Simplify code by factoring out brush transformation for gradients

Emulation of non-logical coordinate mode gradients was implemented by
essentially 3 x 2 repetitions of the same manipulation of the QBrush
transform. Avoid the code duplication by extracting a common method.
Add lancelot test scripts that excersizes these code paths.

Change-Id: I7baa921923231ef9e83e443dba996b82b32ad1e7
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

4 files changed, 235 insertions, 51 deletions

diff --git a/src/gui/painting/qemulationpaintengine.cpp b/src/gui/painting/qemulationpaintengine.cpp
index 586b71557e..e6686e3721 100644
--- a/src/gui/painting/qemulationpaintengine.cpp
+++ b/src/gui/painting/qemulationpaintengine.cpp
@@ -72,6 +72,14 @@ QPainterState *QEmulationPaintEngine::createState(QPainterState *orig) const
     return real_engine->createState(orig);
 }
 
+static inline void combineXForm(QBrush *brush, const QRectF &r)
+{
+    QTransform t = brush->transform();
+    t.translate(r.x(), r.y());
+    t.scale(r.width(), r.height());
+    brush->setTransform(t);
+}
+
 void QEmulationPaintEngine::fill(const QVectorPath &path, const QBrush &brush)
 {
     QPainterState *s = state();
@@ -84,26 +92,14 @@ void QEmulationPaintEngine::fill(const QVectorPath &path, const QBrush &brush)
 
     Qt::BrushStyle style = qbrush_style(brush);
     if (style >= Qt::LinearGradientPattern && style <= Qt::ConicalGradientPattern) {
-        const QGradient *g = brush.gradient();
-
-        if (g->coordinateMode() > QGradient::LogicalMode) {
-            if (g->coordinateMode() == QGradient::StretchToDeviceMode) {
-                QBrush copy = brush;
-                QTransform mat = copy.transform();
-                mat.scale(real_engine->painter()->device()->width(), real_engine->painter()->device()->height());
-                copy.setTransform(mat);
-                real_engine->fill(path, copy);
-                return;
-            } else if (g->coordinateMode() == QGradient::ObjectBoundingMode) {
-                QBrush copy = brush;
-                QTransform mat = copy.transform();
-                QRectF r = path.controlPointRect();
-                mat.translate(r.x(), r.y());
-                mat.scale(r.width(), r.height());
-                copy.setTransform(mat);
-                real_engine->fill(path, copy);
-                return;
-            }
+        QGradient::CoordinateMode coMode = brush.gradient()->coordinateMode();
+        if (coMode > QGradient::LogicalMode) {
+            QBrush copy = brush;
+            const QPaintDevice *d = real_engine->painter()->device();
+            QRectF r = (coMode == QGradient::ObjectBoundingMode) ? path.controlPointRect() : QRectF(0, 0, d->width(), d->height());
+            combineXForm(&copy, r);
+            real_engine->fill(path, copy);
+            return;
         }
     }
 
@@ -124,27 +120,15 @@ void QEmulationPaintEngine::stroke(const QVectorPath &path, const QPen &pen)
     QBrush brush = pen.brush();
     QPen copy = pen;
     Qt::BrushStyle style = qbrush_style(brush);
-    if (style >= Qt::LinearGradientPattern && style <= Qt::ConicalGradientPattern) {
-        const QGradient *g = brush.gradient();
-
-        if (g->coordinateMode() > QGradient::LogicalMode) {
-            if (g->coordinateMode() == QGradient::StretchToDeviceMode) {
-                QTransform mat = brush.transform();
-                mat.scale(real_engine->painter()->device()->width(), real_engine->painter()->device()->height());
-                brush.setTransform(mat);
-                copy.setBrush(brush);
-                real_engine->stroke(path, copy);
-                return;
-            } else if (g->coordinateMode() == QGradient::ObjectBoundingMode) {
-                QTransform mat = brush.transform();
-                QRectF r = path.controlPointRect();
-                mat.translate(r.x(), r.y());
-                mat.scale(r.width(), r.height());
-                brush.setTransform(mat);
-                copy.setBrush(brush);
-                real_engine->stroke(path, copy);
-                return;
-            }
+    if (style >= Qt::LinearGradientPattern && style <= Qt::ConicalGradientPattern ) {
+        QGradient::CoordinateMode coMode = brush.gradient()->coordinateMode();
+        if (coMode > QGradient::LogicalMode) {
+            const QPaintDevice *d = real_engine->painter()->device();
+            QRectF r = (coMode == QGradient::ObjectBoundingMode) ? path.controlPointRect() : QRectF(0, 0, d->width(), d->height());
+            combineXForm(&brush, r);
+            copy.setBrush(brush);
+            real_engine->stroke(path, copy);
+            return;
         }
     }
 
