如何繪製圓角NSImage

Question

我正在嘗試創建一個NSImage或NSImageCell，圓角落在NSTableView的內部。我無法得到任何工作。這裏是最好的我到目前爲止我的自定義NSCell內：

- (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]; 
    } 
} 
... 

上的任何想法如何呢？

Answer 1

您需要在繪製圖像時保留剪輯集，然後恢復上下文。另外，我不認爲你想要使用「in」合成，而是如果你只是想正常繪製圖像而不考慮目標不透明度，則應該使用「合成」。嘗試是這樣的：

[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]; 

Answer 2

只需提供你做了什麼錯多一點信息：

保存和恢復gstate的目的是爲了能夠撤消更改gstate。在你的情況下，剪切後恢復gsave解開剪輯。這就是爲什麼解決方案（如由羅特所解釋的）是爲了在你恢復gstate之前繪製你想要的之前。

Answer 3

+ (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; 
} 

Answer 4

斯威夫特版本：

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)