iOS 如何将阴影应用于UIBezierPath
示例
考虑一个由贝塞尔曲线路径绘制的简单矩形。
UIBezierPath* rectanglePath = [UIBezierPath bezierPathWithRect: CGRectMake(x,y,width,height)]; [UIColor.grayColor setFill]; [rectanglePath fill];
基本的外部填充阴影：
CGContextRef context = UIGraphicsGetCurrentContext(); NSShadow* shadow = [[NSShadow alloc] init]; [shadow setShadowColor: UIColor.blackColor]; [shadow setShadowOffset: CGSizeMake(7.1, 5.1)]; [shadow setShadowBlurRadius: 5]; UIBezierPath* rectanglePath = [UIBezierPath bezierPathWithRect: CGRectMake(x,y,width,height)]; CGContextSaveGState(context); CGContextSetShadowWithColor(context, shadow.shadowOffset, shadow.shadowBlurRadius, [shadow.shadowColor CGColor]); [UIColor.grayColor setFill]; [rectanglePath fill]; CGContextRestoreGState(context);
基本的内部填充阴影：
CGContextRef context = UIGraphicsGetCurrentContext();
NSShadow* shadow = [[NSShadow alloc] init];
[shadow setShadowColor: UIColor.blackColor];
[shadow setShadowOffset: CGSizeMake(9.1, -7.1)];
[shadow setShadowBlurRadius: 6];
UIBezierPath* rectanglePath = [UIBezierPath bezierPathWithRect: CGRectMake(x,y,width,height)];
[UIColor.grayColor setFill];
[rectanglePath fill];
CGContextSaveGState(context);
UIRectClip(rectanglePath.bounds);
CGContextSetShadowWithColor(context, CGSizeZero, 0, NULL);
CGContextSetAlpha(context, CGColorGetAlpha([shadow.shadowColor CGColor]));
CGContextBeginTransparencyLayer(context, NULL);
{
UIColor* opaqueShadow = [shadow.shadowColor colorWithAlphaComponent: 1];
CGContextSetShadowWithColor(context, shadow.shadowOffset, shadow.shadowBlurRadius, [opaqueShadow CGColor]);
CGContextSetBlendMode(context, kCGBlendModeSourceOut);
CGContextBeginTransparencyLayer(context, NULL);
[opaqueShadow setFill];
[rectanglePath fill];
CGContextEndTransparencyLayer(context);
}
CGContextEndTransparencyLayer(context);
CGContextRestoreGState(context);
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