GPUImagePicture类静态图像处理操作，它可以是需要处理的静态图像，也可以是一张作为纹理使用的图片，调用向它发送processImage消息，进行图像滤镜处理。

　　方法

　　- (id)initWithURL:(NSURL *)url

　　说明：使用指定url的图片来初始化GPUImagePicture

 

　　- (id)initWithImage:(UIImage *)newImageSource

　　说明：使用指定的UIImage对象来初始化GPUImagePicture

 

　　- (id)initWithCGImage:(CGImageRef)newImageSource

　　说明：使用指定的CGImageRef对象来初始化GPUImagePicture

 

　　- (id)initWithImage:(UIImage *)newImageSource smoothlyScaleOutput:(BOOL)smoothlyScaleOutput

　　说明：使用指定的UIImage对象来初始化GPUImagePicture，是否按比例调整输入图像的尺寸

 

　　- (void)processImage

　　说明：进行图像处理实际操作。

 

　　- (BOOL)processImageWithCompletionHandler:(void (^)(void))completion

　　说明：进行图像处理实际的操作，completion为当处理结束执行的操作。

完整代码

#import 
     
      #import "GPUImageOutput.h"@interface GPUImagePicture : GPUImageOutput{    CGSize pixelSizeOfImage;    BOOL hasProcessedImage;        dispatch_semaphore_t imageUpdateSemaphore;}// Initialization and teardown- (id)initWithURL:(NSURL *)url;- (id)initWithImage:(UIImage *)newImageSource;- (id)initWithCGImage:(CGImageRef)newImageSource;- (id)initWithImage:(UIImage *)newImageSource smoothlyScaleOutput:(BOOL)smoothlyScaleOutput;- (id)initWithCGImage:(CGImageRef)newImageSource smoothlyScaleOutput:(BOOL)smoothlyScaleOutput;// Image rendering- (void)processImage;- (CGSize)outputImageSize;/** * Process image with all targets and filters asynchronously * The completion handler is called after processing finished in the * GPU's dispatch queue - and only if this method did not return NO. * * @returns NO if resource is blocked and processing is discarded, YES otherwise */- (BOOL)processImageWithCompletionHandler:(void (^)(void))completion;- (void)processImageUpToFilter:(GPUImageOutput
      
        *)finalFilterInChain withCompletionHandler:(void (^)(UIImage *processedImage))block;@end
      
     

