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I have a NSMatrix with a couple of NSButtons in it which have no Text but are only images. One of the images is downloaded from the internet and I would like to have it rounded corners in my OS X application.

I found one answer which nearly is what I was looking for: How to draw a rounded NSImage but sadly it acts crazy when I use it:

// In my NSButtonCell subclass
- (void)drawImage:(NSImage*)image withFrame:(NSRect)imageFrame inView:(NSView*)controlView
{
    // [super drawImage:image withFrame:imageFrame inView:controlView];

    [NSGraphicsContext saveGraphicsState];

    NSBezierPath *path = [NSBezierPath bezierPathWithRoundedRect:imageFrame xRadius:5 yRadius:5];
    [path addClip];

    [image drawInRect:imageFrame fromRect:NSZeroRect operation:NSCompositeSourceOver fraction:1.0];

    [NSGraphicsContext restoreGraphicsState];
}

The problem is that if a image is partly transparent (PNG) then it is completly destroyed and I only see a couple of white pixels on a black background.

And if the image is not transparent then it gets the rounded corners but is rotated 180° and I don't know why.

Any suggestions?

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1 回答 1

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您需要确保在绘制之前正确设置图像的大小，并且您应该使用该NSImage方法drawInRect:fromRect:operation:fraction:respectFlipped:hints:确保图像以正确的方式向上绘制：

- (void)drawImage:(NSImage*)image withFrame:(NSRect)imageFrame inView:(NSView*)controlView
{
    // [super drawImage:image withFrame:imageFrame inView:controlView];

    [NSGraphicsContext saveGraphicsState];

    NSBezierPath *path = [NSBezierPath bezierPathWithRoundedRect:imageFrame xRadius:5 yRadius:5];
    [path addClip];

    //set the size
    [image setSize:imageFrame.size];

    //draw the image
    [image drawInRect:imageFrame fromRect:NSZeroRect operation:NSCompositeSourceOver fraction:1.0 respectFlipped:YES hints:nil];

    [NSGraphicsContext restoreGraphicsState];
}

如果您这样做，图像应该正确绘制，即使它是半透明的 PNG 图像。

于 2011-11-30T23:38:19.007 回答