testsubsurface: Add dmabuf support

Allow attaching dmabuf textures without downloading.

Currently, this is using create_immed, so failure to import a
dmabuf will be deadly.

gdk/gdksurface.c

@@ -493,6 +493,12 @@ gdk_surface_real_get_scale (GdkSurface *surface)
   return 1.0;
 }
 
+static GdkSubsurface *
+gdk_surface_real_create_subsurface (GdkSurface *surface)
+{
+  return NULL;
+}
+
 static void
 gdk_surface_constructed (GObject *object)
 {
@@ -515,6 +521,7 @@ gdk_surface_class_init (GdkSurfaceClass *klass)
 
   klass->beep = gdk_surface_real_beep;
   klass->get_scale = gdk_surface_real_get_scale;
+  klass->create_subsurface = gdk_surface_real_create_subsurface;
 
   /**
    * GdkSurface:cursor: (attributes org.gtk.Property.get=gdk_surface_get_cursor org.gtk.Property.set=gdk_surface_set_cursor)
@@ -3054,3 +3061,40 @@ gdk_surface_leave_monitor (GdkSurface *surface,
 {
   g_signal_emit (surface, signals[LEAVE_MONITOR], 0, monitor);
 }
+
+GdkSubsurface *
+gdk_surface_create_subsurface (GdkSurface *surface)
+{
+  return GDK_SURFACE_GET_CLASS (surface)->create_subsurface (surface);
+}
+
+void
+gdk_subsurface_destroy (GdkSubsurface *subsurface)
+{
+  subsurface->class->destroy (subsurface);
+}
+
+void
+gdk_subsurface_attach (GdkSubsurface         *subsurface,
+                       GdkTexture            *texture,
+                       const graphene_rect_t *bounds)
+{
+  subsurface->class->attach (subsurface, texture, bounds);
+}
+
+/* If sibling is NULL, place the subsurface above its parent */
+void
+gdk_subsurface_place_above (GdkSubsurface *subsurface,
+                            GdkSubsurface *sibling)
+{
+  subsurface->class->place_above (subsurface, sibling);
+}
+
+/* If sibling is NULL, place the subsurface below its parent */
+void
+gdk_subsurface_place_below (GdkSubsurface *subsurface,
+                            GdkSubsurface *sibling)
+{
+  subsurface->class->place_below (subsurface, sibling);
+}
+

gdk/gdksurfaceprivate.h

@@ -23,9 +23,14 @@
 #include "gdkenumtypes.h"
 #include "gdksurface.h"
 #include "gdktoplevel.h"
+#include <graphene.h>
 
 G_BEGIN_DECLS
 
+typedef struct _GdkSubsurface GdkSubsurface;
+
+typedef struct _GskRenderNode GskRenderNode;
+
 struct _GdkSurface
 {
   GObject parent_instance;
@@ -146,6 +151,9 @@ struct _GdkSurfaceClass
                                            cairo_region_t *region);
   void         (* request_layout)         (GdkSurface     *surface);
   gboolean     (* compute_size)           (GdkSurface     *surface);
+
+  GdkSubsurface *
+               (* create_subsurface)      (GdkSurface          *surface);
 };
 
 #define GDK_SURFACE_DESTROYED(d) (((GdkSurface *)(d))->destroyed)
@@ -334,7 +342,34 @@ void           gdk_surface_request_motion (GdkSurface *surface);
 
 gboolean       gdk_surface_supports_edge_constraints    (GdkSurface *surface);
 
+GdkSubsurface * gdk_surface_create_subsurface  (GdkSurface          *surface);
 
+typedef struct _GdkSubsurfaceClass GdkSubsurfaceClass;
+struct _GdkSubsurfaceClass
+{
+  void            (* destroy)     (GdkSubsurface         *subsurface);
+  void            (* attach)      (GdkSubsurface         *subsurface,
+                                   GdkTexture            *texture,
+                                   const graphene_rect_t *bounds);
+  void            (* place_above) (GdkSubsurface         *subsurface,
+                                   GdkSubsurface         *sibling);
+  void            (* place_below) (GdkSubsurface         *subsurface,
+                                   GdkSubsurface         *sibling);
+};
+
+struct _GdkSubsurface
+{
+  const GdkSubsurfaceClass *class;
+};
+
+void            gdk_subsurface_destroy     (GdkSubsurface         *subsurface);
+void            gdk_subsurface_attach      (GdkSubsurface         *subsurface,
+                                            GdkTexture            *texture,
+                                            const graphene_rect_t *bounds);
+void            gdk_subsurface_place_above (GdkSubsurface         *subsurface,
+                                            GdkSubsurface         *sibling);
+void            gdk_subsurface_place_below (GdkSubsurface         *subsurface,
+                                            GdkSubsurface         *sibling);
 
