2014/10/15 下午 10:12:36
iphone Programming Glossary: pixelRetrieving a pixel alpha value for a UIImage http://stackoverflow.com/questions/1042830/retrieving-a-pixel-alpha-value-for-a-uiimage a pixel alpha value for a UIImage I am currently trying to obtain the alpha value of a pixel in a UIImageView... a pixel alpha value for a UIImage I am currently trying to obtain the alpha value of a pixel in a UIImageView. I have obtained the CGImage from UIImageView image and created a RGBA byte array from.. You could do the lookup much more efficient by building the smallest possible CGBitmapContext 1x1 pixel maybe 8x8 have a try and translating the context to your desired position before drawing CGContextTranslateCTM..
iOS 6 apps - how to deal with iPhone 5 screen size? [duplicate] http://stackoverflow.com/questions/12396545/ios-6-apps-how-to-deal-with-iphone-5-screen-size I was just wondering with how should we deal with the iPhone 5 bigger screen size. As it has more pixels in height things like GCRectMake that use coordinates and just doubled the pixels with the retina non.. As it has more pixels in height things like GCRectMake that use coordinates and just doubled the pixels with the retina non retina problem won't work seamlessly between versions as it happened when we got.. It works great out of the box for table views however if your app used pixel perfect layout for displaying content then your best bet would be to re imagine the content so that..
How to get the RGB values for a pixel on an image on the iphone http://stackoverflow.com/questions/144250/how-to-get-the-rgb-values-for-a-pixel-on-an-image-on-the-iphone to get the RGB values for a pixel on an image on the iphone I am writing an iPhone application and need to essentially implement something.. tool in photoshop where you can touch a point on the image and capture the RGB values for the pixel in question to determine and match its color. Getting the UIImage is the easy part but is there a way.. UIImage data into a bitmap representation in which I could extract this information for a given pixel A working code sample would be most appreciated and note that I am not concerned with the alpha value...
The simplest way to resize an UIImage? http://stackoverflow.com/questions/2658738/the-simplest-way-to-resize-an-uiimage an UIImage In my iPhone app I take a picture with the camera then I want to resize it to 290 390 pixels. I was using this method to resize the image UIImage newImage image _imageScaledToSize CGSizeMake 290.. newSize UIGraphicsBeginImageContext newSize In next line pass 0.0 to use the current device's pixel scaling factor and thus account for Retina resolution . Pass 1.0 to force exact pixel size. UIGraphicsBeginImageContextWithOptions.. device's pixel scaling factor and thus account for Retina resolution . Pass 1.0 to force exact pixel size. UIGraphicsBeginImageContextWithOptions newSize NO 0.0 image drawInRect CGRectMake 0 0 newSize.width..
How do I export UIImage array as a movie? http://stackoverflow.com/questions/3741323/how-do-i-export-uiimage-array-as-a-movie have to fill in a lot of blanks but I think that the only really hard remaining part is getting a pixel buffer from a CGImage CVPixelBufferRef newPixelBufferFromCGImage CGImageRef image NSDictionary options..
Gradients on UIView and UILabels On iPhone [duplicate] http://stackoverflow.com/questions/422066/gradients-on-uiview-and-uilabels-on-iphone ios cocoa touch gradient share improve this question You could also use a graphic image one pixel wide as the gradient and set the view property to expand the graphic to fill the view assuming you are..
OpenGL Texture Coordinates in Pixel Space http://stackoverflow.com/questions/5879403/opengl-texture-coordinates-in-pixel-space but I don't have the links at hand so a quick and rough explanation. Let's say the texture is 8 pixels wide 0 1 2 3 4 5 6 7 ^ ^ ^ ^ ^ ^ ^ ^ ^ 0.0 1.0 0 8 1 8 2 8 3 8 4 8 5 8 6 8 7 8 8 8 The digits denote.. 7 ^ ^ ^ ^ ^ ^ ^ ^ ^ 0.0 1.0 0 8 1 8 2 8 3 8 4 8 5 8 6 8 7 8 8 8 The digits denote the texture's pixels the bars the edges of the texture and in case of nearest filtering the border between pixels. You however.. pixels the bars the edges of the texture and in case of nearest filtering the border between pixels. You however want to hit the pixels' centers. So you're interested in the texture coordinates 0 8 1..
