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• Reliable and fast way to convert a zillion ODT files in PDF?

  - by Marco Mariani

  I need to pre-produce a million or two PDF files from a simple template (a few pages and tables) with embedded fonts. Usually, I would stay low level in a case like this, and compose everything with a library like ReportLab, but I joined late in the project. Currently, I have a template.odt and use markers in the content.xml files to fill with data from a DB. I can smoothly create the ODT files, they always look rigth. For the ODT to PDF conversion, I'm using openoffice in server mode (and PyODConverter w/ named pipe), but it's not very reliable: in a batch of documents, there is eventually a point after which all the processed files are converted into garbage (wrong fonts and letters sprawled all over the page). Problem is not predictably reproducible (does not depend on the data), happens in OOo 2.3 and 3.2, in Ubuntu, XP, Server 2003 and Windows 7. My Heisenbug detector is ticking. I tried to reduce the size of batches and restarting OOo after each one; still, a small percentage of the documents are messed up. Of course I'll write about this on the Ooo mailing lists, but in the meanwhile, I have a delivery and lost too much time already. Where do I go? Completely avoid the ODT format and go for another template system. Suggestions? Anything that takes a few seconds to run is way too slow. OOo takes around a second and it sums to 15 days of processing time. I had to write a program for clustering the jobs over several clients. Keep the format but go for another tool/program for the conversion. Which one? There are many apps in the shareware or commercial repositories for windows, but trying each one is a daunting task. Some are too slow, some cannot be run in batch without buying it first, some cannot work from command line, etc. Open source tools tend not to reinvent the wheel and often depend on openoffice. Converting to an intermediate .DOC format could help to avoid the OOo bug, but it would double the processing time and complicate a task that is already too hairy. Try to produce the PDFs twice and compare them, discarding the whole batch if there's something wrong. Although the documents look equal, I know of no way to compare the binary content. Restart OOo after processing each document. it would take a lot more time to produce them it would lower the percentage of the wrong files, and make it very hard to identify them. Go for ReportLab and recreate the pages programmatically. This is the approach I'm going to try in a few minutes. Learn to properly format bulleted lists Thanks a lot.

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• How to find relation between change in latitudes at centre of map and top/bottom

  - by Imran

  Hi, Im having little trouble finding a relation between the movement at centre and edge of a circle, Im doing for panning world map,my map extent is 180,89:-180,-89, my map pans by adding change(dx,dY) to its extents and not its centre. Now a situation has arrrised where I have to move the map to a specific centre, to calculate the change in longitudes is very easy and simple, but its the change in lattitudes that has caused problem. It seems the change in centreY of map is more than the change at edge of the mapY, or simply if I have to move the map centre from 0long,0lat to 73long,33lat, for dX I simply get 73, but for dY apparently it looks 33 but if i add 33 to top of map that is 89 , it will be 122 which is incorrect since Latitudes are between 90 and -90 . It seems a case a projection of a circle on 2D plane where the edge of circle since is moving backward due to angle expereinces less change and the centre expereinces more change, now is there a relation between these two factors? I tried converting the difference between OriginY and destinationY into radians and then add to Top and Bottom of Map, but it did'nt really work for me. Please note that the map is project on a virtual canvas whose width starts from 256 and increases by 256*2^z , z=0 is default and whole world is visible at that extent of canvas code: public void moveMapTo(double destinationLongitude,double destinationLattitude) // moves map to the new centre { double dXLong=destinationLongitude-centreLongitude; double atanhsinO = atanh(Math.sin(destinationLattitude * Math.PI / 180.00)); double atanhsinD = atanh(Math.sin(centreLatitude * Math.PI / 180.00)); double atanhCentre = (atanhsinD + atanhsinO) / 2; double latitudeSpan =destinationLattitude - centreLatitude; double radianOfCentreLatitude = Math.atan(Math.sinh(atanhCentre)); double dXLat=latitudeSpan / Math.cos(radianOfCentreLatitude); dXLat*=getLattitudeSpan()*(Math.PI/180); <--- HERE IS THE PORBLEM System.out.println("dxLong:"+dXLong+"_dxLat:"+dXLat); mapLeft+=dXLong; mapRight+=dXLong; mapTop+=dXLat; mapBottom+=dXLat; } ////latitude span function private double getLattitudeSpan() { double latitudeSpan = mapTop - mapBottom; latitudeSpan = latitudeSpan / Math.cos(radianOfCentreLatitude); return Math.abs(latitudeSpan); } //ht

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• msysgit git-am can't apply it's own git format-patch sequence

  - by Andrian Nord

  I'm using msysgit git on windows to operate on central svn repository. I'm using git as I want to have it's awesome little local branches for everything and rebasing on each other. I also need to update from central repo often, so using separate svn/git is not an option. Problem is - git svn --help (man page) says that it is not a good idea to use git merge into master branch (which is set to track from svn's trunk) from local branches, as this will ruin the party and git svn dcommit would not work anymore. I know that it's not exactly true and you may use git merge if you are merging from branch which was properly rebased on master prior merge, but I'm trying to make it safer and actually use git format-patch and git am. We are using code review, so I'm making patches anyway. I also knew about git cherry-pick, but I want to just git am /reviewed/patches/dir/* without actually recalling what commits was corresponding to this patches (without reading patches, that is). So, what's wrong with git svn and git am? It's simple - git am for a few very hard points is doing CRLF into LF conversion for patches supplied (git-mailsplit is doing this, to be precise), if not rebasing. git format-patch is also producing proper (LF-ended) patches. As my repo is mostly CRLF (and it should remain so), patches are, obviously, failing due to wrong EOL. Converting diffs to CRLF and somehow hacking git am to prevent it from conversion is not working, too. It will fail if any file was removed or deleted - git apply will complain about expected /dev/null (but he got /dev/null^M). And if I'm applying it with git am --ignore-space-change --ignore-whitespace that it will commit LF endings straight to the index, which is also weird. I don't know if it will preserve over commiting into svn (via git svn dcommit) and checking it out and I don't want to try out. Of course, it's still possible to try hacking around patches to convert only actual diffs, but this is too much hacks for simple task. So, I wonder, is there really no established way to produce patches and apply them to the same repo on the same system? It just feels weird that msysgit can't apply it's own patches.

