exo: Initial support for multiple displays in ARC

components/exo/wayland/server.cc

Index: components/exo/wayland/server.cc
diff --git a/components/exo/wayland/server.cc b/components/exo/wayland/server.cc
index 152c72694a5a051e52ba4d28ed73dfc0f02836e2..e75d30b316429aa4403d6a3f02c431b97f9d3e12 100644
--- a/components/exo/wayland/server.cc
+++ b/components/exo/wayland/server.cc
@@ -27,9 +27,9 @@
 #include <cstdlib>
 #include <iterator>
 #include <string>
+#include <unordered_set>
 #include <utility>
 
-#include "ash/common/shell_observer.h"
 #include "ash/public/cpp/shell_window_ids.h"
 #include "ash/shell.h"
 #include "base/bind.h"
@@ -1006,7 +1006,8 @@ uint32_t HandleShellSurfaceConfigureCallback(
     const gfx::Size& size,
     ash::wm::WindowStateType state_type,
     bool resizing,
-    bool activated) {
+    bool activated,
+    const gfx::Point& origin) {
   wl_shell_surface_send_configure(resource, WL_SHELL_SURFACE_RESIZE_NONE,
                                   size.width(), size.height());
   wl_client_flush(wl_resource_get_client(resource));
@@ -1089,8 +1090,6 @@ class WaylandPrimaryDisplayObserver : public display::DisplayObserver {
   }
 
   // Overridden from display::DisplayObserver:
-  void OnDisplayAdded(const display::Display& new_display) override {}
-  void OnDisplayRemoved(const display::Display& new_display) override {}
   void OnDisplayMetricsChanged(const display::Display& display,
                                uint32_t changed_metrics) override {
     if (display::Screen::GetScreen()->GetPrimaryDisplay().id() != display.id())
@@ -1533,7 +1532,8 @@ uint32_t HandleXdgToplevelV6ConfigureCallback(
     const gfx::Size& size,
     ash::wm::WindowStateType state_type,
     bool resizing,
-    bool activated) {
+    bool activated,
+    const gfx::Point& origin) {
   wl_array states;
   wl_array_init(&states);
   if (state_type == ash::wm::WINDOW_STATE_TYPE_MAXIMIZED)
@@ -1670,7 +1670,8 @@ uint32_t HandleXdgSurfaceV5ConfigureCallback(
     const gfx::Size& size,
     ash::wm::WindowStateType state_type,
     bool resizing,
-    bool activated) {
+    bool activated,
+    const gfx::Point& origin) {
   wl_array states;
   wl_array_init(&states);
   if (state_type == ash::wm::WINDOW_STATE_TYPE_MAXIMIZED)
@@ -1967,6 +1968,20 @@ void remote_surface_unset_system_modal(wl_client* client,
   GetUserDataAs<ShellSurface>(resource)->SetSystemModal(false);
 }
 
+void remote_surface_ack_configure(wl_client* client,
+                                  wl_resource* resource,
+                                  uint32_t serial) {
+  GetUserDataAs<ShellSurface>(resource)->AcknowledgeConfigure(serial);
+}
+
+void remote_surface_set_moving(wl_client* client, wl_resource* resource) {
+  GetUserDataAs<ShellSurface>(resource)->SetMoving();
+}
+
+void remote_surface_unset_moving(wl_client* client, wl_resource* resource) {
+  GetUserDataAs<ShellSurface>(resource)->UnsetMoving(false /* revert */);
+}
+
 const struct zcr_remote_surface_v1_interface remote_surface_implementation = {
     remote_surface_destroy,
     remote_surface_set_app_id,
@@ -1985,7 +2000,10 @@ const struct zcr_remote_surface_v1_interface remote_surface_implementation = {
     remote_surface_pin,
     remote_surface_unpin,
     remote_surface_set_system_modal,
-    remote_surface_unset_system_modal};
+    remote_surface_unset_system_modal,
+    remote_surface_ack_configure,
+    remote_surface_set_moving,
+    remote_surface_unset_moving};
 
 ////////////////////////////////////////////////////////////////////////////////
 // notification_surface_interface:
@@ -2002,6 +2020,25 @@ const struct zcr_notification_surface_v1_interface
 
 // Implements remote shell interface and monitors workspace state needed
 // for the remote shell interface.
+//
+// This class is also responsible for conversion between server-side screen
+// coordinates and client-side virtual coordinates. This mapping enables
+// support for multiple displays when the client is limited to a single
+// display. In that case, the client uses a virtual display computed as
+// the bounding box of the physical displays, and the server translates
+// positions based on the display layout. For example, P is the client's
+// origin in virtual coordinates, and Q is the server's origin in screen
+// coordinates.
+//
+//  P        Q
+//  +-----+ /
+//  |     |/
+//  |  2  +-----------+
+//  |     |           |
+//  +-----+     1     |
+//        |           |
+//        +-----------+
+//
 class WaylandRemoteShell : public WMHelper::MaximizeModeObserver,
                            public WMHelper::ActivationObserver,
                            public display::DisplayObserver {
@@ -2019,7 +2056,7 @@ class WaylandRemoteShell : public WMHelper::MaximizeModeObserver,
                        ? ZCR_REMOTE_SHELL_V1_LAYOUT_MODE_TABLET
                        : ZCR_REMOTE_SHELL_V1_LAYOUT_MODE_WINDOWED;
 
