QDockWidget: Use theme font for title

While the QPA theme provides support for dock widgets
title font we never use it.

This is a very similar solution to what we do in
QMdiSubWindow, setting the platform theme font at
few specific points.

This patch also fixes the dock window title font on
macOS, as queried in QCoreTextFontDatabase.

Change-Id: Ie264e4e83e0d3d1e8f78bd378359f3063cc1d525
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/widgets/widgets/qdockwidget.cpp b/src/widgets/widgets/qdockwidget.cpp
index ac76217ece..e17c2c1f4c 100644
--- a/src/widgets/widgets/qdockwidget.cpp
+++ b/src/widgets/widgets/qdockwidget.cpp
@@ -653,6 +653,8 @@ void QDockWidgetPrivate::init()
     QObject::connect(button, SIGNAL(clicked()), q, SLOT(close()));
     layout->setWidgetForRole(QDockWidgetLayout::CloseButton, button);
 
+    font = QApplication::font("QDockWidgetTitle");
+
 #ifndef QT_NO_ACTION
     toggleViewAction = new QAction(q);
     toggleViewAction->setCheckable(true);
@@ -685,6 +687,7 @@ void QDockWidget::initStyleOption(QStyleOptionDockWidget *option) const
     // If we are in a floating tab, init from the parent because the attributes and the geometry
     // of the title bar should be taken from the floating window.
     option->initFrom(floatingTab && !isFloating() ? parentWidget() : this);
+    option->fontMetrics = QFontMetrics(d->font);
     option->rect = dwlayout->titleArea();
     option->title = d->fixedWindowTitle;
     option->closable = hasFeature(this, QDockWidget::DockWidgetClosable);
@@ -1481,6 +1484,7 @@ void QDockWidget::paintEvent(QPaintEvent *event)
         // the title may wish to extend out to all sides (eg. Vista style)
         QStyleOptionDockWidget titleOpt;
         initStyleOption(&titleOpt);
+        p.setFont(d_func()->font);
         p.drawControl(QStyle::CE_DockWidgetTitle, titleOpt);
     }
 }