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• gcc/g++: error when compiling large file

  - by Alexander

  Hi, I have a auto-generated C++ source file, around 40 MB in size. It largely consists of push_back commands for some vectors and string constants that shall be pushed. When I try to compile this file, g++ exits and says that it couldn't reserve enough virtual memory (around 3 GB). Googling this problem, I found that using the command line switches --param ggc-min-expand=0 --param ggc-min-heapsize=4096 may solve the problem. They, however, only seem to work when optimization is turned on. 1) Is this really the solution that I am looking for? 2) Or is there a faster, better (compiling takes ages with these options acitvated) way to do this? Best wishes, Alexander Update: Thanks for all the good ideas. I tried most of them. Using an array instead of several push_back() operations reduced memory usage, but as the file that I was trying to compile was so big, it still crashed, only later. In a way, this behaviour is really interesting, as there is not much to optimize in such a setting -- what does the GCC do behind the scenes that costs so much memory? (I compiled with deactivating all optimizations as well and got the same results) The solution that I switched to now is reading in the original data from a binary object file that I created from the original file using objcopy. This is what I originally did not want to do, because creating the data structures in a higher-level language (in this case Perl) was more convenient than having to do this in C++. However, getting this running under Win32 was more complicated than expected. objcopy seems to generate files in the ELF format, and it seems that some of the problems I had disappeared when I manually set the output format to pe-i386. The symbols in the object file are by standard named after the file name, e.g. converting the file inbuilt_training_data.bin would result in these two symbols: binary_inbuilt_training_data_bin_start and binary_inbuilt_training_data_bin_end. I found some tutorials on the web which claim that these symbols should be declared as extern char _binary_inbuilt_training_data_bin_start;, but this does not seem to be right -- only extern char binary_inbuilt_training_data_bin_start; worked for me.

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• problem while displayin the texture image on view that works fine on iphone simulator but not on dev

  - by yunas

  hello i am trying to display an image on iphone by converting it into texture and then displaying it on the UIView. here is the code to load an image from an UIImage object - (void)loadImage:(UIImage *)image mipmap:(BOOL)mipmap texture:(uint32_t)texture { int width, height; CGImageRef cgImage; GLubyte *data; CGContextRef cgContext; CGColorSpaceRef colorSpace; GLenum err; if (image == nil) { NSLog(@"Failed to load"); return; } cgImage = [image CGImage]; width = CGImageGetWidth(cgImage); height = CGImageGetHeight(cgImage); colorSpace = CGColorSpaceCreateDeviceRGB(); // Malloc may be used instead of calloc if your cg image has dimensions equal to the dimensions of the cg bitmap context data = (GLubyte *)calloc(width * height * 4, sizeof(GLubyte)); cgContext = CGBitmapContextCreate(data, width, height, 8, width * 4, colorSpace, kCGImageAlphaPremultipliedLast); if (cgContext != NULL) { // Set the blend mode to copy. We don't care about the previous contents. CGContextSetBlendMode(cgContext, kCGBlendModeCopy); CGContextDrawImage(cgContext, CGRectMake(0.0f, 0.0f, width, height), cgImage); glGenTextures(1, &(_textures[texture])); glBindTexture(GL_TEXTURE_2D, _textures[texture]); if (mipmap) glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR); else glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data); if (mipmap) glGenerateMipmapOES(GL_TEXTURE_2D); err = glGetError(); if (err != GL_NO_ERROR) NSLog(@"Error uploading texture. glError: 0x%04X", err); CGContextRelease(cgContext); } free(data); CGColorSpaceRelease(colorSpace); } The problem that i currently am facing is this code workd perfectly fine and displays the image on simulator where as on the device as seen on debugger an error is displayed i.e. Error uploading texture. glError: 0x0501 any idea how to tackle this bug.... thnx in advance 4 ur soluitons

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• How to troubleshoot a Highcharts script that's not rendering data when date is added and hanging the JS engine with large datasets?

  - by ylluminate

  I have a Highchart JS graph that I'm building in Rails (although I don't think Ruby has real bearing on this problem unless it's the Date output format) to which I'm adding the timestamp of each datapoint. Presently the array of floats is rendering fine without timestamps, however when I add the timestamp to the series it fails to rend. What's worse is that when the series has hundreds of entries all sorts of problems arise, not the least of which is the browser entirely hanging and requiring a force quit / kill. I'm using the following to build the array of arrays data series: series1 = readings.map{|row| [(row.date.to_i * 1000), (row.data1.to_f if BigDecimal(row.data1) != BigDecimal("-1000.0"))] } This yields a result like this: series: [{"name":"Data 1","data":[[1326262980000,1.79e-09],[1326262920000,1.29e-09],[1326262860000,1.22e-09],[1326262800000,1.42e-09],[1326262740000,1.29e-09],[1326262680000,1.34e-09],[1326262620000,1.31e-09],[1326262560000,1.51e-09],[1326262500000,1.24e-09],[1326262440000,1.7e-09],[1326262380000,1.24e-09],[1326262320000,1.29e-09],[1326262260000,1.53e-09],[1326262200000,1.23e-09],[1326262140000,1.21e-09]],"color":"blue"}] Yet nothing appears on the graph as noted. Notwithstanding, when I compare the data series in one of their very similar examples here: http://www.highcharts.com/demo/spline-irregular-time It appears that really the data series are formatted identically (except in mine I use the timestamp vs date method). This leads me to think I've got a problem with the timestamp output, but I'm just not able to figure out where / how as I'm converting the date output to an integer multipled by 1000 to convert it to milliseconds as per explained in a similar Railscasts tutorial. I would very much appreciate it if someone could point me in the right direction here as to what I may be doing wrong. What could cause no data to appear on the graph in smaller sized sets (<100 points) and when into the hundreds causes an apparent hang in the javascript engine in this case? Perhaps ultimately the key lies here as this is the entire js that's being generated and not rendering: jQuery(function() { // 1. Define JSON options var options = { chart: {"defaultSeriesType":"spline","renderTo":"chart_name"}, title: {"text":"Title"}, legend: {"layout":"vertical","style":{}}, xAxis: {"title":{"text":"UTC Time"},"type":"datetime"}, yAxis: [{"title":{"text":"Left Title","margin":10}},{"title":{"text":"Right Groups Title"},"opposite":true}], tooltip: {"enabled":true}, credits: {"enabled":false}, plotOptions: {"areaspline":{}}, series: [{"name":"Data 1","data":[[1326262980000,1.79e-08],[1326262920000,1.69e-08],[1326262860000,1.62e-08],[1326262800000,1.42e-08],[1326262740000,1.29e-08],[1326262680000,1.34e-08],[1326262620000,1.31e-08],[1326262560000,1.51e-08],[1326262500000,1.64e-08],[1326262440000,1.7e-08],[1326262380000,1.64e-08],[1326262320000,1.69e-08],[1326262260000,1.53e-08],[1326262200000,1.23e-08],[1326262140000,1.21e-08]],"color":"blue"},{"name":"Data 2","data":[[1326262980000,9.79e-09],[1326262920000,9.78e-09],[1326262860000,9.8e-09],[1326262800000,9.82e-09],[1326262740000,9.88e-09],[1326262680000,9.89e-09],[1326262620000,1.3e-06],[1326262560000,1.32e-06],[1326262500000,1.33e-06],[1326262440000,1.33e-06],[1326262380000,1.34e-06],[1326262320000,1.33e-06],[1326262260000,1.32e-06],[1326262200000,1.32e-06],[1326262140000,1.32e-06]],"color":"red"}], subtitle: {} }; // 2. Add callbacks (non-JSON compliant) // 3. Build the chart var chart = new Highcharts.StockChart(options); });