-    SendPrimaryDisplayMetrics();
+    SendDisplayMetrics();
     SendActivated(helper->GetActiveWindow(), nullptr);
   }
   ~WaylandRemoteShell() override {
@@ -2031,7 +2068,19 @@ class WaylandRemoteShell : public WMHelper::MaximizeModeObserver,
 
   std::unique_ptr<ShellSurface> CreateShellSurface(Surface* surface,
                                                    int container) {
-    return display_->CreateRemoteShellSurface(surface, container);
+    std::unique_ptr<ShellSurface> shell_surface =
+        display_->CreateRemoteShellSurface(surface, virtual_origin_, container);
+
+    shell_surfaces_.insert(shell_surface.get());
+    shell_surface->set_destroyed_callback(
+        base::Bind(&WaylandRemoteShell::OnShellSurfaceDestroyed,
+                   weak_ptr_factory_.GetWeakPtr(), shell_surface.get()));
+
+    return shell_surface;
+  }
+
+  void OnShellSurfaceDestroyed(ShellSurface* shell_surface) {
+    shell_surfaces_.erase(shell_surface);
   }
 
   std::unique_ptr<NotificationSurface> CreateNotificationSurface(
@@ -2041,40 +2090,40 @@ class WaylandRemoteShell : public WMHelper::MaximizeModeObserver,
   }
 
   // Overridden from display::DisplayObserver:
-  void OnDisplayAdded(const display::Display& new_display) override {}
-  void OnDisplayRemoved(const display::Display& new_display) override {}
+  void OnDisplayAdded(const display::Display& new_display) override {
+    if (IsMultiDisplaySupported())
+      ScheduleSendDisplayMetrics();
+  }
+
+  void OnDisplayRemoved(const display::Display& old_display) override {
+    if (IsMultiDisplaySupported())
+      ScheduleSendDisplayMetrics();
+  }
+
   void OnDisplayMetricsChanged(const display::Display& display,
                                uint32_t changed_metrics) override {
-    if (display::Screen::GetScreen()->GetPrimaryDisplay().id() != display.id())
+    if (!IsMultiDisplaySupported() &&
+        display::Screen::GetScreen()->GetPrimaryDisplay().id() != display.id())
       return;
 
-    // No need to update when a primary dislpay has changed without bounds
+    // No need to update when a primary display has changed without bounds
     // change. See WaylandPrimaryDisplayObserver::OnDisplayMetricsChanged
     // for more details.
     if (changed_metrics &
         (DISPLAY_METRIC_BOUNDS | DISPLAY_METRIC_DEVICE_SCALE_FACTOR |
          DISPLAY_METRIC_ROTATION | DISPLAY_METRIC_WORK_AREA)) {
-      SendDisplayMetrics(display);
+      ScheduleSendDisplayMetrics();
     }
   }
 
   // Overridden from WMHelper::MaximizeModeObserver:
   void OnMaximizeModeStarted() override {
     layout_mode_ = ZCR_REMOTE_SHELL_V1_LAYOUT_MODE_TABLET;
-
-    send_configure_after_layout_change_ = true;
-    base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
-        FROM_HERE, base::Bind(&WaylandRemoteShell::MaybeSendConfigure,
-                              weak_ptr_factory_.GetWeakPtr()),
-        base::TimeDelta::FromMilliseconds(kConfigureDelayAfterLayoutSwitchMs));
+    ScheduleSendDisplayMetrics(kConfigureDelayAfterLayoutSwitchMs);
   }
   void OnMaximizeModeEnded() override {
     layout_mode_ = ZCR_REMOTE_SHELL_V1_LAYOUT_MODE_WINDOWED;
-    send_configure_after_layout_change_ = true;
-    base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
-        FROM_HERE, base::Bind(&WaylandRemoteShell::MaybeSendConfigure,
-                              weak_ptr_factory_.GetWeakPtr()),
-        base::TimeDelta::FromMilliseconds(kConfigureDelayAfterLayoutSwitchMs));
+    ScheduleSendDisplayMetrics(kConfigureDelayAfterLayoutSwitchMs);
   }
 
   // Overridden from WMHelper::ActivationObserver:
@@ -2084,27 +2133,49 @@ class WaylandRemoteShell : public WMHelper::MaximizeModeObserver,
   }
 
  private:
-  void SendPrimaryDisplayMetrics() {
-    const display::Display primary =
-        display::Screen::GetScreen()->GetPrimaryDisplay();
-
-    SendDisplayMetrics(primary);
+  bool IsMultiDisplaySupported() const {
+    return wl_resource_get_version(remote_shell_resource_) >= 2;
   }
 
