[mutter] wayland/surface: Add support for wp_viewporter

[Jonas Ådahl <jadahl src gnome org>]

commit ba7af4f7d382f44c433a95eb55c489f342e82afc
Author: Robert Mader <robert mader posteo de>
Date:   Sat Nov 24 20:25:38 2018 +0100

    wayland/surface: Add support for wp_viewporter
    
    This adds the required bits to wayland surfaces and ties them up
    to the compositor parts.
    
    It is based on and very similar in nature to buffer transforms.
    
    From the specification:
    > The global interface exposing surface cropping and scaling
    > capabilities is used to instantiate an interface extension for a
    > wl_surface object. This extended interface will then allow cropping
    > and scaling the surface contents, effectively disconnecting the
    > direct relationship between the buffer and the surface size.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/323

 src/meson.build                          |   3 +
 src/wayland/meta-wayland-actor-surface.c |  21 +++
 src/wayland/meta-wayland-surface.c       | 124 ++++++++++++++---
 src/wayland/meta-wayland-surface.h       |  18 +++
 src/wayland/meta-wayland-versions.h      |   1 +
 src/wayland/meta-wayland-viewporter.c    | 230 +++++++++++++++++++++++++++++++
 src/wayland/meta-wayland-viewporter.h    |  30 ++++
 7 files changed, 407 insertions(+), 20 deletions(-)
---
diff --git a/src/meson.build b/src/meson.build
index a3e579d9b..8779c956e 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -523,6 +523,8 @@ if have_wayland
     'wayland/meta-wayland-touch.h',
     'wayland/meta-wayland-types.h',
     'wayland/meta-wayland-versions.h',
+    'wayland/meta-wayland-viewporter.c',
+    'wayland/meta-wayland-viewporter.h',
     'wayland/meta-wayland-wl-shell.c',
     'wayland/meta-wayland-wl-shell.h',
     'wayland/meta-wayland-xdg-foreign.c',
@@ -663,6 +665,7 @@ if have_wayland
     ['relative-pointer', 'unstable', 'v1', ],
     ['tablet', 'unstable', 'v2', ],
     ['text-input', 'unstable', 'v3', ],
+    ['viewporter', 'stable', ],
     ['xdg-foreign', 'unstable', 'v1', ],
     ['xdg-output', 'unstable', 'v1', ],
     ['xdg-shell', 'unstable', 'v6', ],
diff --git a/src/wayland/meta-wayland-actor-surface.c b/src/wayland/meta-wayland-actor-surface.c
index 56ea66e1e..2471de0a9 100644
--- a/src/wayland/meta-wayland-actor-surface.c
+++ b/src/wayland/meta-wayland-actor-surface.c
@@ -207,6 +207,27 @@ meta_wayland_actor_surface_real_sync_actor_state (MetaWaylandActorSurface *actor
 
   meta_surface_actor_set_transform (surface_actor, surface->buffer_transform);
 
+  if (surface->viewport.has_src_rect)
+    {
+      meta_surface_actor_set_viewport_src_rect (surface_actor,
+                                                &surface->viewport.src_rect);
+    }
+  else
+    {
+      meta_surface_actor_reset_viewport_src_rect (surface_actor);
+    }
+
+  if (surface->viewport.has_dst_size)
+    {
+      meta_surface_actor_set_viewport_dst_size (surface_actor,
+                                                surface->viewport.dst_width,
+                                                surface->viewport.dst_height);
+    }
+  else
+    {
+      meta_surface_actor_reset_viewport_dst_size (surface_actor);
+    }
+
   for (l = surface->subsurfaces; l; l = l->next)
     {
       MetaWaylandSurface *subsurface_surface = l->data;
diff --git a/src/wayland/meta-wayland-surface.c b/src/wayland/meta-wayland-surface.c
index f75fefd87..2351fedab 100644
--- a/src/wayland/meta-wayland-surface.c
+++ b/src/wayland/meta-wayland-surface.c
@@ -50,6 +50,7 @@
 #include "wayland/meta-wayland-region.h"
 #include "wayland/meta-wayland-seat.h"
 #include "wayland/meta-wayland-subsurface.h"
+#include "wayland/meta-wayland-viewporter.h"
 #include "wayland/meta-wayland-wl-shell.h"
 #include "wayland/meta-wayland-xdg-shell.h"
 #include "wayland/meta-window-wayland.h"
@@ -280,6 +281,8 @@ surface_process_damage (MetaWaylandSurface *surface,
   cairo_rectangle_int_t buffer_rect;
   cairo_region_t *scaled_region;
   cairo_region_t *transformed_region;
+  cairo_region_t *viewport_region;
+  ClutterRect src_rect;
   int i, n_rectangles;
 
