Visualizza wikitesto di Simulare una ProgressBar mediante una DrawingArea

La simulazione di una "ProgressBar" mediante l'uso di una "DrawingArea", può essere utile, ad esempio, per utilizzare un colore diverso da quello standard fornito dal tema grafico.

Mostriamo di seguito una "DrawingArea" che simula il comportamento di un Oggetto "ProgressBar", ma di colore giallo:
 Private DrawingArea1 As DrawingArea
 Private dw As Short
 Private dh As Short
 Private valore As Single
 Private tempus As Timer
 
 
 Public Sub Form_Open()
 
  With DrawingArea1 = New DrawingArea(Me) As "DrawingArea1"
    .X = 10
    .Y = 10
    .W = 300
    .H = 50
    .Background = Color.Red
    dw = .W / 2
    dh = .H / 2
  End With
 
  With tempus = New Timer As "Tempus"
    .Delay = 40
    .Start
  End With
 
 End
 
 
 Public Sub Tempus_Timer()
  
  If (valore * 100) / DrawingArea1.W >= 100.0 Then tempus.Stop
  valore += 1.0
  DrawingArea1.Refresh
 
 End
 
 
 Public Sub DrawingArea1_Draw()
 
  With Paint
 <FONT Color=gray>' ''Imposta il colore giallo per la "ProgressBar" simulata:''</font>
    .Brush = .Color(Color.Yellow)
    .Rectangle(0, 0, valore, DrawingArea1.H)
    .Fill 
    .Brush = .Color(Color.Blue)
    .DrawText(CStr(Fix((valore * 100) / DrawingArea1.W)) & "%", dw - (.TextExtents(CStr(valore)).W / 2),
              dh - (.TextExtents(CStr(valore)).H / 2), .TextExtents(CStr(valore)).W, .TextExtents(CStr(valore)).H, Align.Normal)
    .End
  End With
 
 End

Nel codice seguente invece si darà un effetto arcobaleno:
 Private DrawingArea1 As DrawingArea
 Private dw As Short
 Private dh As Short
 Private valore As Single
 Private tempus As Timer
 
 
 Public Sub Form_Open()
 
  With DrawingArea1 = New DrawingArea(Me) As "DrawingArea1"
    .X = 10
    .Y = 10
    .W = 300
    .H = 50
    .Background = Color.LightGray
    dw = .W / 2
    dh = .H / 2
  End With
 
  With tempus = New Timer As "Tempus"
    .Delay = 40
    .Start
  End With
 
 End
 
 
 Public Sub Tempus_Timer()
  
  If (valore * 100) / DrawingArea1.W >= 100.0 Then tempus.Stop
  valore += 1.0
  DrawingArea1.Refresh
 
 End
 
 
 Public Sub DrawingArea1_Draw()
 
  Dim c As Integer[] = [Color.Blue, Color.Green, Color.Yellow, Color.Red]
  Dim f As Float[] = [0, 0.34, 0.67, 1]
 
  With Paint
 <FONT Color=gray>' ''Imposta un motivo arcobaleno orizzontale per la "ProgressBar" simulata:''</font>
    .Brush = .LinearGradient(valore, 0, valore, DrawingArea1.H, c, f)
    .Rectangle(0, 0, valore, DrawingArea1.H)
    .Fill 
    .Brush = .Color(Color.Black)
    .DrawText(CStr(Fix((valore * 100) / DrawingArea1.W)) & "%", dw - (.TextExtents(CStr(valore)).W / 2),
              dh - (.TextExtents(CStr(valore)).H / 2), .TextExtents(CStr(valore)).W, .TextExtents(CStr(valore)).H, Align.Normal)
    .End
  End With
 
 End