clutter: Add new ClutterContent type ClutterTextureContent

A simply wrapper around `CoglTexture`, making it easy to reuse
content without roundtrip from GPU to CPU memory and back.

It optionally takes a clip rectangle which is implemented by
creating a `CoglSubTexture`. A limitation here is that floating
point clips are not supported.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1888>

clutter/clutter/clutter-texture-content.c

@@ -0,0 +1,169 @@
+/*
+ * Clutter.
+ *
+ * An OpenGL based 'interactive image' library.
+ *
+ * Copyright (C) 2012  Intel Corporation.
+ * Copyright (C) 2021  Robert Mader.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author:
+ *   Emmanuele Bassi <ebassi@linux.intel.com>
+ *   Robert Mader <robert.mader@posteo.de>
+ */
+
+#include "clutter-build-config.h"
+
+#include "clutter-texture-content.h"
+
+#include "clutter-actor-private.h"
+#include "clutter-content-private.h"
+#include "clutter-paint-node.h"
+
+struct _ClutterTextureContent
+{
+  GObject parent_instance;
+
+  CoglTexture *texture;
+};
+
+static void clutter_content_iface_init (ClutterContentInterface *iface);
+
+G_DEFINE_TYPE_WITH_CODE (ClutterTextureContent, clutter_texture_content,
+                         G_TYPE_OBJECT,
+                         G_IMPLEMENT_INTERFACE (CLUTTER_TYPE_CONTENT,
+                                                clutter_content_iface_init))
+
+static void
+clutter_texture_content_finalize (GObject *gobject)
+{
+  ClutterTextureContent *texture_content = CLUTTER_TEXTURE_CONTENT (gobject);
+
+  g_clear_pointer (&texture_content->texture, cogl_object_unref);
+
+  G_OBJECT_CLASS (clutter_texture_content_parent_class)->finalize (gobject);
+}
+
+static void
+clutter_texture_content_class_init (ClutterTextureContentClass *klass)
+{
+  G_OBJECT_CLASS (klass)->finalize = clutter_texture_content_finalize;
+}
+
+static void
+clutter_texture_content_init (ClutterTextureContent *texture_content)
+{
+}
+
+static void
+clutter_texture_content_paint_content (ClutterContent      *content,
+                                       ClutterActor        *actor,
+                                       ClutterPaintNode    *root,
+                                       ClutterPaintContext *paint_context)
+{
+  ClutterTextureContent *texture_content = CLUTTER_TEXTURE_CONTENT (content);
+  ClutterPaintNode *node;
+
+  node = clutter_actor_create_texture_paint_node (actor,
+                                                  texture_content->texture);
+  clutter_paint_node_set_static_name (node, "Texture Content");
+  clutter_paint_node_add_child (root, node);
+  clutter_paint_node_unref (node);
+}
+
+static gboolean
+clutter_texture_content_get_preferred_size (ClutterContent *content,
+                                            float          *width,
+                                            float          *height)
+{
+  ClutterTextureContent *texture_content = CLUTTER_TEXTURE_CONTENT (content);
+
+  if (width != NULL)
+    *width = cogl_texture_get_width (texture_content->texture);
+
+  if (height != NULL)
+    *height = cogl_texture_get_height (texture_content->texture);
+
+  return TRUE;
+}
+
+static void
+clutter_content_iface_init (ClutterContentInterface *iface)
+{
+  iface->get_preferred_size = clutter_texture_content_get_preferred_size;
+  iface->paint_content = clutter_texture_content_paint_content;
+}
+
+/**
+ * clutter_texture_content_new_from_texture:
+ * @texture: a #CoglTexture
+ * @clip: (nullable): A clipping rectangle
+ *
+ * Creates a new #ClutterTextureContent instance for @texture, taking an
+ * internal reference to @texture.
+ *
+ * If you change the contents of the #CoglTexture you will need
+ * to manually invalidate the @texture_content with clutter_content_invalidate()
+ * in order to update the actors using @texture_content as their content.
+ *
+ * Return value: (transfer full): the newly created #ClutterTextureContent instance.
+ *   Use g_object_unref() when done.
+ */
+ClutterContent *
+clutter_texture_content_new_from_texture (CoglTexture           *texture,
+                                          cairo_rectangle_int_t *clip)
+{
+  ClutterTextureContent *texture_content;
+
+  g_return_val_if_fail (texture != NULL, NULL);
+
+  texture_content = g_object_new (CLUTTER_TYPE_TEXTURE_CONTENT, NULL);
+
+  if (clip)
+    {
+      texture_content->texture =
+        cogl_texture_new_from_sub_texture (texture,
+                                           clip->x,
+                                           clip->y,
+                                           clip->width,
+                                           clip->height);
+    }
+  else
+    {
+      texture_content->texture = cogl_object_ref (texture);
+    }
+
+  return CLUTTER_CONTENT (texture_content);
+}
+
+/**
+ * clutter_texture_content_get_texture:
+ * @texture_content: a #ClutterTextureContent
+ *
+ * Retrieves a pointer to the #CoglTexture used by @texture_content.
+ *
+ * If you change the contents of the returned #CoglTexture you will need
+ * to manually invalidate the @texture_content with clutter_content_invalidate()
+ * in order to update the actors using @texture_content as their content.
+ *
+ * Return value: (transfer none): a pointer to the #CoglTexture
+ */
+CoglTexture *
+clutter_texture_content_get_texture (ClutterTextureContent *texture_content)
+{
+  g_return_val_if_fail (CLUTTER_IS_TEXTURE_CONTENT (texture_content), NULL);
+
+  return texture_content->texture;
+}

