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  • iPhone SDK : UIImageView - Collapsing animation

    - by chris.o.
    Hi All, I'm trying to animating across the screen a horizontal bar with a color gradient. For simplicity, I chose to make a png of the fully extended bar, assign it to a UIImageView, and (attempt to) animate resizing of it using a UIView animation. The problem is that in the "closed" state of the Image, the portion of the image showing is not the part that I want. The image is arranged so that from L to R, a white to red color gradient occurs. The right side (about 20 pixels) is solid red and is the part I want to show when the bar is "collapsed". I'm trying to extend the image out by about 100 pixels to its full width. I referenced the "Buy Now" button example for my code as it seemed relevant" http://stackoverflow.com/questions/1669804/uibutton-appstore-buy-button-animation My code: [UIView beginAnimations:@"barAnimation" context:nil]; [UIView setAnimationDuration:0.6]; CGRect barFrame = bookBar.bounds; if (fExtendBar) { barFrame.origin.x -= 100; barFrame.size.width += 100; } else { barFrame.origin.x += 100; barFrame.size.width -= 100; } bookBar.frame = barFrame; [UIView commitAnimations]; I feel like this should be possible, maybe by setting an "offsetOfImage" to display in the UIImageView, but I can't seem to make it work. Also, I've noticed that the behavior is kind of consistent with what happens in Interface Builder when you resize an image. Then again, I would think there would be a way to override this behavior programmatically. Any suggestions (including other approaches) are welcome. Thanks, chris.o.

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  • Scrolling a Canvas smoothly in Android

    - by prepbgg
    I'm new to Android. I am drawing bitmaps, lines and shapes onto a Canvas inside the OnDraw(Canvas canvas) method of my view. I am looking for help on how to implement smooth scrolling in response to a drag by the user. I have searched but not found any tutorials to help me with this. The reference for Canvas seems to say that if a Canvas is constructed from a Bitmap (called bmpBuffer, say) then anything drawn on the Canvas is also drawn on bmpBuffer. Would it be possible to use bmpBuffer to implement a scroll ... perhaps copy it back to the Canvas shifted by a few pixels at a time? But if I use Canvas.drawBitmap to draw bmpBuffer back to Canvas shifted by a few pixels, won't bmpBuffer be corrupted? Perhaps, therefore, I should copy bmpBuffer to bmpBuffer2 then draw bmpBuffer2 back to the Canvas. A more straightforward approach would be to draw the lines, shapes, etc. straight into a buffer Bitmap then draw that buffer (with a shift) onto the Canvas but so far as I can see the various methods: drawLine(), drawShape() and so on are not available for drawing to a Bitmap ... only to a Canvas. Could I have 2 Canvases? One of which would be constructed from the buffer bitmap and used simply for plotting the lines, shapes, etc. and then the buffer bitmap would be drawn onto the other Canvas for display in the View? I should welcome any advice! Answers to similar questions here (and on other websites) refer to "blitting". I understand the concept but can't find anything about "blit" or "bitblt" in the Android documentation. Are Canvas.drawBitmap and Bitmap.Copy Android's equivalents?

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  • Conversion from Iphone Core Surface RGB Frame into ffmepg AVFarme

    - by Sridhar
    Hello, I am trying to convert Core Surface RGB frame buffer(Iphone) to ffmpeg Avfarme to encode into a movie file. But I am not getting the correct video output (video showing colors dazzling not the correct picture) I guess there is something wrong with converting from core surface frame buffer into AVFrame. Here is my code : Surface *surface = [[Surface alloc]initWithCoreSurfaceBuffer:coreSurfaceBuffer]; [surface lock]; unsigned int height = surface.height; unsigned int width = surface.width; unsigned int alignmentedBytesPerRow = (width * 4); if (!readblePixels) { readblePixels = CGBitmapAllocateData(alignmentedBytesPerRow * height); NSLog(@"alloced readablepixels"); } unsigned int bytesPerRow = surface.bytesPerRow; void *pixels = surface.baseAddress; for (unsigned int j = 0; j < height; j++) { memcpy(readblePixels + alignmentedBytesPerRow * j, pixels + bytesPerRow * j, bytesPerRow); } pFrameRGB->data[0] = readblePixels; // I guess here is what I am doing wrong. pFrameRGB->data[1] = NULL; pFrameRGB->data[2] = NULL; pFrameRGB->data[3] = NULL; pFrameRGB->linesize[0] = pCodecCtx->width; pFrameRGB->linesize[1] = 0; pFrameRGB->linesize[2] = 0; pFrameRGB->linesize[3] = 0; sws_scale (img_convert_ctx, pFrameRGB->data, pFrameRGB->linesize, 0, pCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize); Please help me out. Thanks, Raghu

