Fix drawTiledPixmap() and texture-brush painting with high-DPR images

Although QPainter::drawImage()/drawPixmap() would render images scaled
according to their devicePixelRatio(), that would not happen for
drawTiledPixmap() and when using a textured brush. Implemented here,
in combination with the pending "High-dpi drawTiledPixmap (raster
paint engine)" commit.

[ChangeLog][QtGui] Fix drawTiledPixmap() and texture-brush painting with high-DPR images

Task-number: QTBUG-67248
Change-Id: I037e3f897fa708038a0222d3b0c61c7842d87961
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

src/gui/painting/qemulationpaintengine.cpp

@@ -101,6 +101,14 @@ void QEmulationPaintEngine::fill(const QVectorPath &path, const QBrush &brush)
             real_engine->fill(path, copy);
             return;
         }
+    } else if (style == Qt::TexturePattern) {
+        qreal dpr = qHasPixmapTexture(brush) ? brush.texture().devicePixelRatioF() : brush.textureImage().devicePixelRatioF();
+        if (!qFuzzyCompare(dpr, 1.0)) {
+            QBrush copy = brush;
+            combineXForm(&copy, QRectF(0, 0, 1.0/dpr, 1.0/dpr));
+            real_engine->fill(path, copy);
+            return;
+        }
     }
 
     real_engine->fill(path, brush);

src/gui/painting/qpaintengineex.cpp

@@ -948,6 +948,8 @@ void QPaintEngineEx::drawTiledPixmap(const QRectF &r, const QPixmap &pixmap, con
 {
     QBrush brush(state()->pen.color(), pixmap);
     QTransform xform = QTransform::fromTranslate(r.x() - s.x(), r.y() - s.y());
+    if (!qFuzzyCompare(pixmap.devicePixelRatioF(), 1.0))
+        xform.scale(1.0/pixmap.devicePixelRatioF(), 1.0/pixmap.devicePixelRatioF());
     brush.setTransform(xform);
 
     qreal pts[] = { r.x(), r.y(),

src/gui/painting/qpainter.cpp

@@ -190,6 +190,13 @@ void QPainterPrivate::checkEmulation()
     if (pg && pg->coordinateMode() > QGradient::LogicalMode)
         doEmulation = true;
 
+    if (state->brush.style() == Qt::TexturePattern) {
+        if (qHasPixmapTexture(state->brush))
+            doEmulation |= !qFuzzyCompare(state->brush.texture().devicePixelRatioF(), 1.0);
+        else
+            doEmulation |= !qFuzzyCompare(state->brush.textureImage().devicePixelRatioF(), 1.0);
+    }
+
     if (doEmulation && extended->flags() & QPaintEngineEx::DoNotEmulate)
         return;
 

tests/auto/other/lancelot/paintcommands.cpp

@@ -561,6 +561,10 @@ void PaintCommands::staticInit()
                       "^bitmap_load\\s+([\\w.:\\/]*)\\s*([\\w.:\\/]*)$",
                       "bitmap_load <bitmap filename> <bitmapName>\n  - note that the image is stored as a pixmap",
                       "bitmap_load :/images/bitmap.png myBitmap");
+    DECL_PAINTCOMMAND("pixmap_setDevicePixelRatio", command_pixmap_setDevicePixelRatio,
+                      "^pixmap_setDevicePixelRatio\\s+([\\w.:\\/]*)\\s+([.0-9]*)$",
+                      "pixmap_setDevicePixelRatio <pixmapName> <dpr>",
+                      "pixmap_setDevicePixelRatio myPixmap 2.0");
     DECL_PAINTCOMMAND("image_convertToFormat", command_image_convertToFormat,
                       "^image_convertToFormat\\s+([\\w.:\\/]*)\\s+([\\w.:\\/]+)\\s+([\\w0-9_]*)$",
                       "image_convertToFormat <sourceImageName> <destImageName> <image format enum>",
@@ -577,6 +581,10 @@ void PaintCommands::staticInit()
                       "^image_setColorCount\\s+([\\w.:\\/]*)\\s+([0-9]*)$",
                       "image_setColorCount <imageName> <nbColors>",
                       "image_setColorCount myImage 128");
+    DECL_PAINTCOMMAND("image_setDevicePixelRatio", command_image_setDevicePixelRatio,
+                      "^image_setDevicePixelRatio\\s+([\\w.:\\/]*)\\s+([.0-9]*)$",
+                      "image_setDevicePixelRatio <imageName> <dpr>",
+                      "image_setDevicePixelRatio myImage 2.0");
 
