[client] wayland: move libdecor and xdg into seperate backends

This allows us to build with libdecor enabled as the selection to use it
is decided upon at runtime if the compositor `gnome-shell` is detected.
If the libdecor development headers are installed, by default it will
now be compiled in unless overridden by the user at compile time.

client/displayservers/Wayland/desktops/xdg/CMakeLists.txt

@@ -0,0 +1,15 @@
+cmake_minimum_required(VERSION 3.0)
+project(wayland_desktop_xdg LANGUAGES C)
+
+add_library(wayland_desktop_xdg STATIC
+  xdg.c
+)
+
+target_link_libraries(wayland_desktop_xdg
+  lg_common
+  wayland_protocol
+)
+
+include_directories(
+  "../../"
+)

client/displayservers/Wayland/desktops/xdg/xdg.c

@@ -0,0 +1,314 @@
+/**
+ * Looking Glass
+ * Copyright © 2017-2023 The Looking Glass Authors
+ * https://looking-glass.io
+ *
+ * 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 "wayland.h"
+#include "wayland-xdg-shell-client-protocol.h"
+#include "wayland-xdg-decoration-unstable-v1-client-protocol.h"
+
+#include <stdbool.h>
+#include <string.h>
+#include <sys/epoll.h>
+#include <errno.h>
+
+#include <wayland-client.h>
+
+#include "app.h"
+#include "common/debug.h"
+
+// Maximum number of fds we can process at once in waylandWait
+#define MAX_EPOLL_EVENTS 10
+
+typedef struct XDGState
+{
+  bool configured;
+
+  struct xdg_wm_base                 * wmBase;
+  struct xdg_surface                 * surface;
+  struct xdg_toplevel                * toplevel;
+  struct zxdg_decoration_manager_v1  * decorationManager;
+  struct zxdg_toplevel_decoration_v1 * toplevelDecoration;
+
+  int32_t width, height;
+  uint32_t resizeSerial;
+  bool fullscreen;
+  bool floating;
+  int displayFd;
+}
+XDGState;
+
+static XDGState state = {0};
+
+// XDG WM base listeners.
+
+static void xdgWmBasePing(void * data, struct xdg_wm_base * xdgWmBase, uint32_t serial)
+{
+  xdg_wm_base_pong(xdgWmBase, serial);
+}
+
+static const struct xdg_wm_base_listener xdgWmBaseListener = {
+  .ping = xdgWmBasePing,
+};
+
+// XDG Surface listeners.
+
+static void xdgSurfaceConfigure(void * data, struct xdg_surface * xdgSurface,
+    uint32_t serial)
+{
+  if (state.configured)
+  {
+    state.resizeSerial = serial;
+    waylandNeedsResize();
+  }
+  else
+  {
+    xdg_surface_ack_configure(xdgSurface, serial);
+    state.configured = true;
+  }
+}
+
+static const struct xdg_surface_listener xdgSurfaceListener = {
+  .configure = xdgSurfaceConfigure,
+};
+
+// XDG Toplevel listeners.
+
+static void xdgToplevelConfigure(void * data, struct xdg_toplevel * xdgToplevel,
+    int32_t width, int32_t height, struct wl_array * states)
+{
+  state.width      = width;
+  state.height     = height;
+  state.fullscreen = false;
+  state.floating   = true;
+
+  enum xdg_toplevel_state * s;
+  wl_array_for_each(s, states)
+  {
+    switch (*s)
+    {
+      case XDG_TOPLEVEL_STATE_FULLSCREEN:
+        state.fullscreen = true;
+        // fallthrough
+      case XDG_TOPLEVEL_STATE_MAXIMIZED:
+      case XDG_TOPLEVEL_STATE_TILED_LEFT:
+      case XDG_TOPLEVEL_STATE_TILED_RIGHT:
+      case XDG_TOPLEVEL_STATE_TILED_TOP:
+      case XDG_TOPLEVEL_STATE_TILED_BOTTOM:
+        state.floating = false;
+        break;
+
+      default:
+        break;
+    }
+  }
+}
+
+static void xdgToplevelClose(void * data, struct xdg_toplevel * xdgToplevel)
+{
+  app_handleCloseEvent();
+}
+
+static const struct xdg_toplevel_listener xdgToplevelListener = {
+  .configure = xdgToplevelConfigure,
+  .close     = xdgToplevelClose,
+};
+
+bool xdg_shellInit(struct wl_display * display, struct wl_surface * surface,
+    const char * title, bool fullscreen, bool maximize, bool borderless,
+    bool resizable)
+{
+  if (!state.wmBase)
+  {
+    DEBUG_ERROR("Compositor missing xdg_wm_base, will not proceed");
+    return false;
+  }
+
+  xdg_wm_base_add_listener(state.wmBase, &xdgWmBaseListener, NULL);
+
+  state.surface = xdg_wm_base_get_xdg_surface(state.wmBase, surface);
+  xdg_surface_add_listener(state.surface, &xdgSurfaceListener, NULL);
+
+  state.toplevel = xdg_surface_get_toplevel(state.surface);
+  xdg_toplevel_add_listener(state.toplevel, &xdgToplevelListener, NULL);
+  xdg_toplevel_set_title(state.toplevel, title);