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  • Force a UIView to redraw immediately, instead of during next run loop

    - by Justin Kent
    I've created a UIImagePicker / camera view, with a toolbar and custom button for taking a snapshot. I can't really change to using the default way because of the custom button, and I'm drawing on top of the view. When you hit the button, I want to take a screenshot using UIGetScreenImage(); however, the toolbar is showing up in the image, even if I hide it first: //hide the toolbar self.toolbar.hidden = YES; // capture the screen pixels CGImageRef screenCap = UIGetScreenImage(); I'm pretty sure this is because even though the toolbar is hidden, it gets redrawn once the function returns and we enter the next run loop - after UIGetScreenImage is called. I tried making the following addition, but it didn't help: //hide the toolbar self.toolbar.hidden = YES; [self.toolbar drawRect:CGRectMake(0, 0, 320, 52)]; // capture the screen pixels CGImageRef screenCap = UIGetScreenImage(); I also tried using setNeedsDisplay, but that doesn't work either because once again the draw happens after the current function returns. Any suggestions? Thanks!

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  • Fastest image iteration in Python

    - by Greg
    I am creating a simple green screen app with Python 2.7.4 but am getting quite slow results. I am currently using PIL 1.1.7 to load and iterate the images and saw huge speed-ups changing from the old getpixel() to the newer load() and pixel access object indexing. However the following loop still takes around 2.5 seconds to run for an image of around 720p resolution: def colorclose(Cb_p, Cr_p, Cb_key, Cr_key, tola, tolb): temp = math.sqrt((Cb_key-Cb_p)**2+(Cr_key-Cr_p)**2) if temp < tola: return 0.0 else: if temp < tolb: return (temp-tola)/(tolb-tola) else: return 1.0 .... for x in range(width): for y in range(height): Y, cb, cr = fg_cbcr_list[x, y] mask = colorclose(cb, cr, cb_key, cr_key, tola, tolb) mask = 1 - mask bgr, bgg, bgb = bg_list[x,y] fgr, fgg, fgb = fg_list[x,y] pixels[x,y] = ( (int)(fgr - mask*key_color[0] + mask*bgr), (int)(fgg - mask*key_color[1] + mask*bgg), (int)(fgb - mask*key_color[2] + mask*bgb)) Am I doing anything hugely inefficient here which makes it run so slow? I have seen similar, simpler examples where the loop is replaced by a boolean matrix for instance, but for this case I can't see a way to replace the loop. The pixels[x,y] assignment seems to take the most amount of time but not knowing Python very well I am unsure of a more efficient way to do this. Any help would be appreciated.

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  • Editing 8bpp indexed Bitmaps

    - by Pedro Sá
    hi, i'm trying to edit the pixels of a 8bpp. Since this PixelFormat is indexed i'm aware that it uses a Color Table to map the pixel values. Even though I can edit the bitmap by converting it to 24bpp, 8bpp editing is much faster (13ms vs 3ms). But, changing each value when accessing the 8bpp bitmap results in some random rgb colors even though the PixelFormat remains 8bpp. I'm currently developing in c# and the algorithm is as follows: (C#) 1- Load original Bitmap at 8bpp 2- Create Empty temp Bitmap with 8bpp with the same size as the original 3-LockBits of both bitmaps and, using P/Invoke, calling c++ method where I pass the Scan0 of each BitmapData object. (I used a c++ method as it offers better performance when iterating through the Bitmap's pixels) (C++) 4- Create a int[256] palette according to some parameters and edit the temp bitmap bytes by passing the original's pixel values through the palette. (C#) 5- UnlockBits. My question is how can I edit the pixel values without having the strange rgb colors, or even better, edit the 8bpp bitmap's Color Table? Regards, Pedro

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  • How do you word wrap a RichTextField for Blackberry

