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  • How to configure mspaint on Windows Server 2008R2/ Win 7 to start up with 1-pixel canvas or auto-crop a pasted image?

    - by Fantomas
    I do a lot of screen print capturing, and I have just figured out how to use AutoHotKey to paste screen prints into MsPaint automatically. How to paste Print Screen on MS Paint automatically when press "PrtSc" button ? However, one small problem I have is that ... if I grabbed a screen with Alt-Prt Scr that is only 50x50 pixels, then there would be extra white margin around it, because MSPaint starts out with a larger canvas by default. How can I make it ALWAYS start with 1x1 instead?

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  • What LPR arguments do I need to print a 1400x800 pixel image on a 4x6 label?

    - by Nick
    This is driving me nuts. UPS sends our system a 1400x800 GIF image of a shipping label, which is supposed to fit nicely on a 4x6 page. Unfortunately, I can't seem to get the command line options right to make it happen. We're using an Eltron/Zebra 2844 with a network adapter, and printing from our Ubuntu 8.04 server using CUPS. We're using the correct drivers, and test pages print correctly. No matter what I try though, it insists on printing the UPS labels accross 6 pages, with a little bit of the label on each page, or way too small. I've tried a bazillion different lpr settings, most of them producing garbage. The closest I've gotten is this: lpr -P Eltron2844 -o natural-scaling=55 -o page-right=0 -o page-left=0 -o landscape -o media="4x6" ./1ZY437560399620027.gif but it causes the image to be too small on the page. It's about an inch too short, and there's a 1/2" margin on both sides. If I bump the scale up to 56, it explodes the image onto two pages, and squashes it. Any ideas?

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  • Wpf: Why is WriteableBitmap getting slower?

    - by fritz
    There is a simple MSDN example about WriteableBitmap. It shows how to draw a freehand line with the cursor by just updating one pixel when the mouse is pressed and is moving over a WPF -Image Control. writeableBitmap.Lock(); (...set the writeableBitmap.BackBuffers pixel value...) writeableBitmap.AddDirtyRect(new Int32Rect(column, row, 1, 1)); writeableBitmap.Unlock(); Now I'm trying to understand the following behaviour when moving the mouse pointer very fast: If the image/bitmap size is relatively small e.g. 800:600 pixel, then the last drawn pixel is always "synchronized" with the mouse pointers position, i.e. there is no delay, very fast reaction on mouse movements. But if the bitmap gets larger e.g. 1300:1050 pixel, you can notice a delay, the last drawn pixel always appear a bit delayed behind the moving mouse pointer. So as in both cases only one pixel gets updated with "AddDirtyRect", the reaction speed should be independent from the bitmap size!? But it seems that Writeablebitmap gets slower when it's size gets larger. Or does the whole bitmap somehow get transferred to the graphic device on every writeableBitmap.Unlock(); call , and not only the rectangle area speficied in the AddDirtyRect method? fritz

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  • RMagic Error in rails, with AM Charts

    - by Elliot
    Hi Everyone, I'm using AMCharts and rails. AMCharts uses the Image Magic lib to export an image of the chart. In rails this is done with the gem, RMagic. In a controller this is implemented with the following controller method: def export width = params[:width].to_i height = params[:height].to_i data = {} img = Magick::Image.new(width, height) height.times do |y| row = params["r#{y}"].split(',') row.size.times do |r| pixel = row[r].to_s.split(':') pixel[0] = pixel[0].to_s.rjust(6, '0') if pixel.size == 2 pixel[1].to_i.times do (data[y] ||= []) << pixel[0] end else (data[y] ||= []) << pixel[0] end end width.times do |x| img.pixel_color(x, y, "##{data[y][x]}") end end img.format = "PNG" send_data(img.to_blob , :disposition => 'inline', :type => 'image/png', :filename => "chart.png?#{rand(99999999).to_i}") end When the controller is accessed however, I receive this error in the page: The change you wanted was rejected. Maybe you tried to change something you didn't have access to. And this error in the logs (its running on heroku btw): ActionController::InvalidAuthenticityToken (ActionController::InvalidAuthenticityToken): /home/heroku_rack/lib/static_assets.rb:9:in `call' /home/heroku_rack/lib/last_access.rb:25:in `call' /home/heroku_rack/lib/date_header.rb:14:in `call' thin (1.0.1) lib/thin/connection.rb:80:in `pre_process' thin (1.0.1) lib/thin/connection.rb:78:in `catch' thin (1.0.1) lib/thin/connection.rb:78:in `pre_process' thin (1.0.1) lib/thin/connection.rb:57:in `process' thin (1.0.1) lib/thin/connection.rb:42:in `receive_data' eventmachine (0.12.6) lib/eventmachine.rb:240:in `run_machine' eventmachine (0.12.6) lib/eventmachine.rb:240:in `run' thin (1.0.1) lib/thin/backends/base.rb:57:in `start' thin (1.0.1) lib/thin/server.rb:150:in `start' thin (1.0.1) lib/thin/controllers/controller.rb:80:in `start' thin (1.0.1) lib/thin/runner.rb:173:in `send' thin (1.0.1) lib/thin/runner.rb:173:in `run_command' thin (1.0.1) lib/thin/runner.rb:139:in `run!' thin (1.0.1) bin/thin:6 /usr/local/bin/thin:20:in `load' /usr/local/bin/thin:20 Rendering /disk1/home/slugs/149903_609c236_eb4f/mnt/public/422.html (422 Unprocessable Entity) Anyone have any idea what's going on here?

