Fix for font engines that don't support subpixel positioning

Reviewed-by: aavit

3 files changed, 20 insertions, 5 deletions

diff --git a/src/gui/text/qfontengine.cpp b/src/gui/text/qfontengine.cpp
index 816c14a..24c4664 100644
--- a/src/gui/text/qfontengine.cpp
+++ b/src/gui/text/qfontengine.cpp
@@ -605,12 +605,13 @@ void QFontEngine::addGlyphsToPath(glyph_t *glyphs, QFixedPoint *positions, int n
     addBitmapFontToPath(x, y, g, path, flags);
 }
 
-QImage QFontEngine::alphaMapForGlyph(glyph_t glyph, const QTransform &t)
+QImage QFontEngine::alphaMapForGlyph(glyph_t glyph, QFixed /*subPixelPosition*/)
 {
-    return alphaMapForGlyph(glyph, 0, t);
+    // For font engines don't support subpixel positioning
+    return alphaMapForGlyph(glyph);
 }
 
-QImage QFontEngine::alphaMapForGlyph(glyph_t glyph, QFixed /*subPixelPosition*/, const QTransform &t)
+QImage QFontEngine::alphaMapForGlyph(glyph_t glyph, const QTransform &t)
 {
     QImage i = alphaMapForGlyph(glyph);
     if (t.type() > QTransform::TxTranslate)
@@ -620,6 +621,19 @@ QImage QFontEngine::alphaMapForGlyph(glyph_t glyph, QFixed /*subPixelPosition*/,
     return i;
 }
 
+QImage QFontEngine::alphaMapForGlyph(glyph_t glyph, QFixed subPixelPosition, const QTransform &t)
+{
+    if (! supportsSubPixelPositions())
+        return alphaMapForGlyph(glyph, t);
+
+    QImage i = alphaMapForGlyph(glyph, subPixelPosition);
+    if (t.type() > QTransform::TxTranslate)
+        i = i.transformed(t).convertToFormat(QImage::Format_Indexed8);
+    Q_ASSERT(i.depth() <= 8); // To verify that transformed didn't change the format...
+
+    return i;
+}
+
 QImage QFontEngine::alphaRGBMapForGlyph(glyph_t glyph, QFixed /*subPixelPosition*/, int /* margin */, const QTransform &t)
 {
     QImage alphaMask = alphaMapForGlyph(glyph, t);
diff --git a/src/gui/text/qfontengine_mac.mm b/src/gui/text/qfontengine_mac.mm
index cebd1f5..7efb1cc 100644
--- a/src/gui/text/qfontengine_mac.mm
+++ b/src/gui/text/qfontengine_mac.mm
@@ -713,7 +713,7 @@ QImage QCoreTextFontEngine::imageForGlyph(glyph_t glyph, QFixed subPixelPosition
     return im;
 }
 
-QImage QCoreTextFontEngine::alphaMapForGlyph(glyph_t glyph, QFixed subPixelPosition, const QTransform &t)
+QImage QCoreTextFontEngine::alphaMapForGlyph(glyph_t glyph, QFixed subPixelPosition)
 {
     QImage im = imageForGlyph(glyph, subPixelPosition, 0, false);
 
diff --git a/src/gui/text/qfontengine_p.h b/src/gui/text/qfontengine_p.h
index 061bcfd..be9f48d 100644
--- a/src/gui/text/qfontengine_p.h
+++ b/src/gui/text/qfontengine_p.h
@@ -196,6 +196,7 @@ public:
      * Returns an image indexed_8 with index values ranging from 0=fully transparant to 255=opaque
      */
     virtual QImage alphaMapForGlyph(glyph_t);
+    virtual QImage alphaMapForGlyph(glyph_t glyph, QFixed subPixelPosition);
     virtual QImage alphaMapForGlyph(glyph_t, const QTransform &t);
     virtual QImage alphaMapForGlyph(glyph_t, QFixed subPixelPosition, const QTransform &t);
     virtual QImage alphaRGBMapForGlyph(glyph_t, QFixed subPixelPosition, int margin, const QTransform &t);
@@ -474,7 +475,7 @@ public:
     virtual FaceId faceId() const;
     virtual bool getSfntTableData(uint /*tag*/, uchar * /*buffer*/, uint * /*length*/) const;
     virtual void getUnscaledGlyph(glyph_t glyph, QPainterPath *path, glyph_metrics_t *metrics);
-    virtual QImage alphaMapForGlyph(glyph_t, QFixed subPixelPosition, const QTransform &t);
+    virtual QImage alphaMapForGlyph(glyph_t, QFixed subPixelPosition);
     virtual QImage alphaRGBMapForGlyph(glyph_t, QFixed subPixelPosition, int margin, const QTransform &t);
     virtual qreal minRightBearing() const;
     virtual qreal minLeftBearing() const;