Add virtual function to QFontEngine report if outlines are reliable

GetGlyphOutline fails for ttf fonts with embedded bitmaps. This results in
distancefield rendering not rendering glyphs (for the failed paths). We
need to fall back to texture rendering if this is the case.

Change-Id: Ibdf7dc5c1d34f513c436f88fabbdcc4089bb6fef
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>

4 files changed, 37 insertions, 0 deletions

diff --git a/src/gui/text/qfontengine.cpp b/src/gui/text/qfontengine.cpp
index b2254c4826..078e16574f 100644
--- a/src/gui/text/qfontengine.cpp
+++ b/src/gui/text/qfontengine.cpp
@@ -1335,6 +1335,15 @@ QByteArray QFontEngine::convertToPostscriptFontFamilyName(const QByteArray &fami
     return f;
 }
 
+/**
+ * Some font engines like the windows font engine
+ * can not reliable create outline paths
+ */
+bool QFontEngine::hasUnreliableGlyphOutline() const
+{
+    return false;
+}
+
 QFixed QFontEngine::lastRightBearing(const QGlyphLayout &glyphs, bool round)
 {
     if (glyphs.numGlyphs >= 1) {
diff --git a/src/gui/text/qfontengine_p.h b/src/gui/text/qfontengine_p.h
index 5e40abbda6..fc849d788f 100644
--- a/src/gui/text/qfontengine_p.h
+++ b/src/gui/text/qfontengine_p.h
@@ -251,6 +251,8 @@ public:
 
     static QByteArray convertToPostscriptFontFamilyName(const QByteArray &fontFamily);
 
+    virtual bool hasUnreliableGlyphOutline() const;
+
     enum HintStyle {
         HintNone,
         HintLight,
diff --git a/src/plugins/platforms/windows/qwindowsfontengine.cpp b/src/plugins/platforms/windows/qwindowsfontengine.cpp
index 29c43fc7a5..6f97c8584b 100644
--- a/src/plugins/platforms/windows/qwindowsfontengine.cpp
+++ b/src/plugins/platforms/windows/qwindowsfontengine.cpp
@@ -169,6 +169,20 @@ bool QWindowsFontEngine::hasCMapTable() const
     return GetFontData(hdc, MAKE_TAG('c', 'm', 'a', 'p'), 0, 0, 0) != GDI_ERROR;
 }
 
+bool QWindowsFontEngine::hasGlyfTable() const
+{
+    HDC hdc = m_fontEngineData->hdc;
+    SelectObject(hdc, hfont);
+    return GetFontData(hdc, MAKE_TAG('g', 'l', 'y', 'f'), 0, 0, 0) != GDI_ERROR;
+}
+
+bool QWindowsFontEngine::hasEbdtTable() const
+{
+    HDC hdc = m_fontEngineData->hdc;
+    SelectObject(hdc, hfont);
+    return GetFontData(hdc, MAKE_TAG('E', 'B', 'D', 'T'), 0, 0, 0) != GDI_ERROR;
+}
+
 void QWindowsFontEngine::getCMap()
 {
     ttf = (bool)(tm.tmPitchAndFamily & TMPF_TRUETYPE) || hasCMapTable();
@@ -308,6 +322,8 @@ QWindowsFontEngine::QWindowsFontEngine(const QString &name,
     userData.insert(QStringLiteral("hFont"), QVariant::fromValue(hfont));
     userData.insert(QStringLiteral("trueType"), QVariant(bool(ttf)));
     setUserData(userData);
+
+    hasUnreliableOutline = hasGlyfTable() && hasEbdtTable();
 }
 
 QWindowsFontEngine::~QWindowsFontEngine()
@@ -662,6 +678,11 @@ void QWindowsFontEngine::getGlyphBearings(glyph_t glyph, qreal *leftBearing, qre
 }
 #endif // Q_CC_MINGW
 
+bool QWindowsFontEngine::hasUnreliableGlyphOutline() const
+{
+    return hasUnreliableOutline;
+}
+
 qreal QWindowsFontEngine::minLeftBearing() const
 {
     if (lbearing == SHRT_MIN)
diff --git a/src/plugins/platforms/windows/qwindowsfontengine.h b/src/plugins/platforms/windows/qwindowsfontengine.h
index 7a0803830c..0ddf778fa0 100644
--- a/src/plugins/platforms/windows/qwindowsfontengine.h
+++ b/src/plugins/platforms/windows/qwindowsfontengine.h
@@ -122,6 +122,8 @@ public:
     virtual void getGlyphBearings(glyph_t glyph, qreal *leftBearing = 0, qreal *rightBearing = 0);
 #endif
 
+    bool hasUnreliableGlyphOutline() const Q_DECL_OVERRIDE;
+
     int getGlyphIndexes(const QChar *ch, int numChars, QGlyphLayout *glyphs) const;
     void getCMap();
 
@@ -136,6 +138,8 @@ private:
                                       QImage::Format mask_format);
     bool hasCFFTable() const;
     bool hasCMapTable() const;
+    bool hasGlyfTable() const;
+    bool hasEbdtTable() const;
 
     const QSharedPointer<QWindowsFontEngineData> m_fontEngineData;
 
@@ -146,6 +150,7 @@ private:
     uint        stockFont  : 1;
     uint        ttf        : 1;
     uint        hasOutline : 1;
+    uint        hasUnreliableOutline : 1;
     uint        cffTable   : 1;
     TEXTMETRIC  tm;
     int         lw;