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: <mesa-stable@lists.freedesktop.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 14 insertions, 5 deletions

diff --git a/src/glx/drisw_glx.c b/src/glx/drisw_glx.c
index 749ceb0..76cc321 100644
--- a/src/glx/drisw_glx.c
+++ b/src/glx/drisw_glx.c
@@ -177,9 +177,9 @@ swrastPutImage(__DRIdrawable * draw, int op,
 }
 
 static void
-swrastGetImage(__DRIdrawable * read,
-               int x, int y, int w, int h,
-               char *data, void *loaderPrivate)
+swrastGetImage2(__DRIdrawable * read,
+                int x, int y, int w, int h, int stride,
+                char *data, void *loaderPrivate)
 {
    struct drisw_drawable *prp = loaderPrivate;
    __GLXDRIdrawable *pread = &(prp->base);
@@ -193,20 +193,29 @@ swrastGetImage(__DRIdrawable * read,
    ximage->data = data;
    ximage->width = w;
    ximage->height = h;
-   ximage->bytes_per_line = bytes_per_line(w * ximage->bits_per_pixel, 32);
+   ximage->bytes_per_line = stride ? stride : bytes_per_line(w * ximage->bits_per_pixel, 32);
 
    XGetSubImage(dpy, readable, x, y, w, h, ~0L, ZPixmap, ximage, 0, 0);
 
    ximage->data = NULL;
 }
 
+static void
+swrastGetImage(__DRIdrawable * read,
+               int x, int y, int w, int h,
+               char *data, void *loaderPrivate)
+{
+   swrastGetImage2(read, x, y, w, h, 0, data, loaderPrivate);
+}
+
 static const __DRIswrastLoaderExtension swrastLoaderExtension = {
-   .base = {__DRI_SWRAST_LOADER, 2 },
+   .base = {__DRI_SWRAST_LOADER, 3 },
 
    .getDrawableInfo     = swrastGetDrawableInfo,
    .putImage            = swrastPutImage,
    .getImage            = swrastGetImage,
    .putImage2           = swrastPutImage2,
+   .getImage2           = swrastGetImage2,
 };
 
 static const __DRIextension *loader_extensions[] = {