前言
在日常开发中不免要接触的一些特殊的效果需求 , 随着iOS7的扁平化风格崛起 , 跟随系统风格使用大量毛玻璃的模糊效果成为主流设计之一 , 下面分享一个图片高斯模糊处理的方法 , iOS7 - 9 全部适用.
使用
首先引入
#import <Accelerate/Accelerate.h>
这里采用 Category 的形式
@interface UIImage (ImageEffects)
-(UIImage*)applyLightEffect;
-(UIImage*)applyExtraLightEffect;
-(UIImage*)applyDarkEffect;
-(UIImage*)applyTintEffectWithColor:(UIColor*)tintColor;
-(UIImage*)applyBlurWithRadius:(CGFloat)blurRadius tintColor:(UIColor*)tintColor saturationDeltaFactor:(CGFloat)saturationDeltaFactor maskImage:(UIImage*)maskImage;
@end
实现部分:
@implementation UIImage (ImageEffects)
-(UIImage*)applyLightEffect {
UIColor*tintColor =[UIColor colorWithWhite:1.0 alpha:0.3];
return[self applyBlurWithRadius:30 tintColor:tintColor saturationDeltaFactor:1.8 maskImage:nil];
}
-(UIImage*)applyExtraLightEffect {
UIColor*tintColor =[UIColor colorWithWhite:0.97 alpha:0.82];
return[self applyBlurWithRadius:20 tintColor:tintColor saturationDeltaFactor:1.8 maskImage:nil];
}
-(UIImage*)applyDarkEffect {
UIColor*tintColor =[UIColor colorWithWhite:0.11 alpha:0.73];
return[self applyBlurWithRadius:20 tintColor:tintColor saturationDeltaFactor:1.8 maskImage:nil];
}
-(UIImage*)applyTintEffectWithColor:(UIColor*)tintColor {
const CGFloat EffectColorAlpha = 0.6;
UIColor*effectColor = tintColor;
size_t componentCount = CGColorGetNumberOfComponents(tintColor.CGColor);
if(componentCount == 2) {
CGFloat b;
if([tintColor getWhite:&b alpha:NULL]) {
effectColor = [UIColor colorWithWhite:b alpha:EffectColorAlpha];
}
} else{
CGFloat r, g, b;
if([tintColor getRed:&r green:&g blue:&b alpha:NULL]) {
effectColor = [UIColor colorWithRed:r green:g blue:b alpha:EffectColorAlpha];
}
}
return[self applyBlurWithRadius:10 tintColor:effectColor saturationDeltaFactor:-1.0 maskImage:nil];
}
-(UIImage*)applyBlurWithRadius:(CGFloat)blurRadius tintColor:(UIColor*)tintColor saturationDeltaFactor:(CGFloat)saturationDeltaFactor maskImage:(UIImage*)maskImage {
// Check pre-conditions. 检查前提条件
if(self.size.width <1||self.size.height <1){
NSLog(@"*** error: invalid size: (%.2f x %.2f). Both dimensions must be >= 1: %@",self.size.width,self.size.height,self);
return nil;
}
if(!self.CGImage){
NSLog(@"*** error: image must be backed by a CGImage: %@",self);
return nil;
}
if(maskImage &&!maskImage.CGImage){
NSLog(@"*** error: maskImage must be backed by a CGImage: %@", maskImage);
return nil;
}
CGRect imageRect = {CGPointZero , self.size};
UIImage*effectImage = self;
BOOL hasBlur = blurRadius > __FLT_EPSILON__;
BOOL hasSaturationChange = fabs(saturationDeltaFactor -1.)> __FLT_EPSILON__;
if(hasBlur || hasSaturationChange) {
UIGraphicsBeginImageContextWithOptions(self.size, NO,[[UIScreen mainScreen] scale]);
CGContextRef effectInContext = UIGraphicsGetCurrentContext();
CGContextScaleCTM(effectInContext,1.0,-1.0);
CGContextTranslateCTM(effectInContext,0,-self.size.height);
CGContextDrawImage(effectInContext,imageRect,self.CGImage);
vImage_Buffer effectInBuffer;
effectInBuffer.data = CGBitmapContextGetData(effectInContext);
effectInBuffer.width = CGBitmapContextGetWidth(effectInContext);
effectInBuffer.height = CGBitmapContextGetHeight(effectInContext);
effectInBuffer.rowBytes = CGBitmapContextGetBytesPerRow(effectInContext);
UIGraphicsBeginImageContextWithOptions(self.size, NO, [[UIScreen mainScreen] scale]);
CGContextRef effectOutContext = UIGraphicsGetCurrentContext();
vImage_Buffer effectOutBuffer;
effectOutBuffer.data = CGBitmapContextGetData(effectOutContext);
effectOutBuffer.width = CGBitmapContextGetWidth(effectOutContext);
effectOutBuffer.height = CGBitmapContextGetHeight(effectOutContext);
effectOutBuffer.rowBytes = CGBitmapContextGetBytesPerRow(effectOutContext);
if(hasBlur){
// A description of how to compute the box kernel width from the Gaussian
// radius (aka standard deviation) appears in the SVG spec:
// http://www.w3.org/TR/SVG/filters.html#feGaussianBlurElement
//
// For larger values of 's' (s >= 2.0), an approximation can be used: Three
// successive box-blurs build a piece-wise quadratic convolution kernel, which
// approximates the Gaussian kernel to within roughly 3%.
