Quartz2D-4(图片裁剪)

/**

 *  图片裁剪

 *

 *  先画一个圆，让图片显示在圆的内部，超出的部分不显示。

 */

- (void)drawRect:(CGRect)rect

{

    // 画圆

    CGContextRef ref = UIGraphicsGetCurrentContext();

// CGContextAddArc(ref, 100, 100, self.radius, 0, 2*M_PI, 0);

    CGContextAddEllipseInRect(ref, CGRectMake(10.0,20.0,150.0,150.0));

    //指定上下文中可以显示内容的范围就是圆的范

    CGContextClip(ref);

    UIImage *image = [UIImage imageNamed:@"C128E3B3-6631-4CEF-BD31-423F12EDBCAF"];

    [image drawAtPoint:CGPointMake(0.0,20.0)];

}

/**

 *  三角形

 *

 *  @param rect <#rect description#>

 */

- (void)drawRect:(CGRect)rect

{

    CGContextRef ctx =UIGraphicsGetCurrentContext();

    //三个点确定一个三角形

    CGContextMoveToPoint(ctx,30,30);

    CGContextAddLineToPoint(ctx,30,150);

    CGContextAddLineToPoint(ctx,150,150);

    CGContextClosePath(ctx);

    CGContextClip(ctx);

    UIImage *image = [UIImageimageNamed:@"C128E3B3-6631-4CEF-BD31-423F12EDBCAF"];

    [image drawAtPoint:CGPointMake(0.0,20.0)];

}