[Lazarus] Calling DrawFocusRect() outside the Paint() event

[Mattias Gaertner]

On Mon, 10 Oct 2016 12:05:41 +0200 (CEST)
Michael Van Canneyt via Lazarus <lazarus at lists.lazarus-ide.org> wrote:

>[...]
> > If you want to optimize for mini changes like the focusrect you might
> > want to use a bitmap.  
> 
> Please explain ?

Draw to a bitmap and in OnPaint draw that. Similar to a TImage.
Then you can also use aggpas.


>[...]
> So, if I understand you correctly, when I want to draw a focus rect, I must 
> (roughly):
> - calculate the focusrect, 
> - Call canvas.invalidaterect() with the focusrect
> - in the paint event, check ClipRect (which should equal the focusrect)
> - and redraw anything that intersects with the cliprect ?
> 
> Correct ?

Correct.

Mattias