Draw underlay behind android apps using talkback

components/exo/shell_surface.cc

Index: components/exo/shell_surface.cc
diff --git a/components/exo/shell_surface.cc b/components/exo/shell_surface.cc
index 465477e79c488da48e2b777eaafd631ae51591a8..8952f1cb3b665d988d0ed99d055fc12f8849ab67 100644
--- a/components/exo/shell_surface.cc
+++ b/components/exo/shell_surface.cc
@@ -4,9 +4,13 @@
 
 #include "components/exo/shell_surface.h"
 
+#include <algorithm>
+
 #include "ash/aura/wm_window_aura.h"
+#include "ash/common/accessibility_delegate.h"
 #include "ash/common/shelf/wm_shelf.h"
 #include "ash/common/shell_window_ids.h"
+#include "ash/common/system/tray/system_tray_notifier.h"
 #include "ash/common/wm/window_resizer.h"
 #include "ash/common/wm/window_state.h"
 #include "ash/common/wm/window_state_delegate.h"
@@ -37,6 +41,10 @@
 #include "ui/wm/core/shadow_types.h"
 #include "ui/wm/core/window_util.h"
 
+#if defined(OS_CHROMEOS)

[oshima, 2016/10/01 02:00:09]

Do you need this? I believe this file is compiled only on ChromeOS.

[reveman, 2016/10/01 08:12:30]

Compiling this only on ChromeOS is by choice and technically not something we're
limited by. Initially this code was not only compiled on ChromeOS and that might
change again in the future again. I'd like to keep these ifdefs that are
consistent with the USE_OZONE ifdefs in display.cc. 

+#include "chromeos/audio/chromeos_sounds.h"
+#endif
+
 DECLARE_WINDOW_PROPERTY_TYPE(std::string*)
 
 namespace exo {
@@ -87,7 +95,7 @@ class CustomFrameView : public views::NonClientFrameView {
 
 class CustomWindowTargeter : public aura::WindowTargeter {
  public:
-  CustomWindowTargeter() {}
+  CustomWindowTargeter(views::Widget* widget) : widget_(widget) {}
   ~CustomWindowTargeter() override {}
 
   // Overridden from aura::WindowTargeter:
@@ -98,6 +106,20 @@ class CustomWindowTargeter : public aura::WindowTargeter {
       return false;
 
     gfx::Point local_point = event.location();
+
+    // If the underlay is accepting events, test against it's bounds instead
+    // since it will be larger than (and contain) the surface's bounds.
+    aura::Window* shadow_underlay =
+        static_cast<ShellSurface*>(
+            widget_->widget_delegate()->GetContentsView())
+            ->shadow_underlay();
+    if (shadow_underlay && !shadow_underlay->ignore_events()) {
+      if (window->parent())
+        aura::Window::ConvertPointToTarget(window->parent(), shadow_underlay,
+                                           &local_point);
+      return gfx::Rect(shadow_underlay->layer()->size()).Contains(local_point);
+    }
+
     if (window->parent())
       aura::Window::ConvertPointToTarget(window->parent(), window,
                                          &local_point);
@@ -106,7 +128,30 @@ class CustomWindowTargeter : public aura::WindowTargeter {
     return surface->HitTestRect(gfx::Rect(local_point, gfx::Size(1, 1)));
   }
 
+  ui::EventTarget* FindTargetForEvent(ui::EventTarget* root,
+                                      ui::Event* event) override {
+    aura::Window* window = static_cast<aura::Window*>(root);
+    Surface* surface = ShellSurface::GetMainSurface(window);
+
+    // Send events which are outside of the surface's bounds to the underlay.
+    aura::Window* shadow_underlay =
+        static_cast<ShellSurface*>(
+            widget_->widget_delegate()->GetContentsView())
+            ->shadow_underlay();
+    if (surface && event->IsLocatedEvent() && shadow_underlay &&
+        !shadow_underlay->ignore_events()) {
+      gfx::Point local_point = event->AsLocatedEvent()->location();
+      aura::Window::ConvertPointToTarget(window, surface->window(),
+                                         &local_point);
+      if (!surface->HitTestRect(gfx::Rect(local_point, gfx::Size(1, 1))))
+        return shadow_underlay;
+    }
+    return aura::WindowTargeter::FindTargetForEvent(root, event);
+  }
+
  private:
+  views::Widget* const widget_;
+
   DISALLOW_COPY_AND_ASSIGN(CustomWindowTargeter);
 };
 
@@ -166,6 +211,42 @@ class ShellSurfaceWidget : public views::Widget {
   DISALLOW_COPY_AND_ASSIGN(ShellSurfaceWidget);
 };
 
+class ShadowUnderlayEventHandler : public ui::EventHandler {
+ public:
+  ShadowUnderlayEventHandler() {}
+  ~ShadowUnderlayEventHandler() override {}
+
+  // Overridden from ui::EventHandler:
+  void OnEvent(ui::Event* event) override {
+    // If the event is targeted at the underlay, it means the user has made an
+    // interaction that is outside the surface's bounds and we want to capture
+    // it (usually when in spoken feedback mode). Handle the event (to prevent
+    // behind-windows from receiving it) and play an earcon to notify the user.
+    if (event->IsLocatedEvent()) {
+#if defined(OS_CHROMEOS)
+      const ui::EventType kEarconEventTypes[] = {ui::ET_MOUSE_PRESSED,
+                                                 ui::ET_MOUSEWHEEL,
+                                                 ui::ET_TOUCH_PRESSED,
+                                                 ui::ET_POINTER_DOWN,
+                                                 ui::ET_POINTER_WHEEL_CHANGED,
+                                                 ui::ET_GESTURE_BEGIN,
+                                                 ui::ET_SCROLL,
+                                                 ui::ET_SCROLL_FLING_START};
+      bool is_earcon_event_type =
+          std::find(std::begin(kEarconEventTypes), std::end(kEarconEventTypes),
+                    event->type()) != std::end(kEarconEventTypes);
+      if (is_earcon_event_type)
+        ash::WmShell::Get()->accessibility_delegate()->PlayEarcon(
+            chromeos::SOUND_VOLUME_ADJUST);
+#endif
+      event->SetHandled();
+    }
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ShadowUnderlayEventHandler);
+};
+
 }  // namespace
 