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• C# - calling ext. DLL function containing Delphi "variant record" parameter

  - by CaldonCZE

  Hello, In external (Delphi-created) DLL I've got the following function that I need to call from C# application. function ReadMsg(handle: longword; var Msg: TRxMsg): longword; stdcall; external 'MyDll.dll' name 'ReadMsg'; The "TRxMsg" type is variant record, defined as follows: TRxMsg = record case TypeMsg: byte of 1: (accept, mask: longword); 2: (SN: string[6]); 3: (rx_rate, tx_rate: word); 4: (rx_status, tx_status, ctl0, ctl1, rflg: byte); end; In order to call the function from C#, I declared auxiliary structure "my9Bytes" containing array of bytes and defined that it should be marshalled as 9 bytes long array (which is exactly the size of the Delphi record). private struct my9Bytes { [MarshalAs(UnmanagedType.ByValArray, ArraySubType = UnmanagedType.U1, SizeConst = 9)] public byte[] data; } Then I declared the imported "ReadMsg" function, using the "my9bytes" struct. [DllImport("MyDll.dll")] private static extern uint ReadMsg(uint handle, ref my9Bytes myMsg); I can call the function with no problem... Then I need to create structure corresponding to the original "TRxMsg" variant record and convert my auxiliary "myMsg" array into this structure. I don't know any C# equivalent of Delphi variant array, so I used inheritance and created the following classes. public abstract class TRxMsg { public byte typeMsg; } public class TRxMsgAcceptMask:TRxMsg { public uint accept, mask; //... } public class TRxMsgSN:TRxMsg { public string SN; //... } public class TRxMsgMRate:TRxMsg { public ushort rx_rate, tx_rate; //... } public class TRxMsgStatus:TRxMsg { public byte rx_status, tx_status, ctl0, ctl1, rflg; //... } Finally I create the appropriate object and initialize it with values manually converted from "myMsg" array (I used BitConverter for this). This does work fine, this solution seems to me a little too complicated, and that it should be possible to do this somehow more directly, without the auxiliary "my9bytes" structures or the inheritance and manual converting of individual values. So I'd like to ask you for a suggestions for the best way to do this. Thanks a lot!

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• Creating and writing file from a FileOutputStream in Java

  - by Althane

  Okay, so I'm working on a project where I use a Java program to initiate a socket connection between two classes (a FileSender and FileReceiver). My basic idea was that the FileSender would look like this: try { writer = new DataOutputStream(connect.getOutputStream()); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } //While we have bytes to send while(filein.available() >0){ //We write them out to our buffer writer.write(filein.read(outBuffer)); writer.flush(); } //Then close our filein filein.close(); //And then our socket; connect.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); The constructor contains code that checks to see if the file exists, and that the socket is connected, and so on. Inside my FileReader is this though: input = recvSocket.accept(); BufferedReader br = new BufferedReader(new InputStreamReader(input.getInputStream())); FileOutputStream fOut= new FileOutputStream(filename); String line = br.readLine(); while(line != null){ fOut.write(line.getBytes()); fOut.flush(); line = br.readLine(); } System.out.println("Before RECV close statements"); fOut.close(); input.close(); recvSocket.close(); System.out.println("After RECV clsoe statements"); All inside a try-catch block. So, what I'm trying to do is have the FileSender reading in the file, converting to bytes, sending and flushing it out. FileReceiver, then reads in the bytes, writes to the fileOut, flushes, and continues waiting for more. I make sure to close all the things that I open, so... here comes the weird part. When I try and open the created text file in Eclipse, it tells me "An SWT error has occured ... recommended to exit the workbench... see .log for more details.". Another window pops up saying "Unhandled event loop exception, (no more handles)". However, if I try to open the sent text file in notepad2, I get ThisIsASentTextfile Which is good (well, minus the fact that there should be line breaks, but I'm working on that...). Does anyone know why this is happening? And while we're checking, how to add the line breaks? (And is this a particularly bad way to transfer files over java without getting some other libraries?)

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• union marshalling issue in C#

  - by senthil

  I have union inside structure and the structure looks like struct tDeviceProperty { DWORD Tag; DWORD Size; union _DP value; }; typedef union _DP { short int i; LONG l; ULONG ul; float flt; double dbl; BOOL b; double at; FILETIME ft; LPSTR lpszA; LPWSTR lpszW; LARGE_INTEGER li; struct tBinary bin; BYTE reserved[40]; } __UDP; struct tBinary { ULONG size; BYTE * bin; }; from the tBinary structure bin has to be converted to tImage (structure is given below) struct tImage { DWORD x; DWORD y; DWORD z; DWORD Resolution; DWORD type; DWORD ID; diccid_t SourceID; const void *buffer; const char *Info; const char *UserImageID; }; to use the same in c# I have done marshaling but not giving proper values when converting the pointer to structure. The C# code is follows, tBinary tBin = new tBinary(); IntPtr tBinbuffer = Marshal.AllocCoTaskMem(Marshal.SizeOf(tBin)); Marshal.StructureToPtr(tBin.bin, tBinbuffer, false); tDeviceProperty tDevice = new tDeviceProperty(); tDevice.bin = tBinbuffer; IntPtr tDevicebuffer = Marshal.AllocCoTaskMem(Marshal.SizeOf(tDevice)); Marshal.StructureToPtr(tDevice.bin, tDevicebuffer, false); Battary tbatt = new Battary(); tbatt.value = tDevicebuffer; IntPtr tbattbuffer = Marshal.AllocCoTaskMem(Marshal.SizeOf(tbatt)); Marshal.StructureToPtr(tbatt.value, tbattbuffer, false); result = GetDeviceProperty(ref tbattbuffer); Battary v = (Battary)Marshal.PtrToStructure(tbattbuffer, typeof(Battary)); tDeviceProperty v2 = (tDeviceProperty)Marshal.PtrToStructure(tDevicebuffer, typeof(tDeviceProperty)); tBinary v3 = (tBinary)Marshal.PtrToStructure(tBinbuffer, typeof(tBinary));

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• unable to capture picture using camera in j2me polish?

