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Update for #787 Add an option to scale down large images on iOS - code cleanup

This commit is contained in:
Bogdan Poplauschi 2016-10-06 15:08:53 +03:00
parent 959d965248
commit 00bf467eb7
1 changed files with 96 additions and 104 deletions
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200
SDWebImage/SDWebImageDecoder.m
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@ -9,56 +9,28 @@
#import "SDWebImageDecoder.h"
@implementation UIImage (ForceDecode)
#if SD_UIKIT || SD_WATCH
static const size_t kBytesPerPixel = 4;
static const size_t kBitsPerComponent = 8;
#endif
@implementation UIImage (ForceDecode)
+ (nullable UIImage *)decodedImageWithImage:(nullable UIImage *)image {
if (image == nil) { return nil; } // Prevent "CGBitmapContextCreateImage: invalid context 0x0" error
if (![UIImage shouldDecodeImage:image]) {
return image;
}
#if SD_MAC
return image;
#elif SD_UIKIT || SD_WATCH
// 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];
// 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{
if (image.images != nil) { return image; } // do not decode animated images
CGImageRef imageRef = image.CGImage;
CGImageAlphaInfo alpha = CGImageGetAlphaInfo(imageRef);
BOOL anyAlpha = (alpha == kCGImageAlphaFirst ||
alpha == kCGImageAlphaLast ||
alpha == kCGImageAlphaPremultipliedFirst ||
alpha == kCGImageAlphaPremultipliedLast);
if (anyAlpha) { return image; } // do not decode images with alpha
// current
CGColorSpaceModel imageColorSpaceModel = CGColorSpaceGetModel(CGImageGetColorSpace(imageRef));
CGColorSpaceRef colorspaceRef = CGImageGetColorSpace(imageRef);
BOOL unsupportedColorSpace = (imageColorSpaceModel == kCGColorSpaceModelUnknown ||
imageColorSpaceModel == kCGColorSpaceModelMonochrome ||
imageColorSpaceModel == kCGColorSpaceModelCMYK ||
imageColorSpaceModel == kCGColorSpaceModelIndexed);
if (unsupportedColorSpace) {
colorspaceRef = CGColorSpaceCreateDeviceRGB();
}
CGColorSpaceRef colorspaceRef = [UIImage colorSpaceForImageRef:imageRef];
size_t width = CGImageGetWidth(imageRef);
size_t height = CGImageGetHeight(imageRef);
size_t bytesPerRow = kBytesPerPixel * width;
// kCGImageAlphaNone is not supported in CGBitmapContextCreate.
// Since the original image here has no alpha info, use kCGImageAlphaNoneSkipLast
// to create bitmap graphics contexts without alpha info.
@ -77,16 +49,11 @@ static const size_t kBitsPerComponent = 8;
scale:image.scale
orientation:image.imageOrientation];
if (unsupportedColorSpace) {
CGColorSpaceRelease(colorspaceRef);
}
CGContextRelease(context);
CGImageRelease(imageRefWithoutAlpha);
return imageWithoutAlpha;
}
#endif
}
/*
@ -95,7 +62,7 @@ static const size_t kBitsPerComponent = 8;
* Suggested value for iPad2 and iPhone 4: 120.
* Suggested value for iPhone 3G and iPod 2 and earlier devices: 30.
*/
#define kDestImageSizeMB 60.0f
static const CGFloat kDestImageSizeMB = 60.0f;
/*
* Defines the maximum size in MB of a tile used to decode image when the flag `SDWebImageScaleDownLargeImages` is set
@ -103,47 +70,29 @@ static const size_t kBitsPerComponent = 8;
* Suggested value for iPad2 and iPhone 4: 40.
* Suggested value for iPhone 3G and iPod 2 and earlier devices: 10.
*/
#define kSourceImageTileSizeMB 20.0f
static const CGFloat kSourceImageTileSizeMB = 20.0f;
#define bytesPerMB 1048576.0f
#define pixelsPerMB ( bytesPerMB / kBytesPerPixel )
#define destTotalPixels kDestImageSizeMB * pixelsPerMB
#define tileTotalPixels kSourceImageTileSizeMB * pixelsPerMB
#define destSeemOverlap 2.0f // the numbers of pixels to overlap the seems where tiles meet.
static const CGFloat kBytesPerMB = 1024.0f * 1024.0f;
static const CGFloat kPixelsPerMB = kBytesPerMB * kBytesPerPixel;
static const CGFloat kDestTotalPixels = kDestImageSizeMB * kPixelsPerMB;
static const CGFloat kTileTotalPixels = kSourceImageTileSizeMB * kPixelsPerMB;
static const CGFloat kDestSeemOverlap = 2.0f; // the numbers of pixels to overlap the seems where tiles meet.
