draw a line

[xyz777]

if u draw a line,

anyidea how to rub it off (delete it)#


thank you very much

[wossname]

Depends what you are drawing on, if you are drawing on an image then you have to keep a copy of whatever was underneath.

If you are drawing onto a blank "canvas" so to speak then just use

picturebox1.CreateGraphics().Clear()

to revert the whole area to the default colour.

As soon as you draw the line, it becomes part of the image you drew it onto, it isn't a free floating object that can just be deleted easily.

[xyz777]

this is the code i used to draw a line over the main form

Dim MyPen As Pen = New Pen(Color.Red, 3)
Dim graphicsObject As Graphics = Me.CreateGraphics



graphicsObject.DrawLine(MyPen, Button1.Left + 23, Button1.Top + 12, Button1.Left + 35, Button1.Top + 12)


how I would be able to delete that,

thank you very much, have a nice day

[Pirate]

That's easy . Put 2 buttons :
1-Button1 = this clears the form .
2-Button2 = this draws on the form .

and paste this code . If you face any problem , post here .
This basically checks for the variable "clear" , and the trick is in "Me.Invalidate()" function which calls to redraw the form again in case it's invalid .

Private clear As Boolean = False
 
    Protected Overrides Sub OnPaint(ByVal e As System.Windows.Forms.PaintEventArgs)
        If clear Then
            Dim MyPen As Pen = New Pen(Color.Red, 3)
            Dim graphicsObject As Graphics = Me.CreateGraphics
            graphicsObject.DrawLine(MyPen, 0, 0, Button1.Left + 35, Button1.Top + 12)
            clear = False        
        End If
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click        
        clear = False
        Me.Invalidate()
    End Sub
 
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        clear = True
        Me.Invalidate()
    End Sub