VT Header draws smudged (see screenshot)

[vincentparrett]

From danielfr...@gmail.com on December 19, 2011 22:14:37

I recall VT's painting to be quite smooth when I used it in D7 (with Mike's releases). Now, the painting, when dragging a column, seems to be really lagging behind, and sometimes when you click on the column header and drag really quickly, you get a smudge (see screenshot). I disabled theme awareness; same problem (speaking of theme awareness, even when it was off, the XP mode was a really nice feature, now gone).

Attachment: vt2.png

Original issue: http://code.google.com/p/virtual-treeview/issues/detail?id=248

[vincentparrett]

From joachim....@gmail.com on December 23, 2014 14:02:39

Is the problem still there in V5.5.1?

[vincentparrett]

From ricardo....@gmail.com on January 06, 2015 18:48:51

This fail draw occurs on 5.52 too. When you try to change column order, and mantains cursor in vertical header range the control draws a piece in selececter column color. any solution at this moment?

[vincentparrett]

From joachim....@gmail.com on January 08, 2015 10:44:58

I'm sorry, no solution from me. I personally never worked in this part of the code so far.

[vincentparrett]

From ricardo....@gmail.com on January 08, 2015 16:23:02

Thanks any way, last thing, do you have any clue where can I start to find this bug?, or can you contact the person that work in this behavior.

[vincentparrett]

From danielfr...@gmail.com on January 09, 2015 04:02:38

Let me check if this is still the case - will get back to you ASAP.

[vincentparrett]

From ricardo....@gmail.com on January 14, 2015 17:09:41

Ok, I found a "more or less" solution.
The problem is first capture of the dragging button, in the TVTHeader.HandleHeaderMouseMove make the correct operation, changing DownIndex to NoColumn, and redrawing the header with an Invalidate but it need a direct repaint, not an invalidate, so, the code captures the header button before repaint the button in release state (the WMessage is processed later).

The solution is in TVTHeader.HandleHeaderMouseMove line 12572 in v5.52, you need to add an treview.update after invalidate, then process pending messages before call preparedrag and capture the blue button for background.

Change this ---->

if I > NoColumn then
Invalidate(FColumns[I]);

with this ---->

if I > NoColumn then begin
Invalidate(FColumns[I]);
Treeview.Update;
end;

The problem with a lagging draw is not corrected, but that is another problem, slow folow the mouse cursor and a lor of blinking, and seems that text move into dragable button. Now beautiful to see.

[vincentparrett]

From ricardo....@gmail.com on January 15, 2015 09:40:55

This code (draw on drag, this is an incredible control anyway) seems to be very buggy. Another thing with simply solution is when you drag one column not show dragcursor, to solve this, insert Windows.SetCursor(Screen.Cursors[self.DragCursor]); in first line after begin in DoHeaderDragging method.