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[mutter] clutter/x11: Add xkb accessibility helpers

commit 32c22d375a53f6b4581720cd40bff3edc82e8d29
Author: Olivier Fourdan <ofourdan redhat com>
Date:   Fri Oct 27 18:01:22 2017 +0200

    clutter/x11: Add xkb accessibility helpers
    
    Adds a set of convenient functions that can be shared between x11 input
    device backends (namely core-x11 and xi2) to control XKB accessibility
    features.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=788564

 clutter/clutter/Makefile.am                |    2 +
 clutter/clutter/x11/clutter-xkb-a11y-x11.c |  328 ++++++++++++++++++++++++++++
 clutter/clutter/x11/clutter-xkb-a11y-x11.h |   39 ++++
 3 files changed, 369 insertions(+), 0 deletions(-)
---
diff --git a/clutter/clutter/Makefile.am b/clutter/clutter/Makefile.am
index 1ffb56c..8fbd993 100644
--- a/clutter/clutter/Makefile.am
+++ b/clutter/clutter/Makefile.am
@@ -388,6 +388,7 @@ x11_source_c = \
        x11/clutter-keymap-x11.c                \
        x11/clutter-stage-x11.c         \
        x11/clutter-x11-texture-pixmap.c        \
+       x11/clutter-xkb-a11y-x11.c              \
        $(NULL)
 
 x11_source_h = \
@@ -402,6 +403,7 @@ x11_source_h_priv = \
        x11/clutter-keymap-x11.h                \
        x11/clutter-settings-x11.h              \
        x11/clutter-stage-x11.h         \
+       x11/clutter-xkb-a11y-x11.h              \
        $(NULL)
 
 x11_source_c_priv = \
diff --git a/clutter/clutter/x11/clutter-xkb-a11y-x11.c b/clutter/clutter/x11/clutter-xkb-a11y-x11.c
new file mode 100644
index 0000000..6adde81
--- /dev/null
+++ b/clutter/clutter/x11/clutter-xkb-a11y-x11.c
@@ -0,0 +1,328 @@
+/*
+ *
+ * Copyright © 2001 Ximian, Inc.
+ * Copyright (C) 2007 William Jon McCann <mccann jhu edu>
+ * Copyright (C) 2017 Red Hat
+ *
+ * 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 "clutter-device-manager-private.h"
+#include "clutter-xkb-a11y-x11.h"
+
+#include <X11/XKBlib.h>
+#include <X11/extensions/XKBstr.h>
+
+#define DEFAULT_XKB_SET_CONTROLS_MASK XkbSlowKeysMask         | \
+                                      XkbBounceKeysMask       | \
+                                      XkbStickyKeysMask       | \
+                                      XkbMouseKeysMask        | \
+                                      XkbMouseKeysAccelMask   | \
+                                      XkbAccessXKeysMask      | \
+                                      XkbAccessXTimeoutMask   | \
+                                      XkbAccessXFeedbackMask  | \
+                                      XkbControlsEnabledMask
+
+static int _xkb_event_base;
+
+static XkbDescRec *
+get_xkb_desc_rec (ClutterBackendX11 *backend_x11)
+{
+  XkbDescRec *desc;
+  Status      status = Success;
+
+  clutter_x11_trap_x_errors ();
+  desc = XkbGetMap (backend_x11->xdpy, XkbAllMapComponentsMask, XkbUseCoreKbd);
+  if (desc != NULL)
+    {
+      desc->ctrls = NULL;
+      status = XkbGetControls (backend_x11->xdpy, XkbAllControlsMask, desc);
