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, 10 insertions, 1 deletions

diff --git a/include/GL/internal/dri_interface.h b/include/GL/internal/dri_interface.h
index a0f155a1f42..6bbd3fa87f5 100644
--- a/include/GL/internal/dri_interface.h
+++ b/include/GL/internal/dri_interface.h
@@ -495,7 +495,7 @@ struct __DRIdamageExtensionRec {
  * SWRast Loader extension.
  */
 #define __DRI_SWRAST_LOADER "DRI_SWRastLoader"
-#define __DRI_SWRAST_LOADER_VERSION 2
+#define __DRI_SWRAST_LOADER_VERSION 3
 struct __DRIswrastLoaderExtensionRec {
     __DRIextension base;
 
@@ -528,6 +528,15 @@ struct __DRIswrastLoaderExtensionRec {
     void (*putImage2)(__DRIdrawable *drawable, int op,
                       int x, int y, int width, int height, int stride,
                       char *data, void *loaderPrivate);
+
+   /**
+     * Put image to drawable
+     *
+     * \since 3
+     */
+   void (*getImage2)(__DRIdrawable *readable,
+		     int x, int y, int width, int height, int stride,
+		     char *data, void *loaderPrivate);
 };
 
 /**