iOS開發(fā)的時(shí)候有的時(shí)候需要將圖片設(shè)置模糊捏境，或者通過點(diǎn)擊下拉方法峻村，去除模糊田巴。關(guān)于圖片實(shí)現(xiàn)高斯模糊效果有三種方式钠糊，CoreImage，GPUImage（第三方開源類庫(kù)）和vImage壹哺。GPUImage沒怎么用過抄伍，本文就講兩種方式Core Image和vImage。
Core Image
iOS5.0之后就出現(xiàn)了Core Image的API,Core Image的API被放在CoreImage.framework庫(kù)中,在iOS和OS X平臺(tái)上管宵，Core Image都提供了大量的濾鏡（Filter）截珍，在OS X上有120多種Filter，而在iOS上也有90多箩朴。首先我們擴(kuò)展一下UIImage岗喉，添加類方法:
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+(UIImage *)coreBlurImage:(UIImage *)image withBlurNumber:(CGFloat)blur
{
CIContext *context = [CIContext contextWithOptions:nil];
CIImage *inputImage=[CIImage imageWithCGImage:image.CGImage];
//設(shè)置filter
CIFilter *filter = [CIFilter filterWithName:@"CIGaussianBlur"];
[filter setValue:inputImage forKey:kCIInputImageKey];
[filter setValue:@(blur) forKey: @"inputRadius"];
//模糊圖片
CIImage *result=[filter valueForKey:kCIOutputImageKey];
CGImageRef outImage=[context createCGImage:result fromRect:[result extent]];
UIImage *blurImage=[UIImage imageWithCGImage:outImage];
CGImageRelease(outImage);
return blurImage;
}
其中過濾的選項(xiàng)設(shè)置為高斯模糊:
vImage 方式
vImage屬于Accelerate.Framework，需要導(dǎo)入Accelerate下的Accelerate頭文件炸庞，Accelerate主要是用來(lái)做數(shù)字信號(hào)處理钱床、圖像處理相關(guān)的向量、矩陣運(yùn)算的庫(kù)埠居。圖像可以認(rèn)為是由向量或者矩陣數(shù)據(jù)構(gòu)成的查牌，Accelerate里既然提供了高效的數(shù)學(xué)運(yùn)算API，自然就能方便我們對(duì)圖像做各種各樣的處理滥壕，模糊算法使用的是vImageBoxConvolve_ARGB8888這個(gè)函數(shù)纸颜。
+(UIImage *)boxblurImage:(UIImage *)image withBlurNumber:(CGFloat)blur {
if (blur < 0.f || blur > 1.f) {
blur = 0.5f;
}
int boxSize = (int)(blur * 40);
boxSize = boxSize - (boxSize % 2) + 1;
CGImageRef img = image.CGImage;
vImage_Buffer inBuffer, outBuffer;
vImage_Error error;
void *pixelBuffer;
//從CGImage中獲取數(shù)據(jù)
CGDataProviderRef inProvider = CGImageGetDataProvider(img);
CFDataRef inBitmapData = CGDataProviderCopyData(inProvider);
//設(shè)置從CGImage獲取對(duì)象的屬性
inBuffer.width = CGImageGetWidth(img);
inBuffer.height = CGImageGetHeight(img);
inBuffer.rowBytes = CGImageGetBytesPerRow(img);
inBuffer.data = (void*)CFDataGetBytePtr(inBitmapData);
pixelBuffer = malloc(CGImageGetBytesPerRow(img) *
CGImageGetHeight(img));
if(pixelBuffer == NULL)
NSLog(@"No pixelbuffer");
outBuffer.data = pixelBuffer;
outBuffer.width = CGImageGetWidth(img);
outBuffer.height = CGImageGetHeight(img);
outBuffer.rowBytes = CGImageGetBytesPerRow(img);
error = vImageBoxConvolve_ARGB8888(&inBuffer, &outBuffer, NULL, 0, 0, boxSize, boxSize, NULL, kvImageEdgeExtend);
if (error) {
NSLog(@"error from convolution %ld", error);
}
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef ctx = CGBitmapContextCreate(
outBuffer.data,
outBuffer.width,
outBuffer.height,
8,
outBuffer.rowBytes,
colorSpace,
kCGImageAlphaNoneSkipLast);
CGImageRef imageRef = CGBitmapContextCreateImage (ctx);
UIImage *returnImage = [UIImage imageWithCGImage:imageRef];
//clean up
CGContextRelease(ctx);
CGColorSpaceRelease(colorSpace);
free(pixelBuffer);
CFRelease(inBitmapData);
CGColorSpaceRelease(colorSpace);
CGImageRelease(imageRef);
return returnImage;
}
圖片模糊調(diào)用:
self.imageView=[[UIImageView alloc]initWithFrame:CGRectMake(0, 300, SCREENWIDTH, 100)];
self.imageView.contentMode=UIViewContentModeScaleAspectFill;
self.imageView.image=[UIImage boxblurImage:self.image withBlurNumber:0.5];
self.imageView.clipsToBounds=YES;
[self.view addSubview:self.imageView];
參考資料:http://t.cn/RcCyU01
