On Fri, 18 Aug 2023 13:24:00 GMT, Alexey Ivanov <[email protected]> wrote:
>> **Problem** >> >> Glyphs aren't stretched by applying an affine transform `scale(2, 1)` to a >> font. Instead, the space between glyphs increases. >> >> **Root Cause** >> >> Bitmaps embedded in the font are used to render the glyphs; the bitmaps >> aren't transformed, so white-space is seen which fills the requested >> horizontal size. >> >> **Fix** >> >> Disable using embedded bitmaps if horizontal transform is different from the >> vertical one. >> >> It's similar to [JDK-8204929](https://bugs.openjdk.org/browse/JDK-8204929) >> and [JDK-8255387](https://bugs.openjdk.org/browse/JDK-8255387). >> >> **Test** >> >> When embedded bitmaps are used, the right half of the image remains filled >> with the background colour. The test looks for non-white pixels in the right >> half of the image. If there are only white pixels in the right half of the >> image, the test fails; if there are other colours, the test passes. >> >> I can reproduce the problem on Windows only. Without the fix, the test >> reports 6 failures for "MS Gothic", "MS PGothic" and "MS UI Gothic" fonts >> when text antialiasing is off and when LCD antialiasing is enabled. If >> greyscale antialiasing is enabled, the glyphs are stretched as expected, >> this case was handled in JDK-8204929; it can be used as a workaround. >> >> All client tests pass. >> >> ~~The test could be *headless*, but headless systems, especially with Linux, >> don't have fonts installed. Without fonts, the test is useless, therefore I >> made it *headful*.~~ >> >> The test is *headless*. > > Alexey Ivanov has updated the pull request incrementally with one additional > commit since the last revision: > > Add a translucent color to the test A couple of screenshots of `ScaledFont.java` that's attached to the [JBS issue](https://bugs.openjdk.org/browse/JDK-8312555). The screenshots are taken on an English version of Windows 10. Without the fix:  The *MS Gothic* font is affected: both English characters and hieroglyphs have extra space between the glyphs rather than being stretched. With the fix:  All the characters are stretched as expected. I modified the `ScaledFont.java` app to use a translucent color for rendering the text and enabled LCD text antialiasing for the first row (which uses `deriveFont(transform)`). @mrserb is right, it gives correct rendering in this case because LCD antialiasing is replaced with greyscale one. As we already know, greyscale AA disables using embedded bitmaps.  ------------- PR Comment: https://git.openjdk.org/jdk/pull/15335#issuecomment-1684032432
