gallium/swrast: fix front buffer blitting. (v2)

So I've known this was broken before, cogl has a workaround
for it from what I know, but with the gallium based swrast
drivers BlitFramebuffer from back to front or vice-versa
was pretty broken.

The legacy swrast driver tracks when a front buffer is used
and does the get/put images when it is mapped/unmapped,
so this patch attempts to add the same functionality to the
gallium drivers.

It creates a new context interface to denote when a front
buffer is being created, and passes a private pointer to it,
this pointer is then used to decide on map/unmap if the
contents should be updated from the real frontbuffer using
get/put image.

This is primarily to make gtk's gl code work, the only
thing I've tested so far is the glarea test from
https://github.com/ebassi/glarea-example.git

v2: bump extension version,
check extension version before calling get image. (Ian)

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91930

Cc: <[email protected]>
Signed-off-by: Dave Airlie <[email protected]>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/gallium/include/pipe/p_screen.h b/src/gallium/include/pipe/p_screen.h
index a22fb938dbb..f868d71db23 100644
--- a/src/gallium/include/pipe/p_screen.h
+++ b/src/gallium/include/pipe/p_screen.h
@@ -169,6 +169,10 @@ struct pipe_screen {
    struct pipe_resource * (*resource_create)(struct pipe_screen *,
 					     const struct pipe_resource *templat);
 
+   struct pipe_resource * (*resource_create_front)(struct pipe_screen *,
+                                                   const struct pipe_resource *templat,
+                                                   const void *map_front_private);
+
    /**
     * Create a texture from a winsys_handle. The handle is often created in
     * another process by first creating a pipe texture and then calling