    - by Kai
    I've been trying to modify a rich text field to display correctly in its half of the horizontal field. The goal is this: --------------------------- | address is | ***********| | very long | ** IMAGE **| | state, zip | ***********| --------------------------- Where address is a single string separate from the city and zip. I am modifying the address field like this: RichTextField addrField = new RichTextField(address) { public int getPreferredWidth() { return 200; } protected void layout(int maxWidth,int maxHeight) { super.layout(getPreferredWidth(),maxHeight); setExtent(getPreferredWidth(), getHeight()); } }; The results look like this: ----------------------------- | address is ve| ***********| | state, zip | ** IMAGE **| | | ***********| ----------------------------- where clearly the address is just going under the image. Both horizontal fields are static 200 pixels wide. It's not like the system wouldn't know where to wrap the address. However, I have heard it is not easy to do this and is not done automatically. I have had no success finding a direct answer online. I have found people saying you need to do it in a custom layout manager, some refer to the RichTextField API, which is of no use. But nobody actually mentions how to do it. I understand that I may need to read character by character and set where the line breaks should happen. What I don't know is how exactly to do any of this. You can't just count characters and assume each is worth 5 pixels, and you shouldn't have to. Surely there must be some way to achieve this in a way that makes sense. Any suggestions?

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  • How to scale a sprite image without losing color key information?

    - by Michael P
    Hello everyone, I'm currently developing a simple application that displays map and draws some markers on it. I'm developing for Windows Mobile, so I decided to use DirectDraw and Imaging interfaces to make the application fast and pretty. The map moves when user moves finger on the touchscreen, so the whole map moving/scrolling animation has to be fast, but it is not. On every map update I have to draw portion of the map, control buttons, and markers - buttons and markers are preloaded on DirectDraw surface as a mipmap. So the only thing I do is BitBlit from the mipmap to a back buffer, and from the back buffer to a primary surface (I can't use page flipping due to the windowed mode of my application). Previously I used premultiplied-alpha surface with 32 bit ARGB pixel format for images mipmap, everything was looking good, but drawing entire "scene" was horribly slow - i could forget about smooth map scrolling. Now I'm using mipmap with native (RGB565) pixel format and fuchsia (0xFF00FF) color key. Drawing is much better my mipmap surface is generated on program loading - images are loaded from files, scaled (with filtering) and drawn on mipmap. The problem is, that image scaling process blends pixel colors, and those pixels which are on the border of a sprite region are blended with surrounding fuchsia pixels resulting semi-fuchsia color that is not treated as color key. When I do blitting with color key option, sprites have small fuchsia-like borders, and it looks really bad. How to solve this problem? I can use alpha blitting, but it is too slow - even in ARGB 1555 format.

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  • Clipped UITextField with UITextFieldAlignmentRight

    - by Typeoneerror
    Got a small problem with UITextField. I have a simple UITextField and when I set the textAlignment property to "right", it gets clipped by 1-2 pixels. It looks shite so I'm hoping someone has an idea of how to remedy this. I've tried setting the frame to integers to prevent them from being on .5 pixels. - (UITextField *)textControlForSetting:(NSDictionary *)settings { CGRect frame = CGRectIntegral(CGRectMake(100.0f, 0.0f, 170.0f, 44.0f)); UITextField *textField = [[[UITextField alloc] initWithFrame:frame] autorelease]; NSString *defaultValue = [settings objectForKey:kDefaultValueKey]; NSString *currentValue = [prefs objectForKey:[settings objectForKey:kSettingKey]]; textField.tag = settingsCounter; textField.delegate = self; textField.textAlignment = UITextAlignmentRight; textField.font = [UIFont fontWithName:@"HelveticaNeue" size:14.0f]; textField.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter; textField.placeholder = (currentValue != nil) ? currentValue : defaultValue; settingsCounter++; return textField; }

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  • DWM and painting unresponsive apps

