Show ChromeVox caption panel when spoken feedback is enabled.

chrome/browser/chromeos/accessibility/chromevox_panel.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 "ash/shell.h"
+#include "chrome/browser/chromeos/accessibility/chromevox_panel.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/common/extensions/extension_constants.h"
+#include "content/public/browser/web_contents.h"
+#include "ui/views/controls/webview/webview.h"
+#include "ui/views/layout/fill_layout.h"
+#include "ui/views/widget/widget.h"
+#include "ui/wm/core/shadow_types.h"
+#include "ui/wm/core/window_animations.h"
+
+namespace {
+
+const int kPanelHeight = 35;
+const char kChromeVoxPanelRelativeUrl[] = "/cvox2/background/panel.html";
+const char kFullscreenURLFragment[] = "fullscreen";
+
+class ChromeVoxPanelWebView : public views::WebView {

[Jun Mukai, 2015/11/05 17:38:02]

As I wrote below, OnDeviceScaleFactorChanged() method wouldn't be necessary, and
if you remove that, you could remove this class.

[dmazzoni, 2015/11/05 20:12:58]

Done.

+ public:
+  ChromeVoxPanelWebView(Profile* profile, ChromeVoxPanel* panel)
+      : views::WebView(profile), panel_(panel) {}
+
+  ~ChromeVoxPanelWebView() override {}
+
+  void OnDeviceScaleFactorChanged(float device_scale_factor) override {
+    panel_->OnDeviceScaleFactorChanged(device_scale_factor);
+  }
+
+ private:
+  ChromeVoxPanel* panel_;
+  bool fullscreen_;

[Jun Mukai, 2015/11/05 17:38:02]

not used?

[dmazzoni, 2015/11/05 20:12:58]

Done.

+
+  DISALLOW_COPY_AND_ASSIGN(ChromeVoxPanelWebView);
+};
+
+}  // namespace
+
+class ChromeVoxPanelWebContentsObserver : public content::WebContentsObserver {
+ public:
+  ChromeVoxPanelWebContentsObserver(content::WebContents* web_contents,
+                                    ChromeVoxPanel* panel)
+      : content::WebContentsObserver(web_contents), panel_(panel) {}
+  ~ChromeVoxPanelWebContentsObserver() override {}
+
+  void DidFirstVisuallyNonEmptyPaint() override {
+    panel_->DidFirstVisuallyNonEmptyPaint();
+  }
+
+  void DidFinishNavigation(
+      content::NavigationHandle* navigation_handle) override {
+    // The ChromeVox panel uses the URL fragment to communicate state
+    // to this panel host.
+    std::string fragment = web_contents()->GetLastCommittedURL().ref();
+    if (fragment == kFullscreenURLFragment)
+      panel_->EnterFullscreen();
+    else
+      panel_->ExitFullscreen();
+  }
+
+ private:
+  ChromeVoxPanel* panel_;
+
+  DISALLOW_COPY_AND_ASSIGN(ChromeVoxPanelWebContentsObserver);
+};
+
+ChromeVoxPanel::ChromeVoxPanel(Profile* profile) : profile_(profile) {
+  widget_ = new views::Widget();
+  views::Widget::InitParams params(
+      views::Widget::InitParams::TYPE_WINDOW_FRAMELESS);
+  root_window_ = ash::Shell::GetPrimaryRootWindow();
+  params.parent = root_window_;

[Jun Mukai, 2015/11/05 17:38:01]

Please do not create a window directly under the root window, instead choose a
container which it belongs to.
The containers are listed at ash/shell_window_ids, and you can get it through
Shell::GetContainer().

I think kShellWindowId_SettingBubbleContainer would be the one.

[dmazzoni, 2015/11/05 20:12:58]

Done.

+  params.delegate = this;
+  widget_->Init(params);
+  UpdateWidgetBounds();

[Jun Mukai, 2015/11/05 17:38:01]

IIRC, the initial bounds (set in params) and setting bounds after init is
slightly different. It's better to set the initial bounds.

[dmazzoni, 2015/11/05 20:12:58]

Done.

+
+  std::string url("chrome-extension://");
+  url += extension_misc::kChromeVoxExtensionId;
+  url += kChromeVoxPanelRelativeUrl;
+
+  ChromeVoxPanelWebView* web_view = new ChromeVoxPanelWebView(profile_, this);
+  widget_->SetContentsView(web_view);

[Jun Mukai, 2015/11/05 17:38:01]

It's better to implement GetContentsView() rather than setting here.

