GGC: Redraw Issue

[Patrick Cheng]

Hi,

I have a GGC and it seems that there is a weird behavior with the re-draw of the grid. When I scroll left and right, it seems that the grid will become messy and the data unreadable. I would then have the resize the window the GGC is in, the force a re-paint. The way around this now is to create a time which re-paints every x seconds. Is there a better way to handle this issue?

[Administrator]

This is not expected behavior in our GridGroupingControl. It is probably best to track down the reason for this. Some things to do are:

Check the output window to see if any exceptions are being shown when you see this behavior.

Look through your code to see if you have any grid.BeginUpdate calls that are not paired with grid.EndUpdate calls. And also verify that there is no execuation path that can avoid the matching grid.EndUpdate. This can cause drawing problems.

Try commenting out grid events to see if some event code is causing this behavior.

If you can upload a sample showing this issue either here or in Direct Trac, we can try to spot the problem.

[Patrick]

Hi Clay,

It seems that I have found the cause of the problem. Apparently when I set grid.TableControl.EnableDoubleBufferSurface()
it will cause the re-paint issue. However, now that I have commented it out, it seems that scrolling becomes a bit slower, not a whole lot, but you can see it is not smooth. Is there anything I can do to help smooth out the scroll?

Many thanks!

[Patrick Cheng]

Hi Clay,

Commenting it out also causes a lot of flickering to happen.

[Administrator]

In a simple form with a flat datasource, just calling this method does not cause a problem for me using the latest 6.1 library code.

Does your datasource have nested tables? If so, are you calling EnableDoubleBufferSurface() on the child TableControl as well as the parent TableControl?

Here is something to try to see if it avoids the problem when you call EnableDoubleBufferSurface(). After the scroll has completed, you could try calling grid.Refresh(). To try this, handle the TableControl.HScroll.Scrolled event.

//subscribe to the event somewhere
 this.gridGroupingControl1.TableControl.HScrollBar.Scroll += new ScrollEventHandler(HScrollBar_Scroll);
           

//the event handler code
        void HScrollBar_Scroll(object sender, ScrollEventArgs e)
        {
            if (e.Type == ScrollEventType.EndScroll)
            {
                gridGroupingControl1.Refresh();
            }
        }