Refactor glyph pretransform check

Move paintEngineSupportsTransformations logic from QPainter to paint
engine subclasses. Simplify and consolidate checks for cached drawing
(pretransformed) and path drawing (untransformed) in raster paint
engine. Fix unnecessary transform when paint engines actually take
the path drawing track. Fix scaling and rotation transform in raster
engine for Mac.

Task-number: QTBUG-19086
Change-Id: I1c0c1800a5173d3db765b9fccfd0e7a3628e3815
Reviewed-on: http://codereview.qt.nokia.com/298
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@nokia.com>
(cherry picked from commit 43c0e08ba2e3487840b4063b2099bc17cdd4dce2)

9 files changed, 65 insertions, 56 deletions

diff --git a/src/gui/painting/qpaintengine_mac_p.h b/src/gui/painting/qpaintengine_mac_p.h
index 3e71d6ca6b..45a9f20779 100644
--- a/src/gui/painting/qpaintengine_mac_p.h
+++ b/src/gui/painting/qpaintengine_mac_p.h
@@ -121,6 +121,8 @@ public:
     void drawPolygon(const QPoint *points, int pointCount, PolygonDrawMode mode)
     { QPaintEngine::drawPolygon(points, pointCount, mode); }
 
+    bool supportsTransformations(qreal, const QTransform &) const { return true; };
+
 protected:
     friend class QMacPrintEngine;
     friend class QMacPrintEnginePrivate;
diff --git a/src/gui/painting/qpaintengine_raster.cpp b/src/gui/painting/qpaintengine_raster.cpp
index 71bbbb1f6f..a1d728cfdc 100644
--- a/src/gui/painting/qpaintengine_raster.cpp
+++ b/src/gui/painting/qpaintengine_raster.cpp
@@ -3062,11 +3062,8 @@ void QRasterPaintEngine::drawStaticTextItem(QStaticTextItem *textItem)
     ensurePen();
     ensureState();
 
-    QRasterPaintEngineState *s = state();
-
     QFontEngine *fontEngine = textItem->fontEngine();
-    const qreal pixelSize = fontEngine->fontDef.pixelSize;
-    if (pixelSize * pixelSize * qAbs(s->matrix.determinant()) < 64 * 64) {
+    if (!supportsTransformations(fontEngine)) {
         drawCachedGlyphs(textItem->numGlyphs, textItem->glyphs, textItem->glyphPositions,
                          fontEngine);
     } else {
@@ -3094,36 +3091,7 @@ void QRasterPaintEngine::drawTextItem(const QPointF &p, const QTextItem &textIte
 
 #if defined (Q_WS_WIN) || defined(Q_WS_MAC)
 
-    bool drawCached = true;
-
-    if (s->matrix.type() >= QTransform::TxProject)
-        drawCached = false;
-
-    // don't try to cache huge fonts
-    const qreal pixelSize = ti.fontEngine->fontDef.pixelSize;
-    if (pixelSize * pixelSize * qAbs(s->matrix.determinant()) >= 64 * 64)
-        drawCached = false;
-
-    // ### Remove the TestFontEngine and Box engine crap, in these
-    // ### cases we should delegate painting to the font engine
-    // ### directly...
-
-#if defined(Q_WS_WIN) && !defined(Q_WS_WINCE)
-    QFontEngine::Type fontEngineType = ti.fontEngine->type();
-    // qDebug() << "type" << fontEngineType << s->matrix.type();
-    if ((fontEngineType == QFontEngine::Win && !((QFontEngineWin *) ti.fontEngine)->ttf && s->matrix.type() > QTransform::TxTranslate)
-        || (s->matrix.type() <= QTransform::TxTranslate
-            && (fontEngineType == QFontEngine::TestFontEngine
-                || fontEngineType == QFontEngine::Box))) {
-            drawCached = false;
-    }
-#else
-    if (s->matrix.type() > QTransform::TxTranslate)
-        drawCached = false;
-#endif
-    if (drawCached) {
-        QRasterPaintEngineState *s = state();
-
+    if (!supportsTransformations(ti.fontEngine)) {
         QVarLengthArray<QFixedPoint> positions;
         QVarLengthArray<glyph_t> glyphs;
 
