如何保存JavaFX Canvas的高DPI快照 [英] How to save a high DPI snapshot of a JavaFX Canvas

问题描述

我在Canvas上创建了一个图像，该图像按比例缩小以便使用变换进行显示。它也在ScrollPane中，这意味着只有部分图像可见。

I have created an image on a Canvas which is scaled down for display using a transformation. It is also in a ScrollPane which means only a part of the image is visible.

我需要拍摄整个画布的快照并将其保存为高分辨率图片。当我使用Canvas.snapshot时，我在缩小后得到图像可见部分的可写图像。这会导致保存低分辨率的局部图像。

I need to take a snapshot of the entire canvas and save this as a high-resolution image. When I use Canvas.snapshot I get a Writable image of the visible part of the image after scaling down. This results in a low-res partial image being saved.

那么我该如何创建包含整个画布的快照（不仅仅是滚动窗格的视口）转换前的分辨率是什么？

So how do I go about creating a snapshot which includes the entire canvas (not only the viewport of the scrollpane) and with the resolution before the transformation downwards?

我目前没有做任何奇特的事情，只有这样：

I am not doing anything fancy currently, just this:

public WritableImage getPackageCanvasSnapshot()
{
    SnapshotParameters param = new SnapshotParameters();
    param.setDepthBuffer(true);
    return packageCanvas.snapshot(param, null);
}

推荐答案

我做了以下工作来获取Retina显示屏上的画布快照，其pixelScaleFactor为2.0。它对我有用。

I did the following to get a canvas snapshot on a Retina display with a pixelScaleFactor of 2.0. It worked for me.

public static WritableImage pixelScaleAwareCanvasSnapshot(Canvas canvas, double pixelScale) {
    WritableImage writableImage = new WritableImage((int)Math.rint(pixelScale*canvas.getWidth()), (int)Math.rint(pixelScale*canvas.getHeight()));
    SnapshotParameters spa = new SnapshotParameters();
    spa.setTransform(Transform.scale(pixelScale, pixelScale));
    return canvas.snapshot(spa, writableImage);     
}

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