Fast Grid Layout

[arithmetica]

Hello everyone,

I'm trying to make grids in a picturebox in order to be able to draw some charts on it. I use the following code but it takes a lot of time to draw the grids in each frame. What can one do to make drawing of grids faster?

 Pic.Scale (0, Pic.ScaleHeight)-(Pic.ScaleWidth, 0)
 Dim i As Integer, j As Integer
 For i = 0 To Int((Pic.ScaleWidth) * 0.1)
  For j = 0 To Int((Pic.ScaleTop) * 0.1)
     Pic.Line ((i) * 10, 0)-((i) * 10, Pic.ScaleTop), vbBlue
     Pic.Line (0, (j) * 10)-(Pic.ScaleWidth, (j) * 10), vbBlue
  Next j
 Next i

Thanks for your help!

[Jenner]

Overriding the OnPaint event would yield faster results. Your code would be very similar as well. You wouldn't do it on a PictureBox though. Most advanced graphics techniques start off with throwing away all the useless controls like PictureBoxes and draw directly on the form.

[chemicalNova]

Overriding the OnPaint event would yield faster results. Your code would be very similar as well. You wouldn't do it on a PictureBox though. Most advanced graphics techniques start off with throwing away all the useless controls like PictureBoxes and draw directly on the form.

This is written in VB6..

You will need to look at the GetDIBits and SetDIBits APIs. If you are unsure how to use APIs, then you won't get anything faster.

chem

[technorobbo]

Why are you redrawing the grid in every frame. Draw the grid once and draw over it.
Several ways to do this without resorting to API calls.

1. Set autoredraw to true draw your grid then set autoredraw to false. To redraw the background with grid pic.refresh. Then you can draw the foreground lines over it.

2. Draw the grid into an invisible picturebox with autoredraw set to true. then to update your graph use paintpicture to draw background before you draw foreground

3. Use line controls for plotting they will overlay over the grid - the pic box will be their parent so they'll use the grids coordinate scale.

[arithmetica]

Thanks a lot technorobo! The first way works for me!