iOS开发笔记-将图片处理成圆形或者说特定圆角

1..h文件

#import <UIKit/UIKit.h>
typedef enum {
    UIImageRoundedCornerTopLeft = 1,
    UIImageRoundedCornerTopRight = 1 << 1,
    UIImageRoundedCornerBottomRight = 1 << 2,
    UIImageRoundedCornerBottomLeft = 1 << 3
} UIImageRoundedCorner;
@interface UIImage (JPDealWithImage)
- (UIImage *)image:(UIImage*)image byScalingToSize:(CGSize)targetSize ;
- (UIImage *)roundedRectImage:(UIImage *)srcimage withradius:(float)radius cornerMask:(UIImageRoundedCorner)cornerMask;
@end

2..m文件

#import "UIImage+JPDealWithImage.h"

@implementation UIImage (JPDealWithImage)
- (UIImage *)image:(UIImage*)image byScalingToSize:(CGSize)targetSize {
    UIImage *sourceImage = image;
    UIImage *newImage = nil;

    UIGraphicsBeginImageContext(targetSize);

    CGRect thumbnailRect = CGRectZero;
    thumbnailRect.origin = CGPointZero;
    thumbnailRect.size.width  = targetSize.width;
    thumbnailRect.size.height = targetSize.height;

    [sourceImage drawInRect:thumbnailRect];

    newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return newImage ;
}
- (UIImage *)roundedRectImage:(UIImage *)srcimage withradius:(float)radius cornerMask:(UIImageRoundedCorner)cornerMask
{
    UIImageView *bkImageViewTmp = [[UIImageView alloc] initWithImage:srcimage];
    bkImageViewTmp.layer.shouldRasterize = YES;
    int w = srcimage.size.width;
    int h = srcimage.size.height;

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    //kCGBitmapAlphaInfoMask
//    CGContextRef context = CGBitmapContextCreate(NULL, w, h, 8, 4 * w, colorSpace,kCGBitmapByteOrderMask);
    CGContextRef context = CGBitmapContextCreate(NULL, w, h, 8, 4 * w, colorSpace,kCGImageAlphaPremultipliedFirst);

    CGContextBeginPath(context);
    CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
    [self addRoundedRectToPath:context withrect:bkImageViewTmp.frame radius:radius mask:cornerMask];

    CGContextClosePath(context);
    CGContextClip(context);

    CGContextDrawImage(context, CGRectMake(0, 0, w, h), srcimage.CGImage);

    CGImageRef imageMasked = CGBitmapContextCreateImage(context);
    CGContextRelease(context);
    CGColorSpaceRelease(colorSpace);

    UIImage    *newImage = [UIImage imageWithCGImage:imageMasked];

//    UIGraphicsBeginImageContextWithOptions(newImage.size, NO, 0.0);
//    
//    [newImage drawInRect:CGRectMake(1, 1, newImage.size.width-2, newImage.size.height-2)];

    CGImageRelease(imageMasked);

    return newImage;
}

-(void)addRoundedRectToPath:(CGContextRef)context withrect:(CGRect)rect radius:(float)radius mask:(UIImageRoundedCorner)cornerMask
{
    //原点在左下方，y方向向上。移动到线条2的起点。
    CGContextMoveToPoint(context, rect.origin.x, rect.origin.y + radius);

    //画出线条2, 目前画线的起始点已经移动到线条2的结束地方了。
    CGContextAddLineToPoint(context, rect.origin.x, rect.origin.y + rect.size.height - radius);

    //如果左上角需要画圆角，画出一个弧线出来。
    if (cornerMask & UIImageRoundedCornerTopLeft) {

        //已左上的正方形的右下脚为圆心，半径为radius， 180度到90度画一个弧线，
        CGContextAddArc(context, rect.origin.x + radius, rect.origin.y + rect.size.height - radius,
                        radius, M_PI, M_PI / 2, 1);
    }

    else {
        //如果不需要画左上角的弧度。从线2终点，画到线3的终点，
        CGContextAddLineToPoint(context, rect.origin.x, rect.origin.y + rect.size.height);

        //线3终点，画到线4的起点
        CGContextAddLineToPoint(context, rect.origin.x + radius, rect.origin.y + rect.size.height);
    }

    //画线4的起始，到线4的终点
    CGContextAddLineToPoint(context, rect.origin.x + rect.size.width - radius,
                            rect.origin.y + rect.size.height);

    //画右上角
    if (cornerMask & UIImageRoundedCornerTopRight) {
        CGContextAddArc(context, rect.origin.x + rect.size.width - radius,
                        rect.origin.y + rect.size.height - radius, radius, M_PI / 2, 0.0f, 1);
    }
    else {
        CGContextAddLineToPoint(context, rect.origin.x + rect.size.width, rect.origin.y + rect.size.height);
        CGContextAddLineToPoint(context, rect.origin.x + rect.size.width, rect.origin.y + rect.size.height - radius);
    }

    CGContextAddLineToPoint(context, rect.origin.x + rect.size.width, rect.origin.y + radius);

    //画右下角弧线
    if (cornerMask & UIImageRoundedCornerBottomRight) {
        CGContextAddArc(context, rect.origin.x + rect.size.width - radius, rect.origin.y + radius,
                        radius, 0.0f, -M_PI / 2, 1);
    }
    else {
        CGContextAddLineToPoint(context, rect.origin.x + rect.size.width, rect.origin.y);
        CGContextAddLineToPoint(context, rect.origin.x + rect.size.width - radius, rect.origin.y);
    }

    CGContextAddLineToPoint(context, rect.origin.x + radius, rect.origin.y);

    //画左下角弧线
    if (cornerMask & UIImageRoundedCornerBottomLeft) {
        CGContextAddArc(context, rect.origin.x + radius, rect.origin.y + radius, radius,
                        -M_PI / 2, M_PI, 1);
    }
    else {
        CGContextAddLineToPoint(context, rect.origin.x, rect.origin.y);
        CGContextAddLineToPoint(context, rect.origin.x, rect.origin.y + radius);
    }

    CGContextClosePath(context);
}

-(void)writetofile
{
    NSLog(@"writetofile");

}

-(void)readfile
{
    NSLog(@"button click");

}

@end