Select-to-speak event handler

chrome/browser/chromeos/accessibility/select_to_speak_event_handler.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 "chrome/browser/chromeos/accessibility/select_to_speak_event_handler.h"
+
+#include "ash/shell.h"
+#include "chrome/browser/ui/aura/accessibility/automation_manager_aura.h"
+#include "ui/aura/window.h"
+#include "ui/display/display.h"
+#include "ui/events/event.h"
+#include "ui/views/focus/view_storage.h"
+#include "ui/views/view.h"
+#include "ui/views/widget/widget.h"
+
+namespace chromeos {
+
+SelectToSpeakEventHandler::SelectToSpeakEventHandler() {
+  if (ash::Shell::HasInstance())
+    ash::Shell::GetInstance()->AddPreTargetHandler(this);
+}
+
+SelectToSpeakEventHandler::~SelectToSpeakEventHandler() {
+  if (ash::Shell::HasInstance())
+    ash::Shell::GetInstance()->RemovePreTargetHandler(this);
+}
+
+void SelectToSpeakEventHandler::OnKeyEvent(ui::KeyEvent* event) {
+  if (event->key_code() == ui::VKEY_LWIN) {
+    if (event->type() == ui::ET_KEY_PRESSED) {
+      state_ = SEARCH_DOWN;
+    } else if (event->type() == ui::ET_KEY_RELEASED) {
+      if (state_ == CAPTURING) {
+        SendCancelAXEvent();
+        CancelEvent(event);
+        state_ = WAIT_FOR_MOUSE_RELEASE;
+      } else if (state_ == MOUSE_RELEASED) {
+        CancelEvent(event);
+        state_ = INACTIVE;
+      }
+    }
+  } else if (state_ == SEARCH_DOWN) {
+    state_ = INACTIVE;
+  }
+}
+
+void SelectToSpeakEventHandler::OnMouseEvent(ui::MouseEvent* event) {
+  if (state_ == INACTIVE)
+    return;
+
+  if ((state_ == SEARCH_DOWN || state_ == MOUSE_RELEASED) &&
+      event->type() == ui::ET_MOUSE_PRESSED) {
+    state_ = CAPTURING;
+  }
+
+  if (state_ == WAIT_FOR_MOUSE_RELEASE &&
+      event->type() == ui::ET_MOUSE_RELEASED) {
+    CancelEvent(event);
+    state_ = INACTIVE;
+    return;
+  }
+
+  if (state_ != CAPTURING)
+    return;
+
+  // If we're in the capturing state, send accessibility events to
+  // the Select-to-speak extension based on the mouse event.
+  // First, figure out what event to send.
+  ui::AXEvent ax_event = ui::AX_EVENT_NONE;
+  switch (event->type()) {
+    case ui::ET_MOUSE_PRESSED:
+      ax_event = ui::AX_EVENT_MOUSE_PRESSED;
+      break;
+    case ui::ET_MOUSE_DRAGGED:
+      ax_event = ui::AX_EVENT_MOUSE_DRAGGED;
+      break;
+    case ui::ET_MOUSE_RELEASED:
+      state_ = MOUSE_RELEASED;
+      ax_event = ui::AX_EVENT_MOUSE_RELEASED;
+      break;
+    case ui::ET_MOUSE_MOVED:
+    case ui::ET_MOUSE_ENTERED:
+    case ui::ET_MOUSE_EXITED:
+      ax_event = ui::AX_EVENT_MOUSE_MOVED;
+      break;
+    default:
+      return;
+  }
+
+  CancelEvent(event);
+
+  // Find the View to post the accessibility event on.
+  aura::Window* event_target = static_cast<aura::Window*>(event->target());
+  aura::Window* hit_window = event_target;
+  if (!hit_window)
+    return;
+
+  views::Widget* hit_widget = views::Widget::GetWidgetForNativeView(hit_window);
+  while (!hit_widget) {
+    hit_window = hit_window->parent();
+    if (!hit_window)
+      break;
+
+    hit_widget = views::Widget::GetWidgetForNativeView(hit_window);
+  }
+
+  if (!hit_window || !hit_widget)
+    return;
+
+  gfx::Point window_location = event->location();
+  aura::Window::ConvertPointToTarget(event_target, hit_window,
+                                     &window_location);
+
+  views::View* root_view = hit_widget->GetRootView();
+  views::View* hit_view = root_view->GetEventHandlerForPoint(window_location);
+
+  if (hit_view) {
+    // Send the accessibility event, then save the view so we can post the
+    // cancel event on the same view if possible.
+    hit_view->NotifyAccessibilityEvent(ax_event, true);
+    if (!last_view_storage_id_) {
+      last_view_storage_id_ =
+          views::ViewStorage::GetInstance()->CreateStorageID();
+    }
+    views::ViewStorage::GetInstance()->RemoveView(last_view_storage_id_);
+    views::ViewStorage::GetInstance()->StoreView(last_view_storage_id_,
+                                                 hit_view);
+  }
+}
+
+void SelectToSpeakEventHandler::CancelEvent(ui::Event* event) {
+  if (event->cancelable()) {
+    event->SetHandled();
+    event->StopPropagation();
+  }
+}
+
+void SelectToSpeakEventHandler::SendCancelAXEvent() {
+  // If the user releases Search while the button is still down, cancel
+  // the Select-to-speak gesture. Try to post it on the same View that
+  // was last targeted, but if that's impossible, post it on the desktop.
+  views::View* last_view =
+      last_view_storage_id_
+          ? views::ViewStorage::GetInstance()->RetrieveView(
+                last_view_storage_id_)
+          : nullptr;
+  if (last_view) {
+    last_view->NotifyAccessibilityEvent(ui::AX_EVENT_MOUSE_CANCELED, true);
+  } else {
+    AutomationManagerAura::GetInstance()->HandleEvent(
+        nullptr, nullptr, ui::AX_EVENT_MOUSE_CANCELED);
+  }
+}
+
+}  // namespace chromeos