Retrieve proper glyph outlines from Symbian^4

Up until Symbian^4, the Symbian font Api does not provide access to the
vector data of glyphs. In order to make QPainterPath::addText() and
transformed text rendering work, Qt falls back to a workaound: Tracing
the bitmap of a rasterized glyph. That is neither performant nor is the
result of good quality.

Symbian^4 will add Api that returns glyph outlines encoded as SVG paths.
The code in this commit essentially parses the SVG path and returns a
QPainterPath. The parsing part took some ideas from QSvg, and is
implemented in a very reduced way.

Task-number: QT-809
Reviewed-by: Aleksandar Sasha Babic

1 files changed, 96 insertions, 2 deletions

diff --git a/src/gui/text/qfontengine_s60.cpp b/src/gui/text/qfontengine_s60.cpp
index 52a2c3c4ce..925b3bf5fd 100644
--- a/src/gui/text/qfontengine_s60.cpp
+++ b/src/gui/text/qfontengine_s60.cpp
@@ -50,9 +50,9 @@
 #include <e32std.h>
 #include <eikenv.h>
 #include <gdi.h>
-#ifdef Q_SYMBIAN_HAS_FONTTABLE_API
+#if defined(Q_SYMBIAN_HAS_FONTTABLE_API) || defined(Q_SYMBIAN_HAS_GLYPHOUTLINE_API)
 #include <graphics/gdi/gdiplatapi.h>
-#endif // Q_SYMBIAN_HAS_FONTTABLE_API
+#endif // Q_SYMBIAN_HAS_FONTTABLE_API || Q_SYMBIAN_HAS_GLYPHOUTLINE_API
 
 QT_BEGIN_NAMESPACE
 
@@ -279,6 +279,35 @@ void QFontEngineS60::recalcAdvances(QGlyphLayout *glyphs, QTextEngine::ShaperFla
     }
 }
 
+#ifdef Q_SYMBIAN_HAS_GLYPHOUTLINE_API
+static bool parseGlyphPathData(const char *dataStr, const char *dataEnd, QPainterPath &path,
+                               qreal fontPixelSize, const QPointF &offset, bool hinted);
+#endif //Q_SYMBIAN_HAS_GLYPHOUTLINE_API
+
+void QFontEngineS60::addGlyphsToPath(glyph_t *glyphs, QFixedPoint *positions,
+                                     int nglyphs, QPainterPath *path,
+                                     QTextItem::RenderFlags flags)
+{
+#ifdef Q_SYMBIAN_HAS_GLYPHOUTLINE_API
+    Q_UNUSED(flags)
+    RGlyphOutlineIterator iterator;
+    const TInt error = iterator.Open(*m_activeFont, glyphs, nglyphs);
+    if (KErrNone != error)
+        return;
+    const qreal fontSizeInPixels = qreal(m_activeFont->HeightInPixels());
+    int count = 0;
+    do {
+        const TUint8* outlineUint8 = iterator.Outline();
+        const char* const outlineChar = reinterpret_cast<const char*>(outlineUint8);
+        const char* const outlineEnd = outlineChar + iterator.OutlineLength();
+        parseGlyphPathData(outlineChar, outlineEnd, *path, fontSizeInPixels,
+                positions[count++].toPointF(), false);
+    } while(KErrNone == iterator.Next() && count <= nglyphs);
+#else // Q_SYMBIAN_HAS_GLYPHOUTLINE_API
+    QFontEngine::addGlyphsToPath(glyphs, positions, nglyphs, path, flags);
+#endif //Q_SYMBIAN_HAS_GLYPHOUTLINE_API
+}
+
 QImage QFontEngineS60::alphaMapForGlyph(glyph_t glyph)
 {
     TOpenFontCharMetrics metrics;
@@ -410,4 +439,69 @@ void QFontEngineS60::getCharacterData(glyph_t glyph, TOpenFontCharMetrics& metri
     }
 }
 
+#ifdef Q_SYMBIAN_HAS_GLYPHOUTLINE_API
+static inline void skipSpacesAndComma(const char* &str, const char* const strEnd)
+{
+    while (str <= strEnd && (*str == ' ' || *str == ','))
+        ++str;
+}
+
+static bool parseGlyphPathData(const char *svgPath, const char *svgPathEnd, QPainterPath &path,
+                               qreal fontPixelSize, const QPointF &offset, bool hinted)
+{
+    Q_UNUSED(hinted)
+    QPointF p1, p2, firstSubPathPoint;
+    qreal *elementValues[] =
+        {&p1.rx(), &p1.ry(), &p2.rx(), &p2.ry()};
+    const int unitsPerEm = 2048; // See: http://en.wikipedia.org/wiki/Em_%28typography%29
+    const qreal resizeFactor = fontPixelSize / unitsPerEm;
+
+    while (svgPath < svgPathEnd) {
+        skipSpacesAndComma(svgPath, svgPathEnd);
+        const char pathElem = *svgPath++;
+        skipSpacesAndComma(svgPath, svgPathEnd);
+
+        if (pathElem != 'Z') {
+            char *endStr = 0;
+            int elementValuesCount = 0;
+            for (int i = 0; i < 4; ++i) { // 4 = size of elementValues[]
+                qreal coordinateValue = strtod(svgPath, &endStr);
+                if (svgPath == endStr)
+                    break;
+                if (i % 2) // Flip vertically
+                    coordinateValue = -coordinateValue;
+                *elementValues[i] = coordinateValue * resizeFactor;
+                elementValuesCount++;
+                svgPath = endStr;
+                skipSpacesAndComma(svgPath, svgPathEnd);
+            }
+            p1 += offset;
+            if (elementValuesCount == 2)
+                p2 = firstSubPathPoint;
+            else
+                p2 += offset;
+        }
+
+        switch (pathElem) {
+        case 'M':
+            firstSubPathPoint = p1;
+            path.moveTo(p1);
+            break;
+        case 'Z':
+            path.closeSubpath();
+            break;
+        case 'L':
+            path.lineTo(p1);
+            break;
+        case 'Q':
+            path.quadTo(p1, p2);
+            break;
+        default:
+            return false;
+        }
+    }
+    return true;
+}
+#endif // Q_SYMBIAN_HAS_GLYPHOUTLINE_API
+
 QT_END_NAMESPACE