Cursor tracker: only display the cursor in mouse/trackpad mode

Listen on RawEvents: listen for raw events on the root
window and decide whether the cursor is shown or not. A
touch begin event will hide the cursor a motion or button
press event will show it.

There is no API in XFixes to know whether a cursor is shown
or not so we keep track of the current state. Furthermore
we trap X errors if any bad access should happen.

Signed-off-by: Simon Schampijer <simon@laptop.org>
Reviewed-by: Carlos Garnacho <carlos@lanedo.com>
Acked-by: Manuel Quiñones <manuq@laptop.org>

3 files changed, 235 insertions, 0 deletions

diff --git a/src/sugar3/Makefile.am b/src/sugar3/Makefile.am
index 1eda7d8..f25606b 100644
--- a/src/sugar3/Makefile.am
+++ b/src/sugar3/Makefile.am
@@ -47,6 +47,8 @@ libsugarext_la_SOURCES =		\
 	gsm-xsmp.h			\
 	sugar-grid.c			\
 	sugar-grid.h			\
+	sugar-cursor-tracker.c		\
+	sugar-cursor-tracker.h		\
 	sugar-gesture-grabber.c		\
 	sugar-gesture-grabber.h		\
 	sugar-key-grabber.c		\
@@ -128,6 +130,8 @@ SugarExt_1_0_gir_FILES = \
 	gsm-session.h \
 	gsm-xsmp.c \
 	gsm-xsmp.h \
+	sugar-cursor-tracker.c \
+	sugar-cursor-tracker.h \
 	sugar-gesture-grabber.c \
 	sugar-gesture-grabber.h \
 	sugar-key-grabber.c \
diff --git a/src/sugar3/sugar-cursor-tracker.c b/src/sugar3/sugar-cursor-tracker.c
new file mode 100644
index 0000000..a881c50
--- /dev/null
+++ b/src/sugar3/sugar-cursor-tracker.c
@@ -0,0 +1,177 @@
+/*
+ * Copyright (C) 2012 One laptop per child
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Author: Simon Schampijer  <simon@laptop.org>
+ */
+
+#include <gdk/gdkx.h>
+#include <X11/extensions/XInput2.h>
+#include "sugar-cursor-tracker.h"
+
+typedef struct _SugarCursorTrackerPriv SugarCursorTrackerPriv;
+
+struct _SugarCursorTrackerPriv
+{
+	GdkWindow *root_window;
+        gboolean cursor_shown;
+};
+
+G_DEFINE_TYPE (SugarCursorTracker, sugar_cursor_tracker, G_TYPE_OBJECT)
+
+
+static void
+sugar_cursor_tracker_finalize (GObject *object)
+{
+	SugarCursorTrackerPriv *priv = SUGAR_CURSOR_TRACKER (object)->_priv;
+
+	G_OBJECT_CLASS (sugar_cursor_tracker_parent_class)->finalize (object);
+}
+
+static void
+sugar_cursor_tracker_class_init (SugarCursorTrackerClass *klass)
+{
+	GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+	object_class->finalize = sugar_cursor_tracker_finalize;
+
+	g_type_class_add_private (klass, sizeof (SugarCursorTrackerPriv));
+}
+
+static GdkWindow *
+_get_default_root_window (void)
+{
+        GdkDisplay *display;
+        GdkScreen *screen;
+
+        display = gdk_display_get_default ();
+        screen = gdk_display_get_default_screen (display);
+
+        return gdk_screen_get_root_window (screen);
+}
+
+static void
+_track_raw_events (GdkWindow *window)
+{
+        XIEventMask mask;
+	guchar *evmask;
+	GdkDisplay *display;
+
+	evmask = g_new0 (guchar, XIMaskLen (XI_LASTEVENT));
+	XISetMask (evmask, XI_RawTouchBegin);
+	XISetMask (evmask, XI_RawTouchEnd);
+	XISetMask (evmask, XI_RawTouchUpdate);
+	XISetMask (evmask, XI_RawMotion);
+	XISetMask (evmask, XI_RawButtonPress);
+
+	mask.deviceid = XIAllMasterDevices;
+	mask.mask_len = sizeof (evmask);
+	mask.mask = evmask;
+
+	display = gdk_window_get_display (window);
+	XISelectEvents (gdk_x11_display_get_xdisplay (display),
+			gdk_x11_window_get_xid (window),
+			&mask, 1);
+}
+
+static void
+_set_cursor_visibility (SugarCursorTracker *tracker,
+			gboolean visible)
+{
+        GdkDisplay *display;
+	Display *xdisplay;
+        SugarCursorTrackerPriv *priv;
+
+        priv = tracker->_priv;
+	display = gdk_display_get_default ();
+	xdisplay = GDK_DISPLAY_XDISPLAY (display);
+
+	gdk_error_trap_push ();
+
+	if (visible == TRUE) {
+	    if (priv->cursor_shown == FALSE) {
