[Lazarus] tchart reticule mode

[JoshyFun]

Hello Lazarus-List,

Thursday, March 4, 2010, 12:34:56 AM, you wrote:

AK> Yes, TChart do draw over the control from MouseMove event.
AK> However, there is no "bitmap" for TChart, it is a TCustomControl descendant.
AK> Does that mean that I have to call Invalidate from inside MouseMove
AK> to repaint the chart every time? That would have serious performance impact.

No the invalidaterect is not needed in your case (I think). I'll
explain my case:

I have a bitmap (TImage) which is strenched and I must paint a
selection box over it so I can not paint in the bitmap because the
selection box will be also draw strenched too, so I paint over the
control:

TImage.Canvas.DrawFocusRect(...);

This procedure is not working on QT, I do not know actually if the
problem is known by the QT maintainer(s), or maybe it is regression as
I do not have experience with the QT widgetset.

In you case as you are already drawing the content, drawing in the
same way the selectionbox using a XOR pen should solve the problem at
least partially.


-- 
Best regards,
 JoshyFun