  - by SIVAKUMAR.J

  I'm, developing a mobile app in j2me.Now im converting it into j2me polish. In my app I capture a picture using camera in mobile phone. It works fine in j2me. But it does not work fine in j2me polish. I cannot resolve it. The code snippet given below public class VideoCanvas extends Canvas { // private VideoMIDlet midlet; // Form frm Form frm=null; public VideoCanvas(VideoControl videoControl) { int width = getWidth(); int height = getHeight(); // this.midlet = midlet; //videoControl.initDisplayMode(VideoControl.USE_DIRECT_VIDEO, this); //Canvas canvas = StyleSheet.currentScreen; //canvas = MasterCanvas.instance; videoControl.initDisplayMode( VideoControl.USE_DIRECT_VIDEO,this); try { videoControl.setDisplayLocation(2, 2); videoControl.setDisplaySize(width - 4, height - 4); } catch (MediaException me) {} videoControl.setVisible(true); } public VideoCanvas(VideoControl videoControl,Form ff) { frm=ff; int width = getWidth(); int height = getHeight(); // this.midlet = midlet; Ticker ticker=new Ticker("B4 video controll init"); frm.setTicker(ticker); //Canvas canvas = StyleSheet.currentScreen; videoControl.initDisplayMode(VideoControl.USE_DIRECT_VIDEO,this); ticker=new Ticker("after video controll init"); frm.setTicker(ticker); try { videoControl.setDisplayLocation(2, 2); videoControl.setDisplaySize(width - 4, height - 4); } catch (MediaException me) {} videoControl.setVisible(true); ticker=new Ticker("Device not supported"); frm.setTicker(ticker); } public void paint(Graphics g) { int width = getWidth(); int height = getHeight(); g.setColor(0x00ff00); g.drawRect(0, 0, width - 1, height - 1); g.drawRect(1, 1, width - 3, height - 3); } } In normal j2me the above code works correctly. But in j2me polish videoControl.initDisplayMode(VideoControl.USE_DIRECT_VIDEO,this) here this refers to VideoCanvas (which extends from javax.microedition.lcdui.Canvas). But it throws an "IllegalArgumentException - container should be canvas" like that. How to solve the issue?

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• iPhone Image Resources, ICO vs PNG, app bundle filesize

  - by Jasarien

  My application has a collection of around 1940 icons that are used throughout. They're currently in ICO and new images provided to me come in ICO format too. I have noticed that they contain a 16x16 and 32x32 representation of each icon in one file. Each file is roughly 4KB in filesize (as reported by finder, but ls reports that they vary from being ~1000 bytes to 5000 bytes) A very small number of these icons only contain the 32x32 representation, and as a result are only around 700 bytes in size. Currently I am bundling these icons with my application and they are inflating the size of the app a bit more than I would like. Altogether, the images total just about 25.5MB. Xcode must do some kind of compression because the resulting app bundle is about 12.4MB. Compressing this further into a ZIP (as it would be when submitted to the App Store), results in a final file of 5.8MB. I'm aware that the maximum limit for over the air App Store downloads has been raised to 20MB since the introduction of the iPad (I'm not sure if that extends to iPhone apps as well as iPad apps though, if not the limit would be 10MB). My worry is that new icons are going to be added (sometimes up to 10 icons per week), and will continue to inflate the app bundle over time. What is the best way to distribute these icons with my app? Things I've tried and not had much success with: Converting the icons from ICO to PNG: I tried this in the hopes that the pngcrush utility would help out with the filesize. But it appears that it doesn't make much of a difference between a normal PNG and a crushed png (I believe it just optimises the image for display on the iPhone's GPU rather than compress it's size). Also in going from ICO to PNG actually increased the size of the icon file... Zipping the images, and then uncompressing them on first run. While this did reduce the overall image sizes, I found that the effort needed to unzip them, copy them to the documents folder and ensure that duplication doesn't happen on upgrades was too much hassle to be worth the benefit. Also, on original and 3G iPhones unzipping and copying around 25MB of images takes too long and creates a bad experience... Things I've considered but not yet tried: Instead of distributing the icons within the app bundle, host them online, and download each icon on demand (it depends on the user's data as to which icons will actually be displayed and when). Issues with this is that bandwidth costs money, and image downloads will be bandwidth intensive. However, my app currently has a small userbase of around 5,500 users (of which I estimate around 1500 to be active based on Flurry stats), and I have a huge unused bandwidth allowance with my current hosting package. So I'm open to thoughts on how to solve this tricky issue.

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• Class template specializations with shared functionality

  - by Thomas

  I'm writing a simple maths library with a template vector type: template<typename T, size_t N> class Vector { public: Vector<T, N> &operator+=(Vector<T, N> const &other); // ... more operators, functions ... }; Now I want some additional functionality specifically for some of these. Let's say I want functions x() and y() on Vector<T, 2> to access particular coordinates. I could create a partial specialization for this: template<typename T> class Vector<T, 3> { public: Vector<T, 3> &operator+=(Vector<T, 3> const &other); // ... and again all the operators and functions ... T x() const; T y() const; }; But now I'm repeating everything that already existed in the generic template. I could also use inheritance. Renaming the generic template to VectorBase, I could do this: template<typename T, size_t N> class Vector : public VectorBase<T, N> { }; template<typename T> class Vector<T, 3> : public VectorBase<T, 3> { public: T x() const; T y() const; }; However, now the problem is that all operators are defined on VectorBase, so they return VectorBase instances. These cannot be assigned to Vector variables: Vector<float, 3> v; Vector<float, 3> w; w = 5 * v; // error: no conversion from VectorBase<float, 3> to Vector<float, 3> I could give Vector an implicit conversion constructor to make this possible: template<typename T, size_t N> class Vector : public VectorBase<T, N> { public: Vector(VectorBase<T, N> const &other); }; However, now I'm converting from Vector to VectorBase and back again. Even though the types are the same in memory, and the compiler might optimize all this away, it feels clunky and I don't really like to have potential run-time overhead for what is essentially a compile-time problem. Is there any other way to solve this?