Retrieving a pixel alpha value for a UIImage http://stackoverflow.com/questions/1042830/retrieving-a-pixel-alpha-value-for-a-uiimage a pixel alpha value for a UIImage I am currently trying to obtain the alpha value of a pixel in a UIImageView. I have obtained the CGImage from UIImageView image and created.. a pixel alpha value for a UIImage I am currently trying to obtain the alpha value of a pixel in a UIImageView. I have obtained the CGImage from UIImageView image and created a RGBA byte array from this. Alpha is premultiplied. CGImageRef image uiImage.CGImage.. context kCGBlendModeCopy Edit after thinking You could do the lookup much more efficient by building the smallest possible CGBitmapContext 1x1 pixel maybe 8x8 have a try and translating the context to your desired position before drawing CGContextTranslateCTM context xOffset yOffset share improve this answer..
iOS 6 apps - how to deal with iPhone 5 screen size? [duplicate] http://stackoverflow.com/questions/12396545/ios-6-apps-how-to-deal-with-iphone-5-screen-size to develop or migrate apps for iPhone 5 screen resolution I was just wondering with how should we deal with the iPhone 5 bigger screen size. As it has more pixels in height things like GCRectMake that use coordinates and just doubled the pixels with the retina non retina problem won't work seamlessly between versions as.. with how should we deal with the iPhone 5 bigger screen size. As it has more pixels in height things like GCRectMake that use coordinates and just doubled the pixels with the retina non retina problem won't work seamlessly between versions as it happened when we got the Retina . And will we have to design two storyboards just.. view.autoresizingMask UIViewAutoresizingFlexibleWidth UIViewAutoresizingFlexibleHeight It works great out of the box for table views however if your app used pixel perfect layout for displaying content then your best bet would be to re imagine the content so that it can accommodate varying heights. If that's not a possibility..
How to get the RGB values for a pixel on an image on the iphone http://stackoverflow.com/questions/144250/how-to-get-the-rgb-values-for-a-pixel-on-an-image-on-the-iphone to get the RGB values for a pixel on an image on the iphone I am writing an iPhone application and need to essentially implement something equivalent to the 'eyedropper' tool in photoshop where.. essentially implement something equivalent to the 'eyedropper' tool in photoshop where you can touch a point on the image and capture the RGB values for the pixel in question to determine and match its color. Getting the UIImage is the easy part but is there a way to convert the UIImage data into a bitmap representation in.. the UIImage is the easy part but is there a way to convert the UIImage data into a bitmap representation in which I could extract this information for a given pixel A working code sample would be most appreciated and note that I am not concerned with the alpha value. iphone cocoa touch image bitmap share improve this question..
The simplest way to resize an UIImage? http://stackoverflow.com/questions/2658738/the-simplest-way-to-resize-an-uiimage simplest way to resize an UIImage In my iPhone app I take a picture with the camera then I want to resize it to 290 390 pixels. I was using this method to resize the image UIImage newImage image _imageScaledToSize CGSizeMake 290 390 interpolationQuality 1 It works perfectly but it's an.. image UIImage imageWithImage UIImage image scaledToSize CGSize newSize UIGraphicsBeginImageContext newSize In next line pass 0.0 to use the current device's pixel scaling factor and thus account for Retina resolution . Pass 1.0 to force exact pixel size. UIGraphicsBeginImageContextWithOptions newSize NO 0.0 image drawInRect.. newSize In next line pass 0.0 to use the current device's pixel scaling factor and thus account for Retina resolution . Pass 1.0 to force exact pixel size. UIGraphicsBeginImageContextWithOptions newSize NO 0.0 image drawInRect CGRectMake 0 0 newSize.width newSize.height UIImage newImage UIGraphicsGetImageFromCurrentImageContext..