+ (nullable UIImage *)decodedAndScaledDownImageWithImage:(nullable UIImage *)image {
if (image == nil) { return nil; } // Prevent "CGBitmapContextCreateImage: invalid context 0x0" error
if (![UIImage shouldDecodeImage:image]) {
return image;
}
#if SD_MAC
return image;
#elif SD_UIKIT || SD_WATCH
BOOL shouldDownSize = ({
BOOL shouldDoIt = YES;
CGImageRef sourceImageRef = image.CGImage;
CGSize sourceResolution = CGSizeZero;
sourceResolution.width = CGImageGetWidth(sourceImageRef);
sourceResolution.height = CGImageGetHeight(sourceImageRef);
float sourceTotalPixels = sourceResolution.width * sourceResolution.height;
float imageScale = destTotalPixels / sourceTotalPixels;
if (imageScale < 1) {
shouldDoIt = YES;
} else {
shouldDoIt = NO;
}
shouldDoIt;
});
if (!shouldDownSize) {
if (![UIImage shouldScaleDownImage:image]) {
return [UIImage decodedImageWithImage:image];
}
CGContextRef destContext;
// 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 {
if (image.images != nil) { return image; } // do not decode animated images
CGImageRef sourceImageRef = image.CGImage;
CGSize sourceResolution = CGSizeZero;
@ -153,42 +102,22 @@ static const size_t kBitsPerComponent = 8;
// Determine the scale ratio to apply to the input image
// that results in an output image of the defined size.
// see kDestImageSizeMB, and how it relates to destTotalPixels.
float imageScale = destTotalPixels / sourceTotalPixels;
float imageScale = kDestTotalPixels / sourceTotalPixels;
CGSize destResolution = CGSizeZero;
destResolution.width = (int)(sourceResolution.width*imageScale);
destResolution.height = (int)(sourceResolution.height*imageScale);
CGImageAlphaInfo alpha = CGImageGetAlphaInfo(sourceImageRef);
BOOL anyAlpha = (alpha == kCGImageAlphaFirst ||
alpha == kCGImageAlphaLast ||
alpha == kCGImageAlphaPremultipliedFirst ||
alpha == kCGImageAlphaPremultipliedLast);
if (anyAlpha) { return image; } // do not decode images with alpha
// current color space
CGColorSpaceModel imageColorSpaceModel = CGColorSpaceGetModel(CGImageGetColorSpace(sourceImageRef));
CGColorSpaceRef colorspaceRef = CGImageGetColorSpace(sourceImageRef);
BOOL unsupportedColorSpace = (imageColorSpaceModel == kCGColorSpaceModelUnknown ||
imageColorSpaceModel == kCGColorSpaceModelMonochrome ||
imageColorSpaceModel == kCGColorSpaceModelCMYK ||
imageColorSpaceModel == kCGColorSpaceModelIndexed);
if (unsupportedColorSpace) {
colorspaceRef = CGColorSpaceCreateDeviceRGB();
}
CGColorSpaceRef colorspaceRef = [UIImage colorSpaceForImageRef:sourceImageRef];
size_t bytesPerRow = kBytesPerPixel * destResolution.width;
// Allocate enough pixel data to hold the output image.
void* destBitmapData = malloc( bytesPerRow * destResolution.height );
if (destBitmapData == NULL) {
if (unsupportedColorSpace) {
CGColorSpaceRelease(colorspaceRef);
}
return image;
}
// kCGImageAlphaNone is not supported in CGBitmapContextCreate.
// Since the original image here has no alpha info, use kCGImageAlphaNoneSkipLast
// to create bitmap graphics contexts without alpha info.
@ -200,10 +129,6 @@ static const size_t kBitsPerComponent = 8;
colorspaceRef,
kCGBitmapByteOrderDefault|kCGImageAlphaNoneSkipLast);
if (unsupportedColorSpace) {
CGColorSpaceRelease(colorspaceRef);
}
if (destContext == NULL) {
free( destBitmapData );
return image;
@ -224,7 +149,7 @@ static const size_t kBitsPerComponent = 8;
// The source tile height is dynamic. Since we specified the size
// of the source tile in MB, see how many rows of pixels high it
// can be given the input image width.
sourceTile.size.height = (int)( tileTotalPixels / sourceTile.size.width );
sourceTile.size.height = (int)(kTileTotalPixels / sourceTile.size.width );
sourceTile.origin.x = 0.0f;
// The output tile is the same proportions as the input tile, but
// scaled to image scale.
