[mutter] screen-cast: Move DMA buffer allocation to MetaScreenCast

[Robert Mader <rmader src gnome org>]

commit d725acb267600f97f9926c4110b23c88399c090d
Author: Jonas Ådahl <jadahl gmail com>
Date:   Wed Jun 17 17:48:05 2020 +0200

    screen-cast: Move DMA buffer allocation to MetaScreenCast
    
    The aim with centralizing it is to be able to apply global policy to DMA
    buffer allocations, e.g. disabling due to various hueristics.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1318

 src/backends/meta-screen-cast-stream-src.c | 18 +++++++-----------
 src/backends/meta-screen-cast.c            | 28 ++++++++++++++++++++++++++++
 src/backends/meta-screen-cast.h            |  4 ++++
 3 files changed, 39 insertions(+), 11 deletions(-)
---
diff --git a/src/backends/meta-screen-cast-stream-src.c b/src/backends/meta-screen-cast-stream-src.c
index 0c07f6d8ba..e0aec91152 100644
--- a/src/backends/meta-screen-cast-stream-src.c
+++ b/src/backends/meta-screen-cast-stream-src.c
@@ -720,10 +720,10 @@ on_stream_add_buffer (void             *data,
   MetaScreenCastStreamSrc *src = data;
   MetaScreenCastStreamSrcPrivate *priv =
     meta_screen_cast_stream_src_get_instance_private (src);
-  CoglContext *context =
-    clutter_backend_get_cogl_context (clutter_get_default_backend ());
-  CoglRenderer *renderer = cogl_context_get_renderer (context);
-  g_autoptr (GError) error = NULL;
+  MetaScreenCastStream *stream = meta_screen_cast_stream_src_get_stream (src);
+  MetaScreenCastSession *session = meta_screen_cast_stream_get_session (stream);
+  MetaScreenCast *screen_cast =
+    meta_screen_cast_session_get_screen_cast (session);
   CoglDmaBufHandle *dmabuf_handle;
   struct spa_buffer *spa_buffer = buffer->buffer;
   struct spa_data *spa_data = spa_buffer->datas;
@@ -735,13 +735,9 @@ on_stream_add_buffer (void             *data,
   spa_data[0].mapoffset = 0;
   spa_data[0].maxsize = stride * priv->video_format.size.height;
 
-  dmabuf_handle = cogl_renderer_create_dma_buf (renderer,
-                                                priv->stream_width,
-                                                priv->stream_height,
-                                                &error);
-
-  if (error)
-    g_debug ("Error exporting DMA buffer handle: %s", error->message);
+  dmabuf_handle = meta_screen_cast_create_dma_buf_handle (screen_cast,
+                                                          priv->stream_width,
+                                                          priv->stream_height);
 
   if (dmabuf_handle)
     {
diff --git a/src/backends/meta-screen-cast.c b/src/backends/meta-screen-cast.c
index 6422f4f19e..499598042c 100644
--- a/src/backends/meta-screen-cast.c
+++ b/src/backends/meta-screen-cast.c
@@ -94,6 +94,34 @@ meta_screen_cast_get_backend (MetaScreenCast *screen_cast)
   return screen_cast->backend;
 }
 
+CoglDmaBufHandle *
+meta_screen_cast_create_dma_buf_handle (MetaScreenCast *screen_cast,
+                                        int             width,
+                                        int             height)
+{
+  ClutterBackend *clutter_backend =
+    meta_backend_get_clutter_backend (screen_cast->backend);
+  CoglContext *cogl_context =
+    clutter_backend_get_cogl_context (clutter_backend);
+  CoglRenderer *cogl_renderer = cogl_context_get_renderer (cogl_context);
+  g_autoptr (GError) error = NULL;
+  CoglDmaBufHandle *dmabuf_handle;
+
+  dmabuf_handle = cogl_renderer_create_dma_buf (cogl_renderer,
+                                                width, height,
+                                                &error);
+  if (!dmabuf_handle)
+    {
+      g_warning ("Failed to allocate DMA buffer, "
+                 "disabling DMA buffer based screen casting: %s",
+                 error->message);
+      screen_cast->disable_dma_bufs = TRUE;
+      return NULL;
+    }
+
+  return dmabuf_handle;
+}
+
 static gboolean
 register_remote_desktop_screen_cast_session (MetaScreenCastSession  *session,
                                              const char             *remote_desktop_session_id,
diff --git a/src/backends/meta-screen-cast.h b/src/backends/meta-screen-cast.h
index af265e213e..bc1d3d29c1 100644
--- a/src/backends/meta-screen-cast.h
+++ b/src/backends/meta-screen-cast.h
@@ -56,6 +56,10 @@ GDBusConnection * meta_screen_cast_get_connection (MetaScreenCast *screen_cast);
 
 MetaBackend * meta_screen_cast_get_backend (MetaScreenCast *screen_cast);
 
+CoglDmaBufHandle * meta_screen_cast_create_dma_buf_handle (MetaScreenCast *screen_cast,
+                                                           int             width,
+                                                           int             height);
+
 MetaScreenCast * meta_screen_cast_new (MetaBackend            *backend,
                                        MetaDbusSessionWatcher *session_watcher);