[GRASS5] Driver Update

[Markus Neteler]

Hi Glynn,
hi all,

(cc to GRASS 5).
Thanks for the fix, the d.rast.edit backing store problem is gone now.

So we have to watch out now for any module with backing store problems
(when using the latest Xdriver version). It can be simply fixed like
d.rast.edit. Another candidate is v.digit, there may be more modules
needing the R_stabilize() function.

Markus


On Wed, Apr 25, 2001 at 08:14:20PM +0100, Glynn Clements wrote:
> 
> Markus Neteler wrote:
> 
> > sorry to say, but the backing store is worse now. Try the
> > d.rast.edit: it doesn't display the grid any more unless
> > you wipe the GRASS monitor with aother window... This was
> > o.k. yesterday.
> 
> I suspected that this might happen in some cases. However, to my mind
> this suggests a bug in the client. progmangrass50.pdf says:
> 
>   int
>   R_stabilize ( )
>   
>   Send all pending graphics commands to the graphics driver and cause all
>   pending graphics to be drawn (provided the driver is written to comply).
>   This routine does more than R_flush and in many instances is the more ap-
>   propriate routine fo the two to use.
> 
> If this function is called, the window will be updated.
> 
> The implication of the above description is that output isn't
> guaranteed to actually be displayed until R_stabilize is called, hence
> my opinion of it being a bug in the client.
> 
> I considered adding code to auto-redraw, but I think that it's better
> to fix the clients. Requiring every graphics primitive to update the
> window immediately is potentially expensive; in XDRIVER, it doubles
> the workload; every primitive has to be drawn both to backing store
> and to the window.
> 
> In future, it may be desirable to write drivers for other devices
> where it is very necessary to have a distinct "force update"
> operation.
> 
> -- 
> Glynn Clements <glynn.clements at virgin.net>

-- 
Markus Neteler *  University of Hannover
Institute of Physical Geography and Landscape Ecology
Schneiderberg 50 * D-30167 Hannover * Germany
Tel: ++49-(0)511-762-4494  Fax: -3984

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