圆角头像的几种裁剪

效果1

.h 我就不写了

.m

#import "UIImage+Extension.h"

@implementation UIImage (Extension)
+ (instancetype)sw_icon:(UIImage *)image
{
    UIGraphicsBeginImageContext(image.size);
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    CGRect rect = CGRectMake(0, 0, image.size.width, image.size.height);
    CGContextAddEllipseInRect(ctx, rect);
    CGContextClip(ctx);
    [image drawInRect:rect];
    UIImage *icon = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return icon;
}
@end

效果2

以下方法 是我在控制器里写的, 如需写在分类, 需稍加改动

方法一

// CGContext 裁剪
- (UIImage *)CGContextClip:(UIImage *)img cornerRadius:(CGFloat)c {
    int w = img.size.width * img.scale;
    int h = img.size.height * img.scale;
    
    UIGraphicsBeginImageContextWithOptions(CGSizeMake(w, h), false, 1.0);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextMoveToPoint(context, 0, c);
    CGContextAddArcToPoint(context, 0, 0, c, 0, c);
    CGContextAddLineToPoint(context, w-c, 0);
    CGContextAddArcToPoint(context, w, 0, w, c, c);
    CGContextAddLineToPoint(context, w, h-c);
    CGContextAddArcToPoint(context, w, h, w-c, h, c);
    CGContextAddLineToPoint(context, c, h);
    CGContextAddArcToPoint(context, 0, h, 0, h-c, c);
    CGContextAddLineToPoint(context, 0, c);
    CGContextClosePath(context);
    
    CGContextClip(context);     // 先裁剪 context，再画图，就会在裁剪后的 path 中画
    [img drawInRect:CGRectMake(0, 0, w, h)];       // 画图
    CGContextDrawPath(context, kCGPathFill);
    
    UIImage *ret = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return ret;
}

方法二

// UIBezierPath 裁剪
- (UIImage *)UIBezierPathClip:(UIImage *)img cornerRadius:(CGFloat)c {
    int w = img.size.width * img.scale;
    int h = img.size.height * img.scale;
    CGRect rect = CGRectMake(0, 0, w, h);
    
    UIGraphicsBeginImageContextWithOptions(CGSizeMake(w, h), false, 1.0);
    [[UIBezierPath bezierPathWithRoundedRect:rect cornerRadius:c] addClip];
    [img drawInRect:rect];
    UIImage *ret = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return ret;
}

方法三

// 自定义裁剪算法
- (UIImage *)dealImage:(UIImage *)img cornerRadius:(CGFloat)c {
    // 1.CGDataProviderRef 把 CGImage 转 二进制流
    CGDataProviderRef provider = CGImageGetDataProvider(img.CGImage);
    void *imgData = (void *)CFDataGetBytePtr(CGDataProviderCopyData(provider));
    int width = img.size.width * img.scale;
    int height = img.size.height * img.scale;
    
    // 2.处理 imgData
//    dealImage(imgData, width, height);
    cornerImage(imgData, width, height, c);
    
    // 3.CGDataProviderRef 把 二进制流 转 CGImage
    CGDataProviderRef pv = CGDataProviderCreateWithData(NULL, imgData, width * height * 4, releaseData);
    CGImageRef content = CGImageCreate(width , height, 8, 32, 4 * width, CGColorSpaceCreateDeviceRGB(), kCGBitmapByteOrder32Big | kCGImageAlphaPremultipliedLast, pv, NULL, true, kCGRenderingIntentDefault);
    UIImage *result = [UIImage imageWithCGImage:content];
    CGDataProviderRelease(pv);      // 释放空间
    CGImageRelease(content);
    
    return result;
}

void releaseData(void *info, const void *data, size_t size) {
    free((void *)data);
}

// 在 img 上处理图片, 测试用
void dealImage(UInt32 *img, int w, int h) {
    int num = w * h;
    UInt32 *cur = img;
    for (int i=0; i h ? h : w;
    
    if (c < 0) { c = 0; }
    if (c > min * 0.5) { c = min * 0.5; }
    
    // 左上 y:[0, c), x:[x, c-y)
    for (int y=0; y r * r) {
        return false;
    }
    return true;
}

自定义裁剪 裁剪10000张图片 用时平均 11.3

GContext裁剪 裁剪10000张图片 用时平均 12.7

贝塞尔裁剪 裁剪10000张图片 用时平均 13.0

有图有真相

真相