 // Helper class used to coalesce a number of changes into one "configure"
@@ -302,6 +383,8 @@ ShellSurface::~ShellSurface() {
     surface_->SetSurfaceDelegate(nullptr);
     surface_->RemoveSurfaceObserver(this);
   }
+  ash::WmShell::Get()->system_tray_notifier()->RemoveAccessibilityObserver(
+      this);
 }
 
 void ShellSurface::AcknowledgeConfigure(uint32_t serial) {
@@ -726,6 +809,14 @@ gfx::Size ShellSurface::GetPreferredSize() const {
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+// ash::AccessibilityObserver overrides:
+
+void ShellSurface::OnAccessibilityModeChanged(
+    ash::AccessibilityNotificationVisibility) {
+  UpdateShadow();
+}
+
+////////////////////////////////////////////////////////////////////////////////
 // ash::wm::WindowStateObserver overrides:
 
 void ShellSurface::OnPreWindowStateTypeChange(
@@ -821,6 +912,7 @@ void ShellSurface::OnWindowActivated(
       lost_active == widget_->GetNativeWindow()) {
     DCHECK(activatable_);
     Configure();
+    UpdateShadow();
   }
 }
 
@@ -936,7 +1028,7 @@ void ShellSurface::CreateShellSurfaceWidget(ui::WindowShowState show_state) {
   aura::Window* window = widget_->GetNativeWindow();
   window->SetName("ExoShellSurface");
   window->AddChild(surface_->window());
-  window->SetEventTargeter(base::WrapUnique(new CustomWindowTargeter));
+  window->SetEventTargeter(base::WrapUnique(new CustomWindowTargeter(widget_)));
   SetApplicationId(window, &application_id_);
   SetMainSurface(window, surface_);
 
@@ -982,6 +1074,9 @@ void ShellSurface::CreateShellSurfaceWidget(ui::WindowShowState show_state) {
   window_state->SetDelegate(std::unique_ptr<ash::wm::WindowStateDelegate>(
       new CustomWindowStateDelegate(widget_)));
 
+  // Receive accessibility changes to update shadow underlay.
+  ash::WmShell::Get()->system_tray_notifier()->AddAccessibilityObserver(this);
+
   // Show widget next time Commit() is called.
   pending_show_widget_ = true;
 }
@@ -1241,8 +1336,10 @@ void ShellSurface::UpdateShadow() {
     // Always create and show the underlay, even in maximized/fullscreen.
     if (!shadow_underlay_) {
       shadow_underlay_ = new aura::Window(nullptr);
+      shadow_underlay_event_handler_ =
+          base::MakeUnique<ShadowUnderlayEventHandler>();
+      shadow_underlay_->SetTargetHandler(shadow_underlay_event_handler_.get());
       DCHECK(shadow_underlay_->owned_by_parent());
-      shadow_underlay_->set_ignore_events(true);
       // Ensure the background area inside the shadow is solid black.
       // Clients that provide translucent contents should not be using
       // rectangular shadows as this method requires opaque contents to
@@ -1254,16 +1351,23 @@ void ShellSurface::UpdateShadow() {
       window->StackChildAtBottom(shadow_underlay_);
     }
 
+    bool underlay_capture_events = ash::WmShell::Get()
+                                       ->accessibility_delegate()
+                                       ->IsSpokenFeedbackEnabled() &&
+                                   widget_->IsActive();
+    shadow_underlay_->set_ignore_events(!underlay_capture_events);

[oshima, 2016/10/01 02:00:10]

I think shadow underlay should always consume events so that touching there
shouldn't activate or do something on other windows because they're not visible.

[reveman, 2016/10/01 08:12:30]

+1

[Mr4D (OOO till 08-26), 2016/10/01 08:56:21]

The purpose of this is that blind people can touch the screen anywhere (even
outside of the window) and still get a system reaction. As such the shadow
underlay should react to touch (it's an accessibility feature and we cannot
simply full screen M apps since they might die).

[erosky, 2016/10/03 17:44:02]

Doing that would include things like immersive-mode portrait. It makes sense, to
me, in that case as-well, but just want to make sure that's what you meant.

[oshima, 2016/10/03 19:57:01]

Yes, we want this for both cases. 

[erosky, 2016/10/03 22:35:08]

Done.

+
     float shadow_underlay_opacity = rectangular_shadow_background_opacity_;
     // Put the black background layer behind the window if
-    // 1) the window is in immersive fullscreen.
+    // 1) the window is in immersive fullscreen or is active with
+    //    spoken feedback enabled.
     // 2) the window can control the bounds of the window in fullscreen (
     //    thus the background can be visible).
     // 3) the window has no transform (the transformed background may
     //    not cover the entire background, e.g. overview mode).
-    if (widget_->IsFullscreen() &&
+    if ((widget_->IsFullscreen() || underlay_capture_events) &&
         ash::wm::GetWindowState(window)->allow_set_bounds_in_maximized() &&
-        window->layer()->transform().IsIdentity()) {
+        window->layer()->GetTargetTransform().IsIdentity()) {
       gfx::Point origin;
       origin -= window->bounds().origin().OffsetFromOrigin();
       shadow_bounds.set_origin(origin);