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• Need some constructive criticism on my SSE/Assembly attempt

  - by Brett

  Hello, I'm working on converting a bit of code to SSE, and while I have the correct output it turns out to be slower than standard c++ code. The bit of code that I need to do this for is: float ox = p2x - (px * c - py * s)*m; float oy = p2y - (px * s - py * c)*m; What I've got for SSE code is: void assemblycalc(vector4 &p, vector4 &sc, float &m, vector4 &xy) { vector4 r; __m128 scale = _mm_set1_ps(m); __asm { mov eax, p //Load into CPU reg mov ebx, sc movups xmm0, [eax] //move vectors to SSE regs movups xmm1, [ebx] mulps xmm0, xmm1 //Multiply the Elements movaps xmm2, xmm0 //make a copy of the array shufps xmm2, xmm0, 0x1B //shuffle the array subps xmm0, xmm2 //subtract the elements mulps xmm0, scale //multiply the vector by the scale mov ecx, xy //load the variable into cpu reg movups xmm3, [ecx] //move the vector to the SSE regs subps xmm3, xmm0 //subtract xmm3 - xmm0 movups [r], xmm3 //Save the retun vector, and use elements 0 and 3 } } Since its very difficult to read the code, I'll explain what I did: loaded vector4 , xmm0 _ p = [px , py , px , py ] mult. by vector4, xmm1 _ cs = [c , c , s , s ] _____________mult---------------------------- result,______ xmm0 = [px*c, py*c, px*s, py*s] reuse result, xmm0 = [px*c, py*c, px*s, py*s] shuffle result, xmm2 = [py*s, px*s, py*c, px*c] ___________subtract---------------------------- result, xmm0 = [px*c-py*s, py*c-px*s, px*s-py*c, py*s-px*c] reuse result, xmm0 = [px*c-py*s, py*c-px*s, px*s-py*c, py*s-px*c] load m vector4, scale = [m, m, m, m] ______________mult---------------------------- result, xmm0 = [(px*c-py*s)*m, (py*c-px*s)*m, (px*s-py*c)*m, (py*s-px*c)*m] load xy vector4, xmm3 = [p2x, p2x, p2y, p2y] reuse, xmm0 = [(px*c-py*s)*m, (py*c-px*s)*m, (px*s-py*c)*m, (py*s-px*c)*m] ___________subtract---------------------------- result, xmm3 = [p2x-(px*c-py*s)*m, p2x-(py*c-px*s)*m, p2y-(px*s-py*c)*m, p2y-(py*s-px*c)*m] then ox = xmm3[0] and oy = xmm3[3], so I essentially don't use xmm3[1] or xmm3[4] I apologize for the difficulty reading this, but I'm hoping someone might be able to provide some guidance for me, as the standard c++ code runs in 0.001444ms and the SSE code runs in 0.00198ms. Let me know if there is anything I can do to further explain/clean this up a bit. The reason I'm trying to use SSE is because I run this calculation millions of times, and it is a part of what is slowing down my current code. Thanks in advance for any help! Brett

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• Myself throwing NullReferenceException... needs help

  - by Amit Ranjan

  I know it might be a weird question and its Title too, but i need your help. I am a .net dev , working on platform for the last 1.5 years. I am bit confused on the term usually we say " A Good Programmer ". I dont know ,what are the qualities of a good programmer ? Is the guy who writes a bug free code? or Can develop applications solely? or blah blah blah...lots of points. I dont know... But as far i am concerned , I know I am not a good programmer, still in learning phase an needs a lot to learn in coming days. So you guys are requested to please help me with this two problems of mine My first problem is regarding the proper Error Handling, which is a most debatable aspect of programming. We all know we use ` try { } catch { } finally { } ` in our code to manage exception. But even if I use try { } catch(exception ex) { throw ex } finally { } , different guys have different views. I still dont know the good way to handle errors. I can write code, use try-catch but still i feel I lacks something. When I saw the codes generated by .net fx tools even they uses throw ex or `throw new Exception("this is my exception")`.. I am just wondering what will be the best way to achieve the above. All means the same thing but why we avoid something. If it has some demerits then it must be made obselete.Anyways I still dont have one [how to handle errors efficiently?]. I generally follow the try-catch(execoption ex){throw ex}, and usually got stucked in debates with leads why you follow this why not that... 2.Converting your entire code blocks in modules using Design patterns of some OOPs concepts. How do you guys decide what architeture or pattern will be the best for my upcoming application based on its working, flow etc. I need to know what you guys can see that I can't. Since I know , I dont have that much experience but I can say, with my experience that experience doesnot comes either from degree/certificates or success you made instead it cames from failures you faced or got stucking situations. Pleas help me out.

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• Poor man's "lexer" for C#

  - by Paul Hollingsworth

  I'm trying to write a very simple parser in C#. I need a lexer -- something that lets me associate regular expressions with tokens, so it reads in regexs and gives me back symbols. It seems like I ought to be able to use Regex to do the actual heavy lifting, but I can't see an easy way to do it. For one thing, Regex only seems to work on strings, not streams (why is that!?!?). Basically, I want an implementation of the following interface: interface ILexer : IDisposable { /// <summary> /// Return true if there are more tokens to read /// </summary> bool HasMoreTokens { get; } /// <summary> /// The actual contents that matched the token /// </summary> string TokenContents { get; } /// <summary> /// The particular token in "tokenDefinitions" that was matched (e.g. "STRING", "NUMBER", "OPEN PARENS", "CLOSE PARENS" /// </summary> object Token { get; } /// <summary> /// Move to the next token /// </summary> void Next(); } interface ILexerFactory { /// <summary> /// Create a Lexer for converting a stream of characters into tokens /// </summary> /// <param name="reader">TextReader that supplies the underlying stream</param> /// <param name="tokenDefinitions">A dictionary from regular expressions to their "token identifers"</param> /// <returns>The lexer</returns> ILexer CreateLexer(TextReader reader, IDictionary<string, object> tokenDefinitions); } So, pluz send the codz... No, seriously, I am about to start writing an implementation of the above interface yet I find it hard to believe that there isn't some simple way of doing this in .NET (2.0) already. So, any suggestions for a simple way to do the above? (Also, I don't want any "code generators". Performance is not important for this thing and I don't want to introduce any complexity into the build process.)

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• Are there known problems with >= and <= and the eval function in JS?

  - by Augier

  I am currently writing a JS rules engine which at one point needs to evaluate boolean expressions using the eval() function. Firstly I construct an equation as such: var equation = "relation.relatedTrigger.previousValue" + " " + relation.operator + " " + "relation.value"; relation.relatedTrigger.previousValue is the value I want to compare. relation.operator is the operator (either "==", "!=", <=, "<", "", ="). relation.value is the value I want to compare with. I then simply pass this string to the eval function and it returns true or false as such: return eval(equation); This works absolutely fine (with words and numbers) or all of the operators except for = and <=. E.g. When evaluating the equation: relation.relatedTrigger.previousValue <= 100 It returns true when previousValue = 0,1,10,100 & all negative numbers but false for everything in between. I would greatly appreciate the help of anyone to either answer my question or to help me find an alternative solution. Regards, Augier. P.S. I don't need a speech on the insecurities of the eval() function. Any value given to relation.relatedTrigger.previousValue is predefined. edit: Here is the full function: function evaluateRelation(relation) { console.log("Evaluating relation") var currentValue; //if multiple values if(relation.value.indexOf(";") != -1) { var values = relation.value.split(";"); for (x in values) { var equation = "relation.relatedTrigger.previousValue" + " " + relation.operator + " " + "values[x]"; currentValue = eval(equation); if (currentValue) return true; } return false; } //if single value else { //Evaluate the relation and get boolean var equation = "relation.relatedTrigger.previousValue" + " " + relation.operator + " " + "relation.value"; console.log("relation.relatedTrigger.previousValue " + relation.relatedTrigger.previousValue); console.log(equation); return eval(equation); } } Answer: Provided by KennyTM below. A string comparison doesn't work. Converting to a numerical was needed.