    - by Doug Kavendek
    In Vista and later, if an app becomes unresponsive, the Desktop Window Manager is able to handle redrawing it when necessary (move a window over it, drag it around, etc.) because it has kept a pixel buffer for it. Windows also tries to detect when an app has become unresponsive after some timeout, and tries to make the best of the situation -- I believe it dims out the window, adds "Not Responding" to its title bar, and perhaps some other effects. Now, we have a skinned app that uses window regions and layered windows, and it doesn't play well with these effects. We've been developing on XP, but have noticed a strange effect when testing on Vista. At some points the app may spend a few moments on some calculation or callback, and if it passes the unresponsive threshold (I've read that it's a five second timeout, but I cannot find a link), a strange graphical problem occurs: any pixels that would be 100% transparent due to the window regions turn black, which effectively makes the window rectangular again, with a black background. There seem to be other anomalies, with the original window's pixels being shifted a bit in some child dialogs. I am working on reducing such delays (ideally Windows will never need to step in like this), and trying to maintain responsiveness while it's busy, but I'd still like to figure out what is causing it to render like that, as I can't guarantee I can eliminate all delays. Basically, I just would like to know what Windows is doing when this happens, and how I can make my app behave properly with it. Skinned apps have to still work on Vista and later, so I need to figure out what I'm doing that's non-standard. I don't even know exactly how to look for information into how Windows now handles unresponsive apps, as my searches only return people having issues with apps that are unresponsive, or very rudimentary explanations of what the DWM does with such apps. Heck I'm not even 100% sure it's the DWM responsible, but it seems likely. Any potential leads? Photo of problem; screen shots won't capture the effect (note that the white dialog's buffer is shifted -- it is shifted exactly by the distance it has been offset from the main (blue) window):

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  • GLSL shader render to texture not saving alpha value

    - by quadelirus
    I am rendering to a texture using a GLSL shader and then sending that texture as input to a second shader. For the first texture I am using RGB channels to send color data to the second GLSL shader, but I want to use the alpha channel to send a floating point number that the second shader will use as part of its program. The problem is that when I read the texture in the second shader the alpha value is always 1.0. I tested this in the following way: at the end of the first shader I did this: gl_FragColor(r, g, b, 0.1); and then in the second texture I read the value of the first texture using something along the lines of vec4 f = texture2D(previous_tex, pos); if (f.a != 1.0) { gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0); return; } No pixels in my output are black, whereas if I change the above code to read gl_FragColor(r, g, 0.1, 1.0); //Notice I'm now sending 0.1 for blue and in the second shader vec4 f = texture2D(previous_tex, pos); if (f.b != 1.0) { gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0); return; } All the appropriate pixels are black. This means that for some reason when I set the alpha value to something other than 1.0 in the first shader and render to a texture, it is still seen as being 1.0 by the second shader. Before I render to texture I glDisable(GL_BLEND); It seems pretty clear to me that the problem has to do with OpenGL handling alpha values in some way that isn't obvious to me since I can use the blue channel in the way I want, and figured someone out there will instantly see the problem.

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  • How do I make the left and right gutters different colors with 960.gs?

    - by Andrew Arrow
    How do I make the left and right gutters different colors with 960.gs? When I try something simple like: <div style="background-color: green"> <div class="container_16"> <div class="grid_16"> test </div> </div> </div> <div style="background-color: cyan"> <div class="container_16"> <div class="grid_16"> test </div> </div> </div> The green and cyan colors are ignored. Seems like the "grid_16" class removes the color for some reason? My goal is being able to have different sections of the page in different colors all the way across the page, even past 960 pixels. So if someone makes their browser 1200px the left and right sides have the right color and the rest of the grid system is all contained within the 960 pixels in the middle. I could add a background color to 'body' to do this for just 1 color, but I want multiple colors in the page. Like different colored horizontal stripes. Thanks.

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  • Python pixel manipulation library

    - by silinter
    So I'm going through the beginning stages of producing a game in Python, and I'm looking for a library that is able to manipulate pixels and blit them relatively fast. My first thought was pygame, as it deals in pure 2D surfaces, but it only allows pixel access through pygame.get_at(), pygame.set_at() and pygame.get_buffer(), all of which lock the surface each time they're called, making them slow to use. I can also use the PixelArray and surfarray classes, but they are locked for the duration of their lifetimes, and the only way to blit them to a surface is to either copy the pixels to a new surface, or use surfarray.blit_array, which requires creating a subsurface of the screen and blitting it to that, if the array is smaller than the screen (if it's bigger I can just use a slice of the array, which is no problem). I don't have much experience with PyOpenGL or Pyglet, but I'm wondering if there is a faster library for doing pixel manipulation in, or if there is a faster method, in Pygame, for doing pixel manupilation. I did some work with SDL and OpenGL in C, and I do like the idea of adding vertex/fragment shaders to my program. My program will chiefly be dealing in loading images and writing/reading to/from surfaces.