How do I export UIImage array as a movie? http://stackoverflow.com/questions/3741323/how-do-i-export-uiimage-array-as-a-movie 因 videoWriter finishWriting You 耱l still have to fill in a lot of blanks but I think that the only really hard remaining part is getting a pixel buffer from a CGImage CVPixelBufferRef newPixelBufferFromCGImage CGImageRef image NSDictionary options NSDictionary dictionaryWithObjectsAndKeys NSNumber numberWithBool..
Gradients on UIView and UILabels On iPhone [duplicate] http://stackoverflow.com/questions/422066/gradients-on-uiview-and-uilabels-on-iphone to tackle this Your thoughts are greatly appreciated. iphone ios cocoa touch gradient share improve this question You could also use a graphic image one pixel wide as the gradient and set the view property to expand the graphic to fill the view assuming you are thinking of a simple linear gradient and not some kind of..
OpenGL Texture Coordinates in Pixel Space http://stackoverflow.com/questions/5879403/opengl-texture-coordinates-in-pixel-space share improve this question This has been asked a few times but I don't have the links at hand so a quick and rough explanation. Let's say the texture is 8 pixels wide 0 1 2 3 4 5 6 7 ^ ^ ^ ^ ^ ^ ^ ^ ^ 0.0 1.0 0 8 1 8 2 8 3 8 4 8 5 8 6 8 7 8 8 8 The digits denote the texture's pixels the bars the edges of the texture.. Let's say the texture is 8 pixels wide 0 1 2 3 4 5 6 7 ^ ^ ^ ^ ^ ^ ^ ^ ^ 0.0 1.0 0 8 1 8 2 8 3 8 4 8 5 8 6 8 7 8 8 8 The digits denote the texture's pixels the bars the edges of the texture and in case of nearest filtering the border between pixels. You however want to hit the pixels' centers. So you're interested.. 8 1 8 2 8 3 8 4 8 5 8 6 8 7 8 8 8 The digits denote the texture's pixels the bars the edges of the texture and in case of nearest filtering the border between pixels. You however want to hit the pixels' centers. So you're interested in the texture coordinates 0 8 1 8 2 1 2 8 1 8 2 8 2 3 2 8 ... 7 8 8 8 2 15 2 8 Or more generally..
Retrieving a pixel alpha value for a UIImage http://stackoverflow.com/questions/1042830/retrieving-a-pixel-alpha-value-for-a-uiimage a pixel alpha value for a UIImage I am currently trying to obtain the alpha value of a pixel in a UIImageView. I have obtained.. a pixel alpha value for a UIImage I am currently trying to obtain the alpha value of a pixel in a UIImageView. I have obtained the CGImage from UIImageView image and created a RGBA byte array from this. Alpha is premultiplied... Edit after thinking You could do the lookup much more efficient by building the smallest possible CGBitmapContext 1x1 pixel maybe 8x8 have a try and translating the context to your desired position before drawing CGContextTranslateCTM context xOffset..
iOS 6 apps - how to deal with iPhone 5 screen size? [duplicate] http://stackoverflow.com/questions/12396545/ios-6-apps-how-to-deal-with-iphone-5-screen-size 5 screen resolution I was just wondering with how should we deal with the iPhone 5 bigger screen size. As it has more pixels in height things like GCRectMake that use coordinates and just doubled the pixels with the retina non retina problem won't.. 5 bigger screen size. As it has more pixels in height things like GCRectMake that use coordinates and just doubled the pixels with the retina non retina problem won't work seamlessly between versions as it happened when we got the Retina . And will.. UIViewAutoresizingFlexibleHeight It works great out of the box for table views however if your app used pixel perfect layout for displaying content then your best bet would be to re imagine the content so that it can accommodate varying..