 G_END_DECLS
 

gdk/wayland/gdkdisplay-wayland.c

@@ -24,6 +24,7 @@
 #include <errno.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <sys/sysmacros.h>
 
 #ifdef HAVE_LINUX_MEMFD_H
 #include <linux/memfd.h>
@@ -56,6 +57,7 @@
 #include <wayland/xdg-foreign-unstable-v1-client-protocol.h>
 #include <wayland/xdg-foreign-unstable-v2-client-protocol.h>
 #include <wayland/server-decoration-client-protocol.h>
+#include "linux-dmabuf-unstable-v1-client-protocol.h"
 
 #include "wm-button-layout-translation.h"
 
@@ -267,45 +269,105 @@ postpone_on_globals_closure (GdkWaylandDisplay *display_wayland,
     g_list_append (display_wayland->on_has_globals_closures, closure);
 }
 
-#ifdef G_ENABLE_DEBUG
-
-static const char *
-get_format_name (uint32_t format,
-                 char     name[10])
-{
-  if (format == 0)
-    g_strlcpy (name, "ARGB8888", 10);
-  else if (format == 1)
-    g_strlcpy (name, "XRGB8888", 10);
-  else
-    g_snprintf (name, 10, "4cc %c%c%c%c",
-               (char) (format & 0xff),
-               (char) ((format >> 8) & 0xff),
-               (char) ((format >> 16) & 0xff),
-               (char) ((format >> 24) & 0xff));
-
-  return name;
-}
-
-#endif
-
 static void
 wl_shm_format (void          *data,
                struct wl_shm *wl_shm,
                uint32_t       format)
 {
-#ifdef G_ENABLE_DEBUG
-  char buf[10];
-#endif
-
-  GDK_DEBUG (MISC, "supported pixel format %s (0x%X)",
-                   get_format_name (format, buf), (guint) format);
+  GDK_DEBUG (MISC, "supported shm pixel format %.4s (0x%X)", (char *) &format, format);
 }
 
 static const struct wl_shm_listener wl_shm_listener = {
   wl_shm_format
 };
 
