Re: [Mesa3d-dev] [xserver patch 2/6] dri2: No need to blit from front on DRI2GetBuffers if they're just being reused.

[Michel D. <mi...@da...>]

On Sat, 2010-01-16 at 23:00 +0100, Francisco Jerez wrote: 
> It can be quite an expensive operation, so we're better off not doing
> it unless it's totally required.
> 
> Signed-off-by: Francisco Jerez <cur...@ri...>
> ---
>  hw/xfree86/dri2/dri2.c |    6 +++++-
>  1 files changed, 5 insertions(+), 1 deletions(-)
> 
> diff --git a/hw/xfree86/dri2/dri2.c b/hw/xfree86/dri2/dri2.c
> index 3db826e..3f4ed92 100644
> --- a/hw/xfree86/dri2/dri2.c
> +++ b/hw/xfree86/dri2/dri2.c
> @@ -212,6 +212,7 @@ do_get_buffers(DrawablePtr pDraw, int *width, int *height,
>      int have_fake_front = 0;
>      int front_format = 0;
>      int dimensions_match;
> +    int buffers_changed;
>      int i;
>  
>      if (!pPriv) {
> @@ -224,6 +225,8 @@ do_get_buffers(DrawablePtr pDraw, int *width, int *height,
>      dimensions_match = (pDraw->width == pPriv->width)
>  	&& (pDraw->height == pPriv->height);
>  
> +    buffers_changed = (pPriv->buffers == NULL);
> +
>      buffers = xalloc((count + 1) * sizeof(buffers[0]));
>  
>      for (i = 0; i < count; i++) {
> @@ -280,6 +283,7 @@ do_get_buffers(DrawablePtr pDraw, int *width, int *height,
>  	for (i = 0; i < pPriv->bufferCount; i++) {
>  	    if (pPriv->buffers[i] != NULL) {
>  		(*ds->DestroyBuffer)(pDraw, pPriv->buffers[i]);
> +		buffers_changed = 1;
>  	    }
>  	}
>  
> @@ -298,7 +302,7 @@ do_get_buffers(DrawablePtr pDraw, int *width, int *height,
>       * contents of the real front-buffer.  This ensures correct operation of
>       * applications that call glXWaitX before calling glDrawBuffer.
>       */
> -    if (have_fake_front) {
> +    if (have_fake_front && buffers_changed) {
>  	BoxRec box;
>  	RegionRec region;
>  

>From the comment, I think the intention is to do the copy iff there
wasn't a fake front before but there is one afterwards. Is that what it
does after your change? I'm having a hard time determining that. :}


-- 
Earthling Michel Dänzer           |                http://www.vmware.com
Libre software enthusiast         |          Debian, X and DRI developer