How to get the RGB values for a pixel on an image on the iphone http://stackoverflow.com/questions/144250/how-to-get-the-rgb-values-for-a-pixel-on-an-image-on-the-iphone to get the RGB values for a pixel on an image on the iphone I am writing an iPhone application and need to essentially implement something equivalent to.. to the 'eyedropper' tool in photoshop where you can touch a point on the image and capture the RGB values for the pixel in question to determine and match its color. Getting the UIImage is the easy part but is there a way to convert the UIImage.. a way to convert the UIImage data into a bitmap representation in which I could extract this information for a given pixel A working code sample would be most appreciated and note that I am not concerned with the alpha value. iphone cocoa touch..
The simplest way to resize an UIImage? http://stackoverflow.com/questions/2658738/the-simplest-way-to-resize-an-uiimage way to resize an UIImage In my iPhone app I take a picture with the camera then I want to resize it to 290 390 pixels. I was using this method to resize the image UIImage newImage image _imageScaledToSize CGSizeMake 290 390 interpolationQuality.. scaledToSize CGSize newSize UIGraphicsBeginImageContext newSize In next line pass 0.0 to use the current device's pixel scaling factor and thus account for Retina resolution . Pass 1.0 to force exact pixel size. UIGraphicsBeginImageContextWithOptions.. 0.0 to use the current device's pixel scaling factor and thus account for Retina resolution . Pass 1.0 to force exact pixel size. UIGraphicsBeginImageContextWithOptions newSize NO 0.0 image drawInRect CGRectMake 0 0 newSize.width newSize.height..
How do I export UIImage array as a movie? http://stackoverflow.com/questions/3741323/how-do-i-export-uiimage-array-as-a-movie You 耱l still have to fill in a lot of blanks but I think that the only really hard remaining part is getting a pixel buffer from a CGImage CVPixelBufferRef newPixelBufferFromCGImage CGImageRef image NSDictionary options NSDictionary dictionaryWithObjectsAndKeys..
Gradients on UIView and UILabels On iPhone [duplicate] http://stackoverflow.com/questions/422066/gradients-on-uiview-and-uilabels-on-iphone appreciated. iphone ios cocoa touch gradient share improve this question You could also use a graphic image one pixel wide as the gradient and set the view property to expand the graphic to fill the view assuming you are thinking of a simple..
OpenGL Texture Coordinates in Pixel Space http://stackoverflow.com/questions/5879403/opengl-texture-coordinates-in-pixel-space been asked a few times but I don't have the links at hand so a quick and rough explanation. Let's say the texture is 8 pixels wide 0 1 2 3 4 5 6 7 ^ ^ ^ ^ ^ ^ ^ ^ ^ 0.0 1.0 0 8 1 8 2 8 3 8 4 8 5 8 6 8 7 8 8 8 The digits denote the texture's pixels.. wide 0 1 2 3 4 5 6 7 ^ ^ ^ ^ ^ ^ ^ ^ ^ 0.0 1.0 0 8 1 8 2 8 3 8 4 8 5 8 6 8 7 8 8 8 The digits denote the texture's pixels the bars the edges of the texture and in case of nearest filtering the border between pixels. You however want to hit the.. denote the texture's pixels the bars the edges of the texture and in case of nearest filtering the border between pixels. You however want to hit the pixels' centers. So you're interested in the texture coordinates 0 8 1 8 2 1 2 8 1 8 2 8 2..
iPhone Objective C: How to get a pixel's color of the touched point on an UIImageView? http://stackoverflow.com/questions/1285621/iphone-objective-c-how-to-get-a-pixels-color-of-the-touched-point-on-an-uiimag
Pixel Width of the text in a UILabel http://stackoverflow.com/questions/1340667/pixel-width-of-the-text-in-a-uilabel Width of the text in a UILabel I need to draw a UILabel striked through. Therefore I subclassed UILabel and implemented..
