将方图转成圆图

以前，写过一篇文章：图片圆角显示，这篇文章中的方法，可以将图片的四个角设置成圆角显示，如果将cornerRadius的值设置为图片宽度的一半，显示的则为圆图，本文提供了另一种将方图转成圆图的实现。

 

核心代码如下：

 

- (void)drawRect:(CGRect)rect {
    // Image rect
    CGRect imageRect = CGRectMake((self.borderWidth),
                                  (self.borderWidth),
                                  rect.size.width - (self.borderWidth * 2),
                                  rect.size.height - (self.borderWidth * 2));
    
    // Start working with the mask
    CGColorSpaceRef maskColorSpaceRef = CGColorSpaceCreateDeviceGray();
    CGContextRef mainMaskContextRef = CGBitmapContextCreate(NULL,
                                                            rect.size.width,
                                                            rect.size.height,
                                                            8,
                                                            rect.size.width,
                                                            maskColorSpaceRef,
                                                            0);
    CGContextRef shineMaskContextRef = CGBitmapContextCreate(NULL,
                                                             rect.size.width,
                                                             rect.size.height,
                                                             8,
                                                             rect.size.width,
                                                             maskColorSpaceRef,
                                                             0);
    CGColorSpaceRelease(maskColorSpaceRef);
    CGContextSetFillColorWithColor(mainMaskContextRef, [UIColor blackColor].CGColor);
    CGContextSetFillColorWithColor(shineMaskContextRef, [UIColor blackColor].CGColor);
    CGContextFillRect(mainMaskContextRef, rect);
    CGContextFillRect(shineMaskContextRef, rect);
    CGContextSetFillColorWithColor(mainMaskContextRef, [UIColor whiteColor].CGColor);
    CGContextSetFillColorWithColor(shineMaskContextRef, [UIColor whiteColor].CGColor);
    
    // Create main mask shape
    CGContextMoveToPoint(mainMaskContextRef, 0, 0);
    CGContextAddEllipseInRect(mainMaskContextRef, imageRect);
    CGContextFillPath(mainMaskContextRef);
    // Create shine mask shape
    CGContextTranslateCTM(shineMaskContextRef, -(rect.size.width / 4), rect.size.height / 4 * 3);
    CGContextRotateCTM(shineMaskContextRef, -45.f);
    CGContextMoveToPoint(shineMaskContextRef, 0, 0);
    CGContextFillRect(shineMaskContextRef, CGRectMake(0,
                                                      0,
                                                      rect.size.width / 8 * 5,
                                                      rect.size.height));
    
    CGImageRef mainMaskImageRef = CGBitmapContextCreateImage(mainMaskContextRef);
    CGImageRef shineMaskImageRef = CGBitmapContextCreateImage(shineMaskContextRef);
    CGContextRelease(mainMaskContextRef);
    CGContextRelease(shineMaskContextRef);
    // Done with mask context
    
    CGContextRef contextRef = UIGraphicsGetCurrentContext();
    CGContextSaveGState(contextRef);
    
    CGImageRef imageRef = CGImageCreateWithMask(self.image.CGImage, mainMaskImageRef);
    
    CGContextTranslateCTM(contextRef, 0, rect.size.height);
    CGContextScaleCTM(contextRef, 1.0, -1.0);
    
    CGContextSaveGState(contextRef);
    
    // Draw image
    CGContextDrawImage(contextRef, rect, imageRef);
    
    CGContextRestoreGState(contextRef);
    CGContextSaveGState(contextRef);
    
    // Clip to shine's mask
    CGContextClipToMask(contextRef, self.bounds, mainMaskImageRef);
    CGContextClipToMask(contextRef, self.bounds, shineMaskImageRef);
    CGContextSetBlendMode(contextRef, kCGBlendModeLighten);
    CGContextDrawLinearGradient(contextRef, [self alphaGradient], CGPointMake(0, 0), CGPointMake(0, self.bounds.size.height), 0);
    
    CGImageRelease(mainMaskImageRef);
    CGImageRelease(shineMaskImageRef);
    CGImageRelease(imageRef);
    // Done with image
    
    CGContextRestoreGState(contextRef);
    
    CGContextSetLineWidth(contextRef, self.borderWidth);
    CGContextSetStrokeColorWithColor(contextRef, self.borderColor.CGColor);
    CGContextMoveToPoint(contextRef, 0, 0);
    CGContextAddEllipseInRect(contextRef, imageRect);
    // Drop shadow
    CGContextSetShadowWithColor(contextRef,
                                self.shadowOffset,
                                self.shadowBlur,
                                self.shadowColor.CGColor);
    CGContextStrokePath(contextRef);
    CGContextRestoreGState(contextRef);
}

 

示例图：