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  • Computing "average" of two colors

    - by Francisco P.
    This is only marginally programming related - has much more to do w/ colors and their representation. I am working on a very low level app. I have an array of bytes in memory. Those are characters. They were rendered with anti-aliasing: they have values from 0 to 255, 0 being fully transparent and 255 totally opaque (alpha, if you wish). I am having trouble conceiving an algorithm for the rendering of this font. I'm doing the following for each pixel: // intensity is the weight I talked about: 0 to 255 intensity = glyphs[text[i]][x + GLYPH_WIDTH*y]; if (intensity == 255) continue; // Don't draw it, fully transparent else if (intensity == 0) setPixel(x + xi, y + yi, color, base); // Fully opaque, can draw original color else { // Here's the tricky part // Get the pixel in the destination for averaging purposes pixel = getPixel(x + xi, y + yi, base); // transfer is an int for calculations transfer = (int) ((float)((float) (255.0 - (float) intensity/255.0) * (float) color.red + (float) pixel.red)/2); // This is my attempt at averaging newPixel.red = (Byte) transfer; transfer = (int) ((float)((float) (255.0 - (float) intensity/255.0) * (float) color.green + (float) pixel.green)/2); newPixel.green = (Byte) transfer; // transfer = (int) ((float) ((float) 255.0 - (float) intensity)/255.0 * (((float) color.blue) + (float) pixel.blue)/2); transfer = (int) ((float)((float) (255.0 - (float) intensity/255.0) * (float) color.blue + (float) pixel.blue)/2); newPixel.blue = (Byte) transfer; // Set the newpixel in the desired mem. position setPixel(x+xi, y+yi, newPixel, base); } The results, as you can see, are less than desirable. That is a very zoomed in image, at 1:1 scale it looks like the text has a green "aura". Any idea for how to properly compute this would be greatly appreciated. Thanks for your time!

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  • Restarting nginx with Capistrano results in 502 Bad Gateway

    - by blee
    Here's what cap deploy does: sudo -p 'sudo password: ' -u root /var/rails_apps/fooapp/current/script/process/reaper reaper simply contains /etc/init.d/nginx restart When I run the same command from the shell, I do not get a 502--everything is fine. The nginx error.log is empty. Any thoughts on how to troubleshoot? Thanks in advance for your thoughts.

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  • How to update a user created Bitmap in the Windows API

