TreeModel: Make root item configurable

This is mainly used to communicate the number of columns and
header contents.

Change-Id: Ic3163265338d71f1fa8250e4765bb764e5784197
Reviewed-by: Christian Stenger <christian.stenger@theqtcompany.com>

src/libs/utils/treemodel.cpp

@@ -198,6 +198,14 @@ QVariant TreeModel::data(const QModelIndex &idx, int role) const
     return item ? item->data(idx.column(), role) : QVariant();
 }
 
+QVariant TreeModel::headerData(int section, Qt::Orientation orientation,
+                               int role) const
+{
+    if (orientation == Qt::Horizontal)
+        return m_root->data(section, role);
+    return QVariant();
+}
+
 Qt::ItemFlags TreeModel::flags(const QModelIndex &idx) const
 {
     TreeItem *item = itemFromIndex(idx);
@@ -210,6 +218,12 @@ TreeItem *TreeModel::rootItem() const
     return m_root;
 }
 
+void TreeModel::setRootItem(TreeItem *item)
+{
+    delete m_root;
+    m_root = item;
+}
+
 QModelIndex TreeModel::index(int row, int column, const QModelIndex &parent) const
 {
     checkIndex(parent);

src/libs/utils/treemodel.h

@@ -87,8 +87,10 @@ public:
     QModelIndex index(int, int, const QModelIndex &idx) const;
     QModelIndex parent(const QModelIndex &idx) const;
     Qt::ItemFlags flags(const QModelIndex &idx) const;
+    QVariant headerData(int section, Qt::Orientation orientation, int role) const;
 
     TreeItem *rootItem() const;
+    void setRootItem(TreeItem *item);
     TreeItem *itemFromIndex(const QModelIndex &) const;
     QModelIndex indexFromItem(const TreeItem *needle) const;