@@ -3444,6 +3412,37 @@ void QRasterPaintEngine::releaseDC(HDC) const
 
 #endif
 
+bool QRasterPaintEngine::supportsTransformations(const QFontEngine *fontEngine) const
+{
+    const QTransform &m = state()->matrix;
+#if defined(Q_WS_WIN) && !defined(Q_WS_WINCE)
+    QFontEngine::Type fontEngineType = ti.fontEngine->type();
+    if ((fontEngineType == QFontEngine::Win && !((QFontEngineWin *) ti.fontEngine)->ttf && m.type() > QTransform::TxTranslate)
+        || (m.type() <= QTransform::TxTranslate
+            && (fontEngineType == QFontEngine::TestFontEngine
+                || fontEngineType == QFontEngine::Box))) {
+            return true;
+    }
+#endif
+    return supportsTransformations(fontEngine->fontDef.pixelSize, m);
+}
+
+bool QRasterPaintEngine::supportsTransformations(qreal pixelSize, const QTransform &m) const
+{
+#if defined(Q_WS_MAC)
+    // Mac font engines don't support scaling and rotation
+    if (m.type() > QTransform::TxTranslate)
+#else
+    if (m.type() >= QTransform::TxProject)
+#endif
+        return true;
+
+    if (pixelSize * pixelSize * qAbs(m.determinant()) >= 64 * 64)
+        return true;
+
+    return false;
+}
+
 /*!
     \internal
 */
diff --git a/src/gui/painting/qpaintengine_raster_p.h b/src/gui/painting/qpaintengine_raster_p.h
index 61cf07bf5e..d65e922c28 100644
--- a/src/gui/painting/qpaintengine_raster_p.h
+++ b/src/gui/painting/qpaintengine_raster_p.h
@@ -246,6 +246,8 @@ public:
     virtual void drawBufferSpan(const uint *buffer, int bufsize,
                                 int x, int y, int length, uint const_alpha);
 #endif
+    bool supportsTransformations(const QFontEngine *fontEngine) const;
+    bool supportsTransformations(qreal pixelSize, const QTransform &m) const;
 
 protected:
     QRasterPaintEngine(QRasterPaintEnginePrivate &d, QPaintDevice *);
diff --git a/src/gui/painting/qpaintengineex.cpp b/src/gui/painting/qpaintengineex.cpp
index 304e5fc486..b1dc7809e6 100644
--- a/src/gui/painting/qpaintengineex.cpp
+++ b/src/gui/painting/qpaintengineex.cpp
@@ -1093,4 +1093,14 @@ void QPaintEngineEx::drawStaticTextItem(QStaticTextItem *staticTextItem)
     }
 }
 
+bool QPaintEngineEx::supportsTransformations(qreal pixelSize, const QTransform &m) const
+{
+    Q_UNUSED(pixelSize);
+
+    if (!m.isAffine())
+        return true;
+
+    return false;
+}
+
 QT_END_NAMESPACE
diff --git a/src/gui/painting/qpaintengineex_p.h b/src/gui/painting/qpaintengineex_p.h
index 7d57eee43d..9cfda7404a 100644
--- a/src/gui/painting/qpaintengineex_p.h
+++ b/src/gui/painting/qpaintengineex_p.h
@@ -227,6 +227,7 @@ public:
         IsEmulationEngine = 0x02    // If set, this object is a QEmulationEngine.
     };
     virtual uint flags() const {return 0;}
+    virtual bool supportsTransformations(qreal pixelSize, const QTransform &m) const;
 
 protected:
     QPaintEngineEx(QPaintEngineExPrivate &data);
diff --git a/src/gui/painting/qpainter.cpp b/src/gui/painting/qpainter.cpp
index 0a1e34e8cf..7ec6d6aa31 100644
--- a/src/gui/painting/qpainter.cpp
+++ b/src/gui/painting/qpainter.cpp
@@ -152,14 +152,6 @@ static inline uint line_emulation(uint emulation)
                         | QPaintEngine_OpaqueBackground);
 }
 
-static bool qt_paintengine_supports_transformations(QPaintEngine::Type type)
-{
-    return type == QPaintEngine::OpenGL2
-            || type == QPaintEngine::OpenVG
-            || type == QPaintEngine::OpenGL
-            || type == QPaintEngine::CoreGraphics;
-}
-
 #ifndef QT_NO_DEBUG
 static bool qt_painter_thread_test(int devType, const char *what, bool extraCondition = false)
 {
@@ -5815,20 +5807,19 @@ void QPainter::drawGlyphRun(const QPointF &position, const QGlyphRun &glyphRun)
     int count = qMin(glyphIndexes.size(), glyphPositions.size());
     QVarLengthArray<QFixedPoint, 128> fixedPointPositions(count);
 
