iPhone UIImage扩展方法

1、iPhone UIImage扩展方法,支持放大和旋转#import <Foundation/Foundation.h>interface UIImage (CS_Extensions)- (UIImage *)imageAtRect:(CGRect)rect;- (UIImage *)imageByScalingProportionallyToMinimumSize:(CGSize)targetSize;- (UIImage *)imageByScalingProportionallyToSize:(CGSize)targetSize;- (UIImage *)imageBySca

2、lingToSize:(CGSize)targetSize;- (UIImage *)imageRotatedByRadians:(CGFloat)radians;- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees;end; / UIImage-Extensions.m/ Created by Hardy Macia on 7/1/09./ Copyright 2009 Catamount Software. All rights reserved./#import "UIImage-Extensions.h"CGFloa

3、t DegreesToRadians(CGFloat degrees) return degrees * M_PI / 180;CGFloat RadiansToDegrees(CGFloat radians) return radians * 180/M_PI;implementation UIImage (CS_Extensions)-(UIImage *)imageAtRect:(CGRect)rectCGImageRef imageRef = CGImageCreateWithImageInRect(self CGImage, rect);UIImage* subImage = UII

4、mage imageWithCGImage: imageRef;CGImageRelease(imageRef);return subImage;- (UIImage *)imageByScalingProportionallyToMinimumSize:(CGSize)targetSize UIImage *sourceImage = self;UIImage *newImage = nil;CGSize imageSize = sourceImage.size;CGFloat width = imageSize.width;CGFloat height = imageSize.height

5、;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 = targ

6、etWidth / width;CGFloat heightFactor = targetHeight / height;if (widthFactor > heightFactor)scaleFactor = widthFactor;elsescaleFactor = heightFactor;scaledWidth = width * scaleFactor;scaledHeight = height * scaleFactor;/ center the imageif (widthFactor > heightFactor) thumbnailPoint.y = (targe

7、tHeight - scaledHeight) * 0.5; else if (widthFactor < heightFactor) thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;/ this is actually the interesting part:UIGraphicsBeginImageContext(targetSize);CGRect thumbnailRect = CGRectZero;thumbnailRect.origin = thumbnailPoint;thumbnailRect.size.width

8、 = scaledWidth;thumbnailRect.size.height = scaledHeight;sourceImage drawInRect:thumbnailRect;newImage = UIGraphicsGetImageFromCurrentImageContext();UIGraphicsEndImageContext();if(newImage = nil) NSLog("could not scale image");return newImage ;- (UIImage *)imageByScalingProportionallyToSize

9、:(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

10、= 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;elsesc

11、aleFactor = heightFactor;scaledWidth = width * scaleFactor;scaledHeight = height * scaleFactor;/ center the imageif (widthFactor < heightFactor) thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5; else if (widthFactor > heightFactor) thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;/ t

12、his is actually the interesting part:UIGraphicsBeginImageContext(targetSize);CGRect thumbnailRect = CGRectZero;thumbnailRect.origin = thumbnailPoint;thumbnailRect.size.width = scaledWidth;thumbnailRect.size.height = scaledHeight;sourceImage drawInRect:thumbnailRect;newImage = UIGraphicsGetImageFromC

13、urrentImageContext();UIGraphicsEndImageContext();if(newImage = nil) NSLog("could not scale image");return newImage ;- (UIImage *)imageByScalingToSize:(CGSize)targetSize UIImage *sourceImage = self;UIImage *newImage = nil;/ CGSize imageSize = sourceImage.size;/ CGFloat width = imageSize.wid

14、th;/ 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);/ this is actually the interesting pa

15、rt:UIGraphicsBeginImageContext(targetSize);CGRect thumbnailRect = CGRectZero;thumbnailRect.origin = thumbnailPoint;thumbnailRect.size.width = scaledWidth;thumbnailRect.size.height = scaledHeight;sourceImage drawInRect:thumbnailRect;newImage = UIGraphicsGetImageFromCurrentImageContext();UIGraphicsEnd

16、ImageContext();if(newImage = nil) NSLog("could not scale image");return newImage ;- (UIImage *)imageRotatedByRadians:(CGFloat)radiansreturn self imageRotatedByDegrees:RadiansToDegrees(radians);- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees / calculate the size of the rotated view'

17、s containing box for our drawing spaceUIView *rotatedViewBox = UIView alloc initWithFrame:CGRectMake(0,0,self.size.width, self.size.height);CGAffineTransform t = CGAffineTransformMakeRotation(DegreesToRadians(degrees);rotatedViewBox.transform = t;CGSize rotatedSize = rotatedViewBox.frame.size;rotate

18、dViewBox release;/ Create the bitmap contextUIGraphicsBeginImageContext(rotatedSize);CGContextRef bitmap = UIGraphicsGetCurrentContext();/ Move the origin to the middle of the image so we will rotate and scale around the center.CGContextTranslateCTM(bitmap, rotatedSize.width/2, rotatedSize.height/2);/ / Rotate the image contextCGContextRotateCTM(bitmap, DegreesToRadians(degrees);/ Now, draw the rotated/scaled image into the