+		XFixesShowCursor (xdisplay, GDK_WINDOW_XID (_get_default_root_window ()));
+		priv->cursor_shown = TRUE;
+	    }
+	}
+	else {
+	    if (priv->cursor_shown == TRUE) {
+		XFixesHideCursor (xdisplay, GDK_WINDOW_XID (_get_default_root_window ()));
+		priv->cursor_shown = False;
+	    }
+	}
+
+	if (gdk_error_trap_pop ()) {
+	    g_warning ("An error occurred trying to %s the cursor",
+		       FALSE ? "show" : "hide");
+	}
+}
+
+static GdkFilterReturn
+filter_function (GdkXEvent *xevent,
+                 GdkEvent  *gdkevent,
+                 gpointer   user_data)
+{
+	XEvent *ev = xevent;
+	XIEvent *xiev;
+	SugarCursorTracker *tracker;
+
+	if (ev->type != GenericEvent)
+	        return GDK_FILTER_CONTINUE;
+
+	tracker = user_data;
+
+        xiev = ev->xcookie.data;
+
+	switch (xiev->evtype) {
+	case XI_RawTouchBegin:
+	        _set_cursor_visibility (tracker, FALSE);
+	        return GDK_FILTER_REMOVE;
+	case XI_RawMotion:
+	        _set_cursor_visibility (tracker, TRUE);
+	        return GDK_FILTER_REMOVE;
+	case XI_RawButtonPress:
+	        _set_cursor_visibility (tracker, TRUE);
+	        return GDK_FILTER_REMOVE;
+	default:
+	        return GDK_FILTER_CONTINUE;
+	}
+}
+
+static void
+sugar_cursor_tracker_init (SugarCursorTracker *tracker)
+{
+	SugarCursorTrackerPriv *priv;
+	tracker->_priv = priv = G_TYPE_INSTANCE_GET_PRIVATE (tracker,
+                                                             SUGAR_TYPE_CURSOR_TRACKER,
+                                                             SugarCursorTrackerPriv);
+        priv->root_window = _get_default_root_window ();
+	priv->cursor_shown = True;
+
+	tracker->_priv = priv = G_TYPE_INSTANCE_GET_PRIVATE (tracker,
+							     SUGAR_TYPE_CURSOR_TRACKER,
+							     SugarCursorTrackerPriv);
+	priv->root_window = _get_default_root_window ();
+	_track_raw_events (priv->root_window);
+	gdk_window_add_filter (NULL, filter_function, tracker);
+}
+
+SugarCursorTracker *
+sugar_cursor_tracker_new (void)
+{
+	return g_object_new (SUGAR_TYPE_CURSOR_TRACKER, NULL);
+}
diff --git a/src/sugar3/sugar-cursor-tracker.h b/src/sugar3/sugar-cursor-tracker.h
new file mode 100644
index 0000000..2ca60d1
--- /dev/null
+++ b/src/sugar3/sugar-cursor-tracker.h
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2012 One laptop per child
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Author: Simon Schampijer  <simon@laptop.org>
+ */
+
+#ifndef __SUGAR_CURSOR_TRACKER_H__
+#define __SUGAR_CURSOR_TRACKER_H__
+
+#include <gtk/gtk.h>
+#include "event-controller/sugar-event-controllers.h"
+
+G_BEGIN_DECLS
+
+typedef struct _SugarCursorTracker SugarCursorTracker;
+typedef struct _SugarCursorTrackerClass SugarCursorTrackerClass;
+
+#define SUGAR_TYPE_CURSOR_TRACKER              (sugar_cursor_tracker_get_type())
+#define SUGAR_CURSOR_TRACKER(object)           (G_TYPE_CHECK_INSTANCE_CAST((object), SUGAR_TYPE_CURSOR_TRACKER, SugarCursorTracker))
+#define SUGAR_CURSOR_TRACKER_CLASS(klass)      (G_TYPE_CHACK_CLASS_CAST((klass), SUGAR_TYPE_CURSOR_TRACKER, SugarCursorTrackerClass))
+#define SUGAR_IS_CURSOR_TRACKER(object)        (G_TYPE_CHECK_INSTANCE_TYPE((object), SUGAR_TYPE_CURSOR_TRACKER))
+#define SUGAR_IS_CURSOR_TRACKER_CLASS(klass)   (G_TYPE_CHECK_CLASS_TYPE((klass), SUGAR_TYPE_CURSOR_TRACKER))
+#define SUGAR_CURSOR_TRACKER_GET_CLASS(object) (G_TYPE_INSTANCE_GET_CLASS((object), SUGAR_TYPE_CURSOR_TRACKER, SugarCursorTrackerClass))
+
+struct _SugarCursorTracker {
+	GObject parent_instance;
+	gpointer _priv;
+};
+
+struct _SugarCursorTrackerClass {
+	GObjectClass parent_class;
+};
+
+GType                sugar_cursor_tracker_get_type (void);
+SugarCursorTracker * sugar_cursor_tracker_new      (void);
+
+G_END_DECLS
+
+#endif /* __SUGAR_CURSOR_TRACKER_H__ */