给图片添加马赛克效果

 1 + (UIImage *)transToMosaicImage:(UIImage*)orginImage blockLevel:(NSUInteger)level
 2 {
 3     //获取BitmapData
 4     CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
 5     CGImageRef imgRef = orginImage.CGImage;
 6     CGFloat width = CGImageGetWidth(imgRef);
 7     CGFloat height = CGImageGetHeight(imgRef);
 8     CGContextRef context = CGBitmapContextCreate (nil,
 9                                                   width,
10                                                   height,
11                                                   kBitsPerComponent,        //每个颜色值8bit
12                                                   width*kPixelChannelCount, //每一行的像素点占用的字节数，每个像素点的ARGB四个通道各占8个bit
13                                                   colorSpace,
14                                                   kCGImageAlphaPremultipliedLast);
15     CGContextDrawImage(context, CGRectMake(0, 0, width, height), imgRef);
16     unsigned char *bitmapData = CGBitmapContextGetData (context);
17     
18     //这里把BitmapData进行马赛克转换,就是用一个点的颜色填充一个level*level的正方形
19     unsigned char pixel[kPixelChannelCount] = {0};
20     NSUInteger index,preIndex;
21     for (NSUInteger i = 0; i < height - 1 ; i++) {
22         for (NSUInteger j = 0; j < width - 1; j++) {
23             index = i * width + j;
24             if (i % level == 0) {
25                 if (j % level == 0) {
26                     memcpy(pixel, bitmapData + kPixelChannelCount*index, kPixelChannelCount);
27                 }else{
28                     memcpy(bitmapData + kPixelChannelCount*index, pixel, kPixelChannelCount);
29                 }
30             } else {
31                 preIndex = (i-1)*width +j;
32                 memcpy(bitmapData + kPixelChannelCount*index, bitmapData + kPixelChannelCount*preIndex, kPixelChannelCount);
33             }
34         }
35     }
36     
37     NSInteger dataLength = width*height* kPixelChannelCount;
38     CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, bitmapData, dataLength, NULL);
39     //创建要输出的图像
40     CGImageRef mosaicImageRef = CGImageCreate(width, height,
41                                               kBitsPerComponent,
42                                               kBitsPerPixel,
43                                               width*kPixelChannelCount ,
44                                               colorSpace,
45                                               kCGImageAlphaPremultipliedLast,
46                                               provider,
47                                               NULL, NO,
48                                               kCGRenderingIntentDefault);
49     CGContextRef outputContext = CGBitmapContextCreate(nil,
50                                                        width,
51                                                        height,
52                                                        kBitsPerComponent,
53                                                        width*kPixelChannelCount,
54                                                        colorSpace,
55                                                        kCGImageAlphaPremultipliedLast);
56     CGContextDrawImage(outputContext, CGRectMake(0.0f, 0.0f, width, height), mosaicImageRef);
57     CGImageRef resultImageRef = CGBitmapContextCreateImage(outputContext);
58     UIImage *resultImage = nil;
59     if([UIImage respondsToSelector:@selector(imageWithCGImage:scale:orientation:)]) {
60         float scale = [[UIScreen mainScreen] scale];
61         resultImage = [UIImage imageWithCGImage:resultImageRef scale:scale orientation:UIImageOrientationUp];
62     } else {
63         resultImage = [UIImage imageWithCGImage:resultImageRef];
64     }
65     //释放
66     if(resultImageRef){
67         CFRelease(resultImageRef);
68     }
69     if(mosaicImageRef){
70         CFRelease(mosaicImageRef);
71     }
72     if(colorSpace){
73         CGColorSpaceRelease(colorSpace);
74     }
75     if(provider){
76         CGDataProviderRelease(provider);
77     }
78     if(context){
79         CGContextRelease(context);
80     }
81     if(outputContext){
82         CGContextRelease(outputContext);
83     }
84     
85     return resultImage;
86 }