   /* If the client destroyed the buffer it attached before committing, but
@@ -293,7 +296,6 @@ surface_process_damage (MetaWaylandSurface *surface,
     .width = get_buffer_width (surface),
     .height = get_buffer_height (surface),
   };
-  cairo_region_intersect_rectangle (buffer_region, &buffer_rect);
 
   /* Intersect the damage region with the surface region before scaling in
    * order to avoid integer overflow when scaling a damage region is too large
@@ -307,32 +309,57 @@ surface_process_damage (MetaWaylandSurface *surface,
   /* The damage region must be in the same coordinate space as the buffer,
    * i.e. scaled with surface->scale. */
   scaled_region = meta_region_scale (surface_region, surface->scale);
-  transformed_region = meta_region_transform (scaled_region,
+  if (surface->viewport.has_src_rect)
+    {
+      src_rect = (ClutterRect) {
+        .origin.x = surface->viewport.src_rect.origin.x * surface->scale,
+        .origin.y = surface->viewport.src_rect.origin.y * surface->scale,
+        .size.width = surface->viewport.src_rect.size.width * surface->scale,
+        .size.height = surface->viewport.src_rect.size.height * surface->scale
+      };
+    }
+  else
+    {
+      src_rect = (ClutterRect) {
+        .size.width = surface_rect.width * surface->scale,
+        .size.height = surface_rect.height * surface->scale,
+      };
+    }
+  viewport_region = meta_region_crop_and_scale (scaled_region,
+                                                &src_rect,
+                                                surface_rect.width *
+                                                surface->scale,
+                                                surface_rect.height *
+                                                surface->scale);
+  transformed_region = meta_region_transform (viewport_region,
                                               surface->buffer_transform,
                                               buffer_rect.width,
                                               buffer_rect.height);
 
-  /* Now add the buffer damage on top of the scaled damage region, as buffer
-   * damage is already in that scale. */
-  cairo_region_union (transformed_region, buffer_region);
+  /* Now add the scaled, cropped and transformed damage region to the
+   * buffer damage. Buffer damage is already in the correct coordinate space. */
+  cairo_region_union (buffer_region, transformed_region);
+
+  cairo_region_intersect_rectangle (buffer_region, &buffer_rect);
 
   /* First update the buffer. */
-  meta_wayland_buffer_process_damage (buffer, transformed_region);
+  meta_wayland_buffer_process_damage (buffer, buffer_region);
 
   /* Now damage the actor. The actor expects damage in the unscaled texture
    * coordinate space, i.e. same as the buffer. */
   /* XXX: Should this be a signal / callback on MetaWaylandBuffer instead? */
-  n_rectangles = cairo_region_num_rectangles (transformed_region);
+  n_rectangles = cairo_region_num_rectangles (buffer_region);
   for (i = 0; i < n_rectangles; i++)
     {
       cairo_rectangle_int_t rect;
-      cairo_region_get_rectangle (transformed_region, i, &rect);
+      cairo_region_get_rectangle (buffer_region, i, &rect);
 
       meta_surface_actor_process_damage (meta_wayland_surface_get_actor (surface),
                                          rect.x, rect.y,
                                          rect.width, rect.height);
     }
 
+  cairo_region_destroy (viewport_region);
   cairo_region_destroy (scaled_region);
   cairo_region_destroy (transformed_region);
 }
@@ -422,6 +449,8 @@ pending_state_init (MetaWaylandPendingState *state)
   state->has_new_max_size = FALSE;
 
   state->has_new_buffer_transform = FALSE;
+  state->has_new_viewport_src_rect = FALSE;
+  state->has_new_viewport_dst_size = FALSE;
 }
 
 static void
@@ -535,6 +564,22 @@ merge_pending_state (MetaWaylandPendingState *from,
       to->has_new_buffer_transform = TRUE;
     }
 