    - by gamernb
    In my code I quickly generate images on the fly, and I want to display them as quickly as possible. So the first time I create my image, I create a new BITMAP, but instead of deleting the old one and creating a new one for every subsequent image, I just want to copy my data back into the existing one. Here is my code to do both the initial creation and the updating. The creation works just fine, but the updating one doesn't work. BITMAPINFO bi; HBITMAP Frame::CreateBitmap(HWND hwnd, int tol1, int tol2, bool useWhite, bool useBackground) { ZeroMemory(&bi.bmiHeader, sizeof(BITMAPINFOHEADER)); bi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER); bi.bmiHeader.biWidth = width; bi.bmiHeader.biHeight = height; bi.bmiHeader.biPlanes = 1; bi.bmiHeader.biBitCount = 24; bi.bmiHeader.biCompression = BI_RGB; ZeroMemory(bi.bmiColors, sizeof(RGBQUAD)); // Allocate memory for bitmap bits int size = height * width; Pixel* newPixels = new Pixel[size]; // Recompute the output //memcpy(newPixels, pixels, size*3); ComputeOutput(newPixels, tol1, tol2, useWhite, useBackground); HBITMAP bitmap = CreateDIBitmap(GetDC(hwnd), &bi.bmiHeader, CBM_INIT, newPixels, &bi, DIB_RGB_COLORS); delete newPixels; return bitmap; } and void Frame::UpdateBitmap(HWND hwnd, HBITMAP bitmap, int tol1, int tol2, bool useWhite, bool useBackground) { ZeroMemory(&bi.bmiHeader, sizeof(BITMAPINFOHEADER)); bi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER); HDC hdc = GetDC(hwnd); if(!GetDIBits(hdc, bitmap, 0, bi.bmiHeader.biHeight, NULL, &bi, DIB_RGB_COLORS)) MessageBox(NULL, "Can't get base image info!", "Error!", MB_ICONEXCLAMATION | MB_OK); // Allocate memory for bitmap bits int size = height * width; Pixel* newPixels = new Pixel[size]; // Recompute the output //memcpy(newPixels, pixels, size*3); ComputeOutput(newPixels, tol1, tol2, useWhite, useBackground); // Push back to windows if(!SetDIBits(hdc, bitmap, 0, bi.bmiHeader.biHeight, newPixels, &bi, DIB_RGB_COLORS)) MessageBox(NULL, "Can't set pixel data!", "Error!", MB_ICONEXCLAMATION | MB_OK); delete newPixels; } where the Pixel struct is just this: struct Pixel { unsigned char b, g, r; }; Why does my update function not work. I always get the MessageBox for "Can't set pixel data!" I used code similar to this when I was loading in the original bitmap from file, then editing the data, but now when I manually create it, it doesn't work.

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  • GDI+ Load a jpg and save as 24bit png problem

    - by wookey
    Problem Hello all! I have this code which takes my jpg image loops through altering pixels and finally saving it as a png type. The problem is that the resulting image has a bit depth of 32 bits. I need it to be 24 bit, can any one shiny some light on the correct method of setting it? Am I along the right tracks looking at setting the pixel format to PixelFormat24bppRGB? Code static inline void Brighten(Gdiplus::Bitmap* img) { int width = img->GetWidth()/8,height = img->GetHeight(), max = (width*height),r,g,b; Gdiplus::Color pixel; for(int a = 0,x = 0, y = -1; a < max; ++a) { x = a%width; if(x == 0) ++y; img->GetPixel(x,y,&pixel); r = pixel.GetR(); g = pixel.GetG(); b = pixel.GetB(); if (r > 245) r = 245; if (g > 245) g = 245; if (b > 245) b = 245; r = 10; g = 10; b = 10; pixel = Gdiplus::Color(r,g,b); img->SetPixel(x,y,pixel);; } } ULONG_PTR m_dwToken = 0; Gdiplus::GdiplusStartupInput input; Gdiplus::GdiplusStartupOutput output; Gdiplus::GdiplusStartup( &m_dwToken, &input, &output ); USES_CONVERSION_EX; Gdiplus::ImageCodecInfo* pEncoders = static_cast< Gdiplus::ImageCodecInfo* >( _ATL_SAFE_ALLOCA(1040, _ATL_SAFE_ALLOCA_DEF_THRESHOLD)); Gdiplus::DllExports::GdipGetImageEncoders(5, 1040, pEncoders ); CLSID clsidEncoder = pEncoders[4].Clsid; Gdiplus::Bitmap img1((CT2W)L"IMG_1.JPG"); Brighten(&img1); img1.Save((CT2W)L"IMG_1_R3.PNG",&clsidEncoder,NULL); Thanks in advance!

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  • UV Atlas Generation and Seam Removal

