Add MetaCursorTracker, a new helper for tracking the cursor sprite

Under X, we need to use XFixes to watch the cursor changing, while
on wayland, we're in charge of setting and painting the cursor.
MetaCursorTracker provides the abstraction layer for gnome-shell,
which can thus drop ShellXFixesCursor. In the future, it may grow
the ability to watch for pointer position too, especially if
CursorEvents are added to the next version of XInput2, and thus
it would also replace the PointerWatcher we use for gnome-shell's
magnifier.

https://bugzilla.gnome.org/show_bug.cgi?id=705911

src/Makefile.am

@@ -113,6 +113,8 @@ libmutter_la_SOURCES =				\
 	core/keybindings.c			\
 	core/keybindings-private.h		\
 	core/main.c				\
+	core/meta-cursor-tracker.c		\
+	core/meta-cursor-tracker-private.h	\
 	core/meta-xrandr-shared.h		\
 	core/monitor.c				\
 	core/monitor-config.c			\
@@ -186,6 +188,7 @@ libmutterinclude_base_headers =		\
 	meta/meta-background-actor.h		\
 	meta/meta-background-group.h		\
 	meta/meta-background.h			\
+	meta/meta-cursor-tracker.h		\
 	meta/meta-plugin.h			\
 	meta/meta-shaped-texture.h		\
 	meta/meta-shadow-factory.h		\

src/core/display.c

@@ -2147,6 +2147,7 @@ event_callback (XEvent   *event,
   gboolean filter_out_event;
   XIEvent *input_event;
   MetaMonitorManager *monitor;
+  MetaScreen *screen;
 
   display = data;
   
@@ -2184,6 +2185,13 @@ event_callback (XEvent   *event,
                            display->server_focus_serial);
     }
 
+  screen = meta_display_screen_for_root (display, event->xany.window);
+  if (screen)
+    {
+      if (meta_screen_handle_xevent (screen, event))
+        return TRUE;
+    }
+
   modified = event_get_modified_window (display, event);
 
   input_event = get_input_event (display, event);

src/core/meta-cursor-tracker-private.h

@@ -0,0 +1,34 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+
+/*
+ * Copyright (C) 2013 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ * Author: Giovanni Campagna <gcampagn@redhat.com>
+ */
+
+#ifndef META_CURSOR_TRACKER_PRIVATE_H
+#define META_CURSOR_TRACKER_PRIVATE_H
+
+#include <meta/meta-cursor-tracker.h>
+
+gboolean meta_cursor_tracker_handle_xevent (MetaCursorTracker *tracker,
+					    XEvent            *xevent);
+
+void     meta_cursor_tracker_set_root_cursor (MetaCursorTracker *tracker,
+                                              MetaCursor         cursor);
+#endif

