QDockWidget: fix dock buttons size

The size of the dock buttons did not account the
SH_DockWidget_ButtonsHaveFrame style hint and therefore was too large
when a full 16x16 icon was used (which was the case after the latest
style cleanups) and therefore appeared too large.
This also allows the remove of the hack for the windows style. The
windows vista/11 style is not even affected by this hack because there
the size comes from windows itself and can not be modified via
PM_SmallIconSize.

Fixes: QTBUG-118643
Task-number: QTBUG-118122
Change-Id: Ie09a6a4e89df66b5393c5a57735002da47415c0e
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>

1 files changed, 2 insertions, 23 deletions

diff --git a/src/widgets/widgets/qdockwidget.cpp b/src/widgets/widgets/qdockwidget.cpp
index 23d16dd6d7..2ba0c821d4 100644
--- a/src/widgets/widgets/qdockwidget.cpp
+++ b/src/widgets/widgets/qdockwidget.cpp
@@ -128,33 +128,12 @@ bool QDockWidgetTitleButton::event(QEvent *event)
     return QAbstractButton::event(event);
 }
 
-static inline bool isWindowsStyle(const QStyle *style)
-{
-    // Note: QStyleSheetStyle inherits QWindowsStyle
-    const QStyle *effectiveStyle = style;
-
-#if QT_CONFIG(style_stylesheet)
-    if (style->inherits("QStyleSheetStyle"))
-      effectiveStyle = static_cast<const QStyleSheetStyle *>(style)->baseStyle();
-#endif
-#if !defined(QT_NO_STYLE_PROXY)
-    if (style->inherits("QProxyStyle"))
-      effectiveStyle = static_cast<const QProxyStyle *>(style)->baseStyle();
-#endif
-
-    return effectiveStyle->inherits("QWindowsStyle");
-}
-
 QSize QDockWidgetTitleButton::dockButtonIconSize() const
 {
     if (m_iconSize < 0) {
         m_iconSize = style()->pixelMetric(QStyle::PM_SmallIconSize, nullptr, this);
-        // Dock Widget title buttons on Windows where historically limited to size 10
-        // (from small icon size 16) since only a 10x10 XPM was provided.
-        // Adding larger pixmaps to the icons thus caused the icons to grow; limit
-        // this to qpiScaled(10) here.
-        if (isWindowsStyle(style()))
-            m_iconSize = qMin((10 * logicalDpiX()) / 96, m_iconSize);
+        if (style()->styleHint(QStyle::SH_DockWidget_ButtonsHaveFrame, nullptr, this))
+            m_iconSize = (m_iconSize * 3) / 4;
     }
     return QSize(m_iconSize, m_iconSize);
 }