    - by P. Avery
    I'm generating light maps for scene mesh objects using DirectX's UV Atlas Tool( D3DXUVAtlasCreate() ). I've succeeded in generating an atlas, however, when I try to render the mesh object using the atlas the seams are visible on the mesh. Below are images of a lightmap generated for a cube. Here is the code I use to generate a uv atlas for a cube: struct sVertexPosNormTex { D3DXVECTOR3 vPos, vNorm; D3DXVECTOR2 vUV; sVertexPosNormTex(){} sVertexPosNormTex( D3DXVECTOR3 v, D3DXVECTOR3 n, D3DXVECTOR2 uv ) { vPos = v; vNorm = n; vUV = uv; } ~sVertexPosNormTex() { } }; // create a light map texture to fill programatically hr = D3DXCreateTexture( pd3dDevice, 128, 128, 1, 0, D3DFMT_A8R8G8B8, D3DPOOL_MANAGED, &pLightmap ); if( FAILED( hr ) ) { DebugStringDX( "Main", "Failed to D3DXCreateTexture( lightmap )", __LINE__, hr ); return hr; } // get the zero level surface from the texture IDirect3DSurface9 *pS = NULL; pLightmap->GetSurfaceLevel( 0, &pS ); // clear surface pd3dDevice->ColorFill( pS, NULL, D3DCOLOR_XRGB( 0, 0, 0 ) ); // load a sample mesh DWORD dwcMaterials = 0; LPD3DXBUFFER pMaterialBuffer = NULL; V_RETURN( D3DXLoadMeshFromX( L"cube3.x", D3DXMESH_MANAGED, pd3dDevice, &pAdjacency, &pMaterialBuffer, NULL, &dwcMaterials, &g_pMesh ) ); // generate adjacency DWORD *pdwAdjacency = new DWORD[ 3 * g_pMesh->GetNumFaces() ]; g_pMesh->GenerateAdjacency( 1e-6f, pdwAdjacency ); // create light map coordinates LPD3DXMESH pMesh = NULL; LPD3DXBUFFER pFacePartitioning = NULL, pVertexRemapArray = NULL; FLOAT resultStretch = 0; UINT numCharts = 0; hr = D3DXUVAtlasCreate( g_pMesh, 0, 0, 128, 128, 3.5f, 0, pdwAdjacency, NULL, NULL, NULL, NULL, NULL, 0, &pMesh, &pFacePartitioning, &pVertexRemapArray, &resultStretch, &numCharts ); if( SUCCEEDED( hr ) ) { // release and set mesh SAFE_RELEASE( g_pMesh ); g_pMesh = pMesh; // write mesh to file hr = D3DXSaveMeshToX( L"cube4.x", g_pMesh, 0, ( const D3DXMATERIAL* )pMaterialBuffer->GetBufferPointer(), NULL, dwcMaterials, D3DXF_FILEFORMAT_TEXT ); if( FAILED( hr ) ) { DebugStringDX( "Main", "Failed to D3DXSaveMeshToX() at OnD3D9CreateDevice()", __LINE__, hr ); } // fill the the light map hr = BuildLightmap( pS, g_pMesh ); if( FAILED( hr ) ) { DebugStringDX( "Main", "Failed to BuildLightmap()", __LINE__, hr ); } } else { DebugStringDX( "Main", "Failed to D3DXUVAtlasCreate() at OnD3D9CreateDevice()", __LINE__, hr ); } SAFE_RELEASE( pS ); SAFE_DELETE_ARRAY( pdwAdjacency ); SAFE_RELEASE( pFacePartitioning ); SAFE_RELEASE( pVertexRemapArray ); SAFE_RELEASE( pMaterialBuffer ); Here is code to fill lightmap texture: HRESULT BuildLightmap( IDirect3DSurface9 *pS, LPD3DXMESH pMesh ) { HRESULT hr = S_OK; // validate lightmap texture surface and mesh if( !pS || !pMesh ) return E_POINTER; // lock the mesh vertex buffer sVertexPosNormTex *pV = NULL; pMesh->LockVertexBuffer( D3DLOCK_READONLY, ( void** )&pV ); // lock the mesh index buffer WORD *pI = NULL; pMesh->LockIndexBuffer( D3DLOCK_READONLY, ( void** )&pI ); // get the lightmap texture surface description D3DSURFACE_DESC desc; pS->GetDesc( &desc ); // lock the surface rect to fill with color data D3DLOCKED_RECT rct; hr = pS->LockRect( &rct, NULL, 0 ); if( FAILED( hr ) ) { DebugStringDX( "main.cpp:", "Failed to IDirect3DTexture9::LockRect()", __LINE__, hr ); return hr; } // iterate the pixels of the