src/core/meta-cursor-tracker.c

@@ -0,0 +1,275 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+
+/* 
+ * Copyright 2013 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ * Author: Giovanni Campagna <gcampagn@redhat.com>
+ */
+
+/**
+ * SECTION:cursor-tracker
+ * @title: MetaCursorTracker
+ * @short_description: Mutter cursor tracking helper
+ */
+
+#include <config.h>
+#include <meta/main.h>
+#include <meta/util.h>
+#include <meta/errors.h>
+
+#include <cogl/cogl.h>
+#include <clutter/clutter.h>
+
+#include <X11/extensions/Xfixes.h>
+
+#include "meta-cursor-tracker-private.h"
+#include "screen-private.h"
+
+#define META_WAYLAND_DEFAULT_CURSOR_HOTSPOT_X 7
+#define META_WAYLAND_DEFAULT_CURSOR_HOTSPOT_Y 4
+
+struct _MetaCursorTracker {
+  GObject parent_instance;
+
+  MetaScreen *screen;
+
+  gboolean is_showing;
+
+  CoglTexture2D *sprite;
+  int hot_x, hot_y;
+};
+
+struct _MetaCursorTrackerClass {
+  GObjectClass parent_class;
+};
+
+G_DEFINE_TYPE (MetaCursorTracker, meta_cursor_tracker, G_TYPE_OBJECT);
+
+enum {
+    CURSOR_CHANGED,
+    LAST_SIGNAL
+};
+
+static guint signals[LAST_SIGNAL];
+
+static void
+meta_cursor_tracker_init (MetaCursorTracker *self)
+{
+  /* (JS) Best (?) that can be assumed since XFixes doesn't provide a way of
+   * detecting if the system mouse cursor is showing or not.
+   *
+   * On wayland we start with the cursor showing
+   */
+  self->is_showing = TRUE;
+}
+
+static void
+meta_cursor_tracker_finalize (GObject *object)
+{
+  MetaCursorTracker *self = META_CURSOR_TRACKER (object);
+
+  if (self->sprite)
+    cogl_object_unref (self->sprite);
+
+  G_OBJECT_CLASS (meta_cursor_tracker_parent_class)->finalize (object);
+}
+
+static void
+meta_cursor_tracker_class_init (MetaCursorTrackerClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->finalize = meta_cursor_tracker_finalize;
+
+  signals[CURSOR_CHANGED] = g_signal_new ("cursor-changed",
+                                          G_TYPE_FROM_CLASS (klass),
+                                          G_SIGNAL_RUN_LAST,
+                                          0,
+                                          NULL, NULL, NULL,
+                                          G_TYPE_NONE, 0);
+}
+
+static MetaCursorTracker *
+make_x11_cursor_tracker (MetaScreen *screen)
+{
+  MetaCursorTracker *self = g_object_new (META_TYPE_CURSOR_TRACKER, NULL);
+  self->screen = screen;
+
+  XFixesSelectCursorInput (screen->display->xdisplay,
+                           screen->xroot,
+                           XFixesDisplayCursorNotifyMask);
+
+  return self;
+}
+
+/**
+ * meta_cursor_tracker_get_for_screen:
+ * @screen: the #MetaScreen
+ *
+ * Retrieves the cursor tracker object for @screen.
+ *
+ * Returns: (transfer none):
+ */
+MetaCursorTracker *
+meta_cursor_tracker_get_for_screen (MetaScreen *screen)
+{
+  MetaCursorTracker *self;
+
+  if (screen->cursor_tracker)
+    return screen->cursor_tracker;
+
+  self = make_x11_cursor_tracker (screen);
+
+  screen->cursor_tracker = self;
+  return self;
+}
+
+gboolean
+meta_cursor_tracker_handle_xevent (MetaCursorTracker *tracker,
+                                   XEvent            *xevent)
+{
+  XFixesCursorNotifyEvent *notify_event;
+
+  if (xevent->xany.type != tracker->screen->display->xfixes_event_base + XFixesCursorNotify)
+    return FALSE;
+
+  notify_event = (XFixesCursorNotifyEvent *)xevent;