+static void
+linux_dmabuf_done (void *data,
+                   struct zwp_linux_dmabuf_feedback_v1 *zwp_linux_dmabuf_feedback_v1)
+{
+  GDK_DEBUG (MISC, "dmabuf feedback done");
+}
+
+static void
+linux_dmabuf_format_table (void *data,
+                           struct zwp_linux_dmabuf_feedback_v1 *zwp_linux_dmabuf_feedback_v1,
+                           int32_t fd,
+                           uint32_t size)
+{
+  GdkWaylandDisplay *display_wayland = data;
+
+  display_wayland->linux_dmabuf_n_formats = size / 16;
+  display_wayland->linux_dmabuf_formats = mmap (NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
+
+  GDK_DEBUG (MISC, "got dmabuf format table (%lu entries)", display_wayland->linux_dmabuf_n_formats);
+}
+
+static void
+linux_dmabuf_main_device (void *data,
+                          struct zwp_linux_dmabuf_feedback_v1 *zwp_linux_dmabuf_feedback_v1,
+                          struct wl_array *device)
+{
+  dev_t dev = *(dev_t *)device->data;
+
+  GDK_DEBUG (MISC, "got dmabuf main device: %u %u", major (dev), minor (dev));
+}
+
+static void
+linux_dmabuf_tranche_done (void *data,
+                           struct zwp_linux_dmabuf_feedback_v1 *zwp_linux_dmabuf_feedback_v1)
+{
+  GDK_DEBUG (MISC, "dmabuf feedback tranche done");
+}
+
+static void
+linux_dmabuf_tranche_target_device (void *data,
+                                    struct zwp_linux_dmabuf_feedback_v1 *zwp_linux_dmabuf_feedback_v1,
+                                    struct wl_array *device)
+{
+  dev_t dev = *(dev_t *)device->data;
+
+  GDK_DEBUG (MISC, "got dmabuf tranche target device: %u %u", major (dev), minor (dev));
+}
+
+static void
+linux_dmabuf_tranche_formats (void *data,
+                              struct zwp_linux_dmabuf_feedback_v1 *zwp_linux_dmabuf_feedback_v1,
+                              struct wl_array *indices)
+{
+  GdkWaylandDisplay *display_wayland = data;
+
+  GDK_DEBUG (MISC, "got dmabuf tranche formats (%lu entries):", indices->size / sizeof (guint16));
+  guint16 *pos;
+
+  wl_array_for_each (pos, indices)
+    {
+      LinuxDmabufFormat *fmt = &display_wayland->linux_dmabuf_formats[*pos];
+      uint32_t f = fmt->fourcc;
+      uint64_t m = fmt->modifier;
+      GDK_DEBUG (MISC, "  %.4s:%#" G_GINT64_MODIFIER "x", (char *) &f, m);
+    }
+}
+
+static void
+linux_dmabuf_tranche_flags (void *data,
+                            struct zwp_linux_dmabuf_feedback_v1 *zwp_linux_dmabuf_feedback_v1,
+                            uint32_t flags)
+{
+  GDK_DEBUG (MISC,
+             "got dmabuf tranche flags: %s",
+             flags & ZWP_LINUX_DMABUF_FEEDBACK_V1_TRANCHE_FLAGS_SCANOUT ? "scanout" : "");
+}
+
+static const struct zwp_linux_dmabuf_feedback_v1_listener linux_dmabuf_feedback_listener = {
+  linux_dmabuf_done,
+  linux_dmabuf_format_table,
+  linux_dmabuf_main_device,
+  linux_dmabuf_tranche_done,
+  linux_dmabuf_tranche_target_device,
+  linux_dmabuf_tranche_formats,
+  linux_dmabuf_tranche_flags,
+};
+
 static void
 server_decoration_manager_default_mode (void                                          *data,
                                         struct org_kde_kwin_server_decoration_manager *manager,
@@ -382,6 +444,16 @@ gdk_registry_handle_global (void               *data,
         wl_registry_bind (display_wayland->wl_registry, id, &wl_shm_interface, 1);
       wl_shm_add_listener (display_wayland->shm, &wl_shm_listener, display_wayland);
     }
+  else if (strcmp (interface, "zwp_linux_dmabuf_v1") == 0 && version >= 4)
+    {
+      display_wayland->linux_dmabuf =
+        wl_registry_bind (display_wayland->wl_registry, id, &zwp_linux_dmabuf_v1_interface, version);
+      display_wayland->linux_dmabuf_feedback =
+        zwp_linux_dmabuf_v1_get_default_feedback (display_wayland->linux_dmabuf);
+     zwp_linux_dmabuf_feedback_v1_add_listener (display_wayland->linux_dmabuf_feedback,
+                                                &linux_dmabuf_feedback_listener, display_wayland);
+      _gdk_wayland_display_async_roundtrip (display_wayland);
+    }
   else if (strcmp (interface, "xdg_wm_base") == 0)
     {
       display_wayland->xdg_wm_base_id = id;
@@ -726,6 +798,10 @@ gdk_wayland_display_dispose (GObject *object)
   g_clear_pointer (&display_wayland->xdg_activation, xdg_activation_v1_destroy);
   g_clear_pointer (&display_wayland->fractional_scale, wp_fractional_scale_manager_v1_destroy);
   g_clear_pointer (&display_wayland->viewporter, wp_viewporter_destroy);
+  g_clear_pointer (&display_wayland->linux_dmabuf, zwp_linux_dmabuf_v1_destroy);
+  g_clear_pointer (&display_wayland->linux_dmabuf_feedback, zwp_linux_dmabuf_feedback_v1_destroy);
+  if (display_wayland->linux_dmabuf_formats)
+    munmap (display_wayland->linux_dmabuf_formats, display_wayland->linux_dmabuf_n_formats * 16);
 
   g_clear_pointer (&display_wayland->shm, wl_shm_destroy);
   g_clear_pointer (&display_wayland->wl_registry, wl_registry_destroy);

gdk/wayland/gdkdisplay-wayland.h

@@ -71,6 +71,13 @@ typedef enum _GdkWaylandShellVariant
   GDK_WAYLAND_SHELL_VARIANT_ZXDG_SHELL_V6
 } GdkWaylandShellVariant;
 
+typedef struct
+{
+  uint32_t fourcc;
+  uint32_t padding;
+  uint64_t modifier;
+} LinuxDmabufFormat;
+
 struct _GdkWaylandDisplay
 {
   GdkDisplay parent_instance;
@@ -95,6 +102,10 @@ struct _GdkWaylandDisplay
   struct wl_registry *wl_registry;
   struct wl_compositor *compositor;
   struct wl_shm *shm;
+  struct zwp_linux_dmabuf_v1 *linux_dmabuf;
+  struct zwp_linux_dmabuf_feedback_v1 *linux_dmabuf_feedback;
+  gsize linux_dmabuf_n_formats;
+  LinuxDmabufFormat *linux_dmabuf_formats;
   struct xdg_wm_base *xdg_wm_base;
   struct zxdg_shell_v6 *zxdg_shell_v6;
   struct gtk_shell1 *gtk_shell;

gdk/wayland/gdkprivate-wayland.h

@@ -35,6 +35,7 @@
 #include <gdk/wayland/gdkdisplay-wayland.h>
 #include <gdk/wayland/gdkseat-wayland.h>
 
+#include <gsk/gsk.h>
 #include <xkbcommon/xkbcommon.h>
 
 
@@ -222,4 +223,3 @@ void gdk_wayland_surface_update_scale (GdkSurface *surface);
 
