Improve toolbar keyboard accessibility.

Design doc: https://docs.google.com/a/google.com/Doc?docid=0ATICCjR-gNReY2djdjkyNnNfNzl4ZnpiODQ2Mg&hl=en
BUG=40745
BUG=36728
BUG=36222
TEST=New test added to focus_manager_unittest.cc

Review URL: http://codereview.chromium.org/2737010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@50234 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 120 insertions, 0 deletions

diff --git a/views/focus/focus_search.h b/views/focus/focus_search.h
new file mode 100644
index 0000000..f24864b
--- /dev/null
+++ b/views/focus/focus_search.h
@@ -0,0 +1,120 @@
+// Copyright (c) 2010 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.
+
+#ifndef VIEWS_WIDGET_FOCUS_SEARCH_H_
+#define VIEWS_WIDGET_FOCUS_SEARCH_H_
+
+#include "views/view.h"
+
+namespace views {
+
+class FocusTraversable;
+
+// FocusSearch is an object that implements the algorithm to find the
+// next view to focus.
+class FocusSearch {
+ public:
+  // The direction in which the focus traversal is going.
+  // TODO (jcampan): add support for lateral (left, right) focus traversal. The
+  // goal is to switch to focusable views on the same level when using the arrow
+  // keys (ala Windows: in a dialog box, arrow keys typically move between the
+  // dialog OK, Cancel buttons).
+  enum Direction {
+    UP = 0,
+    DOWN
+  };
+
+  // Constructor.
+  // - |root| is the root of the view hierarchy to traverse. Focus will be
+  //   trapped inside.
+  // - |cycle| should be true if you want FindNextFocusableView to cycle back
+  //           to the first view within this root when the traversal reaches
+  //           the end. If this is true, then if you pass a valid starting
+  //           view to FindNextFocusableView you will always get a valid view
+  //           out, even if it's the same view.
+  // - |accessibility_mode| should be true if full keyboard accessibility is
+  //   needed and you  want to check IsAccessibilityFocusable(),
+  //   rather than IsFocusable().
+  FocusSearch(View* root, bool cycle, bool accessibility_mode);
+  virtual ~FocusSearch() {}
+
+  // Finds the next view that should be focused and returns it. If a
+  // FocusTraversable is found while searching for the focusable view,
+  // returns NULL and sets |focus_traversable| to the FocusTraversable
+  // and |focus_traversable_view| to the view associated with the
+  // FocusTraversable.
+  //
+  // Return NULL if the end of the focus loop is reached, unless this object
+  // was initialized with |cycle|=true, in which case it goes back to the
+  // beginning when it reaches the end of the traversal.
+  // - |starting_view| is the view that should be used as the starting point
+  //   when looking for the previous/next view. It may be NULL (in which case
+  //   the first/last view should be used depending if normal/reverse).
+  // - |reverse| whether we should find the next (reverse is false) or the
+  //   previous (reverse is true) view.
+  // - |direction| specifies whether we are traversing down (meaning we should
+  //   look into child views) or traversing up (don't look at child views).
+  // - |check_starting_view| is true if starting_view may obtain the next focus.
+  // - |focus_traversable| is set to the focus traversable that should be
+  //   traversed if one is found (in which case the call returns NULL).
+  // - |focus_traversable_view| is set to the view associated with the
+  //   FocusTraversable set in the previous parameter (it is used as the
+  //   starting view when looking for the next focusable view).
+  virtual View* FindNextFocusableView(View* starting_view,
+                                      bool reverse,
+                                      Direction direction,
+                                      bool check_starting_view,
+                                      FocusTraversable** focus_traversable,
+                                      View** focus_traversable_view);
+
+ private:
+  // Convenience method that returns true if a view is focusable and does not
+  // belong to the specified group.
+  bool IsViewFocusableCandidate(View* v, int skip_group_id);
+
+  // Convenience method; returns true if a view is not NULL and is focusable
+  // (checking IsAccessibilityFocusable() if accessibility_mode_ is true).
+  bool IsFocusable(View* v);
+
+  // Returns the view selected for the group of the selected view. If the view
+  // does not belong to a group or if no view is selected in the group, the
+  // specified view is returned.
+  View* FindSelectedViewForGroup(View* view);
+
+  // Get the parent, but stay within the root. Returns NULL if asked for
+  // the parent of root_.
+  View* GetParent(View* view);
+
+  // Returns the next focusable view or view containing a FocusTraversable
+  // (NULL if none was found), starting at the starting_view.
+  // |check_starting_view|, |can_go_up| and |can_go_down| controls the
+  // traversal of the views hierarchy. |skip_group_id| specifies a group_id,
+  // -1 means no group. All views from a group are traversed in one pass.
+  View* FindNextFocusableViewImpl(View* starting_view,
+                                  bool check_starting_view,
+                                  bool can_go_up,
+                                  bool can_go_down,
+                                  int skip_group_id,
+                                  FocusTraversable** focus_traversable,
+                                  View** focus_traversable_view);
+
+  // Same as FindNextFocusableViewImpl but returns the previous focusable view.
+  View* FindPreviousFocusableViewImpl(View* starting_view,
+                                      bool check_starting_view,
+                                      bool can_go_up,
+                                      bool can_go_down,
+                                      int skip_group_id,
+                                      FocusTraversable** focus_traversable,
+                                      View** focus_traversable_view);
+
+  View* root_;
+  bool cycle_;
+  bool accessibility_mode_;
+
+  DISALLOW_COPY_AND_ASSIGN(FocusSearch);
+};
+
+}  // namespace views
+
+#endif  // VIEWS_WIDGET_FOCUS_SEARCH_H_