//
// let d = floor(s * 3*sqrt(2*pi)/4 + 0.5)
//
// ... if d is odd, use three box-blurs of size 'd', centered on the output pixel.
//
CGFloat inputRadius = blurRadius *[[UIScreen mainScreen] scale];
NSUInteger radius = floor(inputRadius *3.* sqrt(2* M_PI)/4+0.5);
if(radius %2 != 1) {
radius += 1;// force radius to be odd so that the three box-blur methodology works.
}
vImageBoxConvolve_ARGB8888(&effectInBuffer,&effectOutBuffer, NULL,0,0, (uint32_t)radius, (uint32_t)radius,0, kvImageEdgeExtend);
vImageBoxConvolve_ARGB8888(&effectOutBuffer,&effectInBuffer, NULL,0,0, (uint32_t)radius, (uint32_t)radius,0, kvImageEdgeExtend);
vImageBoxConvolve_ARGB8888(&effectInBuffer,&effectOutBuffer, NULL,0,0, (uint32_t)radius, (uint32_t)radius,0, kvImageEdgeExtend);
}
BOOL effectImageBuffersAreSwapped = NO;
if(hasSaturationChange) {
CGFloat s = saturationDeltaFactor;
CGFloat floatingPointSaturationMatrix[] = {
0.0722+0.9278* s,0.0722-0.0722* s,0.0722-0.0722* s,0,
0.7152-0.7152* s,0.7152+0.2848* s,0.7152-0.7152* s,0,
0.2126-0.2126* s,0.2126-0.2126* s,0.2126+0.7873* s,0,
0,0,0,1,
};
const int32_t divisor = 256;
NSUInteger matrixSize = sizeof(floatingPointSaturationMatrix)/sizeof(floatingPointSaturationMatrix[0]);
int16_t saturationMatrix[matrixSize];
for(NSUInteger i = 0; i < matrixSize; ++i) {
saturationMatrix[i] = (int16_t)roundf(floatingPointSaturationMatrix[i]* divisor);
}
if(hasBlur) {
vImageMatrixMultiply_ARGB8888(&effectOutBuffer,&effectInBuffer, saturationMatrix, divisor, NULL, NULL, kvImageNoFlags);
effectImageBuffersAreSwapped = YES;
} else{
vImageMatrixMultiply_ARGB8888(&effectInBuffer,&effectOutBuffer, saturationMatrix, divisor, NULL, NULL, kvImageNoFlags);
}
}
if(!effectImageBuffersAreSwapped)
effectImage =UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
if(effectImageBuffersAreSwapped)
effectImage =UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
// Set up output context. 设置输出上下文
UIGraphicsBeginImageContextWithOptions(self.size, NO, [[UIScreen mainScreen] scale]);
CGContextRef outputContext = UIGraphicsGetCurrentContext();
CGContextScaleCTM(outputContext, 1.0, -1.0);
CGContextTranslateCTM(outputContext, 0, -self.size.height);
// Draw base image. 绘制基准图像
CGContextDrawImage(outputContext, imageRect, self.CGImage);
// Draw effect image. 绘制效果图像
if(hasBlur) {
CGContextSaveGState(outputContext);
if(maskImage) {
CGContextClipToMask(outputContext, imageRect, maskImage.CGImage);
}
CGContextDrawImage(outputContext, imageRect, effectImage.CGImage);
CGContextRestoreGState(outputContext);
}
// Add in color tint. 添加颜色渲染
if(tintColor) {
CGContextSaveGState(outputContext);
CGContextSetFillColorWithColor(outputContext, tintColor.CGColor);
CGContextFillRect(outputContext, imageRect);
CGContextRestoreGState(outputContext);
}
// Output image is ready. 输出图像
UIImage*outputImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return outputImage;
}
@end
__提示: 调用主要参数 blurRadius: 模糊半径 , tintColor: 渲染颜色 , saturationDeltaFactor: 色彩饱和度 . __
