Make distance fields rendering work with Opentype CFF fonts

If the font has a CFF table, GDI will not label it as
TMPF_TRUETYPE, however, we can still use GetFontData to get
the SFNT tables. This is required to get the maxp table which
contains the glyph count, which is required to use the font
with the distance-field renderer.

Task-number: QTBUG-28746
Change-Id: I3ca1e3d96ea53c453e6fa422b33d1f1f5050a82c
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>

2 files changed, 14 insertions, 1 deletions

diff --git a/src/plugins/platforms/windows/qwindowsfontengine.cpp b/src/plugins/platforms/windows/qwindowsfontengine.cpp
index 578a0cd20b..e51d6d4e7e 100644
--- a/src/plugins/platforms/windows/qwindowsfontengine.cpp
+++ b/src/plugins/platforms/windows/qwindowsfontengine.cpp
@@ -155,9 +155,20 @@ static OUTLINETEXTMETRIC *getOutlineTextMetric(HDC hdc)
     return otm;
 }
 
+bool QWindowsFontEngine::hasCFFTable() const
+{
+    HDC hdc = m_fontEngineData->hdc;
+    SelectObject(hdc, hfont);
+    return GetFontData(hdc, MAKE_TAG('C', 'F', 'F', ' '), 0, 0, 0) != GDI_ERROR;
+}
+
 void QWindowsFontEngine::getCMap()
 {
     ttf = (bool)(tm.tmPitchAndFamily & TMPF_TRUETYPE);
+
+    // TMPF_TRUETYPE is not set for fonts with CFF tables
+    cffTable = !ttf && hasCFFTable();
+
     HDC hdc = m_fontEngineData->hdc;
     SelectObject(hdc, hfont);
     bool symb = false;
@@ -1041,7 +1052,7 @@ void QWindowsFontEngine::getUnscaledGlyph(glyph_t glyph, QPainterPath *path, gly
 
 bool QWindowsFontEngine::getSfntTableData(uint tag, uchar *buffer, uint *length) const
 {
-    if (!ttf)
+    if (!ttf && !cffTable)
         return false;
     HDC hdc = m_fontEngineData->hdc;
     SelectObject(hdc, hfont);
diff --git a/src/plugins/platforms/windows/qwindowsfontengine.h b/src/plugins/platforms/windows/qwindowsfontengine.h
index b1aeb94b18..b1e41e89d1 100644
--- a/src/plugins/platforms/windows/qwindowsfontengine.h
+++ b/src/plugins/platforms/windows/qwindowsfontengine.h
@@ -145,6 +145,7 @@ public:
 private:
     QWindowsNativeImage *drawGDIGlyph(HFONT font, glyph_t, int margin, const QTransform &xform,
                                       QImage::Format mask_format);
+    bool hasCFFTable() const;
 
     const QSharedPointer<QWindowsFontEngineData> m_fontEngineData;
 
@@ -155,6 +156,7 @@ private:
     uint        stockFont  : 1;
     uint        ttf        : 1;
     uint        hasOutline : 1;
+    uint        cffTable   : 1;
     TEXTMETRIC  tm;
     int         lw;
     const unsigned char *cmap;