StyleSheetStyle: Load @Nx images

Perform a @Nx image file lookup when loading pixmaps.

Make drawBackgroundImage() handle high-dpi pixmaps,
here the layout calculations needs to be in device-
independent pixels

Fixes: QTBUG-36825
Change-Id: I61e6f53c59f61f3bd88c34a036349e51e8c8ad92
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>

4 files changed, 34 insertions, 0 deletions

diff --git a/tests/auto/widgets/styles/qstylesheetstyle/images/testimage.png b/tests/auto/widgets/styles/qstylesheetstyle/images/testimage.png
index 06fb34f0d6..a4adc7a47f 100644
--- a/tests/auto/widgets/styles/qstylesheetstyle/images/testimage.png
+++ b/tests/auto/widgets/styles/qstylesheetstyle/images/testimage.png
diff --git a/tests/auto/widgets/styles/qstylesheetstyle/images/testimage@2x.png b/tests/auto/widgets/styles/qstylesheetstyle/images/testimage@2x.png
new file mode 100644
index 0000000000..d55f0c507b
--- /dev/null
+++ b/tests/auto/widgets/styles/qstylesheetstyle/images/testimage@2x.png
diff --git a/tests/auto/widgets/styles/qstylesheetstyle/resources.qrc b/tests/auto/widgets/styles/qstylesheetstyle/resources.qrc
index 248bf80f50..f523070073 100644
--- a/tests/auto/widgets/styles/qstylesheetstyle/resources.qrc
+++ b/tests/auto/widgets/styles/qstylesheetstyle/resources.qrc
@@ -2,5 +2,6 @@
 <RCC version="1.0">
   <qresource>
     <file>images/testimage.png</file>
+    <file>images/testimage@2x.png</file>
   </qresource>
 </RCC>
\ No newline at end of file
diff --git a/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp b/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp
index 43aec651fe..f5d9433f70 100644
--- a/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp
+++ b/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp
@@ -33,6 +33,7 @@
 #include <QMetaObject>
 
 #include <private/qstylesheetstyle_p.h>
+#include <private/qhighdpiscaling_p.h>
 #include <QtTest/private/qtesthelpers_p.h>
 
 using namespace QTestPrivate;
@@ -101,6 +102,9 @@ private slots:
     void styleSheetTargetAttribute();
     void unpolish();
 
+    void highdpiImages_data();
+    void highdpiImages();
+
 private:
     QColor COLOR(const QWidget& w) {
         w.ensurePolished();
@@ -2066,6 +2070,35 @@ void tst_QStyleSheetStyle::unpolish()
     QCOMPARE(w.minimumWidth(), 0);
 }
 
+void tst_QStyleSheetStyle::highdpiImages_data()
+{
+    QTest::addColumn<qreal>("screenFactor");
+    QTest::addColumn<QColor>("color");
+
+    QTest::newRow("highdpi") << 2.0 << QColor(0x00, 0xFF, 0x00);
+    QTest::newRow("lowdpi")  << 1.0 << QColor(0xFF, 0x00, 0x00);
+}
+
+void tst_QStyleSheetStyle::highdpiImages()
+{
+    QFETCH(qreal, screenFactor);
+    QFETCH(QColor, color);
+
+    QWidget w;
+    QScreen *screen = QGuiApplication::screenAt(w.pos());
+    QHighDpiScaling::setScreenFactor(screen, screenFactor);
+    w.setStyleSheet("QWidget { background-image: url(\":/images/testimage.png\"); }");
+    w.show();
+
+    QVERIFY(QTest::qWaitForWindowExposed(&w));
+    QImage image(w.size(), QImage::Format_ARGB32);
+    w.render(&image);
+    QVERIFY(testForColors(image, color));
+
+    QHighDpiScaling::setScreenFactor(screen, 1.0);
+    QHighDpiScaling::updateHighDpiScaling(); // reset to normal
+}
+
 QTEST_MAIN(tst_QStyleSheetStyle)
 #include "tst_qstylesheetstyle.moc"