+  if (notify_event->subtype != XFixesDisplayCursorNotify)
+    return FALSE;
+
+  g_clear_pointer (&tracker->sprite, cogl_object_unref);
+  g_signal_emit (tracker, signals[CURSOR_CHANGED], 0);
+
+  return TRUE;
+}
+
+static void
+ensure_xfixes_cursor (MetaCursorTracker *tracker)
+{
+  XFixesCursorImage *cursor_image;
+  CoglTexture2D *sprite;
+  guint8 *cursor_data;
+  gboolean free_cursor_data;
+  CoglContext *ctx;
+
+  if (tracker->sprite)
+    return;
+
+  cursor_image = XFixesGetCursorImage (tracker->screen->display->xdisplay);
+  if (!cursor_image)
+    return;
+
+  /* Like all X APIs, XFixesGetCursorImage() returns arrays of 32-bit
+   * quantities as arrays of long; we need to convert on 64 bit */
+  if (sizeof(long) == 4)
+    {
+      cursor_data = (guint8 *)cursor_image->pixels;
+      free_cursor_data = FALSE;
+    }
+  else
+    {
+      int i, j;
+      guint32 *cursor_words;
+      gulong *p;
+      guint32 *q;
+
+      cursor_words = g_new (guint32, cursor_image->width * cursor_image->height);
+      cursor_data = (guint8 *)cursor_words;
+
+      p = cursor_image->pixels;
+      q = cursor_words;
+      for (j = 0; j < cursor_image->height; j++)
+        for (i = 0; i < cursor_image->width; i++)
+          *(q++) = *(p++);
+
+      free_cursor_data = TRUE;
+    }
+
+  ctx = clutter_backend_get_cogl_context (clutter_get_default_backend ());
+  sprite = cogl_texture_2d_new_from_data (ctx,
+                                          cursor_image->width,
+                                          cursor_image->height,
+                                          CLUTTER_CAIRO_FORMAT_ARGB32,
+                                          COGL_PIXEL_FORMAT_ANY,
+                                          cursor_image->width * 4, /* stride */
+                                          cursor_data,
+                                          NULL);
+
+  if (free_cursor_data)
+    g_free (cursor_data);
+
+  if (sprite != NULL)
+    {
+      tracker->sprite = sprite;
+      tracker->hot_x = cursor_image->xhot;
+      tracker->hot_y = cursor_image->yhot;
+    }
+  XFree (cursor_image);
+}
+
+/**
+ * meta_cursor_tracker_get_sprite:
+ *
+ * Returns: (transfer none):
+ */
+CoglTexture *
+meta_cursor_tracker_get_sprite (MetaCursorTracker *tracker)
+{
+  g_return_val_if_fail (META_IS_CURSOR_TRACKER (tracker), NULL);
+
+  ensure_xfixes_cursor (tracker);
+
+  return COGL_TEXTURE (tracker->sprite);
+}
+
+/**
+ * meta_cursor_tracker_get_hot:
+ * @tracker:
+ * @x: (out):
+ * @y: (out):
+ *
+ */
+void
+meta_cursor_tracker_get_hot (MetaCursorTracker *tracker,
+                             int               *x,
+                             int               *y)
+{
+  g_return_if_fail (META_IS_CURSOR_TRACKER (tracker));
+
+  ensure_xfixes_cursor (tracker);
+
+  if (x)
+    *x = tracker->hot_x;
+  if (y)
+    *y = tracker->hot_y;
+}
+
+void
+meta_cursor_tracker_set_root_cursor (MetaCursorTracker *tracker,
+                                     MetaCursor         cursor)
+{
+  Cursor xcursor;
+  MetaDisplay *display = tracker->screen->display;
+
+  /* First create a cursor for X11 applications that don't specify their own */
+  xcursor = meta_display_create_x_cursor (display, cursor);
+
+  XDefineCursor (display->xdisplay, tracker->screen->xroot, xcursor);
+  XFlush (display->xdisplay);
+  XFreeCursor (display->xdisplay, xcursor);
+}