lightmap texture // check each pixel to see if it lies between the uv coordinates of a cube face BYTE *pBuffer = ( BYTE* )rct.pBits; for( UINT y = 0; y < desc.Height; ++y ) { BYTE* pBufferRow = ( BYTE* )pBuffer; for( UINT x = 0; x < desc.Width * 4; x+=4 ) { // determine the pixel's uv coordinate D3DXVECTOR2 p( ( ( float )x / 4.0f ) / ( float )desc.Width + 0.5f / 128.0f, y / ( float )desc.Height + 0.5f / 128.0f ); // for each face of the mesh // check to see if the pixel lies within the face's uv coordinates for( UINT i = 0; i < 3 * pMesh->GetNumFaces(); i +=3 ) { sVertexPosNormTex v[ 3 ]; v[ 0 ] = pV[ pI[ i + 0 ] ]; v[ 1 ] = pV[ pI[ i + 1 ] ]; v[ 2 ] = pV[ pI[ i + 2 ] ]; if( TexcoordIsWithinBounds( v[ 0 ].vUV, v[ 1 ].vUV, v[ 2 ].vUV, p ) ) { // the pixel lies b/t the uv coordinates of a cube face // light contribution functions aren't needed yet //D3DXVECTOR3 vPos = TexcoordToPos( v[ 0 ].vPos, v[ 1 ].vPos, v[ 2 ].vPos, v[ 0 ].vUV, v[ 1 ].vUV, v[ 2 ].vUV, p ); //D3DXVECTOR3 vNormal = v[ 0 ].vNorm; // set the color of this pixel red( for demo ) BYTE ba[] = { 0, 0, 255, 255, }; //ComputeContribution( vPos, vNormal, g_sLight, ba ); // copy the byte array into the light map texture memcpy( ( void* )&pBufferRow[ x ], ( void* )ba, 4 * sizeof( BYTE ) ); } } } // go to next line of the texture pBuffer += rct.Pitch; } // unlock the surface rect pS->UnlockRect(); // unlock mesh vertex and index buffers pMesh->UnlockIndexBuffer(); pMesh->UnlockVertexBuffer(); // write the surface to file hr = D3DXSaveSurfaceToFile( L"LightMap.jpg", D3DXIFF_JPG, pS, NULL, NULL ); if( FAILED( hr ) ) DebugStringDX( "Main.cpp", "Failed to D3DXSaveSurfaceToFile()", __LINE__, hr ); return hr; } bool TexcoordIsWithinBounds( const D3DXVECTOR2 &t0, const D3DXVECTOR2 &t1, const D3DXVECTOR2 &t2, const D3DXVECTOR2 &p ) { // compute vectors D3DXVECTOR2 v0 = t1 - t0, v1 = t2 - t0, v2 = p - t0; float f00 = D3DXVec2Dot( &v0, &v0 ); float f01 = D3DXVec2Dot( &v0, &v1 ); float f02 = D3DXVec2Dot( &v0, &v2 ); float f11 = D3DXVec2Dot( &v1, &v1 ); float f12 = D3DXVec2Dot( &v1, &v2 ); // Compute barycentric coordinates float invDenom = 1 / ( f00 * f11 - f01 * f01 ); float fU = ( f11 * f02 - f01 * f12 ) * invDenom; float fV = ( f00 * f12 - f01 * f02 ) * invDenom; // Check if point is in triangle if( ( fU >= 0 ) && ( fV >= 0 ) && ( fU + fV < 1 ) ) return true; return false; } Screenshot Lightmap I believe the problem comes from the difference between the lightmap uv coordinates and the pixel center coordinates...for example, here are the lightmap uv coordinates( generated by D3DXUVAtlasCreate() ) for a specific face( tri ) within the mesh, keep in mind that I'm using the mesh uv coordinates to write the pixels for the texture: v[ 0 ].uv = D3DXVECTOR2( 0.003581, 0.295631 ); v[ 1 ].uv = D3DXVECTOR2( 0.003581, 0.003581 ); v[ 2 ].uv = D3DXVECTOR2( 0.295631, 0.003581 ); the lightmap texture size is 128 x 128 pixels. The upper-left pixel center coordinates are: float halfPixel = 0.5 / 128 = 0.00390625; D3DXVECTOR2 pixelCenter = D3DXVECTOR2( halfPixel, halfPixel ); will the mapping and sampling of the lightmap texture will require that an offset be taken into account or that the uv coordinates are snapped to the pixel centers..? ...Any ideas on the best way to approach this situation would be appreciated...What are the common practices?

