Description: Color subpixel antialiasing with Skia+Vulkan rendering is inaccurate on BGR ordered display, making text difficult to read. Steps to Reproduce: 1. Options > View > Graphics Output > Use Skia for all rendering CHECKED 2. Have a display that is not compatible (i.e. BGR) with the default settings Skia assumes Actual Results: All text rendering, including UI elements as well as in documents, lacks clarity due to being iridescent around the edges https://i.imgur.com/nJS9ntK.png Expected Results: Fonts should render the same with Skia as they do with "Use Skia for all rendering" unchecked https://i.imgur.com/CU9Uj6Z.png The differences in the screenshots will either not be apparent or seem *reversed* on a typical RGB monitor. e.g. on a standard RGB screen, the Skia *off* might appear iridescent or blurry, while Skia *on* look fine. Trust me when I say that is not the case on my display! For more info see: http://www.lagom.nl/lcd-test/subpixel.php Reproducible: Always User Profile Reset: Yes Additional Info: Technical note: Skia requires a preprocessor directive in order to read the ClearType parameters from system settings, which includes pixel order as well as contrast and gamma. https://skia.googlesource.com/skia/+/refs/heads/master/src/ports/SkTypeface_win_dw.cpp#395 https://docs.microsoft.com/en-us/dotnet/framework/wpf/advanced/cleartype-registry-settings This might explain the SK_GAMMA_APPLY_TO_A8 issue described in this commit: https://cgit.freedesktop.org/libreoffice/core/commit/external/skia?id=1ad3f6b8d9e0ef1e921c3ed5526ea352d67265cf Adding #define SK_FONT_HOST_USE_SYSTEM_SETTINGS 1 to config_skia.h.in would probably solve the issue. https://cgit.freedesktop.org/libreoffice/core/tree/config_host/config_skia.h.in Then the user could tune the level of ClearType antialiasing using Windows built-in the "Adjust ClearType Text" Control Panel applet if it was not satisfactory. However, Windows usually sets the correct subpixel order by default.
Luboš Luňák committed a patch related to this issue. It has been pushed to "master": https://git.libreoffice.org/core/commit/fada69d6ee05700fd57c8844591562608a900a9d set also RGB/BGR LCD order for Skia text rendering (tdf#134275) It will be available in 7.1.0. The patch should be included in the daily builds available at https://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: https://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.
What is meant to be the actual problem with the gamma/contrast settings? It's unrelated to the RGB/BGR problem, and it's not enabled by default in Skia, so I do not want to enable it just like that. And it doesn't look related to SK_GAMMA_APPLY_TO_A8, my commit changes the file for non-DirectWrite Skia code, while SK_FONT_HOST_USE_SYSTEM_SETTINGS is used only by the code that does use DirectWrite.
Luboš Luňák committed a patch related to this issue. It has been pushed to "libreoffice-7-0": https://git.libreoffice.org/core/commit/1171d609c52fc1f7cd58787e9ebc1ecca32fe450 set also RGB/BGR LCD order for Skia text rendering (tdf#134275) It will be available in 7.0.0.2. The patch should be included in the daily builds available at https://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: https://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.
No further info, the actual problem is fixed, closing.