+  if (from->has_new_viewport_src_rect)
+    {
+      to->viewport_src_rect.origin.x = from->viewport_src_rect.origin.x;
+      to->viewport_src_rect.origin.y = from->viewport_src_rect.origin.y;
+      to->viewport_src_rect.size.width = from->viewport_src_rect.size.width;
+      to->viewport_src_rect.size.height = from->viewport_src_rect.size.height;
+      to->has_new_viewport_src_rect = TRUE;
+    }
+
+  if (from->has_new_viewport_dst_size)
+    {
+      to->viewport_dst_width = from->viewport_dst_width;
+      to->viewport_dst_height = from->viewport_dst_height;
+      to->has_new_viewport_dst_size = TRUE;
+    }
+
   if (to->buffer && to->buffer_destroy_handler_id == 0)
     {
       to->buffer_destroy_handler_id =
@@ -713,6 +758,22 @@ meta_wayland_surface_apply_pending_state (MetaWaylandSurface      *surface,
   if (pending->has_new_buffer_transform)
     surface->buffer_transform = pending->buffer_transform;
 
+  if (pending->has_new_viewport_src_rect)
+    {
+      surface->viewport.src_rect.origin.x = pending->viewport_src_rect.origin.x;
+      surface->viewport.src_rect.origin.y = pending->viewport_src_rect.origin.y;
+      surface->viewport.src_rect.size.width = pending->viewport_src_rect.size.width;
+      surface->viewport.src_rect.size.height = pending->viewport_src_rect.size.height;
+      surface->viewport.has_src_rect = surface->viewport.src_rect.size.width > 0;
+    }
+
+  if (pending->has_new_viewport_dst_size)
+    {
+      surface->viewport.dst_width = pending->viewport_dst_width;
+      surface->viewport.dst_height = pending->viewport_dst_height;
+      surface->viewport.has_dst_size = surface->viewport.dst_width > 0;
+    }
+
   if (meta_wayland_surface_get_actor (surface) &&
       (!cairo_region_is_empty (pending->surface_damage) ||
        !cairo_region_is_empty (pending->buffer_damage)))
@@ -1369,6 +1430,7 @@ meta_wayland_shell_init (MetaWaylandCompositor *compositor)
   meta_wayland_legacy_xdg_shell_init (compositor);
   meta_wayland_wl_shell_init (compositor);
   meta_wayland_init_gtk_shell (compositor);
+  meta_wayland_init_viewporter (compositor);
 }
 
 void
@@ -1804,25 +1866,47 @@ meta_wayland_surface_notify_geometry_changed (MetaWaylandSurface *surface)
 int
 meta_wayland_surface_get_width (MetaWaylandSurface *surface)
 {
-  int width;
-
-  if (meta_monitor_transform_is_rotated (surface->buffer_transform))
-    width = get_buffer_height (surface);
+  if (surface->viewport.has_dst_size)
+    {
+      return surface->viewport.dst_width;
+    }
+  else if (surface->viewport.has_src_rect)
+    {
+      return ceilf (surface->viewport.src_rect.size.width);
+    }
   else
-    width = get_buffer_width (surface);
+    {
+      int width;
 
-  return width / surface->scale;
+      if (meta_monitor_transform_is_rotated (surface->buffer_transform))
+        width = get_buffer_height (surface);
+      else
+        width = get_buffer_width (surface);
+
+      return width / surface->scale;
+    }
 }
 
 int
 meta_wayland_surface_get_height (MetaWaylandSurface *surface)
 {
-  int height;
-
-  if (meta_monitor_transform_is_rotated (surface->buffer_transform))
-    height = get_buffer_width (surface);
+  if (surface->viewport.has_dst_size)
+    {
+      return surface->viewport.dst_height;
+    }
+  else if (surface->viewport.has_src_rect)
+    {
+      return ceilf (surface->viewport.src_rect.size.height);
+    }
   else
-    height = get_buffer_height (surface);
+    {
+      int height;
+
+      if (meta_monitor_transform_is_rotated (surface->buffer_transform))
+        height = get_buffer_width (surface);
+      else
+        height = get_buffer_height (surface);
 
-  return height / surface->scale;
+      return height / surface->scale;
+    }
 }
diff --git a/src/wayland/meta-wayland-surface.h b/src/wayland/meta-wayland-surface.h
index 62496cfb7..63e088357 100644
--- a/src/wayland/meta-wayland-surface.h
+++ b/src/wayland/meta-wayland-surface.h
@@ -109,6 +109,11 @@ struct _MetaWaylandPendingState
 
   gboolean has_new_buffer_transform;
   MetaMonitorTransform buffer_transform;
+  gboolean has_new_viewport_src_rect;
+  ClutterRect viewport_src_rect;
+  gboolean has_new_viewport_dst_size;
+  int viewport_dst_width;
+  int viewport_dst_height;
 };
 
 struct _MetaWaylandDragDestFuncs
@@ -198,6 +203,19 @@ struct _MetaWaylandSurface
     GSList *pending_placement_ops;
   } sub;
 
