ios图片jpa转bmp.doc

#import interface ImageHelper : NSObject /* Converts a UIImage to RGBA8 bitmap. param image - a UIImage to be converted return a RGBA8 bitmap, or NULL if any memory allocation issues. Cleanup memory with free() when done. */+ (unsigned char *) convertUIImageToBitmapRGBA8:(UIImage *)image;/* A helper routine used to convert a RGBA8 to UIImage return a new context that is owned by the caller */+ (CGContextRef) newBitmapRGBA8ContextFromImage:(CGImageRef)image;/* Converts a RGBA8 bitmap to a UIImage. param buffer - the RGBA8 unsigned char * bitmap param width - the number of pixels wide param height - the number of pixels tall return a UIImage that is autoreleased or nil if memory allocation issues */+ (UIImage *) convertBitmapRGBA8ToUIImage:(unsigned char *)buffer withWidth:(int)width withHeight:(int)height;end#import ImageHelper.himplementation ImageHelper+ (unsigned char *) convertUIImageToBitmapRGBA8:(UIImage *) image CGImageRef imageRef = image.CGImage; / Create a bitmap context to draw the uiimage into CGContextRef context = self newBitmapRGBA8ContextFromImage:imageRef; if(!context) return NULL; size_t width = CGImageGetWidth(imageRef); size_t height = CGImageGetHeight(imageRef); CGRect rect = CGRectMake(0, 0, width, height); / Draw image into the context to get the raw image data CGContextDrawImage(context, rect, imageRef); / Get a pointer to the data unsigned char *bitmapData = (unsigned char *)CGBitmapContextGetData(context); / Copy the data and release the memory (return memory allocated with new) size_t bytesPerRow = CGBitmapContextGetBytesPerRow(context); size_t bufferLength = bytesPerRow * height; unsigned char *newBitmap = NULL; if(bitmapData) newBitmap = (unsigned char *)malloc(sizeof(unsigned char) * bytesPerRow * height); if(newBitmap) / Copy the data for(int i = 0; i bufferLength; +i) newBitmapi = bitmapDatai; free(bitmapData); else NSLog(Error getting bitmap pixel datan); CGContextRelease(context); return newBitmap; + (CGContextRef) newBitmapRGBA8ContextFromImage:(CGImageRef) image CGContextRef context = NULL; CGColorSpaceRef colorSpace; uint32_t *bitmapData; size_t bitsPerPixel = 32; size_t bitsPerComponent = 8; size_t bytesPerPixel = bitsPerPixel / bitsPerComponent; size_t width = CGImageGetWidth(image); size_t height = CGImageGetHeight(image); size_t bytesPerRow = width * bytesPerPixel; size_t bufferLength = bytesPerRow * height; colorSpace = CGColorSpaceCreateDeviceRGB(); if(!colorSpace) NSLog(Error allocating color space RGBn); return NULL; / Allocate memory for image data bitmapData = (uint32_t *)malloc(bufferLength); if(!bitmapData) NSLog(Error allocating memory for bitmapn); CGColorSpaceRelease(colorSpace); return NULL; /Create bitmap context context = CGBitmapContextCreate(bitmapData, width, height, bitsPerComponent, bytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast); / RGBA if(!context) free(bitmapData); NSLog(Bitmap context not created); CGColorSpaceRelease(colorSpace); return context; + (UIImage *) convertBitmapRGBA8ToUIImage:(unsigned char *) buffer withWidth:(int) width withHeight:(int) height size_t bufferLength = width * height * 4; CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, buffer, bufferLength, NULL); size_t bitsPerComponent = 8; size_t bitsPerPixel = 32; size_t bytesPerRow = 4 * width; CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB(); if(colorSpaceRef = NULL) NSLog(Error allocating color space); CGDataProviderRelease(provider); return nil; CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedLast; CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault; CGImageRef iref = CGImageCreate(width, height, bitsPerComponent, bitsPerPixel, bytesPerRow, colorSpaceRef, bitmapInfo, provider, / data provider NULL, / decode YES, / should interpolate renderingIntent); uint32_t* pixels = (uint32_t*)malloc(bufferLength); if(pixels = NULL) NSLog(Error: Memory not allocated for bitmap); CGDataProviderRelease(provider); CGColorSpaceRelease(colorSpaceRef); CGImageRelease(iref); return nil; CGContextRef context = CGBitmapContextCreate(pixels, width, height, bitsPerComponent, bytesPerRow, colorSpaceRef, bitmapInfo); if(context = NULL) NSLog(Error context not created); free(pixels); UIImage *image = nil; if(context) CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, width, height), iref); CGImageRef imageRef = CGBitmapContextCreateImage(context); / Support both iPad 3.2 and iPhone 4 Retina displays with the correct scale if(UIImage respondsToSelector:selector(imageWithCGImage:scale:orientation:) float scale = UIScreen mainScreen scale; image = UIImage imageWithCGImage:imageRef scale:scale orientation:UIImageOr