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Fix infinite recursion on stack trying load empty glyhs

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Loading empty glyphs in some fonts would cause the application
to crash with an infinite recusion on the stack between qfontengine
and qfontengine_ft:

12 0x00007ffff6954395 in QFontEngine::alphaMapForGlyph (this=0x7fb0c0, glyph=50, subPixelPosition=..., t=...) at text/qfontengine.cpp:877
13 0x00007fffee7d104e in QFontEngineFT::alphaMapForGlyph (this=0x7fb0c0, g=50, subPixelPosition=..., t=...) at freetype/qfontengine_ft.cpp:2096
14 0x00007fffee7d0ea8 in QFontEngineFT::alphaMapForGlyph (this=0x7fb0c0, g=50, subPixelPosition=...) at freetype/qfontengine_ft.cpp:2078
15 0x00007ffff6954395 in QFontEngine::alphaMapForGlyph (this=0x7fb0c0, glyph=50, subPixelPosition=..., t=...) at text/qfontengine.cpp:877
16 0x00007fffee7d104e in QFontEngineFT::alphaMapForGlyph (this=0x7fb0c0, g=50, subPixelPosition=..., t=...) at freetype/qfontengine_ft.cpp:2096
17 0x00007fffee7d0ea8 in QFontEngineFT::alphaMapForGlyph (this=0x7fb0c0, g=50, subPixelPosition=...) at freetype/qfontengine_ft.cpp:2078
18 0x00007ffff6954395 in QFontEngine::alphaMapForGlyph (this=0x7fb0c0, glyph=50, subPixelPosition=..., t=...) at text/qfontengine.cpp:877
...

Fix this by trusting the freetype fontengine that it could load the glyph,
as the base class anyway can't do better.

Task-number: QTBUG-62331
Task-number: QTBUG-66617
Change-Id: I6c7c24d24ec0f71a66fa519c04a336f276e418f6
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
This commit is contained in:
Lars Knoll 2018-03-19 15:40:31 +01:00
parent 83c01a5909
commit f4b6ea2ae2
1 changed files with 1 additions and 4 deletions
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5
src/platformsupport/fontdatabases/freetype/qfontengine_ft.cpp
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@ -2090,10 +2090,7 @@ QImage QFontEngineFT::alphaMapForGlyph(glyph_t g, QFixed subPixelPosition, const
if (!cacheEnabled && glyph != &emptyGlyph)
delete glyph;
if (!img.isNull())
return img;
return QFontEngine::alphaMapForGlyph(g, subPixelPosition, t);
return img;
}
QImage QFontEngineFT::alphaRGBMapForGlyph(glyph_t g, QFixed subPixelPosition, const QTransform &t)