Disegnare in una DrawingArea sulla base dei punti cliccati un parallelogramma con angoli retti

Cliccando almeno due volte all'interno di una DrawingArea, si disegnerà un rettangolo o un quadrato ( a seconda dei casi), che sarà definito nella sua posizione in base al punto con i valori X e Y inferiori, e nella sua dimensioni con i predetti valori, ma superiori.

Mostriamo un possibile codice:

Private DrawingArea1 As DrawingArea
Private Button1 As Button
Private xx As New Short[]
Private yy As New Short[]
Private bo As Boolean


Public Sub Form_Open()

 With Me
   .W = Screen.AvailableWidth * 0.5
   .H = Screen.AvailableHeight * 0.5
 End With
 With DrawingArea1 = New DrawingArea(Me) As "DrawingArea1"
   .X = 0
   .Y = 0
   .W = Me.W
   .H = Me.H * 0.8
   .Background = Color.SoftYellow
 End With
 With Button1 = New Button(Me) As "Button1"
   .W = Me.W * 0.15
   .H = Me.H * 0.15
   .X = (Me.W / 2) - (.W / 2)
   .Y = Me.H - .H
 End With
 
End


Public Sub DrawingArea1_MouseUp()
 
 xx.Push(Mouse.X)
 yy.Push(Mouse.Y)

End


Public Sub Button1_Click()

 bo = True
 DrawingArea1.Refresh

End


Public Sub DrawingArea1_Draw()
 
 If Not bo Then Return 

 Dim a, b, c As Short

 With Paint
   For c = 0 To xx.Max
     .Arc(xx[c], yy[c], 2, Rad(0), Rad(360), False)
     .Fill
   Next
   a = xx.Sort(gb.Ascent)[0]
   b = yy.Sort(gb.Ascent)[0]
   .DrawRect(xx.Sort(gb.Ascent)[0], yy.Sort(gb.Ascent)[0], xx.Sort(gb.Descent)[0] - a, yy.Sort(gb.Descent)[0] - b, Color.Red)
   .Stroke
   .End
 End With
 
 xx.Clear
 yy.Clear
 
End