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  • Java2D: if statement doesn`t work with java.awt.Color

    - by DarkSun
    I have a getPixelColour function: Color getPixelColor(int x, int y) { if(mazeImage == null) System.out.println(":("); int pixel = mazeImage.getRGB(x, y); int red = (pixel & 0x00ff0000) >> 16; int green = (pixel & 0x0000ff00) >> 8; int blue = pixel & 0x000000ff; return new Color(red,green,blue); } For example a pixel is black, and System.out.println(getPixelColor(x,y) + " " + Color.BLACK); writes "java.awt.Color[r=0,g=0,b=0] java.awt.Color[r=0,g=0,b=0]" But getPixelColor(x,y) == Color.BLACK return false. What's wrong with it?

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  • How to get pixel data from a UIImage (Cocoa Touch) or CGImage (Core Graphics)?

    - by Olie
    I have a UIImage (Cocoa Touch). From that, I'm happy to get a CGImage or anything else you'd like that's available. I'd like to write this function: - (int)getRGBAFromImage:(UIImage *)image atX:(int)xx andY:(int)yy { // [...] // What do I want to read about to help // me fill in this bit, here? // [...] int result = (red << 24) | (green << 16) | (blue << 8) | alpha; return result; } Thanks!

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  • Java webapp: how to implement a web bug (1x1 pixel)?

    - by NoozNooz42
    In the accepted answer in the following question, a SO regular with 13K+ rep suggests to use a "web bug" (non-cacheable 1x1 img) to be able to track requests in the logs: http://stackoverflow.com/questions/1784893 How can I do this in Java? Basically, I've got two issues: how to make sure the 1x1 image is not cacheable (how to set the header)? how to make sure the query for these 1x1 image will appear in the logs? I'm looking for exact piece of code because I know how to write a .jsp/servlet and I know how to serve an 1x1 image :) My question is really about the exact .jsp/servlet that I should write and how/what needs to be done so that Tomcat logs the request. For example I plan to use the following mapping: <servlet-mapping> <servlet-name>WebBugServlet</servlet-name> <url-pattern>/webbug*</url-pattern> </servlet-mapping> and then use an img tag referencing a "webbug.png" (or .gif), so how do I write the .jsp/servlet? What/where should I look for in the logs?

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  • How to determine pixel color of System.Windows.Controls.Image?

    - by csciguy
    I have an Image from (System.Windows.Controls.Image). This image is positioned on a main canvas. I want to determine the alpha channel value of the mouse cursor when I click on any portion of this image. When doing something like the following, I'm getting an exception. {"Value does not fall within the expected range."} System.Exception {System.ArgumentException} Code: try{ CroppedBitmap cb = new CroppedBitmap(ac.displayImage.Source as BitmapSource, new Int32Rect((int)mousePoint.X, (int)mousePoint.Y, 1, 1)); byte[] pixels = new byte[4]; cb.CopyPixels(pixels, 4, 0); } catch (Exception ex) { System.Diagnostics.Debug.WriteLine(ex.Message); } The mousePoint.X, and mousePoint.Y are obtained when the user clicks on the main window. Is there a better way to do this?

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  • How to create an image from array of pixel colors? (Flash, Actionscript 3)

    - by Ole Jak
    I have a Width and Height parametr. I have been given an array of colors in such format: [r, g, b, a, r, g, b, a, r, g, b, a... etc] Data can be acsessed by something like this for(var y = 0; y < height; y++) { for(var x = 0; x < width; x++) { r = data[y*width + x + 0] g = data[y*width + x + 1] b = data[y*width + x + 2] a = data[y*width + x + 3] } } I want to paint that data on some sprite. How to do such thing? BTW: I use Flash Builder for mxml+actionscript coding. So if it is easy for you you can give example using MXML (not todraw on some sprite but on some MXML component).

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  • C#, hover over bitmap pixel and get the coordinates?

    - by Tom
    Hi, does anyone know how to do this? I presume it uses some sort of event handler but i wondered if anyone could set me on my path? Also, how does one show that yellow textbox which sometimes appears when you hover over processional software and it gives some information about what to fill in the textfield, thats perferably how i wish to show the coordinates? I dont know the name of what its called. In IE 8, if you hover over the name of a tab, it comes up. Thank you in advance

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  • Encode two integers into colour values and compare them in a HLSL shader