clutter/clutter/clutter-texture-content.h

@@ -0,0 +1,53 @@
+/*
+ * Clutter.
+ *
+ * An OpenGL based 'interactive image' library.
+ *
+ * Copyright (C) 2012  Intel Corporation.
+ * Copyright (C) 2021  Robert Mader.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author:
+ *   Emmanuele Bassi <ebassi@linux.intel.com>
+ *   Robert Mader <robert.mader@posteo.de>
+ */
+
+#ifndef CLUTTER_TEXTURE_CONTENT_H
+#define CLUTTER_TEXTURE_CONTENT_H
+
+#if !defined(__CLUTTER_H_INSIDE__) && !defined(CLUTTER_COMPILATION)
+#error "Only <clutter/clutter.h> can be included directly."
+#endif
+
+#include <cogl/cogl.h>
+#include <clutter/clutter-types.h>
+
+G_BEGIN_DECLS
+
+#define CLUTTER_TYPE_TEXTURE_CONTENT (clutter_texture_content_get_type ())
+CLUTTER_EXPORT
+G_DECLARE_FINAL_TYPE (ClutterTextureContent, clutter_texture_content,
+                      CLUTTER, TEXTURE_CONTENT, GObject)
+
+CLUTTER_EXPORT
+ClutterContent * clutter_texture_content_new_from_texture (CoglTexture           *texture,
+                                                           cairo_rectangle_int_t *clip);
+
+CLUTTER_EXPORT
+CoglTexture * clutter_texture_content_get_texture (ClutterTextureContent *texture_content);
+
+G_END_DECLS
+
+#endif /* CLUTTER_TEXTURE_CONTENT_H */

clutter/clutter/clutter.h

@@ -102,6 +102,7 @@
 #include "clutter-stage-view.h"
 #include "clutter-tap-action.h"
 #include "clutter-text.h"
+#include "clutter-texture-content.h"
 #include "clutter-timeline.h"
 #include "clutter-transition-group.h"
 #include "clutter-transition.h"

clutter/clutter/meson.build

@@ -80,6 +80,7 @@ clutter_headers = [
   'clutter-tap-action.h',
   'clutter-text.h',
   'clutter-text-buffer.h',
+  'clutter-texture-content.h',
   'clutter-timeline.h',
   'clutter-transition-group.h',
   'clutter-transition.h',
@@ -173,6 +174,7 @@ clutter_sources = [
   'clutter-tap-action.c',
   'clutter-text.c',
   'clutter-text-buffer.c',
+  'clutter-texture-content.c',
   'clutter-transition-group.c',
   'clutter-transition.c',
   'clutter-timeline.c',