+    }
+  clutter_x11_untrap_x_errors ();
+
+  g_return_val_if_fail (desc != NULL, NULL);
+  g_return_val_if_fail (desc->ctrls != NULL, NULL);
+  g_return_val_if_fail (status == Success, NULL);
+
+  return desc;
+}
+
+static void
+set_xkb_desc_rec (ClutterBackendX11 *backend_x11,
+                  XkbDescRec        *desc)
+{
+  clutter_x11_trap_x_errors ();
+  XkbSetControls (backend_x11->xdpy, DEFAULT_XKB_SET_CONTROLS_MASK, desc);
+  XSync (backend_x11->xdpy, FALSE);
+  clutter_x11_untrap_x_errors ();
+}
+
+static void
+check_settings_changed (ClutterDeviceManager *device_manager)
+{
+  ClutterBackendX11 *backend_x11;
+  ClutterKbdA11ySettings kbd_a11y_settings;
+  ClutterKeyboardA11yFlags what_changed = 0;
+  XkbDescRec *desc;
+
+  backend_x11 = CLUTTER_BACKEND_X11 (clutter_get_default_backend ());
+  desc = get_xkb_desc_rec (backend_x11);
+  if (!desc)
+    return;
+
+  clutter_device_manager_get_kbd_a11y_settings (device_manager, &kbd_a11y_settings);
+
+  if (desc->ctrls->enabled_ctrls & XkbSlowKeysMask &&
+      !(kbd_a11y_settings.controls & CLUTTER_A11Y_SLOW_KEYS_ENABLED))
+    {
+      what_changed |= CLUTTER_A11Y_SLOW_KEYS_ENABLED;
+      kbd_a11y_settings.controls |= CLUTTER_A11Y_SLOW_KEYS_ENABLED;
+    }
+  else if (!(desc->ctrls->enabled_ctrls & XkbSlowKeysMask) &&
+           kbd_a11y_settings.controls & CLUTTER_A11Y_SLOW_KEYS_ENABLED)
+    {
+      what_changed |= CLUTTER_A11Y_SLOW_KEYS_ENABLED;
+      kbd_a11y_settings.controls &= ~CLUTTER_A11Y_SLOW_KEYS_ENABLED;
+    }
+
+  if (desc->ctrls->enabled_ctrls & XkbStickyKeysMask &&
+      !(kbd_a11y_settings.controls & CLUTTER_A11Y_STICKY_KEYS_ENABLED))
+    {
+      what_changed |= CLUTTER_A11Y_STICKY_KEYS_ENABLED;
+      kbd_a11y_settings.controls |= CLUTTER_A11Y_STICKY_KEYS_ENABLED;
+    }
+  else if (!(desc->ctrls->enabled_ctrls & XkbStickyKeysMask) &&
+           kbd_a11y_settings.controls & CLUTTER_A11Y_STICKY_KEYS_ENABLED)
+    {
+      what_changed |= CLUTTER_A11Y_STICKY_KEYS_ENABLED;
+      kbd_a11y_settings.controls &= ~CLUTTER_A11Y_STICKY_KEYS_ENABLED;
+    }
+
+  if (what_changed)
+    g_signal_emit_by_name (device_manager,
+                           "kbd-a11y-flags-changed",
+                           kbd_a11y_settings.controls,
+                           what_changed);
+
+  XkbFreeKeyboard (desc, XkbAllComponentsMask, TRUE);
+}
+
+static ClutterX11FilterReturn
+xkb_a11y_event_filter (XEvent       *xevent,
+                       ClutterEvent *clutter_event,
+                       gpointer      data)
+{
+  ClutterDeviceManager *device_manager = CLUTTER_DEVICE_MANAGER (data);
+  XkbEvent *xkbev = (XkbEvent *) xevent;
+
+  /* 'event_type' is set to zero on notifying us of updates in
+   * response to client requests (including our own) and non-zero
+   * to notify us of key/mouse events causing changes (like
+   * pressing shift 5 times to enable sticky keys).
+   *
+   * We only want to update out settings when it's in response to an
+   * explicit user input event, so require a non-zero event_type.