@ -234,7 +159,7 @@ static const size_t kBitsPerComponent = 8;
destTile.origin.x = 0.0f;
// The source seem overlap is proportionate to the destination seem overlap.
// this is the amount of pixels to overlap each tile as we assemble the ouput image.
float sourceSeemOverlap = (int)((destSeemOverlap/destResolution.height)*sourceResolution.height);
float sourceSeemOverlap = (int)((kDestSeemOverlap/destResolution.height)*sourceResolution.height);
CGImageRef sourceTileImageRef;
// calculate the number of read/write operations required to assemble the
// output image.
@ -248,11 +173,11 @@ static const size_t kBitsPerComponent = 8;
// Add seem overlaps to the tiles, but save the original tile height for y coordinate calculations.
float sourceTileHeightMinusOverlap = sourceTile.size.height;
sourceTile.size.height += sourceSeemOverlap;
destTile.size.height += destSeemOverlap;
destTile.size.height += kDestSeemOverlap;
for( int y = 0; y < iterations; ++y ) {
@autoreleasepool {
sourceTile.origin.y = y * sourceTileHeightMinusOverlap + sourceSeemOverlap;
destTile.origin.y = destResolution.height - (( y + 1 ) * sourceTileHeightMinusOverlap * imageScale + destSeemOverlap);
destTile.origin.y = destResolution.height - (( y + 1 ) * sourceTileHeightMinusOverlap * imageScale + kDestSeemOverlap);
sourceTileImageRef = CGImageCreateWithImageInRect( sourceImageRef, sourceTile );
if( y == iterations - 1 && remainder ) {
float dify = destTile.size.height;
@ -277,8 +202,75 @@ static const size_t kBitsPerComponent = 8;
}
return destImage;
}
#endif
}
+ (BOOL)shouldDecodeImage:(nullable UIImage *)image {
// Prevent "CGBitmapContextCreateImage: invalid context 0x0" error
if (image == nil) {
return NO;
}
// do not decode animated images
if (image.images != nil) {
return NO;
}
CGImageRef imageRef = image.CGImage;
CGImageAlphaInfo alpha = CGImageGetAlphaInfo(imageRef);
BOOL anyAlpha = (alpha == kCGImageAlphaFirst ||
alpha == kCGImageAlphaLast ||
alpha == kCGImageAlphaPremultipliedFirst ||
alpha == kCGImageAlphaPremultipliedLast);
// do not decode images with alpha
if (anyAlpha) {
return NO;
}
return YES;
}
+ (BOOL)shouldScaleDownImage:(nonnull UIImage *)image {
BOOL shouldScaleDown = YES;
CGImageRef sourceImageRef = image.CGImage;
CGSize sourceResolution = CGSizeZero;
sourceResolution.width = CGImageGetWidth(sourceImageRef);
sourceResolution.height = CGImageGetHeight(sourceImageRef);
float sourceTotalPixels = sourceResolution.width * sourceResolution.height;
float imageScale = kDestTotalPixels / sourceTotalPixels;
if (imageScale < 1) {
shouldScaleDown = YES;
} else {
shouldScaleDown = NO;
}
return shouldScaleDown;
}
+ (CGColorSpaceRef)colorSpaceForImageRef:(CGImageRef)imageRef {
// current
CGColorSpaceModel imageColorSpaceModel = CGColorSpaceGetModel(CGImageGetColorSpace(imageRef));
CGColorSpaceRef colorspaceRef = CGImageGetColorSpace(imageRef);
BOOL unsupportedColorSpace = (imageColorSpaceModel == kCGColorSpaceModelUnknown ||
imageColorSpaceModel == kCGColorSpaceModelMonochrome ||
imageColorSpaceModel == kCGColorSpaceModelCMYK ||
imageColorSpaceModel == kCGColorSpaceModelIndexed);
if (unsupportedColorSpace) {
colorspaceRef = CGColorSpaceCreateDeviceRGB();
CFAutorelease(colorspaceRef);
}
return colorspaceRef;
}
#elif SD_MAC
+ (nullable UIImage *)decodedImageWithImage:(nullable UIImage *)image {
return image;
}
+ (nullable UIImage *)decodedAndScaledDownImageWithImage:(nullable UIImage *)image {
return image;
}
#endif
@end