启用图层支持后，NSImageView中的缩放图像看起来很糟糕 [英] Scaled image in NSImageView looks bad with layer-backing on

问题描述

我想要一个带有渐变背景和图像的视图.因此，我为该图层打开了图层支持，添加了NSImageView并将图层设置为CAGradientLayer.但是，这使按比例缩小的图像非常难看.查看比较:

I'd like to have a view with a gradient background and a image. So I turned on layer backing for the layer, added NSImageView and set the layer to CAGradientLayer. However, this makes the scaled-down image very ugly. See the comparison:

图层开启:，图层关闭:

Layer ON: , layer OFF:

有人也观察到过吗?有什么方法可以在不关闭图层支持的情况下解决此问题?

Has anyone observed this too? Is there any way to resolve this problem without turning off layer backing?

推荐答案

在遇到完全相同的问题后，我偶然发现了这个问题.一层支持NSImageView的渲染看起来非常缩放，但是没有一层支持的NSImageView看起来很棒.

I stumbled across this question after running into exactly the same problem. The rendering for a layer-backed NSImageView looked horribly scaled, but non-layer-backed one looked great.

我尝试了许多不同的方法，但最终，实际上是来自我当地CocoaHeads小组的人的建议，最终导致了解决方案.

I tried a number of different things, but in the end it was actually a suggestion from people at my local CocoaHeads group that ultimately led to a solution.

这是对我有用的代码.

    CGImageRef imageRef;
    NSRect     rect;

    rect      = NSZeroRect;
    rect.size = [_imageView bounds].size;

    imageRef = [image CGImageForProposedRect:&rect
                                     context:[NSGraphicsContext currentContext]
                                       hints:@{ NSImageHintInterpolation: @(NSImageInterpolationHigh)}];

    image = [[[NSImage alloc] initWithCGImage:imageRef size:rect.size] autorelease];

    [_imageView setImage:image];

起初，我只是假设插值模式是问题所在.但是，更改该值似乎无济于事.关于从NSImage-> CGImage-> NSImage进行的操作是什么.我讨厌提供一个我不完全了解的解决方案，但至少是这样.

At first, I'd just assumed that the interpolation mode was the problem. But, changing that value does not appear to make a difference. Something about going from NSImage->CGImage->NSImage is what does it. I hate to offer a solution I do not fully understand, but at least it's something.

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