NSBezierPath AddClip遮罩NSImage-大小问题

Question

在macOS（OSX）桌面应用程序上，我使用NSBezierPath绘制看起来像这样的随机封闭形状。

如您所见，虚线显示绘制的闭合路径。

现在正在尝试按照此路径提取蒙版图像。但是我得到了一小部分图像。遮罩的图像似乎可以从BezierPath正确获取轮廓。但是大小是个问题。

这是返回被遮罩/剪切的图像的方法。此图形的sourceImage.size-1021 * 1031

  - (NSImage *)imageByApplyingClippingBezierPath:(NSImage *)sourceImage
                                bezierPath:(NSBezierPath *)bezierPath
                                  newFrame:(NSRect)newFrame
  {
    NSImage* newImage = [[NSImage alloc] initWithSize:newFrame.size];
    NSBitmapImageRep* rep = [[NSBitmapImageRep alloc]
                             initWithBitmapDataPlanes:NULL
                             pixelsWide:newFrame.size.width
                             pixelsHigh:newFrame.size.height
                             bitsPerSample:8
                             samplesPerPixel:4
                             hasAlpha:YES
                             isPlanar:NO
                             colorSpaceName:NSCalibratedRGBColorSpace
                             bytesPerRow:0
                             bitsPerPixel:0];

    [newImage addRepresentation:rep];

    [newImage lockFocus];

    CGContextRef context = [[NSGraphicsContext currentContext] graphicsPort];
    CGContextSaveGState(context);

    [bezierPath addClip];

    NSRect targetFrame = NSMakeRect(0, 0, newFrame.size.width, newFrame.size.height);
    [sourceImage drawInRect:targetFrame];

    [newImage unlockFocus];

    CGContextRestoreGState(context);

    return newImage;
}

如何获得由BezierPath绘制的尺寸合适的图像？任何提示将不胜感激！

更新

请澄清一下，我如何绘制图像。我得到贝塞尔曲线路径的矩形边界和像这样裁剪的矩形图像。

CGRect bezierBounds = CGPathGetPathBoundingBox([self.smartLassoWavyBezierPath quartzPath]);
 NSRect targetFrame = NSMakeRect(0, 0, bezierBounds.size.width, bezierBounds.size.height);
 NSImage *targetImage = [[NSImage alloc initWithSize:targetFrame.size];
[targetImage lockFocus];
[self.view.originalLoadImageOnCanvas 
drawInRect:targetFrame fromRect:bezierBounds operation:NSCompositeCopy 
 fraction:1.0f];
[targetImage unlockFocus];

Answer 1

对于Swift 5；

func imageByApplyingClippingBezierPath(source: NSImage, path: NSBezierPath, frame: NSRect) -> NSImage? {
    let new = NSImage(size: frame.size)
    guard let rep = NSBitmapImageRep(bitmapDataPlanes: nil, pixelsWide: Int(frame.size.width), pixelsHigh: Int(frame.size.height), bitsPerSample: 8, samplesPerPixel: 4, hasAlpha: true, isPlanar: false, colorSpaceName: NSColorSpaceName.calibratedRGB, bitmapFormat: .alphaFirst, bytesPerRow: 0, bitsPerPixel: 0) else { return nil}

    new.addRepresentation(rep)
    new.lockFocus()

    let context = NSGraphicsContext.current?.cgContext
    context?.saveGState()
    path.addClip()

    let targetFrame = NSRect(x: 0, y: 0, width: Int(frame.size.width), height: Int(frame.size.height))

    source.draw(in: targetFrame)
    new.unlockFocus()
    context?.restoreGState()

    return new
}