[Gambas-user] painting graph to image continuously

[Benoît Minisini]

> 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