 GdkModifierType gdk_wayland_keymap_get_gdk_modifiers (GdkKeymap *keymap,
                                                       guint32    mods);
-

gdk/wayland/gdksurface-wayland-private.h

@@ -86,6 +86,8 @@ struct _GdkWaylandSurface
   uint32_t last_configure_serial;
 
   int state_freeze_count;
+
+  GPtrArray *subsurfaces;
 };
 
 typedef struct _GdkWaylandSurfaceClass GdkWaylandSurfaceClass;

gdk/wayland/gdksurface-wayland.c

@@ -33,9 +33,11 @@
 #include "gdksurfaceprivate.h"
 #include "gdktoplevelprivate.h"
 #include "gdkdevice-wayland-private.h"
+#include "gdkdmabuftextureprivate.h"
 
 #include <wayland/xdg-shell-unstable-v6-client-protocol.h>
 #include <wayland/xdg-foreign-unstable-v2-client-protocol.h>
+#include "linux-dmabuf-unstable-v1-client-protocol.h"
 
 #include <stdlib.h>
 #include <stdio.h>
@@ -48,6 +50,7 @@
 #include "gdksurface-wayland-private.h"
 #include "gdktoplevel-wayland-private.h"
 
+
 /**
  * GdkWaylandSurface:
  *
@@ -152,13 +155,17 @@ wl_region_from_cairo_region (GdkWaylandDisplay *display,
 }
 
 /* }}} */
-/* {{{ Surface implementation */
+ /* {{{ Surface implementation */
+
+static void gdk_wayland_subsurface_destroy (GdkSubsurface *sub);
 
 static void
 gdk_wayland_surface_init (GdkWaylandSurface *impl)
 {
   impl->scale = GDK_FRACTIONAL_SCALE_INIT_INT (1);
   impl->viewport_dirty = TRUE;
+
+  impl->subsurfaces = g_ptr_array_new ();
 }
 
 void
@@ -552,6 +559,7 @@ gdk_wayland_surface_finalize (GObject *object)
 
   g_clear_pointer (&impl->opaque_region, cairo_region_destroy);
   g_clear_pointer (&impl->input_region, cairo_region_destroy);
+  g_clear_pointer (&impl->subsurfaces, g_ptr_array_unref);
 
   G_OBJECT_CLASS (gdk_wayland_surface_parent_class)->finalize (object);
 }
@@ -1135,6 +1143,17 @@ gdk_wayland_surface_set_input_region (GdkSurface     *surface,
   impl->input_region_dirty = TRUE;
 }
 
+static void
+gdk_wayland_surface_destroy_subsurfaces (GdkWaylandSurface *impl)
+{
+  for (gsize i = 0;  i < impl->subsurfaces->len; i++)
+    {
+      GdkSubsurface *sub = g_ptr_array_index (impl->subsurfaces, i);
+      gdk_subsurface_destroy (sub);
+    }
+  g_ptr_array_set_size (impl->subsurfaces, 0);
+}
+
 static void
 gdk_wayland_surface_destroy (GdkSurface *surface,
                              gboolean    foreign_destroy)
@@ -1151,6 +1170,7 @@ gdk_wayland_surface_destroy (GdkSurface *surface,
   if (GDK_IS_TOPLEVEL (surface))
     gdk_wayland_toplevel_destroy (GDK_TOPLEVEL (surface));
 
+  gdk_wayland_surface_destroy_subsurfaces (GDK_WAYLAND_SURFACE (surface));
   gdk_wayland_surface_destroy_wl_surface (GDK_WAYLAND_SURFACE (surface));
 
   frame_clock = gdk_surface_get_frame_clock (surface);
@@ -1207,6 +1227,8 @@ gdk_wayland_surface_default_hide_surface (GdkWaylandSurface *surface)
 {
 }
 
+static GdkSubsurface *gdk_wayland_surface_create_subsurface  (GdkSurface          *surface);
+
 static void
 gdk_wayland_surface_class_init (GdkWaylandSurfaceClass *klass)
 {
@@ -1230,6 +1252,7 @@ gdk_wayland_surface_class_init (GdkWaylandSurfaceClass *klass)
   surface_class->get_scale = gdk_wayland_surface_get_scale;
   surface_class->set_opaque_region = gdk_wayland_surface_set_opaque_region;
   surface_class->request_layout = gdk_wayland_surface_request_layout;
+  surface_class->create_subsurface = gdk_wayland_surface_create_subsurface;
 
   klass->handle_configure = gdk_wayland_surface_default_handle_configure;
   klass->handle_frame = gdk_wayland_surface_default_handle_frame;
@@ -1305,4 +1328,236 @@ gdk_wayland_surface_get_wl_surface (GdkSurface *surface)
 }
 
