examples/subclass: show super() calls

examples/subclass/main.go

@@ -7,20 +7,32 @@ import (
 )
 
 func main() {
-
 	qt.NewQApplication(os.Args)
+	qt.QGuiApplication_SetApplicationDisplayName("Right-click to change color")
 
-	widget := qt.NewQWidget2()
-	widget.SetFixedWidth(320)
-	widget.SetFixedHeight(240)
+	w := qt.NewQGroupBox2() // qt.NewQw2()
+	w.SetTitle("QGroupBox title")
 
-	widget.OnPaintEvent(func(ev *qt.QPaintEvent) {
-		panic("xyz")
+	w.SetFixedWidth(320)
+	w.SetFixedHeight(240)
+	w.SetMinimumHeight(100)
+	w.SetMinimumWidth(100)
 
-		ptr := qt.NewQPainter2(widget.QPaintDevice)
+	useColors := []qt.GlobalColor{
+		qt.Black, qt.Red, qt.Green, qt.Blue,
+	}
+	currentColor := 0
+
+	w.OnPaintEvent(func(super func(ev *qt.QPaintEvent), ev *qt.QPaintEvent) {
+		// Call the base class's PaintEvent to get initial content
+		// (Comment this out to see the QGroupBox disappear)
+		super(ev)
+
+		// Then, draw on top of it
+		ptr := qt.NewQPainter2(w.QPaintDevice)
 		defer ptr.Delete()
 
-		br := qt.NewQBrush12(qt.Black, qt.SolidPattern)
+		br := qt.NewQBrush12(useColors[currentColor], qt.SolidPattern)
 		defer br.Delete()
 
 		ptr.SetBrush(br)
@@ -29,9 +41,14 @@ func main() {
 		ptr.End()
 	})
 
-	widget.Show()
-	widget.Repaint()
-	widget.Update()
+	w.OnContextMenuEvent(func(super func(ev *qt.QContextMenuEvent), ev *qt.QContextMenuEvent) {
+		super(ev)
+
+		currentColor = (currentColor + 1) % len(useColors)
+		w.Update() // repaints in next event loop tick
+	})
+
+	w.Show()
 
 	qt.QApplication_Exec()
 }