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/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/views/widget/widget.h"
+
+#if defined(OS_CHROMEOS)

[James Cook, 2016/09/14 17:52:26]

Since this feature only works on chromeos, how about excluding this file in
ash.gyp? Then you don't need ifdefs.

[sammiequon, 2016/09/14 21:44:08]

Done.

+#include "ash/common/system/chromeos/palette/palette_utils.h"
+#endif
+
+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 recieved we add a new point every

[James Cook, 2016/09/14 17:52:26]

nit: received

[sammiequon, 2016/09/14 21:44:08]

Done.

+// |kAddStationaryPointsDelayMs| so that points older than
+// |kPointLifeDurationMs| can get removed.
+const int kAddStationaryPointsDelayMs = 5;
+
+// Returns true if the event should be processed normally, ie, the stylus is
+// over the palette icon or widget.
+bool ShouldSkipEventFiltering(const gfx::Point& point) {
+#if defined(OS_CHROMEOS)
+  return PaletteContainsPointInScreen(point);
+#else
+  return false;
+#endif
+}
+
+aura::Window* GetCurrentRootWindow() {
+  aura::Window::Windows root_windows = ash::Shell::GetAllRootWindows();

[James Cook, 2016/09/14 17:52:25]

nit: no ash

[sammiequon, 2016/09/14 21:44:09]

Done.

+  for (aura::Window* root_window : root_windows) {
+    if (root_window->ContainsPointInRoot(
+            root_window->GetHost()->dispatcher()->GetLastMouseLocationInRoot()))
+      return root_window;
+  }
+  return nullptr;
+}
+}  // namespace
+
+LaserPointerController::LaserPointerController() {
+  timer_.reset(new base::Timer(

[James Cook, 2016/09/14 17:52:26]

do this in constructor initializer list : timer_(new ...) {

[sammiequon, 2016/09/14 21:44:09]

Done.

+      FROM_HERE, base::TimeDelta::FromMilliseconds(kAddStationaryPointsDelayMs),
+      base::Bind(&LaserPointerController::AddStationaryPoint,

[James Cook, 2016/09/14 17:52:25]

So if I instantiate a LaserPointerController, but don't call SetEnabled(), will
it start adding points? Will it crash on null |laser_pointer_view_|?

How about waiting to start the timer until the feature is enabled?

[sammiequon, 2016/09/14 21:44:08]

The timer currently only runs once a drag is detected.

+                 base::Unretained(this)),
+      true));

[James Cook, 2016/09/14 17:52:26]

nit: document /* is_repeating */ or put in const bool is_repeating = true

[sammiequon, 2016/09/14 21:44:09]

Done.

+}
+
+LaserPointerController::~LaserPointerController() {
+  Shell::GetInstance()->RemovePreTargetHandler(this);
+}
+
+void LaserPointerController::SetEnabled(bool enabled) {
+  if (enabled == enabled_)
+    return;
+
+  enabled_ = enabled;
+  if (enabled_)
+    Shell::GetInstance()->AddPreTargetHandler(this);
+  else
+    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) {
+    StopTimer();
+    laser_pointer_view_->Stop();
+    laser_pointer_view_.reset();
+    return;
+  }
+
+  if (!laser_pointer_view_) {
+    laser_pointer_view_.reset(new LaserPointerView(
+        base::TimeDelta::FromMilliseconds(kPointLifeDurationMs),
+        GetCurrentRootWindow()));
+  }
+
+  SwitchTargetRootWindowIfNeeded();

[James Cook, 2016/09/14 17:52:26]

please document what this is doing, either in the method description or here

[sammiequon, 2016/09/14 21:44:08]

Done.

+
+  // 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;

[James Cook, 2016/09/14 17:52:26]

Could you use ui/display/screen.h Screen::GetCursorScreenPoint() and eliminate
this member?  (It returns screen coords.)

[sammiequon, 2016/09/14 21:44:09]

We would need to compute the display origin for when the laser is on the second
screen like line 106. Is that preferred over a class variable?

[James Cook, 2016/09/14 22:53:37]

This is fine.

+  laser_pointer_view_->AddNewPoint(current_mouse_location_);
+
+  timer_repeat_count_ = 0;
+  if (event->type() == ui::ET_MOUSE_DRAGGED) {
+    // Start the timer to add stationary points if dragged.
+    if (!timer_->IsRunning())
+      timer_->Reset();
+  }
+
+  // Consume the event unless it is over the palette tray or palette shelf
+  // button.
+  if (!ShouldSkipEventFiltering(current_mouse_location_))
+    event->StopPropagation();
+}
+
+void LaserPointerController::OnWindowDestroying(aura::Window* window) {
+  SwitchTargetRootWindowIfNeeded();
+}
+
+void LaserPointerController::StopTimer() {
+  timer_repeat_count_ = 0;
+  timer_->Stop();
+}
+
+void LaserPointerController::SwitchTargetRootWindowIfNeeded() {
+  if (enabled_) {
+    // If the current root window has changed, remake the laser pointer view
+    // with the new root window.
+    if (laser_pointer_view_->GetRootWindow() != GetCurrentRootWindow()) {
+      laser_pointer_view_.reset(new LaserPointerView(
+          base::TimeDelta::FromMilliseconds(kPointLifeDurationMs),
+          GetCurrentRootWindow()));
+    }
+  } else {
+    laser_pointer_view_.reset();
+  }
+}
+
+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 (timer_repeat_count_++ * kAddStationaryPointsDelayMs >=
+      kPointLifeDurationMs) {
+    StopTimer();
+  }
+}
+}  // namespace ash