NSImageView 上的 NSCollectionViewItem 选择，带 CALayer 的图像边框

Question

我有一个带有 NSImageView 的 NSCollectionViewItem。

我想在图像周围添加阴影。选择后，我希望图像具有阴影和边框。目前，NSImageView 获取图像周围的边框。

如何实现选区的阴影+边框？似乎图像周围的边框设置正确，但图像视图周围的边框设置正确。

[self.templateImageView setWantsLayer:YES];
self.templateImageView.layer.borderWidth = 0.0;
self.templateImageView.layer.borderColor = borderColor.CGColor;
self.templateImageView.layer.masksToBounds = YES;

[self.templateImageView.layer setShadowColor: [NSColor blackColor].CGColor];
[self.templateImageView.layer setShadowOpacity:0.8];
[self.templateImageView.layer setShadowRadius:5.0];

Answer 1

首先，您的图像必须具有透明背景。然后你可以在图像内容周围画一个边框：

func drawOutlie(image:UIImage, color:UIColor) -> UIImage
{
    let newImageKoef:CGFloat = 1.08

    let outlinedImageRect = CGRect(x: 0.0, y: 0.0, width: image.size.width * newImageKoef, height: image.size.height * newImageKoef)

    let imageRect = CGRect(x: image.size.width * (newImageKoef - 1) * 0.5, y: image.size.height * (newImageKoef - 1) * 0.5, width: image.size.width, height: image.size.height)

    UIGraphicsBeginImageContextWithOptions(outlinedImageRect.size, false, newImageKoef)

    image.draw(in: outlinedImageRect)

    let context = UIGraphicsGetCurrentContext()
    context!.setBlendMode(CGBlendMode.sourceIn)

    context!.setFillColor(color.cgColor)
    context!.fill(outlinedImageRect)
    image.draw(in: imageRect)

    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return newImage!

}

您可以通过更改newImageKoef来更改轮廓大小。

答案基于haawa答案并更新至swift 3.0.

Answer 2

感谢您的回答。它确实有助于找到我要找的东西。这是一个解决方案：

- (NSImage*)borderAroundImage:(NSImage*)image
{
NSSize size = NSMakeSize([image size].width, [image size].height);

NSImage* im = image;
NSBitmapImageRep* rep = [[NSBitmapImageRep alloc]
                         initWithBitmapDataPlanes:NULL
                         pixelsWide:size.width
                         pixelsHigh:size.height
                         bitsPerSample:8
                         samplesPerPixel:4
                         hasAlpha:YES
                         isPlanar:NO
                         colorSpaceName:NSCalibratedRGBColorSpace
                         bytesPerRow:0
                         bitsPerPixel:0];

[im addRepresentation:rep];

[im lockFocus];

CGContextRef ctx = [[NSGraphicsContext currentContext] graphicsPort];

CGContextSetStrokeColorWithColor(ctx, [NSColor colorWithDeviceRed:0.200 green:0.529 blue:0.957 alpha:1.000].CGColor);
CGContextSetLineWidth(ctx, 25.0);
CGContextStrokeRect(ctx, CGRectInset(CGRectMake(0, 0, [image size].width, [image size].height), 0, 0));

[im unlockFocus];

return im;
}

NSImageView 上的 NSCollectionViewItem 选择，带 CALayer 的图像边框

NSCollectionViewItem selection on NSImageView, border around image with CALayer

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