 /* }}}} */
+/* {{{ Subsurface */
+
+typedef struct {
+  GdkSubsurface subsurface;
+
+  GdkWaylandSurface *parent;
+
+  struct wl_surface *wl_surface;
+  struct wl_subsurface *wl_subsurface;
+  struct wp_viewport *wp_viewport;
+} GdkWaylandSubsurface;
+
+static void
+dmabuf_buffer_release (void             *data,
+                       struct wl_buffer *wl_buffer)
+{
+  GdkTexture *texture = data;
+
+  g_object_unref (texture);
+  wl_buffer_destroy (wl_buffer);
+}
+
+static const struct wl_buffer_listener dmabuf_buffer_listener = {
+  dmabuf_buffer_release,
+};
+
+static struct wl_buffer *
+get_dmabuf_wl_buffer (GdkWaylandSubsurface *self,
+                      GdkTexture           *texture)
+{
+  GdkWaylandDisplay *display = GDK_WAYLAND_DISPLAY (gdk_surface_get_display (GDK_SURFACE (self->parent)));
+  const GdkDmabuf *dmabuf;
+  struct zwp_linux_buffer_params_v1 *params;
+  struct wl_buffer *wl_buffer;
+
+  dmabuf = gdk_dmabuf_texture_get_dmabuf (GDK_DMABUF_TEXTURE (texture));
+
+  params = zwp_linux_dmabuf_v1_create_params (display->linux_dmabuf);
+
+  for (gsize i = 0; i < dmabuf->n_planes; i++)
+    zwp_linux_buffer_params_v1_add (params,
+                                    dmabuf->planes[i].fd,
+                                    i,
+                                    dmabuf->planes[i].offset,
+                                    dmabuf->planes[i].stride,
+                                    dmabuf->modifier >> 32,
+                                    dmabuf->modifier & 0xffffffff);
+
+  wl_buffer = zwp_linux_buffer_params_v1_create_immed (params,
+                                                       gdk_texture_get_width (texture),
+                                                       gdk_texture_get_height (texture),
+                                                       dmabuf->fourcc,
+                                                       0);
+
+  wl_buffer_add_listener (wl_buffer, &dmabuf_buffer_listener, g_object_ref (texture));
+
+  return wl_buffer;
+}
+
+static void
+shm_buffer_release (void             *data,
+                    struct wl_buffer *wl_buffer)
+{
+  cairo_surface_t *surface = data;
+
+  /* Note: the wl_buffer is destroyed as cairo user data */
+  cairo_surface_destroy (surface);
+}
+
+static const struct wl_buffer_listener shm_buffer_listener = {
+  shm_buffer_release,
+};
+
+static struct wl_buffer *
+get_shm_wl_buffer (GdkWaylandSubsurface *self,
+                   GdkTexture           *texture)
+{
+  GdkWaylandDisplay *display = GDK_WAYLAND_DISPLAY (gdk_surface_get_display (GDK_SURFACE (self->parent)));
+  int width, height;
+  cairo_surface_t *surface;
+  GdkTextureDownloader *downloader;
+  struct wl_buffer *wl_buffer;
+
+  width = gdk_texture_get_width (texture);
+  height = gdk_texture_get_height (texture);
+  surface = gdk_wayland_display_create_shm_surface (display, width, height, &GDK_FRACTIONAL_SCALE_INIT_INT (1));
+
+  downloader = gdk_texture_downloader_new (texture);
+
+  gdk_texture_downloader_download_into (downloader,
+                                        cairo_image_surface_get_data (surface),
+                                        cairo_image_surface_get_stride (surface));
+
+  gdk_texture_downloader_free (downloader);
+
+  wl_buffer = _gdk_wayland_shm_surface_get_wl_buffer (surface);
+  wl_buffer_add_listener (wl_buffer, &shm_buffer_listener, surface);
+
+  return wl_buffer;
+}
+
+static struct wl_buffer *
+get_wl_buffer (GdkWaylandSubsurface *self,
+               GdkTexture           *texture)
+{
+  if (GDK_IS_DMABUF_TEXTURE (texture))
+    return get_dmabuf_wl_buffer (self, texture);
+  else
+    return get_shm_wl_buffer (self, texture);
+}
+
+static void
+gdk_wayland_subsurface_attach (GdkSubsurface         *sub,
+                               GdkTexture            *texture,
+                               const graphene_rect_t *rect)
+{
+  GdkWaylandSubsurface *self = (GdkWaylandSubsurface *)sub;
+
+  GDK_DEBUG (DMABUF,