+   */
+  if (xevent->xany.type == (_xkb_event_base + XkbEventCode) &&
+      xkbev->any.xkb_type == XkbControlsNotify && xkbev->ctrls.event_type != 0)
+    check_settings_changed (device_manager);
+
+  return  CLUTTER_X11_FILTER_CONTINUE;
+}
+
+static gboolean
+is_xkb_available (ClutterBackendX11 *backend_x11)
+{
+  gint opcode, error_base, event_base, major, minor;
+
+  if (_xkb_event_base)
+    return TRUE;
+
+  if (!XkbQueryExtension (backend_x11->xdpy,
+                          &opcode,
+                          &event_base,
+                          &error_base,
+                          &major,
+                          &minor))
+    return FALSE;
+
+  if (!XkbUseExtension (backend_x11->xdpy, &major, &minor))
+    return FALSE;
+
+  _xkb_event_base = event_base;
+
+  return TRUE;
+}
+
+static unsigned long
+set_value_mask (gboolean      flag,
+                unsigned long value,
+                unsigned long mask)
+{
+  if (flag)
+    return value | mask;
+
+  return value & ~mask;
+}
+
+static gboolean
+set_xkb_ctrl (XkbDescRec               *desc,
+              ClutterKeyboardA11yFlags settings,
+              ClutterKeyboardA11yFlags flag,
+              unsigned long            mask)
+{
+  gboolean result = (settings & flag) == flag;
+  desc->ctrls->enabled_ctrls = set_value_mask (result, desc->ctrls->enabled_ctrls, mask);
+
+  return result;
+}
+
+void
+clutter_device_manager_x11_apply_kbd_a11y_settings (ClutterDeviceManager   *device_manager,
+                                                    ClutterKbdA11ySettings *kbd_a11y_settings)
+{
+  ClutterBackendX11 *backend_x11;
+  XkbDescRec      *desc;
+  gboolean         enable_accessX;
+
+  backend_x11 = CLUTTER_BACKEND_X11 (clutter_get_default_backend ());
+  desc = get_xkb_desc_rec (backend_x11);
+  if (!desc)
+    return;
+
+  /* general */
+  enable_accessX = kbd_a11y_settings->controls & CLUTTER_A11Y_KEYBOARD_ENABLED;
+
+  desc->ctrls->enabled_ctrls = set_value_mask (enable_accessX,
+                                               desc->ctrls->enabled_ctrls,
+                                               XkbAccessXKeysMask);
+
+  if (set_xkb_ctrl (desc, kbd_a11y_settings->controls, CLUTTER_A11Y_TIMEOUT_ENABLED,
+                    XkbAccessXTimeoutMask))
+    {
+      desc->ctrls->ax_timeout = kbd_a11y_settings->timeout_delay;
+      /* disable only the master flag via the server we will disable
+       * the rest on the rebound without affecting settings state
+       * don't change the option flags at all.
+       */
+      desc->ctrls->axt_ctrls_mask = XkbAccessXKeysMask | XkbAccessXFeedbackMask;
+      desc->ctrls->axt_ctrls_values = 0;
+      desc->ctrls->axt_opts_mask = 0;
+    }
+
+  desc->ctrls->ax_options =
+    set_value_mask (kbd_a11y_settings->controls & CLUTTER_A11Y_FEATURE_STATE_CHANGE_BEEP,
+                    desc->ctrls->ax_options,
+                    XkbAccessXFeedbackMask | XkbAX_FeatureFBMask | XkbAX_SlowWarnFBMask);
+
+  /* bounce keys */
+  if (set_xkb_ctrl (desc, kbd_a11y_settings->controls,
+                    CLUTTER_A11Y_BOUNCE_KEYS_ENABLED, XkbBounceKeysMask))
+    {
+      desc->ctrls->debounce_delay = kbd_a11y_settings->debounce_delay;
+      desc->ctrls->ax_options =
+        set_value_mask (kbd_a11y_settings->controls & CLUTTER_A11Y_BOUNCE_KEYS_BEEP_REJECT,
+                        desc->ctrls->ax_options,
+                        XkbAccessXFeedbackMask | XkbAX_BKRejectFBMask);
+    }
+
+  /* mouse keys */
+  if (set_xkb_ctrl (desc, kbd_a11y_settings->controls,
+                    CLUTTER_A11Y_MOUSE_KEYS_ENABLED, XkbMouseKeysMask | XkbMouseKeysAccelMask))
+    {
+      gint mk_max_speed;
+      gint mk_accel_time;
+
+      desc->ctrls->mk_interval     = 100;     /* msec between mousekey events */
+      desc->ctrls->mk_curve        = 50;
+
+      /* We store pixels / sec, XKB wants pixels / event */
+      mk_max_speed = kbd_a11y_settings->mousekeys_max_speed;
+      desc->ctrls->mk_max_speed = mk_max_speed / (1000 / desc->ctrls->mk_interval);
