Drawing Graphics

[mechInferno]

Hi, I have been working on a project for a class project which works similar to MS project. I have been trying to draw lines on a label (just to test) for a timeline. I can get the lines drawn, but when I scroll left to right on the form, the lines disappear. Is there anyway to make them stay or refresh the form when the scroll moves?

Kevin

 

[TipGiver]

Write a sub that paints the label, like:

    Private Sub PaintMyLabel()
        Dim g As Graphics = Label1.CreateGraphics
        g.DrawLine(Pens.Black, 0, 0, Label1.Width, Label1.Height)
    End Sub

and call it also in the paint event, like:

Private Sub Label1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Label1.Paint
    PaintMyLabel()
End Sub

Hope this helps

 

[mechInferno]

Well I kind of use this at this point.

Private Sub btnDraw_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDraw.Click
'get the difference of weeks between todays date and the selected date.
diff = DateDiff(DateInterval.WeekOfYear, today, future)
start = DateDiff(DateInterval.WeekOfYear, mbegin, today).tostring
DrawPhase(start * 25, 65, diff * 25) 'Draws the line at points for length of weeks; not to scale.

End Sub

Public Sub DrawPhase(ByVal x As Integer, ByVal y As Integer, ByVal len As Integer)
Dim Xval As Integer = x
Dim Yval As Integer = y
Dim l As Integer = len

Dim myPen As New Pen(Color.Red, 3) 'new pen object
Dim g As Graphics = Label2.CreateGraphics 'new graphics object
g.DrawLine(myPen, Xval, Yval, Xval + l, Yval) 'draws the line with pen and coordinates
End Sub

This is what I have and it draws a line with coordinates and a length. But, my problem occurs when I run the program, I have the autocroll on and when the line is drawn, the line disappears when I scroll the form. I just don't know how to keep the line there when I scroll back. If I push the draw button again it shows, I want it jsut to stay.

Thanks kevin

 

[TipGiver]

Hi,
you did not seem to have read my post. Once more:

    Private btnDraw_pressed As Boolean = False

    Private Sub btnDraw_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _
    Handles btnDraw.Click

        ' indicate that from now on, the label (after the button click) should be re-painted
        btnDraw_pressed = True
        ' refreshing the form will cause all objects to be re-painted
        Me.Refresh()

    End Sub

    Public Sub DrawPhase(ByVal x As Integer, ByVal y As Integer, ByVal len As Integer)

        Dim Xval As Integer = x
        Dim Yval As Integer = y
        Dim l As Integer = len

        Dim myPen As New Pen(Color.Red, 3)              'new pen object
        Dim g As Graphics = Label2.CreateGraphics       'new graphics object
        'draws the line with pen and coordinates
        g.DrawLine(myPen, Xval, Yval, Xval + l, Yval)

    End Sub

    Private Sub Label2_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) _
    Handles Label2.Paint

        If btnDraw_pressed Then

            'get the difference of weeks between todays date and the selected date.
            diff = DateDiff(DateInterval.WeekOfYear, Today, future)
            start = DateDiff(DateInterval.WeekOfYear, mbegin, Today).tostring
            'Draws the line at points for length of weeks; not to scale.
            DrawPhase(start * 25, 65, diff * 25)

        End If

    End Sub

Hope this now helps.
Just copy and paste it.

 

[mechInferno]

Thanks that does help. Thats exactly what I was trying to get.

Thanks again

Kevin