#import "GPUImagePicture.h"@implementation GPUImagePicture#pragma mark -#pragma mark Initialization and teardown- (id)initWithURL:(NSURL *)url;{    NSData *imageData = [[NSData alloc] initWithContentsOfURL:url];        if (!(self = [self initWithData:imageData]))    {        return nil;    }        return self;}- (id)initWithData:(NSData *)imageData;{    UIImage *inputImage = [[UIImage alloc] initWithData:imageData];        if (!(self = [self initWithImage:inputImage]))    {        return nil;    }        return self;}- (id)initWithImage:(UIImage *)newImageSource;{    if (!(self = [self initWithImage:newImageSource smoothlyScaleOutput:NO]))    {        return nil;    }        return self;}- (id)initWithCGImage:(CGImageRef)newImageSource;{    if (!(self = [self initWithCGImage:newImageSource smoothlyScaleOutput:NO]))    {        return nil;    }    return self;}- (id)initWithImage:(UIImage *)newImageSource smoothlyScaleOutput:(BOOL)smoothlyScaleOutput;{    return [self initWithCGImage:[newImageSource CGImage] smoothlyScaleOutput:smoothlyScaleOutput];}- (id)initWithCGImage:(CGImageRef)newImageSource smoothlyScaleOutput:(BOOL)smoothlyScaleOutput;{    if (!(self = [super init]))    {        return nil;    }        hasProcessedImage = NO;    self.shouldSmoothlyScaleOutput = smoothlyScaleOutput;    imageUpdateSemaphore = dispatch_semaphore_create(0);    dispatch_semaphore_signal(imageUpdateSemaphore);    // TODO: Dispatch this whole thing asynchronously to move image loading off main thread    CGFloat widthOfImage = CGImageGetWidth(newImageSource);    CGFloat heightOfImage = CGImageGetHeight(newImageSource);    // If passed an empty image reference, CGContextDrawImage will fail in future versions of the SDK.    NSAssert( widthOfImage > 0 && heightOfImage > 0, @"Passed image must not be empty - it should be at least 1px tall and wide");        pixelSizeOfImage = CGSizeMake(widthOfImage, heightOfImage);    CGSize pixelSizeToUseForTexture = pixelSizeOfImage;        BOOL shouldRedrawUsingCoreGraphics = NO;        // For now, deal with images larger than the maximum texture size by resizing to be within that limit    CGSize scaledImageSizeToFitOnGPU = [GPUImageContext sizeThatFitsWithinATextureForSize:pixelSizeOfImage];    if (!CGSizeEqualToSize(scaledImageSizeToFitOnGPU, pixelSizeOfImage))    {        pixelSizeOfImage = scaledImageSizeToFitOnGPU;        pixelSizeToUseForTexture = pixelSizeOfImage;        shouldRedrawUsingCoreGraphics = YES;    }        if (self.shouldSmoothlyScaleOutput)    {        // In order to use mipmaps, you need to provide power-of-two textures, so convert to the next largest power of two and stretch to fill        CGFloat powerClosestToWidth = ceil(log2(pixelSizeOfImage.width));        CGFloat powerClosestToHeight = ceil(log2(pixelSizeOfImage.height));                pixelSizeToUseForTexture = CGSizeMake(pow(2.0, powerClosestToWidth), pow(2.0, powerClosestToHeight));                shouldRedrawUsingCoreGraphics = YES;    }        GLubyte *imageData = NULL;    CFDataRef dataFromImageDataProvider = NULL;    GLenum format = GL_BGRA;        if (!shouldRedrawUsingCoreGraphics) {        /* Check that the memory layout is compatible with GL, as we cannot use glPixelStore to         * tell GL about the memory layout with GLES.         */        if (CGImageGetBytesPerRow(newImageSource) != CGImageGetWidth(newImageSource) * 4 ||            CGImageGetBitsPerPixel(newImageSource) != 32 ||            CGImageGetBitsPerComponent(newImageSource) != 8)        {            shouldRedrawUsingCoreGraphics = YES;        } else {            /* Check that the bitmap pixel format is compatible with GL */            CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(newImageSource);            if ((bitmapInfo & kCGBitmapFloatComponents) != 0) {                /* We don't support float components for use directly in GL */                shouldRedrawUsingCoreGraphics = YES;            } else {                CGBitmapInfo byteOrderInfo = bitmapInfo & kCGBitmapByteOrderMask;                if (byteOrderInfo == kCGBitmapByteOrder32Little) {                    /* Little endian, for alpha-first we can use this bitmap directly in GL */                    CGImageAlphaInfo alphaInfo = bitmapInfo & kCGBitmapAlphaInfoMask;                    if (alphaInfo != kCGImageAlphaPremultipliedFirst && alphaInfo != kCGImageAlphaFirst &&                        alphaInfo != kCGImageAlphaNoneSkipFirst) {                        shouldRedrawUsingCoreGraphics = YES;                    }                } else if (byteOrderInfo == kCGBitmapByteOrderDefault || byteOrderInfo == kCGBitmapByteOrder32Big) {                    /* Big endian, for alpha-last we can use this bitmap directly in GL */                    CGImageAlphaInfo alphaInfo = bitmapInfo & kCGBitmapAlphaInfoMask;                    if (alphaInfo != kCGImageAlphaPremultipliedLast && alphaInfo != kCGImageAlphaLast &&                        alphaInfo != kCGImageAlphaNoneSkipLast) {                        shouldRedrawUsingCoreGraphics = YES;                    } else {                        /* Can access directly using GL_RGBA pixel format */                        format = GL_RGBA;                    }                }            }        }    }        //    CFAbsoluteTime elapsedTime, startTime = CFAbsoluteTimeGetCurrent();        if (shouldRedrawUsingCoreGraphics)    {        // For resized or incompatible image: redraw        imageData = (GLubyte *) calloc(1, (int)pixelSizeToUseForTexture.width * (int)pixelSizeToUseForTexture.height * 4);                CGColorSpaceRef genericRGBColorspace = CGColorSpaceCreateDeviceRGB();                CGContextRef imageContext = CGBitmapContextCreate(imageData, (size_t)pixelSizeToUseForTexture.width, (size_t)pixelSizeToUseForTexture.height, 8, (size_t)pixelSizeToUseForTexture.width * 4, genericRGBColorspace,  kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);        //        CGContextSetBlendMode(imageContext, kCGBlendModeCopy); // From Technical Q&A QA1708: http://developer.apple.com/library/ios/#qa/qa1708/_index.html        CGContextDrawImage(imageContext, CGRectMake(0.0, 0.0, pixelSizeToUseForTexture.width, pixelSizeToUseForTexture.height), newImageSource);        CGContextRelease(imageContext);        CGColorSpaceRelease(genericRGBColorspace);    }    else    {        // Access the raw image bytes directly        dataFromImageDataProvider = CGDataProviderCopyData(CGImageGetDataProvider(newImageSource));        imageData = (GLubyte *)CFDataGetBytePtr(dataFromImageDataProvider);    }        //    elapsedTime = (CFAbsoluteTimeGetCurrent() - startTime) * 1000.0;    //    NSLog(@"Core Graphics drawing time: %f", elapsedTime);        //    CGFloat currentRedTotal = 0.0f, currentGreenTotal = 0.0f, currentBlueTotal = 0.0f, currentAlphaTotal = 0.0f;    //    NSUInteger totalNumberOfPixels = round(pixelSizeToUseForTexture.width * pixelSizeToUseForTexture.height);    //    //    for (NSUInteger currentPixel = 0; currentPixel < totalNumberOfPixels; currentPixel++)    //    {    //        currentBlueTotal += (CGFloat)imageData[(currentPixel * 4)] / 255.0f;    //        currentGreenTotal += (CGFloat)imageData[(currentPixel * 4) + 1] / 255.0f;    //        currentRedTotal += (CGFloat)imageData[(currentPixel * 4 + 2)] / 255.0f;    //        currentAlphaTotal += (CGFloat)imageData[(currentPixel * 4) + 3] / 255.0f;    //    }    //    //    NSLog(@"Debug, average input image red: %f, green: %f, blue: %f, alpha: %f", currentRedTotal / (CGFloat)totalNumberOfPixels, currentGreenTotal / (CGFloat)totalNumberOfPixels, currentBlueTotal / (CGFloat)totalNumberOfPixels, currentAlphaTotal / (CGFloat)totalNumberOfPixels);        runSynchronouslyOnVideoProcessingQueue(^{        [GPUImageContext useImageProcessingContext];                outputFramebuffer = [[GPUImageContext sharedFramebufferCache] fetchFramebufferForSize:pixelSizeToUseForTexture onlyTexture:YES];        [outputFramebuffer disableReferenceCounting];        glBindTexture(GL_TEXTURE_2D, [outputFramebuffer texture]);        if (self.shouldSmoothlyScaleOutput)        {            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);        }        // no need to use self.outputTextureOptions here since pictures need this texture formats and type        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, (int)pixelSizeToUseForTexture.width, (int)pixelSizeToUseForTexture.height, 0, format, GL_UNSIGNED_BYTE, imageData);                if (self.shouldSmoothlyScaleOutput)        {            glGenerateMipmap(GL_TEXTURE_2D);        }        glBindTexture(GL_TEXTURE_2D, 0);    });        if (shouldRedrawUsingCoreGraphics)    {        free(imageData);    }    else    {        if (dataFromImageDataProvider)        {            CFRelease(dataFromImageDataProvider);        }    }        return self;}// ARC forbids explicit message send of 'release'; since iOS 6 even for dispatch_release() calls: stripping it out in that case is required.- (void)dealloc;{    [outputFramebuffer enableReferenceCounting];    [outputFramebuffer unlock];#if !OS_OBJECT_USE_OBJC    if (imageUpdateSemaphore != NULL)    {        dispatch_release(imageUpdateSemaphore);    }#endif}#pragma mark -#pragma mark Image rendering- (void)removeAllTargets;{    [super removeAllTargets];    hasProcessedImage = NO;}- (void)processImage;{    [self processImageWithCompletionHandler:nil];}- (BOOL)processImageWithCompletionHandler:(void (^)(void))completion;{    hasProcessedImage = YES;        //    dispatch_semaphore_wait(imageUpdateSemaphore, DISPATCH_TIME_FOREVER);        if (dispatch_semaphore_wait(imageUpdateSemaphore, DISPATCH_TIME_NOW) != 0)    {        return NO;    }        runAsynchronouslyOnVideoProcessingQueue(^{                for (id
     
