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
Reviewed-by: Konstantin Ritt <[email protected]>
Change-Id: I1e084f7e9dbd0bccb9b1ff4de2eaf65d6a5f9f1e
(cherry picked from qtbase/dde09c429ae8b7ad0df4e4b36b8459d2b85a1219)
Reviewed-by: Oswald Buddenhagen <[email protected]>

Author: Eskil Abrahamsen Blomfeldt

src/gui/text/qfontengine_win.cpp

@@ -190,9 +190,20 @@ static OUTLINETEXTMETRIC *getOutlineTextMetric(HDC hdc)
     return otm;
 }
 
+bool QFontEngineWin::hasCFFTable() const
+{
+    HDC hdc = shared_dc();
+    SelectObject(hdc, hfont);
+    return GetFontData(hdc, MAKE_TAG('C', 'F', 'F', ' '), 0, 0, 0) != GDI_ERROR;
+}
+
 void QFontEngineWin::getCMap()
 {
     ttf = (bool)(tm.tmPitchAndFamily & TMPF_TRUETYPE);
+
+    // TMPF_TRUETYPE is not set for fonts with CFF tables
+    cffTable = !ttf && hasCFFTable();
+
     HDC hdc = shared_dc();
     SelectObject(hdc, hfont);
     bool symb = false;
@@ -1072,7 +1083,7 @@ void QFontEngineWin::getUnscaledGlyph(glyph_t glyph, QPainterPath *path, glyph_m
 
 bool QFontEngineWin::getSfntTableData(uint tag, uchar *buffer, uint *length) const
 {
-    if (!ttf)
+    if (!ttf && !cffTable)
         return false;
     HDC hdc = shared_dc();
     SelectObject(hdc, hfont);

src/gui/text/qfontengine_win_p.h

@@ -126,6 +126,7 @@ class QFontEngineWin : public QFontEngine
     uint        stockFont  : 1;
     uint        ttf        : 1;
     uint        hasOutline : 1;
+    uint        cffTable   : 1;
     TEXTMETRIC  tm;
     int         lw;
     const unsigned char *cmap;
@@ -145,6 +146,7 @@ class QFontEngineWin : public QFontEngine
     mutable int designAdvancesSize;
 
 private:
+    bool hasCFFTable() const;
     QNativeImage *drawGDIGlyph(HFONT font, glyph_t, int margin, const QTransform &xform,
                                QImage::Format mask_format);