+  xdg_toplevel_set_app_id(state.toplevel, "looking-glass-client");
+
+  if (fullscreen)
+    xdg_toplevel_set_fullscreen(state.toplevel, NULL);
+
+  if (maximize)
+    xdg_toplevel_set_maximized(state.toplevel);
+
+  if (state.decorationManager)
+  {
+    state.toplevelDecoration = zxdg_decoration_manager_v1_get_toplevel_decoration(
+        state.decorationManager, state.toplevel);
+    if (state.toplevelDecoration)
+    {
+      zxdg_toplevel_decoration_v1_set_mode(state.toplevelDecoration,
+          borderless ?
+            ZXDG_TOPLEVEL_DECORATION_V1_MODE_CLIENT_SIDE :
+            ZXDG_TOPLEVEL_DECORATION_V1_MODE_SERVER_SIDE);
+    }
+  }
+
+  return true;
+}
+
+static void xdg_shellAckConfigureIfNeeded(void)
+{
+  if (state.resizeSerial)
+  {
+    xdg_surface_ack_configure(state.surface, state.resizeSerial);
+    state.resizeSerial = 0;
+  }
+}
+
+static void xdg_setFullscreen(bool fs)
+{
+  if (fs)
+    xdg_toplevel_set_fullscreen(state.toplevel, NULL);
+  else
+    xdg_toplevel_unset_fullscreen(state.toplevel);
+}
+
+static bool xdg_getFullscreen(void)
+{
+  return state.fullscreen;
+}
+
+static void xdg_minimize(void)
+{
+  xdg_toplevel_set_minimized(state.toplevel);
+}
+
+static void xdg_shellResize(int w, int h)
+{
+  if (!state.floating)
+    return;
+
+  state.width  = w;
+  state.height = h;
+  xdg_surface_set_window_geometry(state.surface, 0, 0, w, h);
+
+  waylandNeedsResize();
+}
+
+static void xdg_setSize(int w, int h)
+{
+  state.width  = w;
+  state.height = h;
+}
+
+static void xdg_getSize(int * w, int * h)
+{
+  *w = state.width;
+  *h = state.height;
+}
+
+static bool xdg_registryGlobalHandler(void * data,
+    struct wl_registry * registry, uint32_t name, const char * interface,
+    uint32_t version)
+{
+  if (!strcmp(interface, xdg_wm_base_interface.name))
+  {
+    state.wmBase = wl_registry_bind(registry, name,
+        &xdg_wm_base_interface, 1);
+    return true;
+  }
+
+  if (!strcmp(interface, zxdg_decoration_manager_v1_interface.name))
+  {
+    state.decorationManager = wl_registry_bind(registry, name,
+        &zxdg_decoration_manager_v1_interface, 1);
+    return true;
+  }
+
+  return false;
+}
+
+static void waylandDisplayCallback(uint32_t events, void * opaque)
+{
+  struct wl_display * display = (struct wl_display *)opaque;
+  if (events & EPOLLERR)
+    wl_display_cancel_read(display);
+  else
+    wl_display_read_events(display);
+  wl_display_dispatch_pending(display);
+}
+
+static bool xdg_pollInit(struct wl_display * display)
+{
+  state.displayFd = wl_display_get_fd(display);
+  if (!waylandPollRegister(state.displayFd, waylandDisplayCallback,
+        display, EPOLLIN))
+  {
+    DEBUG_ERROR("Failed register display to epoll: %s", strerror(errno));
+    return false;
+  }
+
+  return true;
+}
+
+void xdg_pollWait(struct wl_display * display, int epollFd,
+    unsigned int time)
+{
+  while (wl_display_prepare_read(display))
+    wl_display_dispatch_pending(display);
+  wl_display_flush(display);
+
+  struct epoll_event events[MAX_EPOLL_EVENTS];
+  int count;
+  if ((count = epoll_wait(epollFd, events, MAX_EPOLL_EVENTS, time)) < 0)
+  {
+    if (errno != EINTR)
+      DEBUG_INFO("epoll failed: %s", strerror(errno));
+    wl_display_cancel_read(display);
+    return;
+  }
+
+  bool sawDisplay = false;
+  for (int i = 0; i < count; ++i) {
+    struct WaylandPoll * poll = events[i].data.ptr;
+    if (!poll->removed)
+      poll->callback(events[i].events, poll->opaque);
+    if (poll->fd == state.displayFd)
+      sawDisplay = true;
+  }
+
+  if (!sawDisplay)
+    wl_display_cancel_read(display);
+}
+
+WL_DesktopOps WLD_xdg =
+{
+  .name                      = "xdg",
+  .compositor                = "",
+  .shellInit                 = xdg_shellInit,
+  .shellAckConfigureIfNeeded = xdg_shellAckConfigureIfNeeded,
+  .setFullscreen             = xdg_setFullscreen,
+  .getFullscreen             = xdg_getFullscreen,
+  .minimize                  = xdg_minimize,
+  .shellResize               = xdg_shellResize,
+  .setSize                   = xdg_setSize,
+  .getSize                   = xdg_getSize,
+  .registryGlobalHandler     = xdg_registryGlobalHandler,
+  .pollInit                  = xdg_pollInit,
+  .pollWait                  = xdg_pollWait
+};