[dmazzoni, 2015/11/05 20:12:58]

Done.

+  SetShadowType(widget_->GetNativeWindow(), wm::SHADOW_TYPE_RECTANGULAR);
+  web_contents_observer_.reset(
+      new ChromeVoxPanelWebContentsObserver(web_view->GetWebContents(), this));
+  web_view->LoadInitialURL(GURL(url));
+
+  ash::Shell::GetScreen()->AddObserver(this);
+}
+
+ChromeVoxPanel::~ChromeVoxPanel() {
+  ash::Shell::GetScreen()->RemoveObserver(this);
+}
+
+int ChromeVoxPanel::GetHeight() {
+  return kPanelHeight;
+}
+
+aura::Window* ChromeVoxPanel::GetRootWindow() {
+  return root_window_;

[Jun Mukai, 2015/11/05 17:38:01]

You don't have to remember the root window.
It's just GetWidget()->GetNativeWindow()->GetRootWindow();

You can still keep this method, but I'd recommend to remove this.

[dmazzoni, 2015/11/05 20:12:58]

Done.

+}
+
+void ChromeVoxPanel::Close() {
+  widget_->Close();
+}
+
+void ChromeVoxPanel::OnDeviceScaleFactorChanged(float device_scale_factor) {
+  UpdateWidgetBounds();

[Jun Mukai, 2015/11/05 17:38:01]

I think you don't have to handle the device scale factor changes, because right
now DSF change causes OnDisplayMetricsChanged() (cc:oshima to confirm).

[dmazzoni, 2015/11/05 20:12:58]

Done.

+}
+
+void ChromeVoxPanel::DidFirstVisuallyNonEmptyPaint() {
+  widget_->Show();
+  ash::Shell::GetInstance()->UpdateDisplayWorkAreaInsets(root_window_);
+}
+
+void ChromeVoxPanel::EnterFullscreen() {
+  fullscreen_ = true;
+  UpdateWidgetBounds();
+}
+
+void ChromeVoxPanel::ExitFullscreen() {
+  fullscreen_ = false;
+  UpdateWidgetBounds();
+}
+
+const views::Widget* ChromeVoxPanel::GetWidget() const {
+  return widget_;
+}
+
+views::Widget* ChromeVoxPanel::GetWidget() {
+  return widget_;
+}
+
+void ChromeVoxPanel::DeleteDelegate() {
+  ash::Shell::GetInstance()->UpdateDisplayWorkAreaInsets(root_window_);

[Jun Mukai, 2015/11/05 17:38:02]

This may not work quite well. At this point, the widget instance (and
ChromeVoxPanel) isn't deleted yet, therefore UpdateWidgetBounds() can be called
incorrectly.
Not always AccessibilityManager closes the panel, sometimes it can be closed by
someone else (for example, at shutdown).

I think the following code path would be better:
- implement views::WidgetObserver in AccessibilityManager side, and observe
OnWidgetDestroying()
- clear |vox_panel_| and invoke UpdateDisplayWorkAreaInsets() on
OnWidgetDestroying()

Or
- create a callback on AccessibilityManager(), say, OnVoxPanelClosing()
- override WindowClosing() method here, invoke that method

[dmazzoni, 2015/11/05 20:12:58]

Thanks.

I went with the first approach, observing OnWidgetDestroying.

+  delete this;
+}
+
+void ChromeVoxPanel::OnDisplayMetricsChanged(const gfx::Display& display,
+                                             uint32_t changed_metrics) {
+  // This is called when the primary display changes. Move the panel to the
+  // new primary display.
+  if (root_window_ != ash::Shell::GetPrimaryRootWindow()) {
+    UpdateWidgetBounds();
+    ash::Shell::GetInstance()->UpdateDisplayWorkAreaInsets(root_window_);
+    root_window_ = ash::Shell::GetPrimaryRootWindow();
+    ash::Shell::GetInstance()->UpdateDisplayWorkAreaInsets(root_window_);
+  }
+}
+
+void ChromeVoxPanel::UpdateWidgetBounds() {
+  gfx::Rect bounds(0, 0, root_window_->bounds().width(),
+                   root_window_->bounds().height());
+  if (!fullscreen_)
+    bounds.set_height(kPanelHeight);
+  widget_->SetBounds(bounds);
+}