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  • What are some programming techniques for converting SD images to HD images

    - by Dr Dork
    I'm taking programming class and instructor loves to work with images so most of our assignments involve manipulating raw RGB image data. One of our assignments is to implement a standard image converter that converts SD images to HD images and vice versa. I always take advantage of these types of assignments to go a little beyond what we were asked to do, so I added a basic anti-aliasing process that uses the average pixel color of the 3x3 surrounding pixels to improve the converted image. While it helps a bit, the resulting image still doesn't look good, which is ok because it's not expected to for the assignment. I've learned that converting an SD to HD images has shown to be much harder than down sampling to SD from HD just because SD to HD effectively involves increasing resolution when it is not there. Obviously, it is hard to create pixels from nothing, but I'd like enhance my anti-aliasing to something that provides better results when upscaling an image. Most of the techniques I find and read on the internet are far beyond my level of image processing and programming. Can anybody suggest any better methods or processes to create good HD content from SD content that may be within my programming skill level? I know that's a difficult thing to gauge since you don't know me, but perhaps knowing that I can write c++ code to read in raw RGB data and upscale/downscale it with simple average-anti-aliasing will give you an idea. Thanks in advance for all your help!

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  • how to tile 3D mesh with image brush in XAML

    - by MC9000
    I have a 2D square in a ViewPort3D that I want to do a tiling of an image (like a checkerboard or flooring with "tiles" effect). I've created an image brush (the image is 50x50 pixels, the surface 250x550 pixels) and a viewport (trying to follow MS's site - though their example is for 2D), but only 1 of the colors in the "tile" image shows up and no tiling is seen. I can't find a single example on the Internet and MS's site has no info (that I can find) on 3D XAML anywhere, so I'm stumped as how to actually do this. <Viewport3D> <Viewport3D.Camera> <PerspectiveCamera Position="125,790,120" LookDirection="0,-.7,-0.25" UpDirection="0,0,1" /> </Viewport3D.Camera> <ModelVisual3D> <ModelVisual3D.Content> <Model3DGroup> <AmbientLight Color="white" /> <GeometryModel3D> <GeometryModel3D.Geometry> <MeshGeometry3D Positions="0,0,0 250,0,0 250,550,0 0,550,0 " TriangleIndices="0 1 3 1 2 3 "/> </GeometryModel3D.Geometry> <GeometryModel3D.Material> <DiffuseMaterial> <DiffuseMaterial.Brush> <ImageBrush ViewportUnits="Absolute" TileMode="Tile" ImageSource="testsquare.gif" Viewport="0,0,50,50" Stretch="None" ViewboxUnits="Absolute" /> </DiffuseMaterial.Brush> </DiffuseMaterial> </GeometryModel3D.Material> </GeometryModel3D> </Model3DGroup> </ModelVisual3D.Content> </ModelVisual3D> </Viewport3D>

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  • NSPredicate as a constraint solver?

    - by Felixyz
    I'm working on a project which includes some slightly more complex dynamic layout of interface elements than what I'm used to. I always feel stupid writing complex code that checks if so-and-so is close to such-and-such and in that case move it x% in some direction, etc. That's just not how programming should be done. Programming should be as declarative as possible! Precisely because what I'm going to do is fairly simple, I thought it would be a good opportunity to try something new, and I thought of using NSPredicate as a simple constraints solver. I've only used NSPredicate for very simple tasks so far, but I know that it capable of much more. Are there any ideas, experiences, examples, warnings, insights that could be useful here? I'll give a very simple example so there will be something concrete to answer. How could I use NSPredicate to solve the following constraints: viewB.xmid = (viewB.leftEdge + viewB.width) / 2 viewB.xmid = max(300, viewA.rightEdge + 20 + viewB.width/2) ("viewB should be horizontally centered on coordinate 300, unless its left edge gets within 20 pixels of viewB's right edge, in which case viewA's left edge should stay fixed at 20 pixels to the right of viewB's right edge and viewA's horizontal center get pushed to the right.") viewA.rightEdge and viewB.width can vary, and those are the 'input variables'. EDIT: Any solution would probably have to use the NSExpression method -(id)expressionValueWithObject:(id)object context:(NSMutableDictionary *)context. This answer is relevant.