+             "Attaching texture %p at %f %f %f %f",
+             texture,
+             rect->origin.x, rect->origin.y, rect->size.width, rect->size.height);
+
+  if (rect)
+    {
+      wl_subsurface_set_position (self->wl_subsurface,
+                                 floorf (rect->origin.x),
+                                 floorf (rect->origin.y));
+      wp_viewport_set_destination (self->wp_viewport,
+                                   ceilf (rect->origin.x + rect->size.width) - floorf (rect->origin.x),
+                                   ceilf (rect->origin.y + rect->size.height) - floorf (rect->origin.y));
+    }
+
+  if (texture)
+    {
+      wl_surface_attach (self->wl_surface, get_wl_buffer (self, texture), 0, 0);
+      wl_surface_damage_buffer (self->wl_surface,
+                                0, 0,
+                                gdk_texture_get_width (texture),
+                                gdk_texture_get_height (texture));
+    }
+  else
+    {
+      wl_surface_attach (self->wl_surface, NULL, 0, 0);
+    }
+
+  wl_surface_commit (self->wl_surface);
+}
+
+static void
+gdk_wayland_subsurface_destroy (GdkSubsurface *sub)
+{
+  GdkWaylandSubsurface *self = (GdkWaylandSubsurface *)sub;
+
+  g_clear_pointer (&self->wp_viewport, wp_viewport_destroy);
+  g_clear_pointer (&self->wl_subsurface, wl_subsurface_destroy);
+  g_clear_pointer (&self->wl_surface, wl_surface_destroy);
+
+  g_ptr_array_remove (self->parent->subsurfaces, self);
+
+  g_free (self);
+}
+
+static void
+gdk_wayland_subsurface_place_above (GdkSubsurface *sub,
+                                    GdkSubsurface *sibling)
+{
+  GdkWaylandSubsurface *self = (GdkWaylandSubsurface *)sub;
+  GdkWaylandSubsurface *sib = (GdkWaylandSubsurface *)sibling;
+
+  g_return_if_fail (sib == NULL || self->parent == sib->parent);
+
+  wl_subsurface_place_above (self->wl_subsurface,
+                             sib ? sib->wl_surface : self->parent->display_server.wl_surface);
+}
+
+static void
+gdk_wayland_subsurface_place_below (GdkSubsurface *sub,
+                                    GdkSubsurface *sibling)
+{
+  GdkWaylandSubsurface *self = (GdkWaylandSubsurface *)sub;
+  GdkWaylandSubsurface *sib = (GdkWaylandSubsurface *)sibling;
+
+  g_return_if_fail (sib == NULL || self->parent == sib->parent);
+
+  wl_subsurface_place_below (self->wl_subsurface,
+                             sib ? sib->wl_surface : self->parent->display_server.wl_surface);
+}
+
+static const GdkSubsurfaceClass subsurface_class = {
+  gdk_wayland_subsurface_destroy,
+  gdk_wayland_subsurface_attach,
+  gdk_wayland_subsurface_place_above,
+  gdk_wayland_subsurface_place_below,
+};
+
+static GdkSubsurface *
+gdk_wayland_surface_create_subsurface (GdkSurface *surface)
+{
+  GdkWaylandSurface *impl = GDK_WAYLAND_SURFACE (surface);
+  GdkWaylandDisplay *display = GDK_WAYLAND_DISPLAY (gdk_surface_get_display (surface));
+  GdkWaylandSubsurface *sub;
+  struct wl_region *wl_region;
+
+  if (display->viewporter == NULL)
+    {
+      GDK_DEBUG (DMABUF, "Can't use subsurfaces without viewporter");
+      return NULL;
+    }
+
+  sub = g_new0 (GdkWaylandSubsurface, 1);
+
+  sub->subsurface.class = &subsurface_class;
+
+  sub->parent = impl;
+  g_ptr_array_add (sub->parent->subsurfaces, sub);
+
+  sub->wl_surface = wl_compositor_create_surface (display->compositor);
+  wl_region = wl_compositor_create_region (display->compositor);
+  wl_surface_set_input_region (sub->wl_surface, wl_region);
+  wl_region_destroy (wl_region);
+  sub->wl_subsurface = wl_subcompositor_get_subsurface (display->subcompositor,
+                                                        sub->wl_surface,
+                                                        impl->display_server.wl_surface);
+  sub->wp_viewport = wp_viewporter_get_viewport (display->viewporter, sub->wl_surface);
+
+  GDK_DEBUG (DMABUF, "Subsurface created");
+
+  return (GdkSubsurface *) sub;
+}
+
+/* }}} */
 /* vim:set foldmethod=marker expandtab: */

