QStyleHelper: pass devicePixelRatio to uniqueName()

QStyleHelper::uniqueName() took the size of the pixmap to cache but not
the dpr. This might lead to a situation (e.g. in a multi-display
environment) where we use a pixmap with the wrong dpr and get a
pixelated result on the screen.

Change-Id: Ifdebeddff3380931398b3284a7757b7da950caa9
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>
Reviewed-by: Wladimir Leuschner <wladimir.leuschner@qt.io>

src/widgets/styles/qcommonstyle.cpp

@@ -759,7 +759,7 @@ void QCommonStyle::drawPrimitive(PrimitiveElement pe, const QStyleOption *opt, Q
             const QString pixmapName = QStyleHelper::uniqueName("$qt_ia-"_L1
                                                      % QLatin1StringView(metaObject()->className())
                                                      % HexString<uint>(pe),
-                                             opt, QSize(size, size) * pixelRatio);
+                                             opt, QSize(size, size), pixelRatio);
             if (!QPixmapCache::find(pixmapName, &pixmap)) {
                 const qreal border = pixelRatio * (size / 5.);
                 const qreal sqsize = pixelRatio * size;

src/widgets/styles/qfusionstyle.cpp

@@ -157,7 +157,7 @@ static void qt_fusion_draw_arrow(Qt::ArrowType type, QPainter *painter, const QS
     const QString cacheKey = QStyleHelper::uniqueName("fusion-arrow"_L1
                                                           % HexString<uint>(type)
                                                           % HexString<uint>(color.rgba()),
-                                                      option, rect.size());
+                                                      option, rect.size(), dpr);
     if (!QPixmapCache::find(cacheKey, &cachePixmap)) {
         cachePixmap = styleCachePixmap(rect.size(), dpr);
         QPainter cachePainter(&cachePixmap);
@@ -1143,7 +1143,7 @@ void QFusionStyle::drawControl(ControlElement element, const QStyleOption *optio
                                                                     % HexString(header->position)
                                                                     % HexString(header->orientation)
                                                                     % QLatin1Char(isSectionDragTarget ? '1' : '0'),
-                                                                option, option->rect.size());
+                                                                option, option->rect.size(), dpr);
             QPixmap cache;
             if (!QPixmapCache::find(pixmapName, &cache)) {
                 cache = styleCachePixmap(rect.size(), dpr);
@@ -1881,7 +1881,7 @@ void QFusionStyle::drawComplexControl(ComplexControl control, const QStyleOption
         if (const QStyleOptionSpinBox *spinBox = qstyleoption_cast<const QStyleOptionSpinBox *>(option)) {
             const qreal dpr = painter->device()->devicePixelRatio();
             QPixmap cache;
-            QString pixmapName = QStyleHelper::uniqueName("spinbox"_L1, spinBox, spinBox->rect.size());
+            QString pixmapName = QStyleHelper::uniqueName("spinbox"_L1, spinBox, spinBox->rect.size(), dpr);
             if (!QPixmapCache::find(pixmapName, &cache)) {
 
                 cache = styleCachePixmap(spinBox->rect.size(), dpr);
@@ -2583,7 +2583,7 @@ void QFusionStyle::drawComplexControl(ComplexControl control, const QStyleOption
                                                                     % QLatin1StringView(comboBox->editable ? "-editable" : "")
                                                                     % QLatin1StringView(isEnabled ? "-enabled" : "")
                                                                     % QLatin1StringView(!comboBox->frame ? "-frameless" : ""),
-                                                                option, comboBox->rect.size());
+                                                                option, comboBox->rect.size(), dpr);
             if (!QPixmapCache::find(pixmapName, &cache)) {
                 cache = styleCachePixmap(comboBox->rect.size(), dpr);
                 QPainter cachePainter(&cache);
@@ -2695,7 +2695,8 @@ void QFusionStyle::drawComplexControl(ComplexControl control, const QStyleOption
                 grooveColor.setHsv(buttonColor.hue(),
                                    qMin(255, (int)(buttonColor.saturation())),
                                    qMin(255, (int)(buttonColor.value()*0.9)));
-                QString groovePixmapName = QStyleHelper::uniqueName("slider_groove"_L1, option, groove.size());
+                QString groovePixmapName = QStyleHelper::uniqueName("slider_groove"_L1, option,
+                                                                    groove.size(), dpr);
                 QRect pixmapRect(0, 0, groove.width(), groove.height());
 
                 // draw background groove
@@ -2838,7 +2839,8 @@ void QFusionStyle::drawComplexControl(ComplexControl control, const QStyleOption
             }
             // draw handle
             if ((option->subControls & SC_SliderHandle) ) {
-                QString handlePixmapName = QStyleHelper::uniqueName("slider_handle"_L1, option, handle.size());
+                QString handlePixmapName = QStyleHelper::uniqueName("slider_handle"_L1, option,
+                                                                    handle.size(), dpr);
                 if (!QPixmapCache::find(handlePixmapName, &cache)) {
                     cache = styleCachePixmap(handle.size(), dpr);
                     QRect pixmapRect(0, 0, handle.width(), handle.height());

src/widgets/styles/qstyle_p.h

@@ -48,7 +48,7 @@ inline QPixmap styleCachePixmap(const QSize &size, qreal pixelRatio)
     QPixmap internalPixmapCache; \
     QPainter *p = painter; \
     const auto dpr = p->device()->devicePixelRatio(); \
-    const QString unique = QStyleHelper::uniqueName((a), option, option->rect.size()); \
+    const QString unique = QStyleHelper::uniqueName((a), option, option->rect.size(), dpr); \
     int txType = painter->deviceTransform().type() | painter->worldTransform().type(); \
     const bool doPixmapCache = (!option->rect.isEmpty()) \
             && ((txType <= QTransform::TxTranslate) || (painter->deviceTransform().type() == QTransform::TxScale)); \

src/widgets/styles/qstylehelper.cpp

@@ -32,7 +32,7 @@ static inline bool usePixmapCache(const QStyleOption *opt)
     return true;
 }
 
-QString uniqueName(const QString &key, const QStyleOption *option, const QSize &size)
+QString uniqueName(const QString &key, const QStyleOption *option, const QSize &size, qreal dpr)
 {
     if (!usePixmapCache(option))
         return {};
@@ -43,7 +43,8 @@ QString uniqueName(const QString &key, const QStyleOption *option, const QSize &
                       % HexString<uint>(complexOption ? uint(complexOption->activeSubControls) : 0u)
                       % HexString<quint64>(option->palette.cacheKey())
                       % HexString<uint>(size.width())
-                      % HexString<uint>(size.height());
+                      % HexString<uint>(size.height())
+                      % HexString<qreal>(dpr);
 
 #if QT_CONFIG(spinbox)
     if (const QStyleOptionSpinBox *spinBox = qstyleoption_cast<const QStyleOptionSpinBox *>(option)) {

src/widgets/styles/qstylehelper_p.h

@@ -39,7 +39,7 @@ class QWindow;
 
 namespace QStyleHelper
 {
-    QString uniqueName(const QString &key, const QStyleOption *option, const QSize &size);
+    QString uniqueName(const QString &key, const QStyleOption *option, const QSize &size, qreal dpr);
 
     Q_WIDGETS_EXPORT qreal dpi(const QStyleOption *option);