Developer Feature: Add Debug Accelerators to Toggle Touchscreen/Touchpad On or Off (CrOS)

ui/events/base_event_utils.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/events/base_event_utils.h"
 
 #include "base/atomic_sequence_num.h"
+#include "base/command_line.h"
 #include "base/logging.h"
 #include "ui/events/event_constants.h"
+#include "ui/events/event_switches.h"
 
 namespace ui {
 
 namespace {
 
+// Determines whether touch events are enabled or disabled.
+bool touch_events_enabled = true;
+
 #if defined(OS_CHROMEOS)
 const int kSystemKeyModifierMask = EF_ALT_DOWN | EF_COMMAND_DOWN;
 #else
 const int kSystemKeyModifierMask = EF_ALT_DOWN;
+
+// Whether the status of the touch screen events has been retrieved and cached
+// from the command line on non-ChromeOS platforms.
+bool is_touch_events_status_cached = false;
+
+// Retrieves the status of the touch screen events from the command line on Non-
+// ChromeOS platforms.
+void UpdateAndCacheTouchStatus() {
+  if (is_touch_events_status_cached)
+    return;
+
+  const base::CommandLine& command_line =
+      *base::CommandLine::ForCurrentProcess();
+  const std::string touch_enabled_switch =
+      command_line.HasSwitch(switches::kTouchEvents) ?
+      command_line.GetSwitchValueASCII(switches::kTouchEvents) :
+      switches::kTouchEventsAuto;
+
+  if (touch_enabled_switch.empty() ||
+      touch_enabled_switch == switches::kTouchEventsEnabled ||
+      touch_enabled_switch == switches::kTouchEventsAuto) {
+    touch_events_enabled = true;
+  } else if (touch_enabled_switch == switches::kTouchEventsDisabled) {
+    touch_events_enabled = false;
+  } else {
+    LOG(ERROR) << "Invalid --touch-events option: " << touch_enabled_switch;
+  }
+
+  is_touch_events_status_cached = true;
+}
+
 #endif  // defined(OS_CHROMEOS)
 
-
 }  // namespace
 
 base::StaticAtomicSequenceNumber g_next_event_id;
 
 uint32 GetNextTouchEventId() {
   // Set the first touch event ID to 1 because we set id to 0 for other types
   // of events.
   uint32 id = g_next_event_id.GetNext();
   if (id == 0)
     id = g_next_event_id.GetNext();
   DCHECK_NE(0U, id);
   return id;
 }
 
 bool IsSystemKeyModifier(int flags) {
   // AltGr modifier is used to type alternative keys on certain keyboard layouts
   // so we don't consider keys with the AltGr modifier as a system key.
   return (kSystemKeyModifierMask & flags) != 0 &&
          (EF_ALTGR_DOWN & flags) == 0;
 }
 
+#if defined(OS_CHROMEOS)
+
+void SetTouchEventsEnabled(bool enabled) {
+  touch_events_enabled = enabled;
+}
+
+#endif  // defined(OS_CHROMEOS)
+
+bool AreTouchEventsEnabled() {
+#if !defined(OS_CHROMEOS)
+  UpdateAndCacheTouchStatus();

[sadrul, 2015/11/09 21:38:53]

You can get rid of is_touch_events_status_cached.

Define |touch_events_enabled| only for chromeos, and use that in
SetTouchEventsEnabled() and AreTouchEventsEnabled().

For non-chromeos, inside AreTouchEventsEnabled(), do:

  static bool touch_events_enabled = ComputeTouchStatus();
  return touch_events_enabled;

where ComputeTouchStatus() has the code in UpdateAndCacheTouchStatus(), except
it would simply return the value (instead of setting the global
|touch_events_enabled|, which isn't defined for non-chromeos)

[afakhry, 2015/11/10 00:37:11]

Done! Thanks for the useful suggestion! :)

+#endif  // !defined(OS_CHROMEOS)
+
+  return touch_events_enabled;
+}
+
 }  // namespace ui