     DECL_PAINTCOMMANDSECTION("transformations");
     DECL_PAINTCOMMAND("resetMatrix", command_resetMatrix,
@@ -1761,7 +1769,9 @@ void PaintCommands::command_setBrush(QRegularExpressionMatch re)
 {
     QStringList caps = re.capturedTexts();
 
-    QImage img = image_load<QImage>(caps.at(1));
+    QImage img = m_imageMap[caps.at(1)]; // try cache first
+    if (img.isNull())
+        img = image_load<QImage>(caps.at(1));
     if (!img.isNull()) { // Assume image brush
         if (m_verboseMode)
             printf(" -(lance) setBrush(image=%s, width=%d, height=%d)\n",
@@ -2132,6 +2142,20 @@ void PaintCommands::command_bitmap_load(QRegularExpressionMatch re)
     m_pixmapMap[name] = bm;
 }
 
+void PaintCommands::command_pixmap_setDevicePixelRatio(QRegularExpressionMatch re)
+{
+    QStringList caps = re.capturedTexts();
+
+    QString name = caps.at(1);
+    double dpr = convertToDouble(caps.at(2));
+
+    if (m_verboseMode)
+        printf(" -(lance) pixmap_setDevicePixelRatio(%s), %.1f -> %.1f\n",
+               qPrintable(name), m_pixmapMap[name].devicePixelRatioF(), dpr);
+
+    m_pixmapMap[name].setDevicePixelRatio(dpr);
+}
+
 /***************************************************************************************************/
 void PaintCommands::command_pixmap_setMask(QRegularExpressionMatch re)
 {
@@ -2196,6 +2220,21 @@ void PaintCommands::command_image_setColor(QRegularExpressionMatch re)
     m_imageMap[name].setColor(index, color.rgba());
 }
 
+/***************************************************************************************************/
+void PaintCommands::command_image_setDevicePixelRatio(QRegularExpressionMatch re)
+{
+    QStringList caps = re.capturedTexts();
+
+    QString name = caps.at(1);
+    double dpr = convertToDouble(caps.at(2));
+
+    if (m_verboseMode)
+        printf(" -(lance) image_setDevicePixelRatio(%s), %.1f -> %.1f\n",
+               qPrintable(name), m_imageMap[name].devicePixelRatioF(), dpr);
+
+    m_imageMap[name].setDevicePixelRatio(dpr);
+}
+
 /***************************************************************************************************/
 void PaintCommands::command_abort(QRegularExpressionMatch)
 {

tests/auto/other/lancelot/paintcommands.h

@@ -229,10 +229,12 @@ private:
     void command_pixmap_load(QRegularExpressionMatch re);
     void command_pixmap_setMask(QRegularExpressionMatch re);
     void command_bitmap_load(QRegularExpressionMatch re);
+    void command_pixmap_setDevicePixelRatio(QRegularExpressionMatch re);
     void command_image_convertToFormat(QRegularExpressionMatch re);
     void command_image_load(QRegularExpressionMatch re);
     void command_image_setColor(QRegularExpressionMatch re);
     void command_image_setColorCount(QRegularExpressionMatch re);
+    void command_image_setDevicePixelRatio(QRegularExpressionMatch re);
 
     // commands: transformation
     void command_resetMatrix(QRegularExpressionMatch re);

tests/auto/other/lancelot/scripts/image_dpr.qps

@@ -0,0 +1,43 @@
+
+setRenderHint Antialiasing true
+setRenderHint SmoothPixmapTransform true
+
+image_load sign.png img1
+pixmap_load sign.png pix1
+
+begin_block drawIt
+save
+
+drawImage img1 20 20 -1 -1
+drawRect 17.5 17.5 85 85
+
+setBrush img1
+setPen NoPen
+drawRect 20 120 120 120
+
+brushRotate 45
+drawRect 20 260 120 120
+
+setBrush NoBrush
+drawTiledPixmap pix1 20 400 120 120
+
+restore
+end_block
+
+save
+translate 150 0
+rotate -5
+repeat_block drawIt
+restore
+
+image_setDevicePixelRatio img1 2.0
+pixmap_setDevicePixelRatio pix1 2.0
+translate 400 0
+repeat_block drawIt
+
+save
+translate 150 0
+rotate -5
+repeat_block drawIt
+restore
+