RFR: JDK-8294427 - Check boxes and radio buttons have rendering issues on Windows in High DPI env [v12]

[Sergey Bylokhov]

On Thu, 8 Jun 2023 00:40:24 GMT, Rajat Mahajan <rmahajan at openjdk.org> wrote:

> So, we ask Windows for the component image based on a particular DPI , not some specific size. The basic premise here is that we expect Windows returning image that would match the DPI , and then we perform our calculations accordingly. In the case above (if Region.clipRound is used) that basic premise is not met (if w, h=19) due to us calculating a DPI value of 140 which is closer to 120 or 125% scaling while our scaling is acytually 150% and Windows returns us a smaller size of the component than expected. So we don't need to add extra code to rescale , I believe. If we provide windows with correctly calculated DPI value which my code change does it should work fine as Windows will give us image of the correct size.


=( I am still missing something.
This is the code we discussing:

            int w = (int) Math.floor(destWidth + 0.5);
            int h = (int) Math.floor(destHeight + 0.5);

It calculates the size of the image we would like to render, it does not calculate the DPI. So if our component is 100x100 in pixels we create the image of that [size](https://github.com/openjdk/jdk/blob/79a4ac791c826656b3e984fe54dc472c62efd028/src/java.desktop/share/classes/sun/swing/CachedPainter.java#L155) and put it into the cache. Later when want to render that image to the place where the component of size 100x100 is located we request it from the PainterMultiResolutionCachedImage.getResolutionVariant.

After this patch we create the image of one size using ceil, then request the image using floor, and it is somehow affected by the fact that the WIndows may return something different than requested.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13701#discussion_r1222582779