eis: Add "viewport" interface

A MetaEisViewport represents an absolute region backend by e.g. a
pointer device. There are two kinds: a standalone viewport, which
corresponds to a viewport that has no neighbours, and a non-standalone,
which represents a region of a global coordinate space.

The reason for having non-standalone viewports is to allow to mirror the
logical monitor layout of a desktop, while the standalone are meant to
represent things that are not part of the logical monitor layout.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3228>

src/backends/meta-eis-viewport.c

@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2023 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "config.h"
+
+#include "backends/meta-eis-viewport.h"
+
+G_DEFINE_INTERFACE (MetaEisViewport, meta_eis_viewport, G_TYPE_OBJECT)
+
+static void
+meta_eis_viewport_default_init (MetaEisViewportInterface *iface)
+{
+}
+
+gboolean
+meta_eis_viewport_is_standalone (MetaEisViewport *viewport)
+{
+  return META_EIS_VIEWPORT_GET_IFACE (viewport)->is_standalone (viewport);
+}
+
+const char *
+meta_eis_viewport_get_mapping_id (MetaEisViewport *viewport)
+{
+  return META_EIS_VIEWPORT_GET_IFACE (viewport)->get_mapping_id (viewport);
+}
+
+gboolean
+meta_eis_viewport_get_position (MetaEisViewport *viewport,
+                                int             *out_x,
+                                int             *out_y)
+{
+  return META_EIS_VIEWPORT_GET_IFACE (viewport)->get_position (viewport,
+                                                               out_x,
+                                                               out_y);
+}
+
+void
+meta_eis_viewport_get_size (MetaEisViewport *viewport,
+                            int             *out_width,
+                            int             *out_height)
+{
+  META_EIS_VIEWPORT_GET_IFACE (viewport)->get_size (viewport,
+                                                    out_width,
+                                                    out_height);
+}
+
+double
+meta_eis_viewport_get_physical_scale (MetaEisViewport *viewport)
+{
+  return META_EIS_VIEWPORT_GET_IFACE (viewport)->get_physical_scale (viewport);
+}
+
+gboolean
+meta_eis_viewport_transform_coordinate (MetaEisViewport *viewport,
+                                        double           x,
+                                        double           y,
+                                        double          *out_x,
+                                        double          *out_y)
+{
+  return META_EIS_VIEWPORT_GET_IFACE (viewport)->transform_coordinate (viewport,
+                                                                       x,
+                                                                       y,
+                                                                       out_x,
+                                                                       out_y);
+}

src/backends/meta-eis-viewport.h

@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2023 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#pragma once
+
+#include <glib-object.h>
+
+#define META_TYPE_EIS_VIEWPORT (meta_eis_viewport_get_type ())
+G_DECLARE_INTERFACE (MetaEisViewport, meta_eis_viewport,
+                     META, EIS_VIEWPORT, GObject)
+
+struct _MetaEisViewportInterface
+{
+  GTypeInterface parent_iface;
+
+  gboolean (* is_standalone) (MetaEisViewport *viewport);
+
+  const char * (* get_mapping_id) (MetaEisViewport *viewport);
+
+  gboolean (* get_position) (MetaEisViewport *viewport,
+                             int             *out_x,
+                             int             *out_y);
+
+  void (* get_size) (MetaEisViewport *viewport,
+                     int             *out_width,
+                     int             *out_height);
+
+  double (* get_physical_scale) (MetaEisViewport *viewport);
+
+  gboolean (* transform_coordinate) (MetaEisViewport *viewport,
+                                     double           x,
+                                     double           y,
+                                     double          *out_x,
+                                     double          *out_y);
+};
+
+gboolean meta_eis_viewport_is_standalone (MetaEisViewport *viewport);
+
+const char * meta_eis_viewport_get_mapping_id (MetaEisViewport *viewport);
+
+gboolean meta_eis_viewport_get_position (MetaEisViewport *viewport,
+                                         int             *out_x,
+                                         int             *out_y);
+
+void meta_eis_viewport_get_size (MetaEisViewport *viewport,
+                                 int             *out_width,
+                                 int             *out_height);
+
+double meta_eis_viewport_get_physical_scale (MetaEisViewport *viewport);
+
+gboolean meta_eis_viewport_transform_coordinate (MetaEisViewport *viewport,
+                                                 double           x,
+                                                 double           y,
+                                                 double          *out_x,
+                                                 double          *out_y);

src/backends/meta-eis.h

@@ -23,6 +23,7 @@
 #include <glib-object.h>
 
 #include "backends/meta-backend-types.h"
+#include "backends/meta-eis-viewport.h"
 
 typedef enum _MetaEisDeviceTypes
 {

src/meson.build

@@ -544,6 +544,8 @@ if have_remote_desktop
     'backends/meta-eis.h',
     'backends/meta-eis-client.c',
     'backends/meta-eis-client.h',
+    'backends/meta-eis-viewport.c',
+    'backends/meta-eis-viewport.h',
     'backends/meta-remote-desktop.c',
     'backends/meta-remote-desktop.h',
     'backends/meta-remote-desktop-session.c',