    - by Ben Slinger
    I am writing a 2D point and click adventure game in Monogame, and I'd like to be able to create an image mask for every room which defines which parts of the background a character can walk behind, and at which Y value a character needs to be at for the background to be drawn above the character. I haven't done any shader work before but after doing some reading I thought the following solution should work: Create a mask for the room with different walk behind areas painted in a colour that defines the baseline Y value (Walk Behind Mask) Render all objects to a RenderTarget2D (Base Texture) Render all objects to a different RenderTarget2D, but changing every pixel of each object to a colour that defines its Y value (Position Mask) Pass these two textures plus the image mask into the shader, and for each pixel compare the colour of the image mask to the colour of the Position Mask to the Walk Behind Mask - if the Position Mask pixel is larger (thus lower on the screen and closer to the camera) than the Walk Behind Mask, draw the pixel from the Base Texture, otherwise draw a transparent pixel (allowing the background to show through). I've got it mostly working, but I'm having trouble packing and unpacking the Y values into colours and retrieving them correctly in the shader. Here are some code examples of how I'm doing it so far: (When drawing to the Position Mask RenderTarget2D) Color posColor = new Color(((int)Position.Y >> 16) & 255, ((int)Position.Y >> 8) & 255, (int)Position.Y & 255); So as far as I can tell, this should be taking the first 3 bytes of the position integer and encoding them into a 4 byte colour (ignoring the alpha as the 4th byte). This seems to work fine, as when my character is at Y = 600, the resulting Color from this is: {[Color: R=0, G=2, B=88, A=255, PackedValue=4283957760]}. I then have an area in my Walk Behind Mask that I only want the character to be displayed behind if his Y value is lower than 655, so I've painted it with R=0, G=2, B=143, A=255. Now, I think I have the shader OK as well, here's what I have: sampler BaseTexture : register(s0); sampler MaskTexture : register(s1); sampler PositionTexture : register(s2); float4 mask( float2 coords : TEXCOORD0 ) : COLOR0 { float4 color = tex2D(BaseTexture, coords); float4 maskColor = tex2D(MaskTexture, coords); float4 positionColor = tex2D(PositionTexture, coords); float maskCompare = (maskColor.r * pow(2,24)) + (maskColor.g * pow(2,16)) + (maskColor.b * pow(2,8)); float positionCompare = (positionColor.r * pow(2,24)) + (positionColor.g * pow(2,16)) + (positionColor.b * pow(2,8)); return positionCompare < maskCompare ? float4(0,0,0,0) : color; } technique Technique1 { pass NoEffect { PixelShader = compile ps_3_0 mask(); } } This isn't working, however - currently all characters are displayed behind the walk behind area, regardless of their Y value. I tried printing out some debug info by grabbing the pixel from both the Position Mask and the Walk Under Mask under the current mouse position, and it seems like maybe the colours aren't being rendered to the Position Mask correctly? When calculating the colour in that code above I'm getting R=0, G=2, B=88, A=255, but when I mouseover my character I get R=0, G=0, B=30, A=255. Any ideas what I'm doing wrong? It seems like maybe I'm losing some information when rendering to the RenderTarget2D, but I'm now knowledgeable enough to figure out what's happening. Also, I should probably ask, is this an efficient way to do this? Will there be a performance impact? Edit: Whoops, turns out there was a bug that I'd introduced myself, I was drawing out the Position Mask with the position Color, left over from some early testing I was doing. So this solution is working perfectly, though I'm still interested in whether this is an efficient solution performance wise.

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  • Best approach to storing image pixels in bottom-up order in Java

    - by finnw
    I have an array of bytes representing an image in Windows BMP format and I would like my library to present it to the Java application as a BufferedImage, without copying the pixel data. The main problem is that all implementations of Raster in the JDK store image pixels in top-down, left-to-right order whereas BMP pixel data is stored bottom-up, left-to-right. If this is not compensated for, the resulting image will be flipped vertically. The most obvious "solution" is to set the SampleModel's scanlineStride property to a negative value and change the band offsets (or the DataBuffer's array offset) to point to the top-left pixel, i.e. the first pixel of the last line in the array. Unfortunately this does not work because all of the SampleModel constructors throw an exception if given a negative scanlineStride argument. I am currently working around it by forcing the scanlineStride field to a negative value using reflection, but I would like to do it in a cleaner and more portable way if possible. e.g. is there another way to fool the Raster or SampleModel into arranging the pixels in bottom-up order but without breaking encapsulation? Or is there a library somewhere that will wrap the Raster and SampleModel, presenting the pixel rows in reverse order? I would prefer to avoid the following approaches: Copying the whole image (for performance reasons. The code must process hundreds of large (= 1Mpixels) images per second and although the whole image must be available to the application, it will normally access only a tiny (but hard-to-predict) portion of the image.) Modifying the DataBuffer to perform coordinate transformation (this actually works but is another "dirty" solution because the buffer should not need to know about the scanline/pixel layout.) Re-implementing the Raster and/or SampleModel interfaces from scratch (but I have a hunch that I will be unable to avoid this.)

