accessible_pane_view.cc

// Copyright (c) 2012 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 "ui/views/accessible_pane_view.h"

#include "base/message_loop/message_loop.h"
#include "ui/accessibility/ax_view_state.h"
#include "ui/views/focus/focus_search.h"
#include "ui/views/focus/view_storage.h"
#include "ui/views/widget/widget.h"

namespace views {

// Create tiny subclass of FocusSearch that overrides GetParent and Contains,
// delegating these to methods in AccessiblePaneView. This is needed so that
// subclasses of AccessiblePaneView can customize the focus search logic and
// include views that aren't part of the AccessiblePaneView's view
// hierarchy in the focus order.
class AccessiblePaneViewFocusSearch : public FocusSearch {
 public:
  explicit AccessiblePaneViewFocusSearch(AccessiblePaneView* pane_view)
      : FocusSearch(pane_view, true, true),
        accessible_pane_view_(pane_view) {}

 protected:
  virtual View* GetParent(View* v) OVERRIDE {
    return accessible_pane_view_->ContainsForFocusSearch(root(), v) ?
        accessible_pane_view_->GetParentForFocusSearch(v) : NULL;
  }

  // Returns true if |v| is contained within the hierarchy rooted at |root|.
  // Subclasses can override this if they need custom focus search behavior.
  virtual bool Contains(View* root, const View* v) OVERRIDE {
    return accessible_pane_view_->ContainsForFocusSearch(root, v);
  }

 private:
  AccessiblePaneView* accessible_pane_view_;
  DISALLOW_COPY_AND_ASSIGN(AccessiblePaneViewFocusSearch);
};

AccessiblePaneView::AccessiblePaneView()
    : pane_has_focus_(false),
      allow_deactivate_on_esc_(false),
      method_factory_(this),
      focus_manager_(NULL),
      home_key_(ui::VKEY_HOME, ui::EF_NONE),
      end_key_(ui::VKEY_END, ui::EF_NONE),
      escape_key_(ui::VKEY_ESCAPE, ui::EF_NONE),
      left_key_(ui::VKEY_LEFT, ui::EF_NONE),
      right_key_(ui::VKEY_RIGHT, ui::EF_NONE) {
  focus_search_.reset(new AccessiblePaneViewFocusSearch(this));
  last_focused_view_storage_id_ = ViewStorage::GetInstance()->CreateStorageID();
}

AccessiblePaneView::~AccessiblePaneView() {
  if (pane_has_focus_) {
    focus_manager_->RemoveFocusChangeListener(this);
  }
}

bool AccessiblePaneView::SetPaneFocus(views::View* initial_focus) {
  if (!visible())
    return false;

  if (!focus_manager_)
    focus_manager_ = GetFocusManager();

  View* focused_view = focus_manager_->GetFocusedView();
  if (focused_view && !ContainsForFocusSearch(this, focused_view)) {
    ViewStorage* view_storage = ViewStorage::GetInstance();
    view_storage->RemoveView(last_focused_view_storage_id_);
    view_storage->StoreView(last_focused_view_storage_id_, focused_view);
  }

  // Use the provided initial focus if it's visible and enabled, otherwise
  // use the first focusable child.
  if (!initial_focus ||
      !ContainsForFocusSearch(this, initial_focus) ||
      !initial_focus->visible() ||
      !initial_focus->enabled()) {
    initial_focus = GetFirstFocusableChild();
  }

  // Return false if there are no focusable children.
  if (!initial_focus)
    return false;

  focus_manager_->SetFocusedView(initial_focus);

  // If we already have pane focus, we're done.
  if (pane_has_focus_)
    return true;

  // Otherwise, set accelerators and start listening for focus change events.
  pane_has_focus_ = true;
  ui::AcceleratorManager::HandlerPriority normal =
      ui::AcceleratorManager::kNormalPriority;
  focus_manager_->RegisterAccelerator(home_key_, normal, this);
  focus_manager_->RegisterAccelerator(end_key_, normal, this);
  focus_manager_->RegisterAccelerator(escape_key_, normal, this);
  focus_manager_->RegisterAccelerator(left_key_, normal, this);
  focus_manager_->RegisterAccelerator(right_key_, normal, this);
  focus_manager_->AddFocusChangeListener(this);

  return true;
}

bool AccessiblePaneView::SetPaneFocusAndFocusDefault() {
  return SetPaneFocus(GetDefaultFocusableChild());
}

views::View* AccessiblePaneView::GetDefaultFocusableChild() {
  return NULL;
}

View* AccessiblePaneView::GetParentForFocusSearch(View* v) {
  return v->parent();
}

bool AccessiblePaneView::ContainsForFocusSearch(View* root, const View* v) {
  return root->Contains(v);
}

