iOS image 切圆角

#import@interface UIImage (RoundedRectImage)

+ (id)createRoundedRectImage:(UIImage*)image size:(CGSize)size radius:(NSInteger)r;

@end

#import "UIImage+RoundedRectImage.h"

@implementation UIImage (RoundedRectImage)

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