path: root/src/gui/text/qfontengine_ft.cpp
diff options
authorEskil Abrahamsen Blomfeldt <>2016-08-01 13:39:53 +0200
committerEskil Abrahamsen Blomfeldt <>2016-08-01 11:58:02 +0000
commit6f423555eba55ccdf7287071e10576bc1b687fd2 (patch)
tree72b13792d09ae692e046ad38998deeb4ca16a79c /src/gui/text/qfontengine_ft.cpp
parent3f1048cca783749c7da9a9f8b3a61959ed35a0de (diff)
REG: Fix unwanted cache flush in Freetype engine
The Freetype cache was almost completely disabled by 134c6db8587a8ce156d4fa31ffa62605821851b2 because after that change, the lockedAlphaMapForGlyph() function would no longer cut off early for empty glyphs like spaces, but rather go through all alpha map functions before it realized that there was nothing to render. This would in turn invalidate the cache for every empty glyph, causing all glyphs to be rerendered for every isolated word. This change adds back a cut off. This is only needed in the lockedAlphaMapForGlyph() function, since the superclass implementation of the other alpha map functions already contains a cut off for width/height == 0. [ChangeLog][Qt Gui][Text] Fixed a performance regression in Freetype engine that was introduced in Qt 5.5. Change-Id: I381285939909e99cc5fb5f3497fecf9fa871f29a Task-number: QTBUG-49452 Reviewed-by: Simon Hausmann <>
Diffstat (limited to 'src/gui/text/qfontengine_ft.cpp')
1 files changed, 5 insertions, 1 deletions
diff --git a/src/gui/text/qfontengine_ft.cpp b/src/gui/text/qfontengine_ft.cpp
index 4de41dfa99..7c878da27f 100644
--- a/src/gui/text/qfontengine_ft.cpp
+++ b/src/gui/text/qfontengine_ft.cpp
@@ -1716,7 +1716,7 @@ glyph_metrics_t QFontEngineFT::alphaMapBoundingBox(glyph_t glyph, QFixed subPixe
static inline QImage alphaMapFromGlyphData(QFontEngineFT::Glyph *glyph, QFontEngine::GlyphFormat glyphFormat)
- if (glyph == Q_NULLPTR)
+ if (glyph == Q_NULLPTR || glyph->height == 0 || glyph->width == 0)
return QImage();
QImage::Format format = QImage::Format_Invalid;
@@ -1764,11 +1764,15 @@ QImage *QFontEngineFT::lockedAlphaMapForGlyph(glyph_t glyphIndex, QFixed subPixe
currentlyLockedAlphaMap = alphaMapFromGlyphData(glyph, neededFormat);
+ const bool glyphHasGeometry = glyph != Q_NULLPTR && glyph->height != 0 && glyph->width != 0;
if (!cacheEnabled && glyph != &emptyGlyph) {
currentlyLockedAlphaMap = currentlyLockedAlphaMap.copy();
delete glyph;
+ if (!glyphHasGeometry)
+ return Q_NULLPTR;
if (currentlyLockedAlphaMap.isNull())
return QFontEngine::lockedAlphaMapForGlyph(glyphIndex, subPixelPosition, neededFormat, t, offset);