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• Calculating rotation and translation matrices between two odometry positions for monocular linear triangulation

  - by user1298891

  Recently I've been trying to implement a system to identify and triangulate the 3D position of an object in a robotic system. The general outline of the process goes as follows: Identify the object using SURF matching, from a set of "training" images to the actual live feed from the camera Move/rotate the robot a certain amount Identify the object using SURF again in this new view Now I have: a set of corresponding 2D points (same object from the two different views), two odometry locations (position + orientation), and camera intrinsics (focal length, principal point, etc.) since it's been calibrated beforehand, so I should be able to create the 2 projection matrices and triangulate using a basic linear triangulation method as in Hartley & Zissermann's book Multiple View Geometry, pg. 312. Solve the AX = 0 equation for each of the corresponding 2D points, then take the average In practice, the triangulation only works when there's almost no change in rotation; if the robot even rotates a slight bit while moving (due to e.g. wheel slippage) then the estimate is way off. This also applies for simulation. Since I can only post two hyperlinks, here's a link to a page with images from the simulation (on the map, the red square is simulated robot position and orientation, and the yellow square is estimated position of the object using linear triangulation.) So you can see that the estimate is thrown way off even by a little rotation, as in Position 2 on that page (that was 15 degrees; if I rotate it any more then the estimate is completely off the map), even in a simulated environment where a perfect calibration matrix is known. In a real environment when I actually move around with the robot, it's worse. There aren't any problems with obtaining point correspondences, nor with actually solving the AX = 0 equation once I compute the A matrix, so I figure it probably has to do with how I'm setting up the two camera projection matrices, specifically how I'm calculating the translation and rotation matrices from the position/orientation info I have relative to the world frame. How I'm doing that right now is: Rotation matrix is composed by creating a 1x3 matrix [0, (change in orientation angle), 0] and then converting that to a 3x3 one using OpenCV's Rodrigues function Translation matrix is composed by rotating the two points (start angle) degrees and then subtracting the final position from the initial position, in order to get the robot's straight and lateral movement relative to its starting orientation Which results in the first projection matrix being K [I | 0] and the second being K [R | T], with R and T calculated as described above. Is there anything I'm doing really wrong here? Or could it possibly be some other problem? Any help would be greatly appreciated.

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• markdown to HTML with customised WMD editor

  - by spirytus

  For my application I customized slightly the way WMD behaves so when user enters empty lines, these are reflected in HTML output as <br />'s. Now I came to a point when I should store it somewhere at backend and so after going thru SO posts for a while I'm not sure what is the best way to do it. I have few options and if you could point out which their pros/cons that would be much appreciated. send to server and store as markdown rather than HTML. To me obvious advantage would be keeping exactly same formatting as user originally entered. But then how can I convert it back to HTML for display to a client? It seems very troublesome to convert it on client side as even if it would be possible what would happen if JS would be disabled? If I wanted to do it on the server, then standard server side implementations of markup to HTML might be resource expensive. Would that be an issue in your opinion? Even if it wouldn't be the case then as I mentioned my WMD implementation is customised and those server side solutions wouldn't probably do the right conversion to markdown anyway and there always would be a risk that something would convert wrong. Send to server as converted HTML. Same as above.. conversion on client side would be difficult, server side same with possibility of getting it wrong. send original markdown and converted HTML and store both. No performance issues related to converting markdown to HTML on client side, nor on server side. Users would have always same markdown they originally entered and same HTML they originally saw in preview (possibly sanitized in php though). It would have to take twice that much storage space though and that is my biggest worry. I tend to lean towards 3rd solution as it seems simplest, but there is a worry of doubled storage space needed for this solution. Please bear in mind that my implementation of WMD is slightly modified and also I'm going with PHP/MySql server side implementation. So apart from 3 options I listed above, are there any other possible solutions to my problem? Did I miss anything important that would make one of the options above better then the rest? And what other pros/cons would apply to each solution I listed? Also how is it implemented on SO? I read somwhere that they using option 3, and so if its good enough for SO would be good enough for me :) but not sure if its true anyway, so how is it done? Also please forgive me, but at least for once I got to say that StackOverflow IS THE BEST DAMN RESOURCE ON THE WEB and I truly appreciate all the people trying to help others here! The site and users here are simply amazing!

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• Modify audio pitch of recorded clip (m4v)

  - by devcube

  I'm writing an app in which I'm trying to change the pitch of the audio when I'm recording a movie (.m4v). Or by modifying the audio pitch of the movie afterwards. I want the end result to be a movie (.m4v) that has the original length (i.e. same visual as original) but with modified sound pitch, e.g. a "chipmunk voice". A realtime conversion is to prefer if possible. I've read alot about changing audio pitch in iOS but most examples focus on playback, i.e. playing the sound with a different pitch. In my app I'm recording a movie (.m4v / AVFileTypeQuickTimeMovie) and saving it using standard AVAssetWriter. When saving the movie I have access to the following elements where I've tried to manipulate the audio (e.g. modify the pitch): audio buffer (CMSampleBufferRef) audio input writer (AVAssetWriterAudioInput) audio input writer options (e.g. AVNumberOfChannelsKey, AVSampleRateKey, AVChannelLayoutKey) asset writer (AVAssetWriter) I've tried to hook into the above objects to modify the audio pitch, but without success. I've also tried with Dirac as described here: Real Time Pitch Change In iPhone Using Dirac And OpenAL with AL_PITCH as described here: Piping output from OpenAL into a buffer And the "BASS" library from un4seen: Change Pitch/Tempo In Realtime I haven't found success with any of the above libs, most likely because I don't really know how to use them, and where to hook them into the audio saving code. There seems to be alot of librarys that have similar effects but focuses on playback or custom recording code. I want to manipulate the audio stream I've already got (AVAssetWriterAudioInput) or modify the saved movie clip (.m4v). I want the video to be unmodifed visually, i.e. played at the same speed. But I want the audio to go faster (like a chipmunk) or slower (like a ... monster? :)). Do you have any suggestions how I can modify the pitch in either real time (when recording the movie) or afterwards by converting the entire movie (.m4v file)? Should I look further into Dirac, OpenAL, SoundTouch, BASS or some other library? I want to be able to share the movie to others with modified audio, that's the reason I can't rely on modifying the pitch for playback only. Any help is appreciated, thanks!

