如何绘制一个圆角NSImage中

StackOverflow https://stackoverflow.com/questions/1849636

  •  13-09-2019
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题

我试图创建一个NSImage或NSImageCell具有圆角的NSTableView内部。我不能得到任何工作。这里是最好的我到目前为止我的自定义NSCell内：

- (void)drawInteriorWithFrame:(NSRect)frame inView:(NSView *)controlView { 
  if (thumbnailLink) {
    NSURL *url = [NSURL URLWithString:thumbnailLink];
    if (url) {
        NSRect imageFrame = [self _imageFrameForInteriorFrame:frame];
        NSImage *image = [[NSImage alloc] initWithContentsOfURL:url];
        [image setScalesWhenResized:YES];
        [image setSize:NSMakeSize(IMAGE_HEIGHT, IMAGE_WIDTH)];

        [NSGraphicsContext saveGraphicsState];
        imageFrame = NSInsetRect(imageFrame, 1, 1);
        NSBezierPath *clipPath = [NSBezierPath bezierPathWithRoundedRect:imageFrame cornerRadius:5.0];
        [clipPath setWindingRule:NSEvenOddWindingRule];
        [clipPath addClip];
        [NSGraphicsContext restoreGraphicsState];   
        [image drawInRect:imageFrame fromRect:NSMakeRect(0, 0, 0, 0) operation:NSCompositeSourceIn fraction:1.0];
        [image release];
    }
}
...

这是任何想法如何呢？

有帮助吗？

解决方案

您需要绘制你的图像时，以保持夹集，而是还原后的上下文。此外，我不认为你想“在”合成而是“过”，如果你只是想正常绘制图像不考虑目标的不透明度在考虑使用。尝试是这样的：

[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];

其他提示

+ (NSImage*)roundCorners:(NSImage *)image
{

NSImage *existingImage = image;
NSSize existingSize = [existingImage size];
NSSize newSize = NSMakeSize(existingSize.width, existingSize.height);
NSImage *composedImage = [[[NSImage alloc] initWithSize:newSize] autorelease];

[composedImage lockFocus];
[[NSGraphicsContext currentContext] setImageInterpolation:NSImageInterpolationHigh];

NSRect imageFrame = NSRectFromCGRect(CGRectMake(0, 0, 1024, 1024));
NSBezierPath *clipPath = [NSBezierPath bezierPathWithRoundedRect:imageFrame xRadius:200 yRadius:200];
[clipPath setWindingRule:NSEvenOddWindingRule];
[clipPath addClip];

[image drawAtPoint:NSZeroPoint fromRect:NSMakeRect(0, 0, newSize.width, newSize.height) operation:NSCompositeSourceOver fraction:1];

[composedImage unlockFocus];

return composedImage;
}

夫特版本：

func roundCorners(image: NSImage, width: CGFloat = 192, height: CGFloat = 192) -> NSImage {
    let xRad = width / 2
    let yRad = height / 2
    let existing = image
    let esize = existing.size
    let newSize = NSMakeSize(esize.width, esize.height)
    let composedImage = NSImage(size: newSize)

    composedImage.lockFocus()
    let ctx = NSGraphicsContext.currentContext()
    ctx?.imageInterpolation = NSImageInterpolation.High

    let imageFrame = NSRect(x: 0, y: 0, width: width, height: height)
    let clipPath = NSBezierPath(roundedRect: imageFrame, xRadius: xRad, yRadius: yRad)
    clipPath.windingRule = NSWindingRule.EvenOddWindingRule
    clipPath.addClip()

    let rect = NSRect(x: 0, y: 0, width: newSize.width, height: newSize.height)
    image.drawAtPoint(NSZeroPoint, fromRect: rect, operation: NSCompositingOperation.CompositeSourceOver, fraction: 1)
    composedImage.unlockFocus()

    return composedImage
}

// then
roundCorners(image)
roundCorners(image, width: 512, height: 512)

只是为了提供更多的信息对你做了什么错：

保存和恢复gstate的目的是为了能够撤消更改gstate。在你的情况下，恢复gsave后裁剪解开了剪辑。这就是为什么该解决方案（如Rhult解释）是吸引你想要什么修剪的 的你恢复gstate之前。

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