How to get the RGB values for a pixel on an image on the iphone http://stackoverflow.com/questions/144250/how-to-get-the-rgb-values-for-a-pixel-on-an-image-on-the-iphone provided by previous posts and at the bottom of this post provides a read only reference to data . Method 1 Writable Pixel Information I defined constants #define RGBA 4 #define RGBA_8_BIT 8 In my UIImage subclass I declared instance variables.. context CGColorSpaceRef colorSpace UInt8 pixelByteData A pointer to an array of RGBA bytes in memory RPVW_RGBAPixel pixelData The pixel struct with alpha in this version typedef struct RGBAPixel byte red byte green byte blue byte alpha.. array of RGBA bytes in memory RPVW_RGBAPixel pixelData The pixel struct with alpha in this version typedef struct RGBAPixel byte red byte green byte blue byte alpha RGBAPixel Bitmap function returns pre calculated RGBA divide RGB by A to get unmodified..
Pixel-Position of Cursor in UITextView http://stackoverflow.com/questions/2633379/pixel-position-of-cursor-in-uitextview Position of Cursor in UITextView is there a way of getting the position CGPoint of the cursor blinking bar in an UITextView..
http://stackoverflow.com/questions/3284185/get-pixel-color-of-uiimage Pixel color of UIImage How can I get the RGB value of a particular pixel in a UIImage iphone uiimage rgb pixel share improve..
PVR textures versus PNG in OpenGL ES http://stackoverflow.com/questions/501956/pvr-textures-versus-png-in-opengl-es internal hardware format will go through drivers unchanged. fast rendering because of smaller memory bandwidth usage. Pixel rendering speed is mostly limited by other factors when PVR textures are used. Take a little RAM VRAM space. Mip maps must..
OpenGL Texture Coordinates in Pixel Space http://stackoverflow.com/questions/5879403/opengl-texture-coordinates-in-pixel-space Texture Coordinates in Pixel Space I'm working on an iPhone app that uses OpenGL ES 2 for its drawing. I know that typically texture coordinates are..
Getting RGB pixel data from CGImage http://stackoverflow.com/questions/6073259/getting-rgb-pixel-data-from-cgimage cgimage size_t height CGImageGetHeight cgimage size_t bpr CGImageGetBytesPerRow cgimage size_t bpp CGImageGetBitsPerPixel cgimage size_t bpc CGImageGetBitsPerComponent cgimage size_t bytes_per_pixel bpp bpc CGBitmapInfo info CGImageGetBitmapInfo.. cgimage NSLog @ n @ n CGImageGetHeight d n CGImageGetWidth d n CGImageGetColorSpace @ n CGImageGetBitsPerPixel d n CGImageGetBitsPerComponent d n CGImageGetBytesPerRow d n CGImageGetBitmapInfo 0x .8X n kCGBitmapAlphaInfoMask s n kCGBitmapFloatComponents.. cgimage NSData data id CGDataProviderCopyData provider data autorelease const uint8_t bytes data bytes printf Pixel Data n for size_t row 0 row height row for size_t col 0 col width col const uint8_t pixel bytes row bpr col bytes_per_pixel..
OpenGL ES: Undo in a Pixel Painting App http://stackoverflow.com/questions/6281789/opengl-es-undo-in-a-pixel-painting-app ES Undo in a Pixel Painting App I'm currently working on an app that allows the user to draw pixelated images using OpenGL ES but I don't..
Decode video frames on iPhone GPU http://stackoverflow.com/questions/9332807/decode-video-frames-on-iphone-gpu writes the result out to an output video file. The code uses some serious low level magic to bind a Core Video Pixel buffer from an AVCaptureSession to OpenGL so they share memory in the graphics hardware. It should be fairly straightforward..
Faster alternative to glReadPixels in iPhone OpenGL ES 2.0 http://stackoverflow.com/questions/9550297/faster-alternative-to-glreadpixels-in-iphone-opengl-es-2-0 alternative to glReadPixels in iPhone OpenGL ES 2.0 Is there any faster way to access the frame buffer than using glReadPixels I would need read only.. to glReadPixels in iPhone OpenGL ES 2.0 Is there any faster way to access the frame buffer than using glReadPixels I would need read only access to a small rectangular rendering area in the frame buffer to process the data further in.. because I have to perform this operation repeatedly. I have searched the web and found some approach like using Pixel Buffer Object and glMapBuffer but it seems that OpenGL ES 2.0 does not support them. iphone ios opengl es opengl es 2.0..
|