@@ -179,18 +163,16 @@ void QEmulationPaintEngine::drawTextItem(const QPointF &p, const QTextItem &text
         QGradient g = *s->pen.brush().gradient();
 
         if (g.coordinateMode() > QGradient::LogicalMode) {
-            QTransform mat = s->pen.brush().transform();
-            if (g.coordinateMode() == QGradient::StretchToDeviceMode) {
-                mat.scale(real_engine->painter()->device()->width(), real_engine->painter()->device()->height());
-            } else if (g.coordinateMode() == QGradient::ObjectBoundingMode) {
-                const QTextItemInt &ti = static_cast<const QTextItemInt &>(textItem);
-                QRectF r(p.x(), p.y() - ti.ascent.toReal(), ti.width.toReal(), (ti.ascent + ti.descent + 1).toReal());
-                mat.translate(r.x(), r.y());
-                mat.scale(r.width(), r.height());
-            }
+            QBrush copy = s->pen.brush();
+            const QPaintDevice *d = real_engine->painter()->device();
+            const QTextItemInt &ti = static_cast<const QTextItemInt &>(textItem);
+            QRectF r = (g.coordinateMode() == QGradient::ObjectBoundingMode) ?
+                        QRectF(p.x(), p.y() - ti.ascent.toReal(), ti.width.toReal(), (ti.ascent + ti.descent + 1).toReal()) :
+                        QRectF(0, 0, d->width(), d->height());
+            combineXForm(&copy, r);
             g.setCoordinateMode(QGradient::LogicalMode);
             QBrush brush(g);
-            brush.setTransform(mat);
+            brush.setTransform(copy.transform());
             s->pen.setBrush(brush);
             penChanged();
             real_engine->drawTextItem(p, textItem);
diff --git a/tests/auto/other/lancelot/scripts/gradientxform_device.qps b/tests/auto/other/lancelot/scripts/gradientxform_device.qps
new file mode 100644
index 0000000000..82ebb536bb
--- /dev/null
+++ b/tests/auto/other/lancelot/scripts/gradientxform_device.qps
@@ -0,0 +1,67 @@
+# Version: 1
+# CheckVsReference: 5%
+
+gradient_clearStops
+gradient_appendStop 0      black
+gradient_appendStop 0.4   yellow
+gradient_appendStop 1      gray
+
+gradient_setSpread PadSpread
+
+gradient_setCoordinateMode StretchToDeviceMode
+
+# first run is dummy, make it offscreen
+save
+translate -500 -500
+
+begin_block row
+save
+
+setPen nopen
+drawRect 50 0 100 100
+
+setPen brush 30
+setBrush lightblue
+drawRect 175 15 70 70
+
+setFont "times" 110 99
+drawText 270 100 "X"
+
+restore
+end_block row
+
+restore
+
+drawText 160 20 "PLAIN"
+drawText 560 20 "BRUSH XFORM"
+translate 0 20
+
+begin_block block
+save
+
+drawText 75 20 "Brush Fill"
+drawText 176 20 "Pen Stroke"
+drawText 277 20 "Text Stroke"
+translate 0 30
+drawText 0 50 "Linear"
+drawText 0 160 "Radial"
+drawText 0 270 "Conical"
+
+gradient_setLinear 0.0 0.0 0.4 0.0
+repeat_block row
+
+translate 0 110
+gradient_setRadial 0.04 0.08 0.3 0.3 0.05
+repeat_block row
+
+translate 0 110
+gradient_setConical 0.25 0.1 45
+repeat_block row
