[Win] Some Tibetan characters aren't shown Both AppleWin and WinCairo have the issue. https://unicode.org/charts/nameslist/c_0F00.html https://ja.wikipedia.org/wiki/%E3%83%81%E3%83%99%E3%83%83%E3%83%88%E8%AA%9E
Created attachment 400906 [details] [Screenshot] WinCairo port
Created attachment 400907 [details] DOTTED CIRCLE + TIBETAN ASTROLOGICAL SIGN SDONG TSHUGS
FontCache::systemFallbackForCharacters of FontCacheWin.cpp is using three steps to choose a fallback font. 1. Try IMLangFontLink::MapFont method 2. If no font found, try meta file method 3. If no font found, try FontLink registry method For the missing Tibetan characters, IMLangFontLink::MapFont method returns "Arial Unicode MS" font, but Uniscribe returns USP_E_SCRIPT_NOT_IN_FONT for the font. For other Tibetan characters, IMLangFontLink::MapFont method returns "Microsoft Himalaya" font
Following StackOverflow suggests reffering Chromium's render_text_win.cc. How to automatically choose most suitable font for different language? - Stack Overflow https://stackoverflow.com/q/16828868 Check if Unicode character is displayed or tofu - Stack Overflow https://stackoverflow.com/q/47840800 Chromium UI was using Uniscribe, but it was replaced by HarfBuzz. https://codereview.chromium.org/891013003 https://chromium.googlesource.com/chromium/src.git/+/2e9885788692f69203a98fb42347428ef553d640/ui/gfx/render_text_win.cc https://chromium.googlesource.com/chromium/src.git/+/2e9885788692f69203a98fb42347428ef553d640/ui/gfx/font_fallback_win.cc
Created attachment 401504 [details] [Screenshot] WinCairo (after r262804) r262804 (Bug 212947) changed the situation. After the change, some Tibetan characters start to show while combining marks still doesn't render correctly.
Created attachment 401505 [details] [Screenshot] Tibetan Wikipedia in WinCairo (after r262804) Tibetan pages look broken. https://bo.wikipedia.org/
I'm going to try stop using MLang font linking in the following ticket. Bug 213008 – [Win] Stop using MLang font linking for system font fallback