UIImage圖片處理

#pragma mark -
#pragma mark - 縮放處理

+ (UIImage *)scaleImage:(UIImage *)image withScale:(float)scale
{
    UIGraphicsBeginImageContext(CGSizeMake(image.size.width * scale, image.size.height * scale));
    
    [image drawInRect:CGRectMake(0, 0, image.size.width * scale, image.size.height * scale)];
    UIImage *scaledImage = UIGraphicsGetImageFromCurrentImageContext();
    
    UIGraphicsEndImageContext();
    
    return scaledImage;
}

+ (UIImage *)scaleImage:(UIImage *)image toSize:(CGSize)size
{
    UIGraphicsBeginImageContext(CGSizeMake(size.width, size.height));
    
    [image drawInRect:CGRectMake(0, 0, size.width, size.height)];
    UIImage *scaledImage = UIGraphicsGetImageFromCurrentImageContext();
    
    UIGraphicsEndImageContext();
    
    return scaledImage;
}

#pragma mark -
#pragma mark - 馬賽克處理

static CGContextRef CreateRGBABitmapContext (CGImageRef inImage)
{
    CGContextRef context = NULL;
    CGColorSpaceRef colorSpace;
    void *bitmapData; //內存空間的指針，該內存空間的大小等於圖像使用RGB通道所佔用的字節數。
    int bitmapByteCount;
    int bitmapBytesPerRow;
    
    size_t pixelsWide = CGImageGetWidth(inImage); //獲取橫向的像素點的個數
    size_t pixelsHigh = CGImageGetHeight(inImage);
    
    bitmapBytesPerRow    = (pixelsWide * 4); //每一行的像素點佔用的字節數，每一個像素點的ARGB四個通道各佔8個bit(0-255)的空間
    bitmapByteCount    = (bitmapBytesPerRow * pixelsHigh); //計算整張圖佔用的字節數
    
    colorSpace = CGColorSpaceCreateDeviceRGB();//建立依賴於設備的RGB通道
    //分配足夠容納圖片字節數的內存空間
    bitmapData = malloc( bitmapByteCount );
    //建立CoreGraphic的圖形上下文，該上下文描述了bitmaData指向的內存空間須要繪製的圖像的一些繪製參數
    context = CGBitmapContextCreate (bitmapData,
                                     pixelsWide,
                                     pixelsHigh,
                                     8,
                                     bitmapBytesPerRow,
                                     colorSpace,
                                     kCGImageAlphaPremultipliedLast);
    //Core Foundation中經過含有Create、Alloc的方法名字建立的指針，須要使用CFRelease()函數釋放
    CGColorSpaceRelease( colorSpace );
    return context;
}

static unsigned char *RequestImagePixelData(UIImage *inImage)
{
    CGImageRef img = [inImage CGImage];
    CGSize size = [inImage size];
    //使用上面的函數建立上下文
    CGContextRef cgctx = CreateRGBABitmapContext(img);
    
    CGRect rect = {{0,0},{size.width, size.height}};
    //將目標圖像繪製到指定的上下文，實際爲上下文內的bitmapData。
    CGContextDrawImage(cgctx, rect, img);
    unsigned char *data = CGBitmapContextGetData (cgctx);
    //釋放上面的函數建立的上下文
    CGContextRelease(cgctx);
    return data;
}

+ (UIImage *)mosaicImage:(UIImage *)image withLevel:(int)level
{
    unsigned char *imgPixel = RequestImagePixelData(image);
    CGImageRef inImageRef = [image CGImage];
    GLuint width = CGImageGetWidth(inImageRef);
    GLuint height = CGImageGetHeight(inImageRef);
    unsigned char prev[4] = {0};
    int bytewidth = width*4;
    int i,j;
    int val = level;
    for(i=0;i<height;i++) {
        if (((i+1)%val) == 0) {
            memcpy(imgPixel+bytewidth*i, imgPixel+bytewidth*(i-1), bytewidth);
            continue;
        }
        for(j=0;j<width;j++) {
            if (((j+1)%val) == 1) {
                memcpy(prev, imgPixel+bytewidth*i+j*4, 4);
                continue;
            }
            memcpy(imgPixel+bytewidth*i+j*4, prev, 4);
        }
    }
    NSInteger dataLength = width*height* 4;
    
