[Gambas-user] painting graph to image continuously

[wally]

On Wednesday 15 December 2010 15:10:46 Benoît Minisini wrote:
> > I'm trying to paint a continuous graph to an image, the image should grow
> > in width as needed. I thought the following code might do the job but it
> > generates not a clear graph after first Image.Resize. (see attachment)
> > 
> > How looks a better coding to do this job ?
> > thanks wally
> > 
> > code:  GB3
> > Public Sub Button4_Click()
> >   Dim t As Integer
> >   Dim y As Integer
> > 
> >   myImage1 = New Image(210, 128, Color.RGB(255, 255, 223))
> > 
> >   For t = 0 To 2000
> >     If (t Mod 25 = 0) Then
> >       y = CInt(Rnd(0, 128))
> >     Endif
> > 
> >     If t > myImage1.W Then
> >       myImage1.Resize(myImage1.w + 10, myImage1.H)
> >       PictureBox1.w += 10
> >     Endif
> > 
> > 
> >    Paint.Begin(myImage1)
> >      Paint.Brush = Paint.Color(Color.RGB(0, 0, 0))
> >      Paint.LineWidth = 1
> >      Paint.MoveTo(last_t, last_y)
> >      Paint.LineTo(t, y)
> >      Paint.Stroke
> >    Paint.End
> > 
> >    Wait 0.05
> > 
> >    PictureBox1.H = myImage1.H
> >    PictureBox1.Picture = myImage1.Picture
> >    ScrollView1.EnsureVisible(t, 64, 50, 50)
> > 
> >    last_t = t
> >    last_y = y
> >   Next
> > End
> 
> When you create an image, or enlarge it, the contents is never initialized 
by 
> default. You must paint the background of the new part first.
> 
> Regards,
> 
> -- 
> Benoît Minisini
> 
> 
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Benoit, 
thank you,
but how to paint the background of the new part first ? 
wally  :)
 
this works :          ... but isn't there a smarter way ?
              

If t > myImage1.W Then
      myImage1.Resize(myImage1.w + 1, myImage1.H)
      
      Paint.Begin(myImage1)
        Paint.Brush = Paint.Color(Color.RGB(255, 255, 223))
        Paint.Rectangle(myImage1.W - 1, 0, 1, myImage1.H)
        Paint.Fill
      Paint.End 
           
      PictureBox1.w += 1
      
    Endif