Description: Fix caching of the scalableBitmapFactor for colour fonts
 Associate the scalableBitmapFactor with the freetype QFontEngine so that
 it is preserved when caching the engine.
Author: Michael Sheldon <michael.sheldon@canonical.com>
Bug-Ubuntu: https://bugs.launchpad.net/bugs/1594851

Bug: https://bugreports.qt.io/browse/QTBUG-53652
Forwarded: https://codereview.qt-project.org/#/c/161161/
Last-Update: 2016-05-26

--- qtbase-opensource-src-5.4.1+dfsg.orig/src/gui/text/qfontengine_ft.cpp
+++ qtbase-opensource-src-5.4.1+dfsg/src/gui/text/qfontengine_ft.cpp
@@ -276,7 +276,6 @@ QFreetypeFace *QFreetypeFace::getFace(co
         newFreetype->ref.store(1);
         newFreetype->xsize = 0;
         newFreetype->ysize = 0;
-        newFreetype->scalableBitmapScaleFactor = 1;
         newFreetype->matrix.xx = 0x10000;
         newFreetype->matrix.yy = 0x10000;
         newFreetype->matrix.xy = 0;
@@ -355,10 +354,11 @@ void QFreetypeFace::release(const QFontE
 }
 
 
-void QFreetypeFace::computeSize(const QFontDef &fontDef, int *xsize, int *ysize, bool *outline_drawing)
+void QFreetypeFace::computeSize(const QFontDef &fontDef, int *xsize, int *ysize, bool *outline_drawing, QFixed *scalableBitmapScaleFactor)
 {
     *ysize = qRound(fontDef.pixelSize * 64);
     *xsize = *ysize * fontDef.stretch / 100;
+    *scalableBitmapScaleFactor = 1;
     *outline_drawing = false;
 
     if (!(face->face_flags & FT_FACE_FLAG_SCALABLE)) {
@@ -396,7 +396,7 @@ void QFreetypeFace::computeSize(const QF
         // to make sure we can select the desired bitmap strike index
         if (FT_Select_Size(face, best) == 0) {
             if (isScalableBitmap())
-                scalableBitmapScaleFactor = QFixed::fromReal((qreal)fontDef.pixelSize / face->available_sizes[best].height);
+                *scalableBitmapScaleFactor = QFixed::fromReal((qreal)fontDef.pixelSize / face->available_sizes[best].height);
             *xsize = X_SIZE(face, best);
             *ysize = Y_SIZE(face, best);
         } else {
@@ -734,7 +734,7 @@ bool QFontEngineFT::init(FaceId faceId,
     }
 
     lbearing = rbearing = SHRT_MIN;
-    freetype->computeSize(fontDef, &xsize, &ysize, &defaultGlyphSet.outline_drawing);
+    freetype->computeSize(fontDef, &xsize, &ysize, &defaultGlyphSet.outline_drawing, &scalableBitmapScaleFactor);
 
     FT_Face face = lockFace();
 
@@ -1284,24 +1284,24 @@ int QFontEngineFT::synthesized() const
 QFixed QFontEngineFT::ascent() const
 {
     QFixed v = QFixed::fromFixed(metrics.ascender);
-    if (freetype->scalableBitmapScaleFactor != 1)
-        v *= freetype->scalableBitmapScaleFactor;
+    if (scalableBitmapScaleFactor != 1)
+        v *= scalableBitmapScaleFactor;
     return v;
 }
 
 QFixed QFontEngineFT::descent() const
 {
     QFixed v = QFixed::fromFixed(-metrics.descender);
-    if (freetype->scalableBitmapScaleFactor != 1)
-        v *= freetype->scalableBitmapScaleFactor;
+    if (scalableBitmapScaleFactor != 1)
+        v *= scalableBitmapScaleFactor;
     return v;
 }
 
 QFixed QFontEngineFT::leading() const
 {
     QFixed v = QFixed::fromFixed(metrics.height - metrics.ascender + metrics.descender);
-    if (freetype->scalableBitmapScaleFactor != 1)
-        v *= freetype->scalableBitmapScaleFactor;
+    if (scalableBitmapScaleFactor != 1)
+        v *= scalableBitmapScaleFactor;
     return v;
 }
 