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  • Image Gurus: Optimize my Python PNG transparency function

    - by ozone
    I need to replace all the white(ish) pixels in a PNG image with alpha transparency. I'm using Python in AppEngine and so do not have access to libraries like PIL, imagemagick etc. AppEngine does have an image library, but is pitched mainly at image resizing. I found the excellent little pyPNG module and managed to knock up a little function that does what I need: make_transparent.py pseudo-code for the main loop would be something like: for each pixel: if pixel looks "quite white": set pixel values to transparent otherwise: keep existing pixel values and (assuming 8bit values) "quite white" would be: where each r,g,b value is greater than "240" AND each r,g,b value is within "20" of each other This is the first time I've worked with raw pixel data in this way, and although works, it also performs extremely poorly. It seems like there must be a more efficient way of processing the data without iterating over each pixel in this manner? (Matrices?) I was hoping someone with more experience in dealing with these things might be able to point out some of my more obvious mistakes/improvements in my algorithm. Thanks!

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  • Creating a GTK theme, but Qt and Java apps are not affected, and title bar button layout is ugly

    - by Mr. Pixel
    I'm playing with a gtk2 / gtk3 theme which I use in the Mate desktop. Everything is looking well, even gtk3 apps, but I still have 3 important issues: Java apps ignore the theme QT apps ignore the theme I'm using those nice ubuntu 10 title bar buttons, but the problem is, when only the close button appears, the title bar looks ugly. Can I make it so that it shows the two other buttons, but disabled? I don't know how Ubuntu 10 handled this. Here's a screenshot showing the 3 problems (above is a small java app, below is a Qt app): Under my previous desktop environments, Unity and Cinnamon, both apps seemed to be taking the right theme correctly, but I did not use my custom theme yet. Cinnamon is based on gnome-shell by the way, and mate is a gnome2-fork. Please note that the shown java app explicitely tries to load the gtk theme at runtime. By default, java apps don't, but this one has the necessary code, which worked in unity and cinnamon. Any suggestions how I could make my theme better so these problems disappear? Thank you very much!

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  • PCF shadow shader math causing artifacts

    - by user2971069
    For a while now I used PCSS for my shadow technique of choice until I discovered a type of percentage closer filtering. This method creates really smooth shadows and with hopes of improving performance, with only a fraction of texture samples, I tried to implement PCF into my shader. This is the relevant code: float c0, c1, c2, c3; float f = blurFactor; float2 coord = ProjectedTexCoords; if (receiverDistance - tex2D(lightSampler, coord + float2(0, 0)).x > 0.0007) c0 = 1; if (receiverDistance - tex2D(lightSampler, coord + float2(f, 0)).x > 0.0007) c1 = 1; if (receiverDistance - tex2D(lightSampler, coord + float2(0, f)).x > 0.0007) c2 = 1; if (receiverDistance - tex2D(lightSampler, coord + float2(f, f)).x > 0.0007) c3 = 1; coord = (coord % f) / f; return 1 - (c0 * (1 - coord.x) * (1 - coord.y) + c1 * coord.x * (1 - coord.y) + c2 * (1 - coord.x) * coord.y + c3 * coord.x * coord.y); This is a very basic implementation. blurFactor is initialized with 1 / LightTextureSize. So the if statements fetch the occlusion values for the four adjacent texels. I now want to weight each value based on the actual position of the texture coordinate. If it's near the bottom-right pixel, that occlusion value should be preferred. The weighting itself is done with a simple bilinear interpolation function, however this function takes a 2d vector in the range [0..1] so I have to convert my texture coordinate to get the distance from my first pixel to the second one in range [0..1]. For that I used the mod operator to get it into [0..f] range and then divided by f. This code makes sense to me, and for specific blurFactors it works, producing really smooth one pixel wide shadows, but not for all blurFactors. Initially blurFactor is (1 / LightTextureSize) to sample the 4 adjacent texels. I now want to increase the blurFactor by factor x to get a smooth interpolation across maybe 4 or so pixels. But that is when weird artifacts show up. Here is an image: Using a 1x on blurFactor produces a good result, 0.5 is as expected not so smooth. 2x however doesn't work at all. I found that only a factor of 1/2^n produces an good result, every other factor produces artifacts. I'm pretty sure the error lies here: coord = (coord % f) / f; Maybe the modulo is not calculated correctly? I have no idea how to fix that. Is it even possible for pixel that are further than 1 pixel away?

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