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UIImage+ProportionalFill.m
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UIImage+ProportionalFill.m
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//
// UIImage+ProportionalFill.m
//
// Created by Matt Gemmell on 20/08/2008.
// Copyright 2008 Instinctive Code.
//
#import "UIImage+ProportionalFill.h"
@implementation UIImage (MGProportionalFill)
- (UIImage *)imageToFitSize:(CGSize)fitSize method:(MGImageResizingMethod)resizeMethod
{
float imageScaleFactor = 1.0;
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_4_0
if ([self respondsToSelector:@selector(scale)]) {
imageScaleFactor = [self scale];
}
#endif
float sourceWidth = [self size].width * imageScaleFactor;
float sourceHeight = [self size].height * imageScaleFactor;
float targetWidth = fitSize.width;
float targetHeight = fitSize.height;
BOOL cropping = !(resizeMethod == MGImageResizeScale);
// Calculate aspect ratios
float sourceRatio = sourceWidth / sourceHeight;
float targetRatio = targetWidth / targetHeight;
// Determine what side of the source image to use for proportional scaling
BOOL scaleWidth = (sourceRatio <= targetRatio);
// Deal with the case of just scaling proportionally to fit, without cropping
scaleWidth = (cropping) ? scaleWidth : !scaleWidth;
// Proportionally scale source image
float scalingFactor, scaledWidth, scaledHeight;
if (scaleWidth) {
scalingFactor = 1.0 / sourceRatio;
scaledWidth = targetWidth;
scaledHeight = round(targetWidth * scalingFactor);
} else {
scalingFactor = sourceRatio;
scaledWidth = round(targetHeight * scalingFactor);
scaledHeight = targetHeight;
}
float scaleFactor = scaledHeight / sourceHeight;
// Calculate compositing rectangles
CGRect sourceRect, destRect;
if (cropping) {
destRect = CGRectMake(0, 0, targetWidth, targetHeight);
float destX, destY;
if (resizeMethod == MGImageResizeCrop) {
// Crop center
destX = round((scaledWidth - targetWidth) / 2.0);
destY = round((scaledHeight - targetHeight) / 2.0);
} else if (resizeMethod == MGImageResizeCropStart) {
// Crop top or left (prefer top)
if (scaleWidth) {
// Crop top
destX = 0.0;
destY = 0.0;
} else {
// Crop left
destX = 0.0;
destY = round((scaledHeight - targetHeight) / 2.0);
}
} else if (resizeMethod == MGImageResizeCropEnd) {
// Crop bottom or right
if (scaleWidth) {
// Crop bottom
destX = round((scaledWidth - targetWidth) / 2.0);
destY = round(scaledHeight - targetHeight);
} else {
// Crop right
destX = round(scaledWidth - targetWidth);
destY = round((scaledHeight - targetHeight) / 2.0);
}
}
sourceRect = CGRectMake(destX / scaleFactor, destY / scaleFactor,
targetWidth / scaleFactor, targetHeight / scaleFactor);
} else {
sourceRect = CGRectMake(0, 0, sourceWidth, sourceHeight);
destRect = CGRectMake(0, 0, scaledWidth, scaledHeight);
}
// Create appropriately modified image.
UIImage *image = nil;
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_4_0
CGImageRef sourceImg = nil;
if ([UIScreen instancesRespondToSelector:@selector(scale)]) {
UIGraphicsBeginImageContextWithOptions(destRect.size, NO, 0.f); // 0.f for scale means "scale for device's main screen".
sourceImg = CGImageCreateWithImageInRect([self CGImage], sourceRect); // cropping happens here.
image = [UIImage imageWithCGImage:sourceImg scale:0.0 orientation:self.imageOrientation]; // create cropped UIImage.
} else {
UIGraphicsBeginImageContext(destRect.size);
sourceImg = CGImageCreateWithImageInRect([self CGImage], sourceRect); // cropping happens here.
image = [UIImage imageWithCGImage:sourceImg]; // create cropped UIImage.
}
CGImageRelease(sourceImg);
[image drawInRect:destRect]; // the actual scaling happens here, and orientation is taken care of automatically.
image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
#endif
if (!image) {
// Try older method.
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(NULL, scaledWidth, scaledHeight, 8, (scaledWidth * 4),
colorSpace, kCGImageAlphaPremultipliedLast);
CGImageRef sourceImg = CGImageCreateWithImageInRect([self CGImage], sourceRect);
CGContextDrawImage(context, destRect, sourceImg);
CGImageRelease(sourceImg);
CGImageRef finalImage = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
image = [UIImage imageWithCGImage:finalImage];
CGImageRelease(finalImage);
}
return image;
}
- (UIImage *)imageCroppedToFitSize:(CGSize)fitSize
{
return [self imageToFitSize:fitSize method:MGImageResizeCrop];
}
- (UIImage *)imageScaledToFitSize:(CGSize)fitSize
{
return [self imageToFitSize:fitSize method:MGImageResizeScale];
}
@end