RCTImageBlurUtils.m
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/**
* Copyright (c) 2015-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*/
#import "RCTImageBlurUtils.h"
UIImage *RCTBlurredImageWithRadius(UIImage *inputImage, CGFloat radius)
{
CGImageRef imageRef = inputImage.CGImage;
CGFloat imageScale = inputImage.scale;
UIImageOrientation imageOrientation = inputImage.imageOrientation;
// Image must be nonzero size
if (CGImageGetWidth(imageRef) * CGImageGetHeight(imageRef) == 0) {
return inputImage;
}
//convert to ARGB if it isn't
if (CGImageGetBitsPerPixel(imageRef) != 32 ||
CGImageGetBitsPerComponent(imageRef) != 8 ||
!((CGImageGetBitmapInfo(imageRef) & kCGBitmapAlphaInfoMask))) {
UIGraphicsBeginImageContextWithOptions(inputImage.size, NO, inputImage.scale);
[inputImage drawAtPoint:CGPointZero];
imageRef = UIGraphicsGetImageFromCurrentImageContext().CGImage;
UIGraphicsEndImageContext();
}
vImage_Buffer buffer1, buffer2;
buffer1.width = buffer2.width = CGImageGetWidth(imageRef);
buffer1.height = buffer2.height = CGImageGetHeight(imageRef);
buffer1.rowBytes = buffer2.rowBytes = CGImageGetBytesPerRow(imageRef);
size_t bytes = buffer1.rowBytes * buffer1.height;
buffer1.data = malloc(bytes);
buffer2.data = malloc(bytes);
// 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
uint32_t boxSize = floor((radius * imageScale * 3 * sqrt(2 * M_PI) / 4 + 0.5) / 2);
boxSize |= 1; // Ensure boxSize is odd
//create temp buffer
void *tempBuffer = malloc((size_t)vImageBoxConvolve_ARGB8888(&buffer1, &buffer2, NULL, 0, 0, boxSize, boxSize,
NULL, kvImageEdgeExtend + kvImageGetTempBufferSize));
//copy image data
CFDataRef dataSource = CGDataProviderCopyData(CGImageGetDataProvider(imageRef));
memcpy(buffer1.data, CFDataGetBytePtr(dataSource), bytes);
CFRelease(dataSource);
//perform blur
vImageBoxConvolve_ARGB8888(&buffer1, &buffer2, tempBuffer, 0, 0, boxSize, boxSize, NULL, kvImageEdgeExtend);
vImageBoxConvolve_ARGB8888(&buffer2, &buffer1, tempBuffer, 0, 0, boxSize, boxSize, NULL, kvImageEdgeExtend);
vImageBoxConvolve_ARGB8888(&buffer1, &buffer2, tempBuffer, 0, 0, boxSize, boxSize, NULL, kvImageEdgeExtend);
//free buffers
free(buffer2.data);
free(tempBuffer);
//create image context from buffer
CGContextRef ctx = CGBitmapContextCreate(buffer1.data, buffer1.width, buffer1.height,
8, buffer1.rowBytes, CGImageGetColorSpace(imageRef),
CGImageGetBitmapInfo(imageRef));
//create image from context
imageRef = CGBitmapContextCreateImage(ctx);
UIImage *outputImage = [UIImage imageWithCGImage:imageRef scale:imageScale orientation:imageOrientation];
CGImageRelease(imageRef);
CGContextRelease(ctx);
free(buffer1.data);
return outputImage;
}