+  /* wp_viewport */
+  struct {
+    struct wl_resource *resource;
+    gulong destroy_handler_id;
+
+    gboolean has_src_rect;
+    ClutterRect src_rect;
+
+    gboolean has_dst_size;
+    int dst_width;
+    int dst_height;
+  } viewport;
+
   /* table of seats for which shortcuts are inhibited */
   GHashTable *shortcut_inhibited_seats;
 };
diff --git a/src/wayland/meta-wayland-versions.h b/src/wayland/meta-wayland-versions.h
index 19a558016..674b6c4e5 100644
--- a/src/wayland/meta-wayland-versions.h
+++ b/src/wayland/meta-wayland-versions.h
@@ -54,5 +54,6 @@
 #define META_ZWP_XWAYLAND_KEYBOARD_GRAB_V1_VERSION 1
 #define META_GTK_TEXT_INPUT_VERSION         1
 #define META_ZWP_TEXT_INPUT_V3_VERSION      1
+#define META_WP_VIEWPORTER_VERSION          1
 
 #endif
diff --git a/src/wayland/meta-wayland-viewporter.c b/src/wayland/meta-wayland-viewporter.c
new file mode 100644
index 000000000..7548998c1
--- /dev/null
+++ b/src/wayland/meta-wayland-viewporter.c
@@ -0,0 +1,230 @@
+/*
+ * Wayland Support
+ *
+ * Copyright (C) 2018-2019 Robert Mader <robert mader posteo de>
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ */
+
+#include "config.h"
+
+#include "meta-wayland-viewporter.h"
+
+#include <glib.h>
+
+#include "wayland/meta-wayland-private.h"
+#include "wayland/meta-wayland-subsurface.h"
+#include "wayland/meta-wayland-surface.h"
+#include "wayland/meta-wayland-versions.h"
+
+#include "viewporter-server-protocol.h"
+
+static void
+wp_viewport_destructor (struct wl_resource *resource)
+{
+  MetaWaylandSurface *surface;
+
+  surface = wl_resource_get_user_data (resource);
+  if (!surface)
+    return;
+
+  g_signal_handler_disconnect (surface, surface->viewport.destroy_handler_id);
+  surface->viewport.destroy_handler_id = 0;
+
+  surface->pending->viewport_src_rect.size.width = -1;
+  surface->pending->viewport_dst_width = -1;
+  surface->pending->has_new_viewport_src_rect = TRUE;
+  surface->pending->has_new_viewport_dst_size = TRUE;
+
+  surface->viewport.resource = NULL;
+}
+
+static void
+on_surface_destroyed (MetaWaylandSurface *surface)
+{
+  wl_resource_set_user_data (surface->viewport.resource, NULL);
+}
+
+static void
+wp_viewport_destroy (struct wl_client   *client,
+                     struct wl_resource *resource)
+{
+  wl_resource_destroy (resource);
+}
+
+static void
+wp_viewport_set_source (struct wl_client   *client,
+                        struct wl_resource *resource,
+                        wl_fixed_t          src_x,
+                        wl_fixed_t          src_y,
+                        wl_fixed_t          src_width,
+                        wl_fixed_t          src_height)
+{
+  MetaWaylandSurface *surface;
+  float new_x;
+  float new_y;
+  float new_width;
+  float new_height;
+
+  surface = wl_resource_get_user_data (resource);
+  if (!surface)
+    {
+      wl_resource_post_error (resource,
+                              WP_VIEWPORT_ERROR_NO_SURFACE,
+                              "wl_surface for this viewport no longer exists");
+      return;
+    }
+
+  new_x = wl_fixed_to_double (src_x);
+  new_y = wl_fixed_to_double (src_y);
+  new_width = wl_fixed_to_double (src_width);
+  new_height = wl_fixed_to_double (src_height);
+
+  if ((new_x >= 0 && new_y >= 0 &&
+       new_width > 0 && new_height > 0) ||
+      (new_x == -1 && new_y == -1 &&
+       new_width == -1 && new_height == -1))
+    {
+      surface->pending->viewport_src_rect.origin.x = new_x;
+      surface->pending->viewport_src_rect.origin.y = new_y;
+      surface->pending->viewport_src_rect.size.width = new_width;
+      surface->pending->viewport_src_rect.size.height = new_height;
+      surface->pending->has_new_viewport_src_rect = TRUE;
+    }
+  else
+    {
+      wl_resource_post_error (resource,
+                              WP_VIEWPORT_ERROR_BAD_VALUE,
+                              "x and y values must be zero or positive and "
+                              "width and height valuest must be positive or "
+                              "all values must be -1 to unset the viewport");
+    }
+}
+
+static void
+wp_viewport_set_destination (struct wl_client   *client,
+                             struct wl_resource *resource,
+                             int                 dst_width,
