Quartz2D指定显示范围

在qq中，可以看到头像是圆形显示的，通过CGContextClip可以设置

CGContextRef context=UIGraphicsGetCurrentContext();CGContextAddEllipseInRect(context, CGRectMake(100, 100, 100, 100));CGContextClip(context);UIImage *img=[UIImage imageNamed:@"img.jpg"];[img drawAtPoint:CGPointMake(100, 100)];

 

 CGContextRef context=UIGraphicsGetCurrentContext();UIImage *img=[UIImage imageNamed:@"img.jpg"];CGContextMoveToPoint(context, 30, 120);CGContextAddLineToPoint(context, 50, 200);CGContextAddLineToPoint(context, 200, 60);CGContextClosePath(context);CGContextClip(context);[img drawAtPoint:CGPointMake(30, 120)];