gdk/wayland/meson.build

@@ -67,6 +67,7 @@ proto_sources = [
   ['idle-inhibit', 'unstable', 'v1', ],
   ['xdg-activation', 'staging', 'v1', ],
   ['fractional-scale', 'staging', 'v1', ],
+  ['linux-dmabuf', 'unstable', 'v1', ],
 ]
 
 gdk_wayland_gen_headers = []

tests/meson.build

@@ -149,3 +149,11 @@ foreach t: gtk_tests
     dependencies: [libgtk_dep, libm],
   )
 endforeach
+
+executable('testsubsurface',
+  sources: '@0@.c'.format('testsubsurface'),
+  c_args: common_cflags + ['-DGTK_COMPILATION'],
+  dependencies: libgtk_static_dep,
+  install: false,
+)
+

tests/testsubsurface.c

@@ -0,0 +1,257 @@
+#include <gtk/gtk.h>
+#include "gtk/gtkwidgetprivate.h"
+#include "gdk/gdksurfaceprivate.h"
+
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include <linux/dma-heap.h>
+#include <drm_fourcc.h>
+
+static int dma_heap_fd = -1;
+
+static gboolean
+initialize_dma_heap (void)
+{
+  dma_heap_fd = open ("/dev/dma_heap/system", O_RDONLY | O_CLOEXEC);
+  return dma_heap_fd != -1;
+}
+
+static int
+allocate_dma_buf (gsize size)
+{
+  struct dma_heap_allocation_data heap_data;
+  int ret;
+
+  heap_data.len = size;
+  heap_data.fd = 0;
+  heap_data.fd_flags = O_RDWR | O_CLOEXEC;
+  heap_data.heap_flags = 0;
+
+  ret = ioctl (dma_heap_fd, DMA_HEAP_IOCTL_ALLOC, &heap_data);
+  if (ret)
+    g_error ("dma-buf allocation failed");
+
+  return heap_data.fd;
+}
+
+static void
+free_dmabuf (gpointer data)
+{
+  close (GPOINTER_TO_INT (data));
+}
+
+static GdkTexture *
+make_dmabuf_color_texture (int width,
+                           int height,
+                           GdkRGBA *color)
+{
+  int fd;
+  guchar *buf;
+  GdkDmabufTextureBuilder *builder;
+  GdkTexture *texture;
+  gsize stride, size;
+  GError *error = NULL;
+
+  stride = width * 4;
+  size = height * stride;
+  fd = allocate_dma_buf (size);
+
+  buf = mmap (NULL, size, PROT_WRITE, MAP_SHARED, fd, 0);
+
+  for (gsize i = 0; i < width * height * 4; i += 4)
+    {
+      buf[i]     = 255 * color->blue;
+      buf[i + 1] = 255 * color->green;
+      buf[i + 2] = 255 * color->red;
+      buf[i + 3] = 255 * color->alpha;
+    }
+
+  munmap (buf, size);
+
+  builder = gdk_dmabuf_texture_builder_new ();
+  gdk_dmabuf_texture_builder_set_display (builder, gdk_display_get_default ());
+  gdk_dmabuf_texture_builder_set_width (builder, width);
+  gdk_dmabuf_texture_builder_set_height (builder, height);
+  gdk_dmabuf_texture_builder_set_fourcc (builder, DRM_FORMAT_ARGB8888);
+  gdk_dmabuf_texture_builder_set_modifier (builder, DRM_FORMAT_MOD_LINEAR);
+  gdk_dmabuf_texture_builder_set_n_planes (builder, 1);
+  gdk_dmabuf_texture_builder_set_fd (builder, 0, fd);
+  gdk_dmabuf_texture_builder_set_offset (builder, 0, 0);
+  gdk_dmabuf_texture_builder_set_stride (builder, 0, stride);
+
+  texture = gdk_dmabuf_texture_builder_build (builder, free_dmabuf, GINT_TO_POINTER (fd), &error);
+  if (texture == NULL)
+    g_error ("%s", error->message);
+
+  g_object_unref (builder);
+
+  return texture;
+}
+
+static GdkTexture *
+make_shm_color_texture (int width,
+                        int height,
+                        GdkRGBA *color)
+{
+  cairo_surface_t *surface;
+  cairo_t *cr;
+  guchar *data;
+  gsize stride;
+  GBytes *bytes;
+  GdkTexture *texture;
+
+  stride = 4 * width;
+  data = g_new (guchar, stride * height);
+
+  surface = cairo_image_surface_create_for_data (data,
+                                                 CAIRO_FORMAT_ARGB32,
+                                                 width, height,
+                                                 stride);
+  cr = cairo_create (surface);
+  gdk_cairo_set_source_rgba (cr, color);
+  cairo_paint (cr);
+
+  cairo_destroy (cr);
+  cairo_surface_destroy (surface);
+
+  bytes = g_bytes_new_take (data, stride * height);
+  texture = gdk_memory_texture_new (width, height, GDK_MEMORY_DEFAULT, bytes, stride);
+  g_bytes_unref (bytes);
+
+  return texture;
+}
+
+static GdkTexture *
+make_color_texture (int width,
+                    int height,
+                    GdkRGBA *color)
+{
+  if (dma_heap_fd != -1)
+    return make_dmabuf_color_texture (width, height, color);
+  else