+                             int                 dst_height)
+{
+  MetaWaylandSurface *surface;
+
+  surface = wl_resource_get_user_data (resource);
+  if (!surface)
+    {
+      wl_resource_post_error (resource,
+                              WP_VIEWPORT_ERROR_NO_SURFACE,
+                              "wl_surface for this viewport no longer exists");
+      return;
+    }
+
+  if ((dst_width > 0 && dst_height > 0) ||
+      (dst_width == -1 && dst_height == -1))
+    {
+      surface->pending->viewport_dst_width = dst_width;
+      surface->pending->viewport_dst_height = dst_height;
+      surface->pending->has_new_viewport_dst_size = TRUE;
+    }
+  else
+    {
+      wl_resource_post_error (resource,
+                              WP_VIEWPORT_ERROR_BAD_VALUE,
+                              "all values must be either positive or -1");
+    }
+}
+
+static const struct wp_viewport_interface meta_wayland_viewport_interface = {
+  wp_viewport_destroy,
+  wp_viewport_set_source,
+  wp_viewport_set_destination,
+};
+
+static void
+wp_viewporter_destroy (struct wl_client   *client,
+                       struct wl_resource *resource)
+{
+  wl_resource_destroy (resource);
+}
+
+static void
+wp_viewporter_get_viewport (struct wl_client   *client,
+                            struct wl_resource *resource,
+                            uint32_t            viewport_id,
+                            struct wl_resource *surface_resource)
+{
+  MetaWaylandSurface *surface;
+  struct wl_resource *viewport_resource;
+
+  surface = wl_resource_get_user_data (surface_resource);
+  if (surface->viewport.resource)
+    {
+      wl_resource_post_error (resource,
+                              WP_VIEWPORTER_ERROR_VIEWPORT_EXISTS,
+                              "viewport already exists on surface");
+      return;
+    }
+
+  viewport_resource = wl_resource_create (client,
+                                          &wp_viewport_interface,
+                                          wl_resource_get_version (resource),
+                                          viewport_id);
+  wl_resource_set_implementation (viewport_resource,
+                                  &meta_wayland_viewport_interface,
+                                  surface,
+                                  wp_viewport_destructor);
+
+  surface->viewport.resource = viewport_resource;
+  surface->viewport.destroy_handler_id =
+    g_signal_connect (surface,
+                      "destroy",
+                      G_CALLBACK (on_surface_destroyed),
+                      NULL);
+}
+
+static const struct wp_viewporter_interface meta_wayland_viewporter_interface = {
+  wp_viewporter_destroy,
+  wp_viewporter_get_viewport,
+};
+
+static void
+wp_viewporter_bind (struct wl_client *client,
+                    void             *data,
+                    uint32_t          version,
+                    uint32_t          id)
+{
+  struct wl_resource *resource;
+
+  resource = wl_resource_create (client,
+                                 &wp_viewporter_interface,
+                                 version,
+                                 id);
+  wl_resource_set_implementation (resource,
+                                  &meta_wayland_viewporter_interface,
+                                  data,
+                                  NULL);
+}
+
+void
+meta_wayland_init_viewporter (MetaWaylandCompositor *compositor)
+{
+  if (wl_global_create (compositor->wayland_display,
+                        &wp_viewporter_interface,
+                        META_WP_VIEWPORTER_VERSION,
+                        compositor,
+                        wp_viewporter_bind) == NULL)
+    g_error ("Failed to register a global wl-viewporter object");
+}
diff --git a/src/wayland/meta-wayland-viewporter.h b/src/wayland/meta-wayland-viewporter.h
new file mode 100644
index 000000000..8cc099b11
--- /dev/null
+++ b/src/wayland/meta-wayland-viewporter.h
@@ -0,0 +1,30 @@
+/*
+ * Wayland Support
+ *
+ * Copyright (C) 2018-2019 Robert Mader <robert mader posteo de>
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ */
+
+#ifndef META_WAYLAND_VIEWPORTER_H
+#define META_WAYLAND_VIEWPORTER_H
+
+#include "wayland/meta-wayland-types.h"
+
+void meta_wayland_init_viewporter (MetaWaylandCompositor *compositor);
+
+#endif /* META_WAYLAND_VIEWPORTER_H */