void AccessiblePaneView::RemovePaneFocus() {
  focus_manager_->RemoveFocusChangeListener(this);
  pane_has_focus_ = false;

  focus_manager_->UnregisterAccelerator(home_key_, this);
  focus_manager_->UnregisterAccelerator(end_key_, this);
  focus_manager_->UnregisterAccelerator(escape_key_, this);
  focus_manager_->UnregisterAccelerator(left_key_, this);
  focus_manager_->UnregisterAccelerator(right_key_, this);
}

views::View* AccessiblePaneView::GetFirstFocusableChild() {
  FocusTraversable* dummy_focus_traversable;
  views::View* dummy_focus_traversable_view;
  return focus_search_->FindNextFocusableView(
      NULL, false, views::FocusSearch::DOWN, false,
      &dummy_focus_traversable, &dummy_focus_traversable_view);
}

views::View* AccessiblePaneView::GetLastFocusableChild() {
  FocusTraversable* dummy_focus_traversable;
  views::View* dummy_focus_traversable_view;
  return focus_search_->FindNextFocusableView(
      this, true, views::FocusSearch::DOWN, false,
      &dummy_focus_traversable, &dummy_focus_traversable_view);
}

////////////////////////////////////////////////////////////////////////////////
// View overrides:

views::FocusTraversable* AccessiblePaneView::GetPaneFocusTraversable() {
  if (pane_has_focus_)
    return this;
  else
    return NULL;
}

bool AccessiblePaneView::AcceleratorPressed(
    const ui::Accelerator& accelerator) {

  views::View* focused_view = focus_manager_->GetFocusedView();
  if (!ContainsForFocusSearch(this, focused_view))
    return false;

  switch (accelerator.key_code()) {
    case ui::VKEY_ESCAPE: {
      RemovePaneFocus();
      View* last_focused_view = ViewStorage::GetInstance()->RetrieveView(
          last_focused_view_storage_id_);
      if (last_focused_view) {
        focus_manager_->SetFocusedViewWithReason(
            last_focused_view, FocusManager::kReasonFocusRestore);
      } else if (allow_deactivate_on_esc_) {
        focused_view->GetWidget()->Deactivate();
      }
      return true;
    }
    case ui::VKEY_LEFT:
      focus_manager_->AdvanceFocus(true);
      return true;
    case ui::VKEY_RIGHT:
      focus_manager_->AdvanceFocus(false);
      return true;
    case ui::VKEY_HOME:
      focus_manager_->SetFocusedViewWithReason(
          GetFirstFocusableChild(), views::FocusManager::kReasonFocusTraversal);
      return true;
    case ui::VKEY_END:
      focus_manager_->SetFocusedViewWithReason(
          GetLastFocusableChild(), views::FocusManager::kReasonFocusTraversal);
      return true;
    default:
      return false;
  }
}

void AccessiblePaneView::SetVisible(bool flag) {
  if (visible() && !flag && pane_has_focus_) {
    RemovePaneFocus();
    focus_manager_->RestoreFocusedView();
  }
  View::SetVisible(flag);
}

void AccessiblePaneView::GetAccessibleState(ui::AXViewState* state) {
  state->role = ui::AX_ROLE_PANE;
}

void AccessiblePaneView::RequestFocus() {
  SetPaneFocusAndFocusDefault();
}

////////////////////////////////////////////////////////////////////////////////
// FocusChangeListener overrides:

void AccessiblePaneView::OnWillChangeFocus(views::View* focused_before,
                                           views::View* focused_now) {
  //  Act when focus has changed.
}

void AccessiblePaneView::OnDidChangeFocus(views::View* focused_before,
                                          views::View* focused_now) {
  if (!focused_now)
    return;

  views::FocusManager::FocusChangeReason reason =
      focus_manager_->focus_change_reason();

  if (!ContainsForFocusSearch(this, focused_now) ||
      reason == views::FocusManager::kReasonDirectFocusChange) {
    // We should remove pane focus (i.e. make most of the controls
    // not focusable again) because the focus has left the pane,
    // or because the focus changed within the pane due to the user
    // directly focusing to a specific view (e.g., clicking on it).
    RemovePaneFocus();
  }
}

////////////////////////////////////////////////////////////////////////////////
// FocusTraversable overrides:

views::FocusSearch* AccessiblePaneView::GetFocusSearch() {
  DCHECK(pane_has_focus_);
  return focus_search_.get();
}

views::FocusTraversable* AccessiblePaneView::GetFocusTraversableParent() {
  DCHECK(pane_has_focus_);
  return NULL;
}

views::View* AccessiblePaneView::GetFocusTraversableParentView() {
  DCHECK(pane_has_focus_);
  return NULL;
}

}  // namespace views