IOS图片压缩的类

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//
//  UIImage+UIImageExt.m
//  MyHomeBuy
//
//  Created by first on 13-9-13.
//  Copyright (c) 2013年 __MyCompanyName__. All rights reserved.
//
#import "UIImage+UIImageExt.h"
@implementation UIImage (UIImageExt)
- (UIImage*)imageByScalingAndCroppingForSize:(CGSize)targetSize;
{
UIImage *sourceImage = self;
UIImage *newImage = nil;
CGSize imageSize = sourceImage.size;
CGFloat width = imageSize.width;
CGFloat height = imageSize.height;
CGFloat targetWidth = targetSize.width;
CGFloat targetHeight = targetSize.height;
CGFloat scaleFactor = 0.0;
CGFloat scaledWidth = targetWidth;
CGFloat scaledHeight = targetHeight;
CGPoint thumbnailPoint = CGPointMake(0.0,0.0);
if (CGSizeEqualToSize(imageSize, targetSize) == NO)
{
CGFloat widthFactor = targetWidth / width;
CGFloat heightFactor = targetHeight / height;
if (widthFactor > heightFactor)
scaleFactor = widthFactor; // scale to fit height
else
scaleFactor = heightFactor; // scale to fit width
scaledWidth= width * scaleFactor;
scaledHeight = height * scaleFactor;
// center the image
if (widthFactor > heightFactor)
{
thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
}
else if (widthFactor < heightFactor)
{
thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
}
}
UIGraphicsBeginImageContext(targetSize); // this will crop
CGRect thumbnailRect = CGRectZero;
thumbnailRect.origin = thumbnailPoint;
thumbnailRect.size.width= scaledWidth;
thumbnailRect.size.height = scaledHeight;
[sourceImage drawInRect:thumbnailRect];
newImage = UIGraphicsGetImageFromCurrentImageContext();
//if(newImage == nil)
//NSLog(@"could not scale image");
//pop the context to get back to the default
UIGraphicsEndImageContext();
return newImage;
}
@end
//
//  UIImage+UIImageExt.h
//  MyHomeBuy
//
//  Created by first on 13-9-13.
//  Copyright (c) 2013年 __MyCompanyName__. All rights reserved.
//
#import <UIKit/UIKit.h>
@interface UIImage (UIImageExt)
- (UIImage*)imageByScalingAndCroppingForSize:(CGSize)targetSize;
@end

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