Cleanup QtWidgets (tools) examples

Cleanup QtWidgets tools examples:
 - use member-init (clang-tidy)
 - fix includes/don't include QtWidgets globally
 - include own header first
 - use nullptr (clang-tidy)
 - avoid c-style casts
 - use QVector instead QList
 - use QItemDelegate instead QStyledItemDelegate

Change-Id: Ibe9440cdf711e5cc2138c054864edebe1fc95731
Reviewed-by: Paul Wicking <paul.wicking@qt.io>

1 files changed, 3 insertions, 2 deletions

diff --git a/examples/widgets/tools/undoframework/diagramitem.h b/examples/widgets/tools/undoframework/diagramitem.h
index 1638dcbea8..13ff614427 100644
--- a/examples/widgets/tools/undoframework/diagramitem.h
+++ b/examples/widgets/tools/undoframework/diagramitem.h
@@ -66,9 +66,10 @@ public:
     enum { Type = UserType + 1 };
     enum DiagramType { Box, Triangle };
 
-    explicit DiagramItem(DiagramType diagramType, QGraphicsItem *item = 0);
+    explicit DiagramItem(DiagramType diagramType, QGraphicsItem *item = nullptr);
 
-    DiagramType diagramType() const {
+    DiagramType diagramType() const
+    {
         return polygon() == boxPolygon ? Box : Triangle;
     }
     int type() const override { return Type; }