IOS毛玻璃效果

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毛玻璃效果

////  UIImage+Blur.m//  hw8264////  Created by ericyang on 14-3-26.//  Copyright (c) 2014年 Eric Yang. All rights reserved.//#import "UIImage+Blur.h"#import <Accelerate/Accelerate.h>@implementation UIImage (Blur)- (UIImage *)applyBlurWithRadius:(CGFloat)blurRadius tintColor:(UIColor *)tintColor saturationDeltaFactor:(CGFloat)saturationDeltaFactor maskImage:(UIImage *)maskImage{    // Check pre-conditions.    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, radius, radius, 0, kvImageEdgeExtend);            vImageBoxConvolve_ARGB8888(&effectOutBuffer, &effectInBuffer, NULL, 0, 0, radius, radius, 0, kvImageEdgeExtend);            vImageBoxConvolve_ARGB8888(&effectInBuffer, &effectOutBuffer, NULL, 0, 0, radius, 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.    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.    CGContextDrawImage(outputContext, imageRect, self.CGImage);        // Draw effect image.    if (hasBlur) {        CGContextSaveGState(outputContext);        if (maskImage) {            CGContextClipToMask(outputContext, imageRect, maskImage.CGImage);        }        CGContextDrawImage(outputContext, imageRect, effectImage.CGImage);        CGContextRestoreGState(outputContext);    }        // Add in color tint.    if (tintColor) {        CGContextSaveGState(outputContext);        CGContextSetFillColorWithColor(outputContext, tintColor.CGColor);        CGContextFillRect(outputContext, imageRect);        CGContextRestoreGState(outputContext);    }        // Output image is ready.    UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext();    UIGraphicsEndImageContext();        return outputImage;}@end