PommeDev : le blog

//
//  UIImage+Resize.h
//
//  Created by Olivier HALLIGON on 12/08/09.
//  Copyright 2009 AliSoftware. All rights reserved.
//
 
#import "Foundation/Foundation.h"
 
@interface UIImage (ResizeCategory)
-(UIImage*)resizedImageToSize:(CGSize)dstSize;
-(UIImage*)resizedImageToFitInSize:(CGSize)boundingSize scaleIfSmaller:(BOOL)scale;
@end

//
//  UIImage+Resize.m
//
//  Created by Olivier HALLIGON on 12/08/09.
//  Copyright 2009 AliSoftware. All rights reserved.
//
 
#import "UIImage+Resize.h"
 
@implementation UIImage (ResizeCategory)
 
-(UIImage*)resizedImageToSize:(CGSize)dstSize
{
	//NSLog(@"resizing image from %@ to %@" , NSStringFromCGSize(self.size), NSStringFromCGSize(dstSize));
 
	if (CGSizeEqualToSize(dstSize, self.size) || CGSizeEqualToSize(dstSize, CGSizeZero) ){
		// avoid useless resizing
		return self;
	}
 
	// Créer le contexte Bitmap pour dessiner la miniature
	CGImageRef img = [self CGImage];
 
	CGBitmapInfo alphaInfo = CGImageGetBitmapInfo(img);
	if (alphaInfo == kCGImageAlphaFirst) alphaInfo = kCGImageAlphaPremultipliedFirst;
	if (alphaInfo == kCGImageAlphaLast) alphaInfo = kCGImageAlphaPremultipliedLast;
 
	CGContextRef ctx = CGBitmapContextCreate(	NULL,
											 dstSize.width,		// width
											 dstSize.height,		// height
											 8, 0, // nbits per component, bytes per row
											 CGImageGetColorSpace(img), // colorspace
											 alphaInfo // bitmapinfo
											 );
 
	// Prendre en considération l'imageOrientation
	CGAffineTransform tr = CGAffineTransformIdentity;
	switch (self.imageOrientation)
	{
		case UIImageOrientationLeft:
			tr = CGAffineTransformMakeRotation(M_PI_2);
			break;
		case UIImageOrientationUp:
			//tr = CGAffineTransformIdentity;
			break;
		case UIImageOrientationRight:
			tr = CGAffineTransformMakeRotation(-M_PI_2);
			break;
		case UIImageOrientationDown:
			tr = CGAffineTransformMakeRotation(M_PI);
			break;
		default:
			break;
	}
	CGContextConcatCTM(ctx, CGAffineTransformMakeTranslation(dstSize.width/2, dstSize.height/2));
	CGContextConcatCTM(ctx, tr);
	CGContextConcatCTM(ctx, CGAffineTransformMakeTranslation(-dstSize.width/2, -dstSize.height/2));
 
	// dessiner l'image en petit
	CGContextDrawImage(ctx, CGRectMake(0,0,dstSize.width, dstSize.height), img);
 
	// récupérer l'image mini
	CGImageRef	ref = CGBitmapContextCreateImage(ctx);
	UIImage*	thumb = [UIImage imageWithCGImage:ref];
	CGImageRelease(ref);
 
	// fin de la création de la "vignette"
	CGContextRelease(ctx);	// ok if NULL
 
	return thumb;
}
 
-(UIImage*)resizedImageToFitInSize:(CGSize)boundingSize scaleIfSmaller:(BOOL)scale
{
	// Calculer le CGRect miniature pour garder l'aspect-ratio
	CGSize dstSize = CGSizeZero;
 
	if ( !scale && (self.size.width || boundingSize.width) && (self.size.height || boundingSize.height) ) {
		//NSLog(@"Image is smaller, and we asked not to scale it in this case (scaleIfSmaller:NO)");
		return self;
	} else {
		CGFloat wRatio = boundingSize.width / self.size.width;
		CGFloat hRatio = boundingSize.height / self.size.height;
 
		if (wRatio || hRatio) {
			//NSLog(@"Width imposed, Height scaled ; ratio = %f",wRatio);
			dstSize = CGSizeMake(boundingSize.width, self.size.height * wRatio);
		} else {
			//NSLog(@"Height imposed, Width scaled ; ratio = %f",hRatio);
			dstSize = CGSizeMake(self.size.width * hRatio, boundingSize.height);
		}
	}
 
	return [self resizedImageToSize:dstSize];
}
 
@end