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  • Java 2D Resize

    - by jon077
    I have some old Java 2D code I want to reuse, but was wondering, is this the best way to get the highest quality images? public static BufferedImage getScaled(BufferedImage imgSrc, Dimension dim) { // This code ensures that all the pixels in the image are loaded. Image scaled = imgSrc.getScaledInstance( dim.width, dim.height, Image.SCALE_SMOOTH); // This code ensures that all the pixels in the image are loaded. Image temp = new ImageIcon(scaled).getImage(); // Create the buffered image. BufferedImage bufferedImage = new BufferedImage(temp.getWidth(null), temp.getHeight(null), BufferedImage.TYPE_INT_RGB); // Copy image to buffered image. Graphics g = bufferedImage.createGraphics(); // Clear background and paint the image. g.setColor(Color.white); g.fillRect(0, 0, temp.getWidth(null),temp.getHeight(null)); g.drawImage(temp, 0, 0, null); g.dispose(); // j2d's image scaling quality is rather poor, especially when // scaling down an image to a much smaller size. We'll post filter // our images using a trick found at // http://blogs.cocoondev.org/mpo/archives/003584.html // to increase the perceived quality.... float origArea = imgSrc.getWidth() * imgSrc.getHeight(); float newArea = dim.width * dim.height; if (newArea <= (origArea / 2.)) { bufferedImage = blurImg(bufferedImage); } return bufferedImage; } public static BufferedImage blurImg(BufferedImage src) { // soften factor - increase to increase blur strength float softenFactor = 0.010f; // convolution kernel (blur) float[] softenArray = { 0, softenFactor, 0, softenFactor, 1-(softenFactor*4), softenFactor, 0, softenFactor, 0}; Kernel kernel = new Kernel(3, 3, softenArray); ConvolveOp cOp = new ConvolveOp(kernel, ConvolveOp.EDGE_NO_OP, null); return cOp.filter(src, null); }

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  • Drawing a relative line in C#

    - by icemanind
    Guys, I know this is going to turn out to be a simple answer, but I can't seem to figure it out. I have a C# Winform application that I am trying to build. I am trying to draw a white line 60 pixels above the bottom of the form. I am using this code: private void MainForm_Paint(object sender, PaintEventArgs e) { e.Graphics.DrawLine(Pens.White, 10, this.Height-60, 505, this.Height-60); } Simple enough, however no line is drawn. After some debugging, I figured out that it IS drawing the line, but it is drawing it outside my form. If I change the -60 to -175, then I can see it at the bottom of my form. This would solve my problem, except as my form's height changes, the line draws closer and closer to the bottom of my form until eventually, its off the form again. What am I doing wrong? Am I using the wrong graphics unit? Or is there a more complex calculation I need to do to determine 60 pixels from the bottom of my form?

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  • Orthogonal projection and texture coordinates in opengl

    - by knuck
    I'm writing a 2D game in Opengl. I already set up the orthogonal projection so I can easily know where a quad will end up on screen. The problem is, I also want to be able to map pixels directly to texture coords, so I also applied an orthogonal transformation (using gluOrtho2d) to the texture. Now I can map pixels directly using integers and glTexCoord2i. The thing is, after googling/reading/asking, I found out no one really knows (apparently) the behavior of glTexCoord2i, but it works just fine the way I'm using. Some sample test code I wrote follows: glBegin(GL_QUADS); glTexCoord2i(16,0); glVertex2f(X, Y); glTexCoord2i(16,16); glVertex2f(X, Y+32); glTexCoord2i(32, 16); glVertex2f(X+32, Y+32); glTexCoord2i(32, 0); glVertex2f(X+32, Y); glEnd(); So, is there any problem with what I'm doing, or is what I'm doing correct?