-  void MaybeSendConfigure() {
-    if (send_configure_after_layout_change_)
-      SendPrimaryDisplayMetrics();
+  void ScheduleSendDisplayMetrics(int delay_ms = 0) {
+    needs_send_display_metrics_ = true;
+    base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
+        FROM_HERE, base::Bind(&WaylandRemoteShell::SendDisplayMetrics,
+                              weak_ptr_factory_.GetWeakPtr()),
+        base::TimeDelta::FromMilliseconds(delay_ms));
   }
 
-  void SendDisplayMetrics(const display::Display& display) {
-    send_configure_after_layout_change_ = false;
+  void SendDisplayMetrics() {
+    if (!needs_send_display_metrics_)
+      return;
+    needs_send_display_metrics_ = false;
+
+    const display::Screen* screen = display::Screen::GetScreen();
+    const display::Display primary = screen->GetPrimaryDisplay();
+
+    gfx::Size size = primary.size();
 
-    const gfx::Insets& work_area_insets = display.GetWorkAreaInsets();
+    if (IsMultiDisplaySupported()) {
+      // Virtual screen is the bounding box of the displays in screen
+      // coordinates.
+      gfx::Rect bounds;
+      for (const auto& display : screen->GetAllDisplays())
+        bounds.Union(display.bounds());
+
+      virtual_origin_ = bounds.origin();
+      size = bounds.size();
+
+      for (ShellSurface* shell_surface : shell_surfaces_)
+        shell_surface->SetOrigin(virtual_origin_);
+    }
+
+    // TODO(domlaskowski): Send insets for each workspace.
+    const gfx::Insets& work_area_insets = primary.GetWorkAreaInsets();
 
     zcr_remote_shell_v1_send_configuration_changed(
-        remote_shell_resource_, display.size().width(), display.size().height(),
-        OutputTransform(display.rotation()),
-        wl_fixed_from_double(display.device_scale_factor()),
+        remote_shell_resource_, size.width(), size.height(),
+        OutputTransform(primary.rotation()),
+        wl_fixed_from_double(primary.device_scale_factor()),
         work_area_insets.left(), work_area_insets.top(),
         work_area_insets.right(), work_area_insets.bottom(), layout_mode_);
     wl_client_flush(wl_resource_get_client(remote_shell_resource_));
@@ -2149,10 +2220,15 @@ class WaylandRemoteShell : public WMHelper::MaximizeModeObserver,
   // The remote shell resource associated with observer.
   wl_resource* const remote_shell_resource_;
 
-  bool send_configure_after_layout_change_ = false;
+  bool needs_send_display_metrics_ = true;
 
   int layout_mode_ = ZCR_REMOTE_SHELL_V1_LAYOUT_MODE_WINDOWED;
 
+  // Origin of the virtual screen relative to the primary display.
+  gfx::Point virtual_origin_;
+
+  std::unordered_set<ShellSurface*> shell_surfaces_;  // Unowned.
+
   base::WeakPtrFactory<WaylandRemoteShell> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WaylandRemoteShell);
@@ -2210,6 +2286,21 @@ void HandleRemoteSurfaceStateChangedCallback(
   wl_client_flush(wl_resource_get_client(resource));
 }
 
+uint32_t HandleRemoteSurfaceConfigureCallback(
+    wl_resource* resource,
+    const gfx::Size& size,
+    ash::wm::WindowStateType state_type,
+    bool resizing,
+    bool activated,
+    const gfx::Point& origin) {
+  uint32_t serial = wl_display_next_serial(
+      wl_client_get_display(wl_resource_get_client(resource)));
+  zcr_remote_surface_v1_send_configure(resource, origin.x(), origin.y(),
+                                       serial);
+  wl_client_flush(wl_resource_get_client(resource));
+  return serial;
+}
+
 void remote_shell_get_remote_surface(wl_client* client,
                                      wl_resource* resource,
                                      uint32_t id,
@@ -2234,6 +2325,9 @@ void remote_shell_get_remote_surface(wl_client* client,
   shell_surface->set_state_changed_callback(
       base::Bind(&HandleRemoteSurfaceStateChangedCallback,
                  base::Unretained(remote_surface_resource)));
+  shell_surface->set_configure_callback(
+      base::Bind(&HandleRemoteSurfaceConfigureCallback,
+                 base::Unretained(remote_surface_resource)));
 
   SetImplementation(remote_surface_resource, &remote_surface_implementation,
                     std::move(shell_surface));
@@ -2272,7 +2366,7 @@ const struct zcr_remote_shell_v1_interface remote_shell_implementation = {
     remote_shell_destroy, remote_shell_get_remote_surface,
     remote_shell_get_notification_surface};
 
-const uint32_t remote_shell_version = 1;
+const uint32_t remote_shell_version = 2;
 
 void bind_remote_shell(wl_client* client,
                        void* data,