Linux: Fix mispositioned, misclipped glyphs in large fonts (QStaticText)

While drawText() will use the path fallback for large fonts, and never
hit this problem, QStaticText will draw the large fonts into the glyph
cache. This broke when the freetype (or any other font engine) falls
back to the generic implementation of alphaMapForGlyph() which uses
path drawing. The problem was that alphaMapForGlyph() is not supposed
to contain the bearing of the glyph, only the actual pixels. Since
QFontEngine did not honor this contract, we would sample the wrong
area in the glyph cache to get the glyph image.

Task-number: QTBUG-12540
Reviewed-by: Gunnar

1 files changed, 2 insertions, 2 deletions

diff --git a/src/gui/text/qfontengine.cpp b/src/gui/text/qfontengine.cpp
index 1e8461f..a3f4d8a 100644
--- a/src/gui/text/qfontengine.cpp
+++ b/src/gui/text/qfontengine.cpp
@@ -631,10 +631,10 @@ QImage QFontEngine::alphaMapForGlyph(glyph_t glyph)
     if (glyph_width <= 0 || glyph_height <= 0)
         return QImage();
     QFixedPoint pt;
-    pt.x = 0;
+    pt.x = -glyph_x;
     pt.y = -glyph_y; // the baseline
     QPainterPath path;
-    QImage im(glyph_width + qAbs(glyph_x) + 4, glyph_height, QImage::Format_ARGB32_Premultiplied);
+    QImage im(glyph_width + 4, glyph_height, QImage::Format_ARGB32_Premultiplied);
     im.fill(Qt::transparent);
     QPainter p(&im);
     p.setRenderHint(QPainter::Antialiasing);