[RESOLVED] Drawn paths won't go away.

[Troy Lundin]

I have this code for drawing a path.

        Dim map As New Bitmap(l1.Size.Width, l1.Size.Height, l1.CreateGraphics)
        Dim nextPoint As Point

        Using g As Drawing.Graphics = Graphics.FromImage(map)
            Dim dPath As New Drawing2D.GraphicsPath
            For i As Integer = 0 To path.Count - 1

                Try
                    nextPoint = path(i + 1)
                Catch
                End Try

                dPath.AddLine(path(i).X * 12 + xMod, _
                              path(i).Y * 13 + yMod, _
                              nextPoint.X * 12 + xMod, _
                              nextPoint.Y * 13 + yMod)
            Next
            l1.CreateGraphics.DrawPath(Drawing.Pens.Black, dPath)
        End Using

l1 is a Label. When I call this it draws the path fine, but when I call it again it draws another path but doesn't get rid of the first path.

Basically, I only want one path on the Label at a time.

[.paul.]

invalidate l1 before drawing the next path

[Troy Lundin]

I have already tried invalidating.
I tried place l1.Invalidate() at the start and end of the method.
I even tried placing it in the calling method.

Using l1.Invalidate() causes the paths to not be drawn at all.

[.paul.]

l1.Invalidate() at the start and not at the end of the method should have the right effect

[Shaggy Hiker]

I know nothing about those objects, but I see the AddLine method of dPath being called. That suggests that dPath contains a collection of lines to which you are adding. If that is the case, then there should be a means to clear that collection or else the lines will just be redrawn.

[.paul.]

try changing this line:

Dim map As New Bitmap(l1.Size.Width, l1.Size.Height, l1.CreateGraphics)

to this:

Dim map As New Bitmap(l1.Size.Width, l1.Size.Height)

[Troy Lundin]

I figured it out. I just put all the code into the Paint event of the label. When I want to draw a line I call l1.Refesh()

@ Shaggy Hiker
dPath does contain multiple lines. The points are stored in path.
Each time I call the method I am creating dPath, so it is empty when I start.

@ .paul.
I did try your second suggestion to no avail.

If there is a way to do this without using the Paint event, I would love to know it. Until then, I am marking this as resolved. Thanks.

[.paul.]

in fact, after looking at it again, there is lots of redundant code in your first post.

first you create a bitmap, that you don't use, then a graphics object that you don't use.
i really couldn't suggest what you should try next unless you post the full code, including the values for path() + the values of xMod + yMod, so i can debug it for you.

[.paul.]

the problem with drawing on controls is that your drawing is erased next time the control is painted, which is why you should draw in the Paint event