@@ -1316,7 +1316,7 @@ QFixed QFontEngineFT::xHeight() const
             return answer;
         }
     } else {
-        return QFixed(freetype->face->size->metrics.y_ppem) * freetype->scalableBitmapScaleFactor;
+        return QFixed(freetype->face->size->metrics.y_ppem) * scalableBitmapScaleFactor;
     }
     return QFontEngine::xHeight();
 }
@@ -1342,8 +1342,8 @@ QFixed QFontEngineFT::averageCharWidth()
 qreal QFontEngineFT::maxCharWidth() const
 {
     QFixed max_advance = QFixed::fromFixed(metrics.max_advance);
-    if (freetype->scalableBitmapScaleFactor != 1)
-        max_advance *= freetype->scalableBitmapScaleFactor;
+    if (scalableBitmapScaleFactor != 1)
+        max_advance *= scalableBitmapScaleFactor;
     return max_advance.toReal();
 }
 
@@ -1675,7 +1675,7 @@ bool QFontEngineFT::shouldUseDesignMetri
 
 QFixed QFontEngineFT::scaledBitmapMetrics(QFixed m) const
 {
-    return m * freetype->scalableBitmapScaleFactor;
+    return m * scalableBitmapScaleFactor;
 }
 
 glyph_metrics_t QFontEngineFT::scaledBitmapMetrics(const glyph_metrics_t &m) const
@@ -1713,8 +1713,8 @@ void QFontEngineFT::recalcAdvances(QGlyp
                 delete g;
         }
 
-        if (freetype->scalableBitmapScaleFactor != 1)
-            glyphs->advances[i] *= freetype->scalableBitmapScaleFactor;
+        if (scalableBitmapScaleFactor != 1)
+            glyphs->advances[i] *= scalableBitmapScaleFactor;
     }
     if (face)
         unlockFace();
@@ -2084,9 +2084,9 @@ QImage QFontEngineFT::bitmapForGlyph(gly
     else if (defaultFormat == GlyphFormat::Format_Mono)
         img = QImage(glyph->data, glyph->width, glyph->height, QImage::Format_Mono).copy();
 
-    if (!img.isNull() && (!t.isIdentity() || freetype->scalableBitmapScaleFactor != 1)) {
+    if (!img.isNull() && (!t.isIdentity() || scalableBitmapScaleFactor != 1)) {
         QTransform trans(t);
-        const qreal scaleFactor = freetype->scalableBitmapScaleFactor.toReal();
+        const qreal scaleFactor = scalableBitmapScaleFactor.toReal();
         trans.scale(scaleFactor, scaleFactor);
         img = img.transformed(trans, Qt::SmoothTransformation);
     }
--- qtbase-opensource-src-5.4.1+dfsg.orig/src/gui/text/qfontengine_ft_p.h
+++ qtbase-opensource-src-5.4.1+dfsg/src/gui/text/qfontengine_ft_p.h
@@ -69,7 +69,7 @@ class QFontconfigDatabase;
 class QFreetypeFace
 {
 public:
-    void computeSize(const QFontDef &fontDef, int *xsize, int *ysize, bool *outline_drawing);
+    void computeSize(const QFontDef &fontDef, int *xsize, int *ysize, bool *outline_drawing, QFixed *scalableBitmapScaleFactor);
     QFontEngine::Properties properties() const;
     bool getSfntTable(uint tag, uchar *buffer, uint *length) const;
 
@@ -90,7 +90,6 @@ public:
     FT_Face face;
     int xsize; // 26.6
     int ysize; // 26.6
-    QFixed scalableBitmapScaleFactor;
     FT_Matrix matrix;
     FT_CharMap unicode_map;
     FT_CharMap symbol_map;
@@ -336,6 +335,7 @@ private:
 
     FT_Size_Metrics metrics;
     mutable bool kerning_pairs_loaded;
+    QFixed scalableBitmapScaleFactor;
 };
 
 inline uint qHash(const QFontEngineFT::GlyphAndSubPixelPosition &g)