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  • Sending series of images to display like a movie on iPhone

    - by unknownthreat
    Allow me to elaborate more. On the server, we will have a program that will take data from iPhone and process that data and produce series of images. Each time an image is generated, it will be send back to display on iPhone. I have done all of the things above using UDP, OpenGL, and such. It works. The images are transferred to iPhone and can be displayed, but it is slow. The image's resolution is around 320 x 420 and we send the image pixels by pixels. This naive implementation leads to a slow framerate. I can see around 2-3 frames per second. There are also some UDP packets dropped, and this is expected. Are there any sort of compression method available for something like this? Are there any other method that can make this better? NOTE: please don't just write "compression" as an answer, because we are aware that we will need to do it in some ways.

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  • How to create a CGBitmapContext which works for Retina display and not wasting space for regular display?

    - by ????
    Is it true that if it is in UIKit, including drawRect, the HD aspect of Retina display is automatically handled? So does that mean in drawRect, the current graphics context for a 1024 x 768 view is actually a 2048 x 1536 pixel Bitmap context? (is there a way to print this size out to verify it). We actually enjoy the luxury of 1 point = 4 pixels automatically handled for us. However, if we use CGBitmapContextCreate, then those will really be pixels, not points? (at least if we provide a data buffer for that bitmap, the size is not for the higher resolution, but for the standard resolution, and even if we pass NULL as the buffer so that CGBitmapContextCreate handles the buffer for us, the size probably is the same as if we pass in a data buffer, and it is just standard resolution, not Retina's resolution). We can always create 2048 x 1536 for iPad 1 and iPad 2 as well as the New iPad, but it will waste memory and processor and GPU power, as it is only needed for the New iPad. So do we have to use a if () { } else { } to create such a bitmap context and how do we actually do so? And all our code CGContextMoveToPoint has to be adjusted for Retina display to use x * 2 and y * 2 vs non-retina display of just using x, y as well? That can be quite messy for the code. (or maybe we can define a local variable scaleFactor and set it to 1 for standard resolution and 2 if it is retina, so our x and y will always be x * scaleFactor, y * scaleFactor instead of just x and y.) It seems that UIGraphicsBeginImageContextWithOptions can create one for Retina automatically if the scale of 0.0 is passed in, but I don't think it can be used if I need to create the context and keep it (and using ivar or property of UIViewController to hold it). If I don't release it using UIGraphicsEndImageContext, then it stays in the graphics context stack, so it seems like I have to use CGBitmapContextCreate instead. (or do we just let it stay at the bottom of the stack and not worry about it?)

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  • Automatic tracking algorithm

    - by nico
    Hi everyone, I'm trying to write a simple tracking routine to track some points on a movie. Essentially I have a series of 100-frames-long movies, showing some bright spots on dark background. I have ~100-150 spots per frame, and they move over the course of the movie. I would like to track them, so I'm looking for some efficient (but possibly not overkilling to implement) routine to do that. A few more infos: the spots are a few (es. 5x5) pixels in size the movement are not big. A spot generally does not move more than 5-10 pixels from its original position. The movements are generally smooth. the "shape" of these spots is generally fixed, they don't grow or shrink BUT they become less bright as the movie progresses. the spots don't move in a particular direction. They can move right and then left and then right again the user will select a region around each spot and then this region will be tracked, so I do not need to automatically find the points. As the videos are b/w, I though I should rely on brigthness. For instance I thought I could move around the region and calculate the correlation of the region's area in the previous frame with that in the various positions in the next frame. I understand that this is a quite naïve solution, but do you think it may work? Does anyone know specific algorithms that do this? It doesn't need to be superfast, as long as it is accurate I'm happy. Thank you nico

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  • Turning off antialiasing in Löve2D

    - by cjanssen
    I'm using Löve2D for writing a small game. Löve2D is an open source game engine for Lua. The problem I'm encountering is that some antialias filter is automatically applied to your sprites when you draw it at non-integer positions. love.graphics.draw( sprite, x, y ) So when x or y is not round (for example, x=100.24), the sprite appears blurred. The same happens when the sprite size is not even, because (x,y) points to the center of the sprite. For example, a sprite which is 31x30 big will appear blurred again, because its pixels are painted in non-integer positions. Since I am using pixel art, I want to avoid this all the way, otherwise the art is destroyed by this effect. The workaround I am using so far is to force the coordinates to be round by littering the code with calls to math.floor(), and forcing all the sprites to have even sizes by adding a row or column of transparent pixels with the paint program, if needed. Is there some command to deactivate the antialiasing I can call at program startup?