       currentTarget in targets)        {            NSInteger indexOfObject = [targets indexOfObject:currentTarget];            NSInteger textureIndexOfTarget = [[targetTextureIndices objectAtIndex:indexOfObject] integerValue];                        [currentTarget setCurrentlyReceivingMonochromeInput:NO];            [currentTarget setInputSize:pixelSizeOfImage atIndex:textureIndexOfTarget];            [currentTarget setInputFramebuffer:outputFramebuffer atIndex:textureIndexOfTarget];            [currentTarget newFrameReadyAtTime:kCMTimeIndefinite atIndex:textureIndexOfTarget];        }                dispatch_semaphore_signal(imageUpdateSemaphore);                if (completion != nil) {            completion();        }    });        return YES;}- (void)processImageUpToFilter:(GPUImageOutput
      
        *)finalFilterInChain withCompletionHandler:(void (^)(UIImage *processedImage))block;{    [finalFilterInChain useNextFrameForImageCapture];    [self processImageWithCompletionHandler:^{        UIImage *imageFromFilter = [finalFilterInChain imageFromCurrentFramebuffer];        block(imageFromFilter);    }];}- (CGSize)outputImageSize;{    return pixelSizeOfImage;}- (void)addTarget:(id
       
        )newTarget atTextureLocation:(NSInteger)textureLocation;{    [super addTarget:newTarget atTextureLocation:textureLocation];        if (hasProcessedImage)    {        [newTarget setInputSize:pixelSizeOfImage atIndex:textureLocation];        [newTarget newFrameReadyAtTime:kCMTimeIndefinite atIndex:textureLocation];    }}@end