    //下面的代碼建立要輸出的圖像的相關參數
    CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, imgPixel, dataLength, NULL);
    // prep the ingredients
    int bitsPerComponent = 8;
    int bitsPerPixel = 32;
    CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
    CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault;
    CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault;
    //建立要輸出的圖像
    CGImageRef imageRef = CGImageCreate(width, height,
                                        bitsPerComponent,
                                        bitsPerPixel,
                                        bytewidth,
                                        colorSpaceRef,
                                        bitmapInfo,
                                        provider,
                                        NULL, NO, renderingIntent);
    UIImage *mosaicImage = [UIImage imageWithCGImage:imageRef scale:image.scale orientation:image.imageOrientation];
    CFRelease(imageRef);
    CGColorSpaceRelease(colorSpaceRef);
    CGDataProviderRelease(provider);
    return mosaicImage;
}

#define kBitsPerComponent (8)
#define kBitsPerPixel (32)
#define kPixelChannelCount (4)

/*
 *轉換成馬賽克,level表明一個點轉爲多少level*level的正方形
 */
+ (UIImage *)transToMosaicImage:(UIImage*)orginImage blockLevel:(NSUInteger)level
{
    //獲取BitmapData
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGImageRef imgRef = orginImage.CGImage;
    CGFloat width = CGImageGetWidth(imgRef);
    CGFloat height = CGImageGetHeight(imgRef);
    CGContextRef context = CGBitmapContextCreate (nil,
                                                  width,
                                                  height,
                                                  kBitsPerComponent,        //每一個顏色值8bit
                                                  width*kPixelChannelCount, //每一行的像素點佔用的字節數，每一個像素點的ARGB四個通道各佔8個bit
                                                  colorSpace,
                                                  kCGImageAlphaPremultipliedLast);
    CGContextDrawImage(context, CGRectMake(0, 0, width, height), imgRef);
    unsigned char *bitmapData = CGBitmapContextGetData (context);
    
    //這裏把BitmapData進行馬賽克轉換,就是用一個點的顏色填充一個level*level的正方形
    unsigned char pixel[kPixelChannelCount] = {0};
    NSUInteger index,preIndex;
    for (NSUInteger i = 0; i < height - 1 ; i++) {
        for (NSUInteger j = 0; j < width - 1; j++) {
            index = i * width + j;
            if (i % level == 0) {
                if (j % level == 0) {
                    memcpy(pixel, bitmapData + kPixelChannelCount*index, kPixelChannelCount);
                }else{
                    memcpy(bitmapData + kPixelChannelCount*index, pixel, kPixelChannelCount);
                }
            } else {
                preIndex = (i-1)*width +j;
                memcpy(bitmapData + kPixelChannelCount*index, bitmapData + kPixelChannelCount*preIndex, kPixelChannelCount);
            }
        }
    }
    
    NSInteger dataLength = width*height* kPixelChannelCount;
    CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, bitmapData, dataLength, NULL);
    //建立要輸出的圖像
    CGImageRef mosaicImageRef = CGImageCreate(width, height,
                                              kBitsPerComponent,
                                              kBitsPerPixel,
                                              width*kPixelChannelCount ,
                                              colorSpace,
                                              kCGImageAlphaPremultipliedLast,
                                              provider,
                                              NULL, NO,
                                              kCGRenderingIntentDefault);
    CGContextRef outputContext = CGBitmapContextCreate(nil,
                                                       width,
                                                       height,
                                                       kBitsPerComponent,
                                                       width*kPixelChannelCount,
                                                       colorSpace,
                                                       kCGImageAlphaPremultipliedLast);
    CGContextDrawImage(outputContext, CGRectMake(0.0f, 0.0f, width, height), mosaicImageRef);
    CGImageRef resultImageRef = CGBitmapContextCreateImage(outputContext);
    UIImage *resultImage = nil;
    if([UIImage respondsToSelector:@selector(imageWithCGImage:scale:orientation:)]) {
//        float scale = [[UIScreen mainScreen] scale];
//        resultImage = [UIImage imageWithCGImage:resultImageRef scale:scale orientation:UIImageOrientationUp];
        resultImage = [UIImage imageWithCGImage:resultImageRef scale:orginImage.scale orientation:orginImage.imageOrientation];
    } else {
        resultImage = [UIImage imageWithCGImage:resultImageRef];
    }
    //釋放
    if(resultImageRef){
        CFRelease(resultImageRef);
    }
    if(mosaicImageRef){
        CFRelease(mosaicImageRef);
    }
    if(colorSpace){
        CGColorSpaceRelease(colorSpace);
    }
    if(provider){
        CGDataProviderRelease(provider);
    }
    if(context){
        CGContextRelease(context);
    }
    if(outputContext){
        CGContextRelease(outputContext);
    }
//    return [[resultImage retain] autorelease];
    return resultImage;
    
}