src/core/screen-private.h

@@ -83,6 +83,7 @@ struct _MetaScreen
   MetaStack *stack;
   MetaStackTracker *stack_tracker;
 
+  MetaCursorTracker *cursor_tracker;
   MetaCursor current_cursor;
 
   Window flash_window;
@@ -249,4 +250,7 @@ int meta_screen_xinerama_index_to_monitor_index (MetaScreen *screen,
 int meta_screen_monitor_index_to_xinerama_index (MetaScreen *screen,
                                                  int         index);
 
+gboolean meta_screen_handle_xevent (MetaScreen *screen,
+                                    XEvent     *xevent);
+
 #endif

src/core/screen.c

@@ -45,6 +45,7 @@
 #include <meta/compositor.h>
 #include "mutter-enum-types.h"
 #include "core.h"
+#include "meta-cursor-tracker-private.h"
 
 #include <X11/extensions/Xinerama.h>
 
@@ -706,6 +707,7 @@ meta_screen_new (MetaDisplay *display,
 
   reload_monitor_infos (screen);
 
+  meta_cursor_tracker_get_for_screen (screen);
   meta_screen_set_cursor (screen, META_CURSOR_DEFAULT);
 
   /* Handle creating a no_focus_window for this screen */  
@@ -1461,29 +1463,18 @@ void
 meta_screen_set_cursor (MetaScreen *screen,
                         MetaCursor  cursor)
 {
-  Cursor xcursor;
-
   if (cursor == screen->current_cursor)
     return;
 
   screen->current_cursor = cursor;
-  
-  xcursor = meta_display_create_x_cursor (screen->display, cursor);
-  XDefineCursor (screen->display->xdisplay, screen->xroot, xcursor);
-  XFlush (screen->display->xdisplay);
-  XFreeCursor (screen->display->xdisplay, xcursor);
+  meta_cursor_tracker_set_root_cursor (screen->cursor_tracker, cursor);
 }
 
 void
 meta_screen_update_cursor (MetaScreen *screen)
 {
-  Cursor xcursor;
-
-  xcursor = meta_display_create_x_cursor (screen->display, 
-					  screen->current_cursor);
-  XDefineCursor (screen->display->xdisplay, screen->xroot, xcursor);
-  XFlush (screen->display->xdisplay);
-  XFreeCursor (screen->display->xdisplay, xcursor);
+  meta_cursor_tracker_set_root_cursor (screen->cursor_tracker,
+                                       screen->current_cursor);
 }
 
 void
@@ -3688,3 +3679,17 @@ meta_screen_get_monitor_in_fullscreen (MetaScreen  *screen,
   /* We use -1 as a flag to mean "not known yet" for notification purposes */
   return screen->monitor_infos[monitor].in_fullscreen == TRUE;
 }
+
+gboolean
+meta_screen_handle_xevent (MetaScreen *screen,
+                           XEvent     *xevent)
+{
+  /* Go through our helpers and see if they want this event.
+     Currently, only MetaCursorTracker.
+  */
+
+  if (meta_cursor_tracker_handle_xevent (screen->cursor_tracker, xevent))
+    return TRUE;
+
+  return FALSE;
+}

src/meta/meta-cursor-tracker.h

@@ -0,0 +1,50 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+
+/*
+ * Copyright (C) 2013 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ * Author: Giovanni Campagna <gcampagn@redhat.com>
+ */
+
+#ifndef META_CURSOR_TRACKER_H
+#define META_CURSOR_TRACKER_H
+
+#include <glib-object.h>
+#include <meta/types.h>
+#include <meta/workspace.h>
+#include <cogl/cogl.h>
+
+#define META_TYPE_CURSOR_TRACKER            (meta_cursor_tracker_get_type ())
+#define META_CURSOR_TRACKER(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), META_TYPE_CURSOR_TRACKER, MetaCursorTracker))
+#define META_CURSOR_TRACKER_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass),  META_TYPE_CURSOR_TRACKER, MetaCursorTrackerClass))
+#define META_IS_CURSOR_TRACKER(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), META_TYPE_CURSOR_TRACKER))
+#define META_IS_CURSOR_TRACKER_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass),  META_TYPE_CURSOR_TRACKER))
+#define META_CURSOR_TRACKER_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj),  META_TYPE_CURSOR_TRACKER, MetaCursorTrackerClass))
+
+typedef struct _MetaCursorTrackerClass   MetaCursorTrackerClass;
+
+GType meta_cursor_tracker_get_type (void);
+
+MetaCursorTracker *meta_cursor_tracker_get_for_screen (MetaScreen *screen);
+
+void           meta_cursor_tracker_get_hot    (MetaCursorTracker *tracker,
+                                               int               *x,
+                                               int               *y);
+CoglTexture   *meta_cursor_tracker_get_sprite (MetaCursorTracker *tracker);
+
+#endif

src/meta/types.h

@@ -38,5 +38,6 @@ typedef struct _MetaWorkspace   MetaWorkspace;
  */
 typedef struct _MetaGroup       MetaGroup;
 typedef struct _MetaKeyBinding  MetaKeyBinding;
+typedef struct _MetaCursorTracker MetaCursorTracker;
 
 #endif