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• ASP.NET MVC: How can I explain an invalid type violation to an end-user with Html.ValidationSummary?

  - by Terminal Frost

  Serious n00b warning here; please take mercy! So I finished the Nerd Dinner MVC Tutorial and I'm now in the process of converting a VB.NET application to ASP.NET MVC using the Nerd Dinner program as a sort of rough template. I am using the "IsValid / GetRuleViolations()" pattern to identify invalid user input or values that violate business rules. I am using LINQ to SQL and am taking advantage of the "OnValidate()" hook that allows me to run the validation and throw an application exception upon trying to save changes to the database via the CustomerRepository class. Anyway, everything works well, except that by the time the form values reach my validation method invalid types have already been converted to a default or existing value. (I have a "StreetNumber" property that is an integer, though I imagine this would be a problem for DateTime or any other non-strings as well.) Now, I am guessing that the UpdateModel() method throws an exception and then alters the value because the Html.ValidationMessage is displayed next to the StreetNumber field but my validation method never sees the original input. There are two problems with this: While the Html.ValidationMessage does signal that something is wrong, there is no corresponding entry in the Html.ValidationSummary. If I could even get the exception message to show up there indicating an invalid cast or something that would be better than nothing. My validation method which resides in my Customer partial class never sees the original user input so I do not know if the problem is a missing entry or an invalid type. I can't figure out how I can keep my validation logic nice and neat in one place and still get access to the form values. I could of course write some logic in the View that processes the user input, however that seems like the exact opposite of what I should be doing with MVC. Do I need a new validation pattern or is there some way to pass the original form values to my model class for processing? CustomerController Code // POST: /Customers/Edit/[id] [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(int id, FormCollection formValues) { Customer customer = customerRepository.GetCustomer(id); try { UpdateModel(customer); customerRepository.Save(); return RedirectToAction("Details", new { id = customer.AccountID }); } catch { foreach (var issue in customer.GetRuleViolations()) ModelState.AddModelError(issue.PropertyName, issue.ErrorMessage); } return View(customer); }

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• ActionResult - Service

  - by cem

  I bored, writing same code for service and ui. Then i tried to write a converter for simple actions. This converter, converting Service Results to MVC result, seems like good solution for me but anyway i think this gonna opposite MVC pattern. So here, I need help, what you think about algorithm - is this good or not? Thanks ServiceResult - Base: public abstract class ServiceResult { public static NoPermissionResult Permission() { return new NoPermissionResult(); } public static SuccessResult Success() { return new SuccessResult(); } public static SuccessResult<T> Success<T>(T result) { return new SuccessResult<T>(result); } protected ServiceResult(ServiceResultType serviceResultType) { _resultType = serviceResultType; } private readonly ServiceResultType _resultType; public ServiceResultType ResultType { get { return _resultType; } } } public class SuccessResult<T> : ServiceResult { public SuccessResult(T result) : base(ServiceResultType.Success) { _result = result; } private readonly T _result; public T Result { get { return _result; } } } public class SuccessResult : SuccessResult<object> { public SuccessResult() : this(null) { } public SuccessResult(object o) : base(o) { } } Service - eg. ForumService: public ServiceResult Delete(IVUser user, int id) { Forum forum = Repository.GetDelete(id); if (!Permission.CanDelete(user, forum)) { return ServiceResult.Permission(); } Repository.Delete(forum); return ServiceResult.Success(); } Controller: public class BaseController { public ActionResult GetResult(ServiceResult result) { switch (result.ResultType) { case ServiceResultType.Success: var successResult = (SuccessResult)result; return View(successResult.Result); break; case ServiceResultType.NoPermission: return View("Error"); break; default: return View(); break; } } } [HandleError] public class ForumsController : BaseController { [ValidateAntiForgeryToken] [Transaction] [AcceptVerbs(HttpVerbs.Post)] public ActionResult Delete(int id) { ServiceResult result = ForumService.Delete(WebUser.Current, id); /* Custom result */ if (result.ResultType == ServiceResultType.Success) { TempData[ControllerEnums.GlobalViewDataProperty.PageMessage.ToString()] = "The forum was successfully deleted."; return this.RedirectToAction(ec => Index()); } /* Custom result */ /* Execute Permission result etc. */ TempData[ControllerEnums.GlobalViewDataProperty.PageMessage.ToString()] = "A problem was encountered preventing the forum from being deleted. " + "Another item likely depends on this forum."; return GetResult(result); } }

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• writing a Simplest XML DeSerialization class for the simplest xml file. How to avoid the nesting? de

  - by Enggr

  Hi, I want to deserialize an xml file which has to be just in this form <Basket> <Fruit>Apple</Fruit> <Fruit>Orange</Fruit> <Fruit>Grapes</Fruit> </Basket> Out of the examples I read on internet the least possible format I could find was the following <Basket> <FruitArray> <Fruit>Apple</Fruit> </FruitArray> <FruitArray> <Fruit>Orange</Fruit> </FruitArray> <FruitArray> <Fruit>Grapes</Fruit> </FruitArray> </Basket> and that has the following deserialization class for converting it into a class object. using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace XMLSerialization_Basket { [System.Xml.Serialization.XmlRootAttribute("Basket", Namespace = "BasketNamespace", IsNullable = false)] public class Basket { /// <remarks/> [System.Xml.Serialization.XmlElementAttribute("FruitArray")] public FruitArray[] objFruitArray; } /// <remarks/> [System.Xml.Serialization.XmlTypeAttribute(Namespace = "BasketNamespace")] public class FruitArray { /// <remarks/> private string _Fruit; public string Fruit { get { return _Fruit; } set { _Fruit = value; } } } } Can I add something like the following directly under top class private string _Fruit; public string Fruit { get { return _Fruit; } set { _Fruit = value; } } and avoid the array nesting? my goal is to deserialize an xml of following format <Basket> <Fruit>Apple</Fruit> <Fruit>Orange</Fruit> <Fruit>Grapes</Fruit> </Basket>

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• iPhone: how to keep integer value on UILabel

