摘要：
过去，在设置图像圆角时，图像视图总是设置为圆形，然后maskToBounds设置为YES。事实上，这个过程非常消耗性能。当有许多图像时，这更困难，因此最好裁剪图像并显示它们；以下是可以使用的分类：UIImage+wiRoundedRectImage。h#import @interfaceUIImage（wiRoundedRectImage）+（id）createRoundedRec
以前设置图片圆角总是把imageView设置成圆形，然后设置maskToBounds为YES,其实这样处理很消耗性能，图片多了之后比较卡，最好将图片进行裁剪后显示；这里有个分类可以用：
UIImage+wiRoundedRectImage.h
#import <UIKit/UIKit.h> @interface UIImage (wiRoundedRectImage) + (id)createRoundedRectImage:(UIImage*)image size:(CGSize)size radius:(NSInteger)r; @end
UIImage+wiRoundedRectImage.m
#import "UIImage+wiRoundedRectImage.h"
@implementation UIImage (wiRoundedRectImage)
static void addRoundedRectToPath(CGContextRef context, CGRect rect, float ovalWidth,
float ovalHeight)
{
float fw, fh;
if (ovalWidth == 0 || ovalHeight == 0)
{
CGContextAddRect(context, rect);
return;
}
CGContextSaveGState(context);
CGContextTranslateCTM(context, CGRectGetMinX(rect), CGRectGetMinY(rect));
CGContextScaleCTM(context, ovalWidth, ovalHeight);
fw = CGRectGetWidth(rect) / ovalWidth;
fh = CGRectGetHeight(rect) / ovalHeight;
CGContextMoveToPoint(context, fw, fh/2); // Start at lower right corner
CGContextAddArcToPoint(context, fw, fh, fw/2, fh, 1); // Top right corner
CGContextAddArcToPoint(context, 0, fh, 0, fh/2, 1); // Top left corner
CGContextAddArcToPoint(context, 0, 0, fw/2, 0, 1); // Lower left corner
CGContextAddArcToPoint(context, fw, 0, fw, fh/2, 1); // Back to lower right
CGContextClosePath(context);
CGContextRestoreGState(context);
}
+ (id)createRoundedRectImage:(UIImage*)image size:(CGSize)size radius:(NSInteger)r
{
// the size of CGContextRef
int w = size.width;
int h = size.height;
UIImage *img = image;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(NULL, w, h, 8, 4 * w, colorSpace, kCGImageAlphaPremultipliedFirst);
CGRect rect = CGRectMake(0, 0, w, h);
CGContextBeginPath(context);
addRoundedRectToPath(context, rect, r, r);
CGContextClosePath(context);
CGContextClip(context);
CGContextDrawImage(context, CGRectMake(0, 0, w, h), img.CGImage);
CGImageRef imageMasked = CGBitmapContextCreateImage(context);
img = [UIImage imageWithCGImage:imageMasked];
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
CGImageRelease(imageMasked);
return img;
}
@end调用方法:
1 UIImage * image = [UIImageimageNamed:@"123.jpg"]; // 设置原图 2 3 CGSize size = CGSizeMake(100,100); // 设置尺寸 4 5 UIImageView *testImageView = [[UIImageView alloc] init]; 6 7 testImageView.frame = CGRectMake(30, 30, imageWidth, imageWidth); 8 9 testImageView.backgroundColor = [UIColor lightGrayColor]; 10 11 testImageView.contentMode = UIViewContentModeScaleAspectFit; 12 13 [self.view addSubview:testImageView]; 14 15 testImageView.image = [UIImagecreateRoundedRectImage:image size:size radius:10]; // 设置radius
其实github上有个提供对image多种处理的库：
UIImage+Resize 调整图片大小
GitHub：https://github.com/coryalder/UIImage_Resize
提供多种方法为图片设置透明度、圆角、裁剪、调整大小等：
1 - (UIImage *)imageWithAlpha; 2 - (UIImage *)transparentBorderImage:(NSUInteger)borderSize; 3 - (UIImage *)roundedCornerImage:(NSInteger)cornerSize borderSize:(NSInteger)borderSize; 4 - (UIImage *)croppedImage:(CGRect)bounds; 5 - (UIImage *)thumbnailImage:(NSInteger)thumbnailSize 6 transparentBorder:(NSUInteger)borderSize 7 cornerRadius:(NSUInteger)cornerRadius 8 interpolationQuality:(CGInterpolationQuality)quality; 9 - (UIImage *)resizedImage:(CGSize)newSize 10 interpolationQuality:(CGInterpolationQuality)quality; 11 - (UIImage *) 12 resizedImageWithContentMode:(UIViewContentMode)contentMode 13 bounds:(CGSize)bounds 14 interpolationQuality:(CGInterpolationQuality)quality;
更详细使用见：http://vocaro.com/trevor/blog/2009/10/12/resize-a-uiimage-the-right-way/
参考链接：1. http://www.cnblogs.com/thefeelingofsimple/archive/2013/02/20/2918547.html