+      if (desc->ctrls->mk_max_speed <= 0)
+        desc->ctrls->mk_max_speed = 1;
+
+      mk_accel_time = kbd_a11y_settings->mousekeys_accel_time;
+      desc->ctrls->mk_time_to_max = mk_accel_time / desc->ctrls->mk_interval;
+
+      if (desc->ctrls->mk_time_to_max <= 0)
+        desc->ctrls->mk_time_to_max = 1;
+
+      desc->ctrls->mk_delay = kbd_a11y_settings->mousekeys_init_delay;
+    }
+
+  /* slow keys */
+  if (set_xkb_ctrl (desc, kbd_a11y_settings->controls,
+                    CLUTTER_A11Y_SLOW_KEYS_ENABLED, XkbSlowKeysMask))
+    {
+      desc->ctrls->ax_options =
+        set_value_mask (kbd_a11y_settings->controls & CLUTTER_A11Y_SLOW_KEYS_BEEP_PRESS,
+                        desc->ctrls->ax_options, XkbAccessXFeedbackMask | XkbAX_SKPressFBMask);
+      desc->ctrls->ax_options =
+        set_value_mask (kbd_a11y_settings->controls & CLUTTER_A11Y_SLOW_KEYS_BEEP_ACCEPT,
+                        desc->ctrls->ax_options, XkbAccessXFeedbackMask | XkbAX_SKAcceptFBMask);
+      desc->ctrls->ax_options =
+        set_value_mask (kbd_a11y_settings->controls & CLUTTER_A11Y_SLOW_KEYS_BEEP_REJECT,
+                        desc->ctrls->ax_options, XkbAccessXFeedbackMask | XkbAX_SKRejectFBMask);
+      desc->ctrls->slow_keys_delay = kbd_a11y_settings->slowkeys_delay;
+      /* anything larger than 500 seems to loose all keyboard input */
+      if (desc->ctrls->slow_keys_delay > 500)
+        desc->ctrls->slow_keys_delay = 500;
+    }
+
+  /* sticky keys */
+  if (set_xkb_ctrl (desc, kbd_a11y_settings->controls,
+                    CLUTTER_A11Y_STICKY_KEYS_ENABLED, XkbStickyKeysMask))
+  {
+    desc->ctrls->ax_options |= XkbAX_LatchToLockMask;
+    desc->ctrls->ax_options =
+      set_value_mask (kbd_a11y_settings->controls & CLUTTER_A11Y_STICKY_KEYS_TWO_KEY_OFF,
+                      desc->ctrls->ax_options, XkbAccessXFeedbackMask | XkbAX_TwoKeysMask);
+    desc->ctrls->ax_options =
+      set_value_mask (kbd_a11y_settings->controls &  CLUTTER_A11Y_STICKY_KEYS_BEEP,
+                      desc->ctrls->ax_options, XkbAccessXFeedbackMask | XkbAX_StickyKeysFBMask);
+  }
+
+  /* toggle keys */
+  desc->ctrls->ax_options =
+    set_value_mask (kbd_a11y_settings->controls & CLUTTER_A11Y_TOGGLE_KEYS_ENABLED,
+                    desc->ctrls->ax_options, XkbAccessXFeedbackMask | XkbAX_IndicatorFBMask);
+
+  set_xkb_desc_rec (backend_x11, desc);
+  XkbFreeKeyboard (desc, XkbAllComponentsMask, TRUE);
+}
+
+gboolean
+clutter_device_manager_x11_a11y_init (ClutterDeviceManager *device_manager)
+{
+  ClutterBackendX11 *backend_x11;
+  guint event_mask;
+
+  backend_x11 =
+    CLUTTER_BACKEND_X11 (_clutter_device_manager_get_backend (device_manager));
+
+  if (!is_xkb_available (backend_x11))
+    return FALSE;
+
+  event_mask = XkbControlsNotifyMask | XkbAccessXNotifyMask;
+
+  XkbSelectEvents (backend_x11->xdpy, XkbUseCoreKbd, event_mask, event_mask);
+
+  clutter_x11_add_filter (xkb_a11y_event_filter, device_manager);
+
+  return TRUE;
+}
diff --git a/clutter/clutter/x11/clutter-xkb-a11y-x11.h b/clutter/clutter/x11/clutter-xkb-a11y-x11.h
new file mode 100644
index 0000000..8446bc8
--- /dev/null
+++ b/clutter/clutter/x11/clutter-xkb-a11y-x11.h
@@ -0,0 +1,39 @@
+/*
+ *
+ * Copyright © 2001 Ximian, Inc.
+ * Copyright (C) 2007 William Jon McCann <mccann jhu edu>
+ * Copyright (C) 2017 Red Hat
+ *
+ * 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 CLUTTER_XKB_A11Y_X11_H
+#define CLUTTER_XKB_A11Y_X11_H
+
+#include "clutter-device-manager-private.h"
+#include "clutter-backend-x11.h"
+
+#include <X11/Xlib.h>
+
+void
+clutter_device_manager_x11_apply_kbd_a11y_settings (ClutterDeviceManager   *device_manager,
+                                                    ClutterKbdA11ySettings *kbd_a11y_settings);
+
+gboolean
+clutter_device_manager_x11_a11y_init               (ClutterDeviceManager *device_manager);
+
+#endif /* CLUTTER_XKB_A11Y_X11_H */
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