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iphone 压缩图片到指定的大小

2012-08-14 22:20 447 查看

1.本文摘自：http://www.cocoachina.com/bbs/read.php?tid-20940.html

#import <Foundation/Foundation.h>

@interface UIImage (UIImageExt)

- (UIImage*)imageByScalingAndCroppingForSize:(CGSize)targetSize;

@end

复制代码

#import "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

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标签： iphone interface image

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