Pods/SDWebImage/SDWebImage/SDWebImageDecoder.m
/*
 * This file is part of the SDWebImage package.
 * (c) Olivier Poitrey <rs@dailymotion.com>
 *
 * Created by james <https://github.com/mystcolor> on 9/28/11.
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

#import "SDWebImageDecoder.h"

@implementation UIImage (ForceDecode)

+ (UIImage *)decodedImageWithImage:(UIImage *)image {
    // while downloading huge amount of images
    // autorelease the bitmap context
    // and all vars to help system to free memory
    // when there are memory warning.
    // on iOS7, do not forget to call
    // [[SDImageCache sharedImageCache] clearMemory];
    @autoreleasepool{
        // do not decode animated images
        if (image.images) { return image; }
    
        CGImageRef imageRef = image.CGImage;
    
        CGImageAlphaInfo alpha = CGImageGetAlphaInfo(imageRef);
        BOOL anyAlpha = (alpha == kCGImageAlphaFirst ||
                         alpha == kCGImageAlphaLast ||
                         alpha == kCGImageAlphaPremultipliedFirst ||
                         alpha == kCGImageAlphaPremultipliedLast);
    
        if (anyAlpha) { return image; }
    
        size_t width = CGImageGetWidth(imageRef);
        size_t height = CGImageGetHeight(imageRef);
    
        // current
        CGColorSpaceModel imageColorSpaceModel = CGColorSpaceGetModel(CGImageGetColorSpace(imageRef));
        CGColorSpaceRef colorspaceRef = CGImageGetColorSpace(imageRef);
        
        bool unsupportedColorSpace = (imageColorSpaceModel == 0 || imageColorSpaceModel == -1 || imageColorSpaceModel == kCGColorSpaceModelCMYK || imageColorSpaceModel == kCGColorSpaceModelIndexed);
        if (unsupportedColorSpace)
            colorspaceRef = CGColorSpaceCreateDeviceRGB();
    
        CGContextRef context = CGBitmapContextCreate(NULL, width,
                                                     height,
                                                     CGImageGetBitsPerComponent(imageRef),
                                                     0,
                                                     colorspaceRef,
                                                     kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedFirst);
    
        // Draw the image into the context and retrieve the new image, which will now have an alpha layer
        CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);
        CGImageRef imageRefWithAlpha = CGBitmapContextCreateImage(context);
        UIImage *imageWithAlpha = [UIImage imageWithCGImage:imageRefWithAlpha scale:image.scale orientation:image.imageOrientation];
    
        if (unsupportedColorSpace)
            CGColorSpaceRelease(colorspaceRef);
        
        CGContextRelease(context);
        CGImageRelease(imageRefWithAlpha);
        
        return imageWithAlpha;
    }
}

@end