-    bool paintEngineSupportsTransformations =
-            d->extended != 0
-            ? qt_paintengine_supports_transformations(d->extended->type())
-            : qt_paintengine_supports_transformations(d->engine->type());
-
-    // If the matrix is not affine, the paint engine will fall back to
-    // drawing the glyphs as paths, which in turn means we should not
-    // preprocess the glyph positions
-    if (!d->state->matrix.isAffine())
-        paintEngineSupportsTransformations = true;
+    QRawFontPrivate *fontD = QRawFontPrivate::get(font);
+    bool supportsTransformations;
+    if (d->extended != 0) {
+        supportsTransformations = d->extended->supportsTransformations(fontD->fontEngine->fontDef.pixelSize,
+                                                                       d->state->matrix);
+    } else {
+        supportsTransformations = d->engine->type() == QPaintEngine::CoreGraphics
+                                  || d->state->matrix.isAffine();
+    }
 
     for (int i=0; i<count; ++i) {
         QPointF processedPosition = position + glyphPositions.at(i);
-        if (!paintEngineSupportsTransformations)
+        if (!supportsTransformations)
             processedPosition = d->state->transform().map(processedPosition);
         fixedPointPositions[i] = QFixedPoint::fromPointF(processedPosition);
     }
@@ -6004,11 +5995,12 @@ void QPainter::drawStaticText(const QPointF &topLeftPosition, const QStaticText
         return;
     }
 
-    bool paintEngineSupportsTransformations = qt_paintengine_supports_transformations(d->extended->type());
-    if (paintEngineSupportsTransformations && !staticText_d->untransformedCoordinates) {
+    bool supportsTransformations = d->extended->supportsTransformations(staticText_d->font.pixelSize(),
+                                                                        d->state->matrix);
+    if (supportsTransformations && !staticText_d->untransformedCoordinates) {
         staticText_d->untransformedCoordinates = true;
         staticText_d->needsRelayout = true;
-    } else if (!paintEngineSupportsTransformations && staticText_d->untransformedCoordinates) {
+    } else if (!supportsTransformations && staticText_d->untransformedCoordinates) {
         staticText_d->untransformedCoordinates = false;
         staticText_d->needsRelayout = true;
     }
diff --git a/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h b/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h
index f7ec5f5c2f..a97223de44 100644
--- a/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h
+++ b/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h
@@ -158,6 +158,7 @@ public:
     void setRenderTextActive(bool);
 
     bool isNativePaintingActive() const;
+    bool supportsTransformations(qreal, const QTransform &) const { return true; }
 private:
     Q_DISABLE_COPY(QGL2PaintEngineEx)
 };
diff --git a/src/opengl/qpaintengine_opengl_p.h b/src/opengl/qpaintengine_opengl_p.h
index 8f12be40f6..aaca48a4fe 100644
--- a/src/opengl/qpaintengine_opengl_p.h
+++ b/src/opengl/qpaintengine_opengl_p.h
@@ -143,6 +143,7 @@ public:
     Qt::HANDLE handle() const;
 #endif
     inline Type type() const { return QPaintEngine::OpenGL; }
+    bool supportsTransformations(qreal, const QTransform &) const { return true; }
 
 private:
     void drawPolyInternal(const QPolygonF &pa, bool close = true);
diff --git a/src/openvg/qpaintengine_vg_p.h b/src/openvg/qpaintengine_vg_p.h
index 1e9103bc81..2aba5a2cc9 100644
--- a/src/openvg/qpaintengine_vg_p.h
+++ b/src/openvg/qpaintengine_vg_p.h
@@ -159,6 +159,7 @@ public:
     QVGPaintEnginePrivate *vgPrivate() { Q_D(QVGPaintEngine); return d; }
 
     void fillRegion(const QRegion& region, const QColor& color, const QSize& surfaceSize);
+    bool supportsTransformations(qreal, const QTransform &) const { return true; }
 
 protected:
     QVGPaintEngine(QVGPaintEnginePrivate &data);