Hi,
How can I force the grid to invalidate (or draw if visible) a single cell ?
Michael.
Mailing lists / lazarus / 2008-11
Grid question
6 messages · 4 people ·
- Jesus Reyes 2
- Michael Van Canneyt 2
- Alexander Klenin 1
- Graeme Geldenhuys 1
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Michael Van Canneyt wroteHow can I force the grid to invalidate (or draw if visible) a single cell ?
Grid.InvalidateCell(aCol, aRow)?
Alexander S. Klenin
Insight Experts Ltd.
How can I force the grid to invalidate (or draw if visible) a single cell ? Michael.
--- El mar 4-nov-08, Michael Van Canneyt escribi?:
Show quoted text 10 lines
De:: Michael Van Canneyt
Asunto: [Lazarus] Grid question
A: "Lazarus mailing list"
Fecha: martes, 4 noviembre, 2008, 9:23 am
Hi,
How can I force the grid to invalidate (or draw if visible)
a single cell ?
Michael.
grid.InvalidateCell(ColIndx,RowIndex);Jesus Reyes A.
?Todo sobre Amor y Sexo!
La gu?a completa para tu vida en Mujer de Hoy.
http://mx.mujer.yahoo.com/
Jesus Reyes wrote 9 lines
>
> How can I force the grid to invalidate (or draw if visible)
> a single cell ?
>
grid.InvalidateCell(ColIndx,RowIndex);
Jesus Reyes A.
Just curious....but why would you need that? Isn't the grid painting double buffered?
Regards,
- Graeme -
_______________________________________________
fpGUI - a cross-platform Free Pascal GUI toolkit
http://opensoft.homeip.net/fpgui/
--- El mar 4-nov-08, Graeme Geldenhuys escribi?:
Show quoted text 25 lines
De:: Graeme Geldenhuys
Asunto: Re: [Lazarus] Grid question
A: "General mailing list"
Fecha: martes, 4 noviembre, 2008, 10:48 am
On 11/4/08, Jesus Reyes wrote:
> >
> > How can I force the grid to invalidate (or draw
if visible)
> > a single cell ?
> >
>
>
> grid.InvalidateCell(ColIndx,RowIndex);
>
> Jesus Reyes A.
Just curious....but why would you need that? Isn't the
grid painting
double buffered?
Regards,
- Graeme -
grid does (or knows?) nothing about doublebuffer, that is handled in some other layer, but even then, it's needed in cases like the spreadsheet example when column and row header needs to be repainted because selection has changed, the grid can handle the selection change but not the headers change. It's supposedly more efficient to blit a portion of area than the whole area.
Jesus Reyes A.
?Todo sobre Amor y Sexo!
La gu?a completa para tu vida en Mujer de Hoy.
http://mx.mujer.yahoo.com/
Just curious....but why would you need that? Isn't the grid painting double buffered? -…
Graeme Geldenhuys wrote 8 lines
On 11/4/08, Jesus Reyes wrote:
> >
> > How can I force the grid to invalidate (or draw if visible)
> > a single cell ?
> >
>
>
> grid.InvalidateCell(ColIndx,RowIndex);
That is what I also expected...
Show quoted text 5 lines
>
> Jesus Reyes A.
Just curious....but why would you need that? Isn't the grid painting
double buffered?
Well, I have a special grid mediator that must redraw a TCustomDrawGrid cell, but I don't want it to do this unless it is absolutely necessary. So I tell the grid to invalidate the cell and have it figure out whether the repaint is needed or not. (and in doing so, it calculates all needed parameters such as the cell rectangle and so on)
For a stringgrid, setting the cell text will do whatever is needed, but that doesn't work in a TCustomDrawGrid.
But somehow the InvalidateCell doesn't show up in the code completion. I just get "Invalidate", which I found strange, and so I asked the question. I'll investigate this.
Thanks to everyone for the answers.
Michael.