add group delegate

copied from Qt source and modified according to our needs

GUI/Views/widgetbox/SampleToolBoxTreeWidget.cpp

@@ -16,17 +16,96 @@
 #include "Base/Utils/Assert.h"
 #include "GUI/Views/widgetbox/SampleToolBoxGroupView.h"
 
-// shared
-#include "GUI/Views/widgetbox/sheet_delegate_p.h"
-
 #include <QAction>
 #include <QActionGroup>
 #include <QApplication>
 #include <QContextMenuEvent>
 #include <QHeaderView>
+#include <QItemDelegate>
 #include <QMenu>
+#include <QPainter>
 #include <QTreeWidgetItem>
 
+namespace {
+
+//! Draws the group title items as buttons with an arrow to show "collapsed/expanded".
+//! This work is based on qdesigner_internal::SheetDelegate
+class GroupTitleDelegate : public QItemDelegate {
+public:
+    GroupTitleDelegate(QTreeView* view, QWidget* parent) : QItemDelegate(parent), m_view(view) {}
+
+    virtual void paint(QPainter* painter, const QStyleOptionViewItem& option,
+                       const QModelIndex& index) const override
+    {
+        const QAbstractItemModel* model = index.model();
+        const bool isGroupTitleItem = !model->parent(index).isValid();
+
+        if (!isGroupTitleItem) {
+            QItemDelegate::paint(painter, option, index);
+            return;
+        }
+
+        painter->save();
+        QColor buttonColor(230, 230, 230);
+        const QBrush buttonBrush = option.palette.button();
+        if (!buttonBrush.gradient() && buttonBrush.texture().isNull())
+            buttonColor = buttonBrush.color();
+        QColor outlineColor = buttonColor.darker(150);
+        QColor highlightColor = buttonColor.lighter(130);
+
+        // Only draw topline if the previous item is expanded
+        const QModelIndex previousIndex = model->index(index.row() - 1, index.column());
+        const bool drawTopline = (index.row() > 0 && m_view->isExpanded(previousIndex));
+        const int highlightOffset = drawTopline ? 1 : 0;
+
+        QLinearGradient gradient(option.rect.topLeft(), option.rect.bottomLeft());
+        gradient.setColorAt(0, buttonColor.lighter(102));
+        gradient.setColorAt(1, buttonColor.darker(106));
+
+        painter->setPen(Qt::NoPen);
+        painter->setBrush(gradient);
+        painter->drawRect(option.rect);
+        painter->setPen(highlightColor);
+        painter->drawLine(option.rect.topLeft() + QPoint(0, highlightOffset),
+                          option.rect.topRight() + QPoint(0, highlightOffset));
+        painter->setPen(outlineColor);
+        if (drawTopline)
+            painter->drawLine(option.rect.topLeft(), option.rect.topRight());
+        painter->drawLine(option.rect.bottomLeft(), option.rect.bottomRight());
+        painter->restore();
+
+        QStyleOption branchOption;
+        static const int i = 9;
+        const QRect r = option.rect;
+        branchOption.rect = QRect(r.left() + i / 2, r.top() + (r.height() - i) / 2, i, i);
+        branchOption.palette = option.palette;
+        branchOption.state = QStyle::State_Children;
+
+        if (m_view->isExpanded(index))
+            branchOption.state |= QStyle::State_Open;
+
+        m_view->style()->drawPrimitive(QStyle::PE_IndicatorBranch, &branchOption, painter, m_view);
+
+        // draw text
+        const QRect textrect =
+            QRect(r.left() + i * 2, r.top(), r.width() - ((5 * i) / 2), r.height());
+        const QString text = elidedText(option.fontMetrics, textrect.width(), Qt::ElideMiddle,
+                                        model->data(index, Qt::DisplayRole).toString());
+        m_view->style()->drawItemText(painter, textrect, Qt::AlignCenter, option.palette,
+                                      m_view->isEnabled(), text);
+    }
+
+    virtual QSize sizeHint(const QStyleOptionViewItem& opt, const QModelIndex& index) const override
+    {
+        return QItemDelegate::sizeHint(opt, index) + QSize(2, 2);
+    }
+
+private:
+    QTreeView* m_view;
+};
+
+} // namespace
+
 SampleToolBoxTreeWidget::SampleToolBoxTreeWidget(QWidget* parent)
     : QTreeWidget(parent), m_iconMode(false)
 {
@@ -41,7 +120,7 @@ SampleToolBoxTreeWidget::SampleToolBoxTreeWidget(QWidget* parent)
     setTextElideMode(Qt::ElideMiddle);
     setVerticalScrollMode(ScrollPerPixel);
 
-    setItemDelegate(new qdesigner_internal::SheetDelegate(this, this));
+    setItemDelegate(new GroupTitleDelegate(this, this));
 
     connect(this, &QTreeWidget::itemPressed, this, &SampleToolBoxTreeWidget::handleMousePress);
 }