Laser tool blocks events from propagating.

ash/laser/laser_pointer_controller.cc

+// Copyright 2016 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/laser/laser_pointer_controller.h"
+
+#include "ash/common/system/chromeos/palette/palette_utils.h"
+#include "ash/laser/laser_pointer_view.h"
+#include "ash/shell.h"
+#include "ui/aura/window_event_dispatcher.h"
+#include "ui/aura/window_tree_host.h"
+#include "ui/display/screen.h"
+#include "ui/views/widget/widget.h"
+
+namespace ash {
+namespace {
+
+// A point gets removed from the collection if it is older than
+// |kPointLifeDurationMs|.
+const int kPointLifeDurationMs = 200;
+
+// When no move events are being received we add a new point every
+// |kAddStationaryPointsDelayMs| so that points older than
+// |kPointLifeDurationMs| can get removed.
+const int kAddStationaryPointsDelayMs = 5;
+
+aura::Window* GetCurrentRootWindow() {
+  aura::Window::Windows root_windows = Shell::GetAllRootWindows();
+  for (aura::Window* root_window : root_windows) {
+    if (root_window->ContainsPointInRoot(
+            root_window->GetHost()->dispatcher()->GetLastMouseLocationInRoot()))
+      return root_window;
+  }
+  return nullptr;
+}
+}  // namespace
+
+LaserPointerController::LaserPointerController()
+    : stationary_timer_(new base::Timer(
+          FROM_HERE,
+          base::TimeDelta::FromMilliseconds(kAddStationaryPointsDelayMs),
+          base::Bind(&LaserPointerController::AddStationaryPoint,
+                     base::Unretained(this)),
+          true /* is_repeating */)) {}
+
+LaserPointerController::~LaserPointerController() {
+  Shell::GetInstance()->RemovePreTargetHandler(this);
+}
+
+void LaserPointerController::SetEnabled(bool enabled) {
+  if (enabled == enabled_)
+    return;
+
+  enabled_ = enabled;
+  if (enabled_) {
+    Shell::GetInstance()->AddPreTargetHandler(this);
+  } else {
+    laser_pointer_view_.reset();
+    Shell::GetInstance()->RemovePreTargetHandler(this);
+  }
+}
+
+void LaserPointerController::OnMouseEvent(ui::MouseEvent* event) {
+  if (!enabled_)
+    return;
+
+  if (event->pointer_details().pointer_type !=
+      ui::EventPointerType::POINTER_TYPE_PEN)
+    return;
+
+  if (event->type() != ui::ET_MOUSE_DRAGGED &&
+      event->type() != ui::ET_MOUSE_PRESSED &&
+      event->type() != ui::ET_MOUSE_RELEASED)
+    return;
+
+  // Delete the LaserPointerView instance if mouse is released.
+  if (event->type() == ui::ET_MOUSE_RELEASED) {
+    stationary_timer_->Stop();
+    laser_pointer_view_->Stop();
+    laser_pointer_view_.reset();
+    return;
+  }
+
+  // This will handle creating the initial laser pointer view on
+  // ET_MOUSE_PRESSED events.
+  SwitchTargetRootWindowIfNeeded(GetCurrentRootWindow());
+
+  if (laser_pointer_view_) {
+    // Remap point from where it was captured to the display it is actually on.
+    gfx::Point event_location = event->root_location();
+    aura::Window* target = static_cast<aura::Window*>(event->target());
+    aura::Window* event_root = target->GetRootWindow();
+    aura::Window::ConvertPointToTarget(
+        event_root, laser_pointer_view_->GetRootWindow(), &event_location);
+
+    current_mouse_location_ = event_location;
+    laser_pointer_view_->AddNewPoint(current_mouse_location_);
+
+    stationary_timer_repeat_count_ = 0;
+    if (event->type() == ui::ET_MOUSE_DRAGGED) {
+      // Start the timer to add stationary points if dragged.
+      if (!stationary_timer_->IsRunning())
+        stationary_timer_->Reset();
+    }
+
+    // If the stylus is over the palette icon or widget, do not consume the
+    // event.
+    if (!PaletteContainsPointInScreen(current_mouse_location_))
+      event->StopPropagation();
+  }
+}
+
+void LaserPointerController::OnWindowDestroying(aura::Window* window) {
+  SwitchTargetRootWindowIfNeeded(window);
+}
+
+void LaserPointerController::SwitchTargetRootWindowIfNeeded(
+    aura::Window* root_window) {
+  if (!root_window) {
+    stationary_timer_->Stop();
+    laser_pointer_view_.reset();
+  } else if (laser_pointer_view_) {
+    laser_pointer_view_->ReparentWidget(root_window);
+  } else if (enabled_) {
+    laser_pointer_view_.reset(new LaserPointerView(
+        base::TimeDelta::FromMilliseconds(kPointLifeDurationMs), root_window));
+  }
+}
+
+void LaserPointerController::AddStationaryPoint() {
+  laser_pointer_view_->AddNewPoint(current_mouse_location_);
+  // We can stop repeating the timer once the mouse has been stationary for
+  // longer than the life of a point.
+  if (stationary_timer_repeat_count_++ * kAddStationaryPointsDelayMs >=

[James Cook, 2016/09/16 23:47:00]

nit: This would be clearer if you did the increment on a different line, like
below the {}. (This is probably why I thought the variable was unread.)

[sammiequon, 2016/09/17 00:04:24]

Done.

+      kPointLifeDurationMs) {
+    stationary_timer_->Stop();
+  }
+}
+}  // namespace ash