QGtkStyle: Remove widget dependency from GroupBox

This patch makes it possible to draw a checkable groupbox without
passing a widget pointer.

Task-number: QTBUG-29867

Change-Id: I9b74bcffa0401c88f9dcbcd9816081b7f03a5173
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>

1 files changed, 20 insertions, 18 deletions

diff --git a/src/widgets/styles/qgtkstyle.cpp b/src/widgets/styles/qgtkstyle.cpp
index 15fa00d8a6..2697afb077 100644
--- a/src/widgets/styles/qgtkstyle.cpp
+++ b/src/widgets/styles/qgtkstyle.cpp
@@ -3629,7 +3629,7 @@ QRect QGtkStyle::subControlRect(ComplexControl control, const QStyleOptionComple
 #ifndef QT_NO_GROUPBOX
 
     case CC_GroupBox:
-        if (qstyleoption_cast<const QStyleOptionGroupBox *>(option)) {
+        if (const QStyleOptionGroupBox * groupBox = qstyleoption_cast<const QStyleOptionGroupBox *>(option)) {
             rect = option->rect.adjusted(0, groupBoxTopMargin, 0, -groupBoxBottomMargin);
             int topMargin = 0;
             int topHeight = 0;
@@ -3645,27 +3645,29 @@ QRect QGtkStyle::subControlRect(ComplexControl control, const QStyleOptionComple
                 return frameRect.adjusted(leftMarginExtension + margin, margin + topHeight + groupBoxTitleMargin, -margin, -margin);
             }
 
-            if (const QGroupBox *groupBoxWidget = qobject_cast<const QGroupBox *>(widget)) {
+            QFontMetrics fontMetrics = option->fontMetrics;
+            if (qobject_cast<const QGroupBox *>(widget)) {
                 //Prepare metrics for a bold font
                 QFont font = widget->font();
                 font.setBold(true);
-                QFontMetrics fontMetrics(font);
-                QSize textRect = fontMetrics.boundingRect(groupBoxWidget->title()).size() + QSize(4, 4);
-                int indicatorWidth = proxy()->pixelMetric(PM_IndicatorWidth, option, widget);
-                int indicatorHeight = proxy()->pixelMetric(PM_IndicatorHeight, option, widget);
-
-                if (subControl == SC_GroupBoxCheckBox) {
-                    rect.setWidth(indicatorWidth);
-                    rect.setHeight(indicatorHeight);
-                    rect.moveTop((textRect.height() - indicatorHeight) / 2);
-
-                } else if (subControl == SC_GroupBoxLabel) {
-                    if (groupBoxWidget->isCheckable())
-                        rect.adjust(indicatorWidth + 4, 0, 0, 0);
-                    rect.setSize(textRect);
-                }
-                rect = visualRect(option->direction, option->rect, rect);
+                fontMetrics = QFontMetrics(font);
+            }
+
+            QSize textRect = fontMetrics.boundingRect(groupBox->text).size() + QSize(4, 4);
+            int indicatorWidth = proxy()->pixelMetric(PM_IndicatorWidth, option, widget);
+            int indicatorHeight = proxy()->pixelMetric(PM_IndicatorHeight, option, widget);
+
+            if (subControl == SC_GroupBoxCheckBox) {
+                rect.setWidth(indicatorWidth);
+                rect.setHeight(indicatorHeight);
+                rect.moveTop((textRect.height() - indicatorHeight) / 2);
+
+            } else if (subControl == SC_GroupBoxLabel) {
+                if (groupBox->subControls & SC_GroupBoxCheckBox)
+                    rect.adjust(indicatorWidth + 4, 0, 0, 0);
+                rect.setSize(textRect);
             }
+            rect = visualRect(option->direction, option->rect, rect);
         }
 
         return rect;