Block keyboard and mouse input when maximize mode is activated by accelerometer.

ash/wm/maximize_mode/maximize_mode_controller.cc

 // Copyright 2014 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 "ash/wm/maximize_mode/maximize_mode_controller.h"
 
 #include "ash/accelerometer/accelerometer_controller.h"
 #include "ash/display/display_manager.h"
 #include "ash/shell.h"
+#include "ui/aura/client/cursor_client.h"
+#include "ui/events/event_handler.h"
 #include "ui/gfx/vector3d_f.h"
 
 namespace ash {
 
 namespace {
 
 // The hinge angle at which to enter maximize mode.
 const float kEnterMaximizeModeAngle = 200.0f;
 
 // The angle at which to exit maximize mode, this is specifically less than the
@@ skipping 41 matching lines @@
   gfx::Vector3dF cross(base);
   cross.Cross(other);
   // If the dot product of this cross product is normal, it means that the
   // shortest angle between |base| and |other| was counterclockwise with respect
   // to the surface represented by |normal| and this angle must be reversed.
   if (gfx::DotProduct(cross, normal) > 0.0f)
     angle = 360.0f - angle;
   return angle;
 }
 
+// Filter to prevent delivery of mouse and touch events while maximize mode is
+// active.
+// TODO(flackr): This should only stop events from the internal keyboard and
+// touchpad.
+class BlockKeyboardAndTouchpadFilter : public ui::EventHandler {
+ public:
+  BlockKeyboardAndTouchpadFilter();
+  virtual ~BlockKeyboardAndTouchpadFilter();
+
+  // Overridden from ui::EventHandler:
+  virtual void OnKeyEvent(ui::KeyEvent* event) OVERRIDE;
+  virtual void OnMouseEvent(ui::MouseEvent* event) OVERRIDE;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(BlockKeyboardAndTouchpadFilter);
+};
+
+BlockKeyboardAndTouchpadFilter::BlockKeyboardAndTouchpadFilter() {
+  // This needs to be the first handler to block events.
+  Shell::GetInstance()->PrependPreTargetHandler(this);

[sadrul, 2014/04/09 16:54:18]

Can you install a WindowTargeter on the root-window that returns NULL for
key/mouse events, instead of event-handlers?

[flackr, 2014/04/09 17:11:49]

It looks like event targeters are per window / root window, which means it'll
have to install on each root window and track new root window creation. Is there
a global event targeter?

Wouldn't this also mean that if something else set an event targeter afterwards
we could accept events again?

[sadrul, 2014/04/09 17:33:30]

There isn't a global event targeter. If a new root-window is added, you would
have to install a targeter on that.
Yes. But so does for event-handlers: there can be some other pre-handler that is
pre-pended and does things with key/mouse events. Between an event-handler and
event-targeter, the latter is the more correct way of doing this.

[flackr, 2014/04/10 02:30:02]

Just wanted to be sure I wasn't just missing something, thanks.
No problem, done. I refactored two other classes which had OnRootWindowAdded
being manually called on them to use ShellObserver to be notified of this event.
Done.

+  aura::client::CursorClient* cursor_client_ =
+      aura::client::GetCursorClient(Shell::GetTargetRootWindow());
+  if (cursor_client_)
+    cursor_client_->HideCursor();
+}
+
+BlockKeyboardAndTouchpadFilter::~BlockKeyboardAndTouchpadFilter() {
+  Shell::GetInstance()->RemovePreTargetHandler(this);
+}
+
+void BlockKeyboardAndTouchpadFilter::OnKeyEvent(ui::KeyEvent* event) {
+  if (event->HasNativeEvent())
+    event->StopPropagation();
+}
+
+void BlockKeyboardAndTouchpadFilter::OnMouseEvent(ui::MouseEvent* event) {
+  if (event->HasNativeEvent())
+    event->StopPropagation();
+}
+
 }  // namespace
 
 MaximizeModeController::MaximizeModeController() {
   Shell::GetInstance()->accelerometer_controller()->AddObserver(this);
 }
 
 MaximizeModeController::~MaximizeModeController() {
   Shell::GetInstance()->accelerometer_controller()->RemoveObserver(this);
 }
 
@@ skipping 25 matching lines @@
   float angle = ClockwiseAngleBetweenVectorsInDegrees(base, lid, hinge_vector);
 
   // Toggle maximize mode on or off when corresponding thresholds are passed.
   // TODO(flackr): Make MaximizeModeController own the MaximizeModeWindowManager
   // such that observations of state changes occur after the change and shell
   // has fewer states to track.
   if (maximize_mode_engaged &&
       angle > kFullyOpenAngleErrorTolerance &&
       angle < kExitMaximizeModeAngle) {
     Shell::GetInstance()->EnableMaximizeModeWindowManager(false);
+    event_handler_.reset();
   } else if (!maximize_mode_engaged &&
       angle > kEnterMaximizeModeAngle) {
     Shell::GetInstance()->EnableMaximizeModeWindowManager(true);
+    event_handler_.reset(new BlockKeyboardAndTouchpadFilter);
   }
 }
 
 void MaximizeModeController::HandleScreenRotation(const gfx::Vector3dF& lid) {
   bool maximize_mode_engaged =
       Shell::GetInstance()->IsMaximizeModeWindowManagerEnabled();
 
   DisplayManager* display_manager =
       Shell::GetInstance()->display_manager();
   gfx::Display::Rotation current_rotation = display_manager->GetDisplayInfo(
@@ skipping 63 matching lines @@
   // When exiting maximize mode return rotation to 0. When entering, rotate to
   // match screen orientation.
   if (new_rotation == gfx::Display::ROTATE_0 ||
       maximize_mode_engaged) {
     display_manager->SetDisplayRotation(gfx::Display::InternalDisplayId(),
                                         new_rotation);
   }
 }
 
 }  // namespace ash