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  • How to create dynamic panel layout for this logo creation wizard ?

    - by Rebol Tutorial
    I want to create a wizard for the logo badge below with 3 parameters. I can make the title dynamic but for image and gradient it's hardcoded because I can't see how to make them dynamic. Code follows after pictures: custom-styles: stylize [ lab: label 60x20 right bold middle font-size 11 btn: button 64x20 font-size 11 edge [size: 1x1] fld: field 200x20 font-size 11 middle edge [size: 1x1] inf: info font-size 11 middle edge [size: 1x1] ari: field wrap font-size 11 edge [size: 1x1] with [flags: [field tabbed]] ] panel1: layout/size [ origin 0 space 2x2 across styles custom-styles h3 "Parameters" font-size 14 return lab "Title" fld_title: fld "EXPERIMENT" return lab "Logo" fld_logo: fld "http://www.rebol.com/graphics/reb-logo.gif" return lab "Gradient" fld_gradient: fld "5 55 5 10 10 71.0.6 30.10.10 71.0.6" ] 278x170 panel2: layout/size [ ;layout (window client area) size is 278x170 at the end of the spec block at 0x0 ;put the banner on the top left corner box 278x170 effect [ ; default box face size is 100x100 draw [ anti-alias on line-width 2.5 ; number of pixels in width of the border pen black ; color of the edge of the next draw element fill-pen radial 100x50 5 55 5 10 10 71.0.6 30.10.10 71.0.6 ; the draw element box ; another box drawn as an effect 15 ; size of rounding in pixels 0x0 ; upper left corner 278x170 ; lower right corner ] ] pad 30x-150 Text fld_title/text font [name: "Impact" size: 24 color: white] image http://www.rebol.com/graphics/reb-logo.gif ] 278x170 main: layout [ vh2 "Logo Badge Wizard" guide pad 20 button "Parameters" [panels/pane: panel1 show panels ] button "Rendering" [show panel2 panels/pane: panel2 show panels] button "Quit" [Unview] return box 2x170 maroon return panels: box 278x170 ] panel1/offset: 0x0 panel2/offset: 0x0 panels/pane: panel1 view main

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  • Trouble when changing pixel data with alpha on png on iphone --okay on simulator

    - by Ted
    I'm trying to change the color of the pixels (lighten or darken) without changing the value of the alpha channel using CGDataProviderCopyData. I leave every 4th databyte untouched. It work fine of the iphone simulator, however on the real thing the alpha goes white as I increase the values of the other pixels. I've tried changing just the first byte, or the second, or the third. Does anybody have any idea what is going on? The basic code is borrowed from Jorge. I like this simple approach --I'm new to this. But I want to make it work with png images with some transparency. here is most of the code by Jorge : CFDataRef CopyImagePixels(CGImageRef inImage){ return CGDataProviderCopyData(CGImageGetDataProvider(inImage)); } CGImageRef img=originalImage.CGImage; CFDataRef dataref=CopyImagePixels(img); UInt8 *data=(UInt8 *)CFDataGetBytePtr(dataref); int length=CFDataGetLength(dataref); for(int index=0;index255){ data[index+i]=255; }else{ data[index+i]+=value; } } } } size_t width=CGImageGetWidth(img); size_t height=CGImageGetHeight(img); size_t bitsPerComponent=CGImageGetBitsPerComponent(img); size_t bitsPerPixel=CGImageGetBitsPerPixel(img); size_t bytesPerRow=CGImageGetBytesPerRow(img); CGColorSpaceRef colorspace=CGImageGetColorSpace(img); CGBitmapInfo bitmapInfo=CGImageGetBitmapInfo(img); CGImageAlphaInfo alphaInfo = kCGBitmapAlphaInfoMask(img); NSLog(@"bitmapinfo: %d",bitmapInfo); CFDataRef newData=CFDataCreate(NULL,data,length); CGDataProviderRef provider=CGDataProviderCreateWithCFData(newData); CGImageRef newImg=CGImageCreate(width,height,bitsPerComponent,bitsPerPixel,bytesPerRow,colorspace,bitmapInfo,provider,NULL,true,kCGRenderingIntentDefault); [iv setImage:[UIImage imageWithCGImage:newImg]]; CGImageRelease(newImg); CGDataProviderRelease(provider);

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