From ef763e195892a6d8ce207f5d947fe508f645cb6d Mon Sep 17 00:00:00 2001 From: Eskil Abrahamsen Blomfeldt Date: Fri, 5 Feb 2021 12:36:37 +0100 Subject: [PATCH] Fix crash when requesting A32 glyph on Wayland On Wayland we aren't getting any information about the subpixel layout of the screen. On Freetype, this triggers an assert / memory corruption when explicitly requesting a subpixel antialiased glyph (via QRawFont) because it needs to know the layout to render the glyphs. It might be possible to get this information in the Wayland plugin, but at least we should have a failsafe which doesn't crash when the problem occurs. This simply falls back to using A8 antialiasing when it doesn't know the subpixel layout. [ChangeLog][Freetype] Fixed crash when calling QRawFont::alphaMapForGlyph() with subpixel antialiasing on Wayland. Fixes: QTBUG-90236 Pick-to: 6.0 Pick-to: 6.1 Pick-to: 5.15 Change-Id: Iddee2e171a81664ae9e3989115881f23262b2182 Reviewed-by: Allan Sandfeld Jensen --- src/gui/text/freetype/qfontengine_ft.cpp | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/src/gui/text/freetype/qfontengine_ft.cpp b/src/gui/text/freetype/qfontengine_ft.cpp index 42985fcaa6..280498f98d 100644 --- a/src/gui/text/freetype/qfontengine_ft.cpp +++ b/src/gui/text/freetype/qfontengine_ft.cpp @@ -1078,7 +1078,11 @@ QFontEngineFT::Glyph *QFontEngineFT::loadGlyph(QGlyphSet *set, uint glyph, renderMode = FT_RENDER_MODE_MONO; break; case Format_A32: - Q_ASSERT(hsubpixel || vfactor != 1); + if (!hsubpixel && vfactor == 1) { + qWarning("Format_A32 requested, but subpixel layout is unknown."); + return nullptr; + } + renderMode = hsubpixel ? FT_RENDER_MODE_LCD : FT_RENDER_MODE_LCD_V; break; case Format_A8: