Alex

  I am using CastleProject ActiveRecord and I use lazy load feature of this ORM. In order to make lazy load work, it is required to create SessionScope. I do this in Program.cs: public static SessionScope sessionScope; private static void InitializeActiveRecord() { ActiveRecordStarter.Initialize(); sessionScope = new SessionScope(); } This works fine for loading, however, when I try to save my objects, I get an exception saying "Illegal attempt to associate a collection with two open sessions". I guess this is due to the fact that I created one session myself. How to avoid this exception?

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