+    return make_shm_color_texture (width, height, color);
+}
+
+static GdkSubsurface *
+add_subsurface (GtkWidget *window,
+                GdkRGBA *color,
+                const graphene_rect_t *rect)
+{
+  GdkSurface *surface;
+  GdkSubsurface *subsurface;
+  GdkTexture *texture;
+
+  surface = gtk_widget_get_surface (GTK_WIDGET (window));
+
+  subsurface = gdk_surface_create_subsurface (surface);
+
+  texture = make_color_texture (20, 20, color);
+
+  gdk_subsurface_attach (subsurface, texture, rect);
+
+  g_object_unref (texture);
+
+  return subsurface;
+}
+
+static GdkSubsurface *red, *blue;
+
+static void red_above_blue (GtkButton *button) { gdk_subsurface_place_above (red, blue); }
+static void red_below_blue (GtkButton *button) { gdk_subsurface_place_below (red, blue); }
+static void blue_above_red (GtkButton *button) { gdk_subsurface_place_above (blue, red); }
+static void blue_below_red (GtkButton *button) { gdk_subsurface_place_below (blue, red); }
+static void red_above_main (GtkButton *button) { gdk_subsurface_place_above (red, NULL); }
+static void red_below_main (GtkButton *button) { gdk_subsurface_place_below (red, NULL); }
+static void blue_above_main (GtkButton *button) { gdk_subsurface_place_above (blue, NULL); }
+static void blue_below_main (GtkButton *button) { gdk_subsurface_place_below (blue, NULL); }
+
+static GtkWidget *
+make_button (const char *name, gpointer cb)
+{
+  GtkWidget *button;
+
+  button = gtk_button_new_with_label (name);
+  g_signal_connect (button, "clicked", G_CALLBACK (cb), NULL);
+
+  return button;
+}
+
+static void
+change_colors (GtkButton *button)
+{
+  GdkRGBA color;
+  GdkTexture *texture;
+
+  color.red = g_random_double_range (0.5, 1);
+  color.green = g_random_double_range (0, 0.5);
+  color.blue = g_random_double_range (0, 0.5);
+  color.alpha = 1;
+
+  texture = make_color_texture (20, 20, &color);
+  gdk_subsurface_attach (red, texture, &GRAPHENE_RECT_INIT (200, 100, 50, 50));
+  g_object_unref (texture);
+
+  color.red = g_random_double_range (0, 0.5);
+  color.green = g_random_double_range (0, 0.5);
+  color.blue = g_random_double_range (0.5, 1);
+  color.alpha = 1;
+
+  texture = make_color_texture (20, 20, &color);
+  gdk_subsurface_attach (blue, texture, &GRAPHENE_RECT_INIT (180, 120, 100, 20));
+  g_object_unref (texture);
+}
+
+static GtkWidget *
+make_buttons (void)
+{
+  GtkWidget *box;
+
+  box = gtk_box_new (GTK_ORIENTATION_VERTICAL, 0);
+  gtk_box_append (GTK_BOX (box), make_button ("Red above blue", red_above_blue));
+  gtk_box_append (GTK_BOX (box), make_button ("Red below blue", red_below_blue));
+  gtk_box_append (GTK_BOX (box), make_button ("Red above main", red_above_main));
+  gtk_box_append (GTK_BOX (box), make_button ("Red below main", red_below_main));
+  gtk_box_append (GTK_BOX (box), make_button ("Blue above red", blue_above_red));
+  gtk_box_append (GTK_BOX (box), make_button ("Blue below red", blue_below_red));
+  gtk_box_append (GTK_BOX (box), make_button ("Blue above main", blue_above_main));
+  gtk_box_append (GTK_BOX (box), make_button ("Blue below main", blue_below_main));
+  gtk_box_append (GTK_BOX (box), make_button ("Change colors", change_colors));
+
+  return box;
+}
+
+int
+main (int argc, char *argv[])
+{
+  GtkWidget *window, *box;
+
+  gtk_init ();
+
+  window = gtk_window_new ();
+  gtk_window_set_default_size (GTK_WINDOW (window), 210, -1);
+  gtk_window_set_resizable (GTK_WINDOW (window), TRUE);
+
+  gtk_widget_realize (window);
+
+  if (initialize_dma_heap ())
+    g_print ("Using dambufs\n");
+  else
+    g_print ("Failed to initialize dma-heap, using shm\n");
+
+  red = add_subsurface (window, &(GdkRGBA) { 1, 0, 0, 1 }, &GRAPHENE_RECT_INIT (200, 100, 50, 50));
+  blue = add_subsurface (window, &(GdkRGBA) { 0, 0, 1, 1 }, &GRAPHENE_RECT_INIT (180, 120, 100, 20));
+
+  box = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 0);
+  gtk_window_set_child (GTK_WINDOW (window), box);
+
+  gtk_box_append (GTK_BOX (box), make_buttons ());
+
+  gtk_window_present (GTK_WINDOW (window));
+
+  while (g_list_model_get_n_items (gtk_window_get_toplevels ()) > 0)
+    g_main_context_iteration (NULL, TRUE);
+
+  return 0;
+}