  - by Nandakishore

  i am working on Twitter on iPhone now i have to keep the count of Friend, Tweets, Followers etc on UILabel how to work with this (void)userInfoReceived:(NSArray *)userInfo forRequest:(NSString *)connectionIdentifier { NSLog(@"User Info Received: %@", userInfo); // userInfo contains all user details like userName, screenName, count of Friends, Followers, Following, Status Count etc NSLog(@"User Info Received: %d", [userInfo count]); NSMutableDictionary *profileData = [userInfo objectAtIndex:0]; //converting userInfo array into profileData dictionary lblUserName.text = [profileData objectForKey:@"name"]; // lblUserName is UILabel, userName keeping on Label lblLocation.text = [profileData objectForKey:@"location"]; // lblLocation is UILabel, Location keeping on Label lblDescription.text = [profileData objectForKey:@"description"]; // lblDescription is UILabel, Location keeping on Label /////* Up to here all working but how to Keep integer value on UILabel *///// lblFolCount = (NSNumber *)[profileData objectForKey:@"followers_count"]; //how to keep user Followers Count on UILable lblFavCount = (NSNumber *)[profileData objectForKey:@"favourites_count"]; //how to keep user Followers Count on UILable lblStatusCount = (NSNumber *) [profileData objectForKey:@"statuses_count"]; //how to keep user statuses count on UILable lblFriends = (NSNumber *) [profileData objectForKey:@"friends_count"]; //how to keep user friends count on UILable } ////**This info Display on debugger console*/////// ////NSLog(@"User Info Received: %@", userInfo); // by this we get info on debugger console User Info Received: ( { "created_at" = "Tue Nov 02 14:42:42 +0000 2010"; description = "being honest"; favorited = false; "favourites_count" = 0; "followers_count" = 5; "friends_count" = 21; "listed_count" = 0; location = Chennai; name = "nanda kishore reddyv"; "profile_background_color" = EDECE9; "profile_background_image_url" = "http://a2.twimg.com/a/1292975674/images/themes/theme3/bg.gif"; "profile_background_tile" = false; "profile_image_url" = "http://a2.twimg.com/a/1292975674/images/default_profile_6_normal.png"; "retweet_count" = 0; "screen_name" = velugotinanda; source = "<a href=\"http://www.icodeblog.com\" rel=\"nofollow\">iCodeBlog Oauth Demo</a>"; status = "Mon Dec 27 09:22:44 +0000 2010"; "statuses_count" = 15; "time_zone" = "Indiana (East)"; verified = false; } ) 2011-01-01 10:38:29.460 IdeaTweet[471:207] User Info Received: 1 Thanks YOU can you tell me how to Keep integer Value on UILabel

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• Windows phone app xaml error

  - by thewarri0r9

  i am developing an app for windows phone 8 and i stuck on this code which visual studio showing invalid xaml. But Code compiles and works well. Invalid xaml Code is : <DataTemplate x:Key="AddrBookItemTemplate"> <StackPanel Margin="0,0,0,2" Orientation="Horizontal"> <StackPanel Width="80" Orientation="Horizontal" Height="80"> <Ellipse Margin="0" Height="70" Width="70" HorizontalAlignment="Left" Stroke="{x:Null}"> <Ellipse.Fill> <ImageBrush Stretch="Fill" ImageSource="{Binding imageBytes, Converter={StaticResource BytesToImageConverter}}"/> </Ellipse.Fill> </Ellipse> </StackPanel> <StackPanel Height="80" Margin="0" Width="380" HorizontalAlignment="Left"> <TextBlock FontWeight="Bold" Text="{Binding FirstName}" FontFamily="Segoe WP Semibold" FontSize="30" VerticalAlignment="Top" Margin="5,0,0,0" HorizontalAlignment="Left" /> <TextBlock Text="{Binding Phone}" FontFamily="Segoe WP" FontSize="24" Foreground="{StaticResource PhoneTextBoxReadOnlyBrush}" Margin="5,0,0,-12" Width="320" HorizontalAlignment="Left" VerticalAlignment="Top"/> </StackPanel> </StackPanel> </DataTemplate> I am serializing image by converting it to byte, it works fine but if image is null it gives an error. code behind: if (e.Results != null) { List<AddressBook> source = new List<AddressBook>(); foreach (var result in e.Results) { if (result.PhoneNumbers.FirstOrDefault() != null && result.GetPicture()!=null) { BitmapImage bmp = new BitmapImage(); BitmapImage nullbmp = new BitmapImage(); if (result.GetPicture() == null) { bmp.UriSource = new Uri(@"/Images/ci2.png", UriKind.RelativeOrAbsolute); } else { bmp.SetSource(result.GetPicture()); } listobj.Add(new AddressBook() { FirstName = result.DisplayName != null ? result.DisplayName : "", imageBytes = AddressBook.imageConvert(bmp), EmailAddress = "", LastName = "", Phone = result.PhoneNumbers.FirstOrDefault() != null ? result.PhoneNumbers.FirstOrDefault().PhoneNumber : "", }); } } Above code show an error "object reference not set to instance of an object". I want to show the default image (or color) in ellipse when image is null.What should I do?

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• Helping linqtosql datacontext use implicit conversion between varchar column in the database and tab

  - by user213256

  I am creating an mssql database table, "Orders", that will contain a varchar(50) field, "Value" containing a string that represents a slightly complex data type, "OrderValue". I am using a linqtosql datacontext class, which automatically types the "Value" column as a string. I gave the "OrderValue" class implicit conversion operators to and from a string, so I can easily use implicit conversion with the linqtosql classes like this: // get an order from the orders table MyDataContext db = new MyDataContext(); Order order = db.Orders(o => o.id == 1); // use implicit converstion to turn the string representation of the order // value into the complex data type. OrderValue value = order.Value; // adjust one of the fields in the complex data type value.Shipping += 10; // use implicit conversion to store the string representation of the complex // data type back in the linqtosql order object order.Value = value; // save changes db.SubmitChanges(); However, I would really like to be able to tell the linqtosql class to type this field as "OrderValue" rather than as "string". Then I would be able to avoid complex code and re-write the above as: // get an order from the orders table MyDataContext db = new MyDataContext(); Order order = db.Orders(o => o.id == 1); // The Value field is already typed as the "OrderValue" type rather than as string. // When a string value was read from the database table, it was implicity converted // to "OrderValue" type. order.Value.Shipping += 10; // save changes db.SubmitChanges(); In order to achieve this desired goal, I looked at the datacontext designer and selected the "Value" field of the "Order" table. Then, in properties, I changed "Type" to "global::MyApplication.OrderValue". The "Server Data Type" property was left as "VarChar(50) NOT NULL" The project built without errors. However, when reading from the database table, I was presented with the following error message: Could not convert from type 'System.String' to type 'MyApplication.OrderValue'. at System.Data.Linq.DBConvert.ChangeType(Object value, Type type) at Read_Order(ObjectMaterializer1 ) at System.Data.Linq.SqlClient.ObjectReaderCompiler.ObjectReader2.MoveNext() at System.Linq.Buffer1..ctor(IEnumerable1 source) at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source) at Example.OrdersProvider.GetOrders() at ... etc From the stack trace, I believe this error is happening while reading the data from the table. When presented with converting a string to my custom data type, even though the implicit conversion operators are present, the DBConvert class gets confused and throws an error. Is there anything I can do to help it not get confused and do the implicit conversion? Thanks in advance, and apologies if I have posted in the wrong forum. cheers / Ben

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