Drawing Multiple Lines
 

I'm using the code

Sub PicCanvasMouseDown(sender As Object, e As MouseEventArgs)

        XPrev = e.X

        YPrev = e.Y

End Sub

        

Sub PicCanvasMouseUp(sender As Object, e As MouseEventArgs)

        XCur = e.X

        YCur = e.Y

End Sub

        

Sub PicCanvasPaint(sender As Object, e As PaintEventArgs)

        Dim p As New Pen(Color.Black, 10)

        Dim g As Graphics = e.Graphics

        g.DrawLine(p, XPrev, YPrev, XCur, YCur)

        PicCanvas.Invalidate()

End Sub

To draw a line on a PictureBox. It works fine, until you go to draw another line, when the first line dissapears, i presume this is because i'm using the same integer variables for each one (XPrev, YPrev, XCur, YCur.) How would i be able to use the same integer variables, but be able to draw more than one line ?

Re: Drawing Multiple Lines
 

Hi,
> Save the All lines Points (Make a class Line Has X and Y member and Save it in an ArrayList)
> Draw All the Lines (ArrayList) in Paint Event

Re: Drawing Multiple Lines
 

That's not really what i meant. I'm capturing the points on mouse up and down, and that works, but only for one line. i want to be able to keep that line on the picturebox, and draw another, using the same variables for capturing.

Re: Drawing Multiple Lines
 

Yes, I am also meant the same thing.

To draw all the lines you need to store it. so you should have an ArrayList or some other dynamic data structure.

ArrayList can have any object. so you need to group your Line into a class like

Public Class Line

   Public StartPoint As Point

   Public EndPoint As Point

End Class

Then create a new Line object whenever you draw line.

Sub PicCanvasMouseUp(sender As Object, e As MouseEventArgs)

        XCur = e.X

        YCur = e.Y

        Dim CurLine As New Line

        CurLine.StartPoint = New Point( XPrev,YPrev)

        CurLine.EndPoint = e.Location

        'Now Add to ArrayList for further use

        ArrayList.Add ( CurLine )

End Sub

To repaint, Iterate through the ArrayList and Draw all the Lines in the ArrayList.

Sub PicCanvasPaint(sender As Object, e As PaintEventArgs)

        Dim p As New Pen(Color.Black, 10)

        Dim g As Graphics = e.Graphics



        'Here Iterate all the Lines in the ArrayList and Draw It



        PicCanvas.Invalidate()

End Sub

This is what i meant.