+restore
+end_block block
+
+translate 400 0
+brushRotate 30.0
+brushScale 1.5 .5
+brushTranslate 0 -80
+repeat_block block
diff --git a/tests/auto/other/lancelot/scripts/gradientxform_logical.qps b/tests/auto/other/lancelot/scripts/gradientxform_logical.qps
new file mode 100644
index 0000000000..1bb157b635
--- /dev/null
+++ b/tests/auto/other/lancelot/scripts/gradientxform_logical.qps
@@ -0,0 +1,67 @@
+# Version: 1
+# CheckVsReference: 5%
+
+gradient_clearStops
+gradient_appendStop 0      black
+gradient_appendStop 0.4   yellow
+gradient_appendStop 1      gray
+
+gradient_setSpread PadSpread
+
+gradient_setCoordinateMode LogicalMode
+
+# first run is dummy, make it offscreen
+save
+translate -500 -500
+
+begin_block row
+save
+
+setPen nopen
+drawRect 50 0 100 100
+
+setPen brush 30
+setBrush lightblue
+drawRect 175 15 70 70
+
+setFont "times" 110 99
+drawText 270 100 "X"
+
+restore
+end_block row
+
+restore
+
+drawText 160 20 "PLAIN"
+drawText 560 20 "BRUSH XFORM"
+translate 0 20
+
+begin_block block
+save
+
+drawText 75 20 "Brush Fill"
+drawText 176 20 "Pen Stroke"
+drawText 277 20 "Text Stroke"
+translate 0 30
+drawText 0 50 "Linear"
+drawText 0 160 "Radial"
+drawText 0 270 "Conical"
+
+gradient_setLinear 0 0 400 0
+repeat_block row
+
+translate 0 110
+gradient_setRadial 200 50 140 70 20
+repeat_block row
+
+translate 0 110
+gradient_setConical 220 60 45
+repeat_block row
+restore
+end_block block
+
+translate 400 0
+brushRotate 30.0
+brushScale 1.5 .5
+brushTranslate 0 -80
+repeat_block block
diff --git a/tests/auto/other/lancelot/scripts/gradientxform_object.qps b/tests/auto/other/lancelot/scripts/gradientxform_object.qps
new file mode 100644
index 0000000000..d785a008c0
--- /dev/null
+++ b/tests/auto/other/lancelot/scripts/gradientxform_object.qps
@@ -0,0 +1,68 @@
+# Version: 1
+# CheckVsReference: 5%
+
+gradient_clearStops
+gradient_appendStop 0      black
+gradient_appendStop 0.4   yellow
+gradient_appendStop 1      gray
+
+gradient_setSpread PadSpread
+
+gradient_setCoordinateMode ObjectBoundingMode
+
+# first run is dummy, make it offscreen
+save
+translate -500 -500
+
+begin_block row
+save
+
+setPen nopen
+drawRect 50 0 100 100
+
+setPen brush 30
+setBrush lightblue
+translate 110 0
+drawRect 65 15 70 70
+
+translate 110 0
+setFont "times" 110 99
+drawText 50 100 "X"
+
+restore
+end_block row
+
+restore
+
+drawText 160 20 "PLAIN"
+drawText 560 20 "BRUSH XFORM"
+translate 0 20
+
+begin_block block
+save
+
+drawText 75 20 "Brush Fill"
+drawText 176 20 "Pen Stroke"
+drawText 277 20 "Text Stroke"
+translate 0 30
+drawText 0 50 "Linear"
+drawText 0 160 "Radial"
+drawText 0 270 "Conical"
+
+gradient_setLinear 0.1 0.0 0.5 0.0
+repeat_block row
+
+translate 0 110
+gradient_setRadial 0.3 0.2 0.5 0.4 0.5
+repeat_block row
+
+translate 0 110
+gradient_setConical 0.5 0.7 45
+repeat_block row
+restore
+end_block block
+
+translate 400 0
+brushRotate 30.0
+brushScale 1.5 .5
+repeat_block block