| // Copyright 2013 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 UI_ACCESSIBILITY_AX_TREE_H_ |
| #define UI_ACCESSIBILITY_AX_TREE_H_ |
| |
| #include <set> |
| |
| #include "base/containers/hash_tables.h" |
| #include "ui/accessibility/ax_export.h" |
| #include "ui/accessibility/ax_tree_update.h" |
| |
| namespace ui { |
| |
| class AXNode; |
| struct AXTreeUpdateState; |
| |
| // Used when you want to be notified when changes happen to the tree. |
| // |
| // Some of the notifications are called in the middle of an update operation. |
| // Be careful, as the tree may be in an inconsistent state at this time; |
| // don't walk the parents and children at this time: |
| // OnNodeWillBeDeleted |
| // OnNodeCreated |
| // OnNodeChanged |
| // |
| // Other notifications are called at the end of an atomic update operation. |
| // From these, it's safe to walk the tree and do any initialization that |
| // assumes the tree is in a consistent state. |
| // OnNodeCreationFinished |
| // OnNodeChangeFinished |
| // OnRootChanged |
| class AX_EXPORT AXTreeDelegate { |
| public: |
| AXTreeDelegate(); |
| virtual ~AXTreeDelegate(); |
| |
| // Called just before a node is deleted. Its id and data will be valid, |
| // but its links to parents and children are invalid. This is called |
| // in the middle of an update, the tree may be in an invalid state! |
| virtual void OnNodeWillBeDeleted(AXNode* node) = 0; |
| |
| // Called immediately after a new node is created. The tree may be in |
| // the middle of an update, don't walk the parents and children now. |
| virtual void OnNodeCreated(AXNode* node) = 0; |
| |
| // Called when a node changes its data or children. The tree may be in |
| // the middle of an update, don't walk the parents and children now. |
| virtual void OnNodeChanged(AXNode* node) = 0; |
| |
| // Called for each new node at the end of an update operation, |
| // when the tree is in a consistent state. |
| virtual void OnNodeCreationFinished(AXNode* node) = 0; |
| |
| // Called for each existing node that changed at the end of an update |
| // operation, when the tree is in a consistent state. |
| virtual void OnNodeChangeFinished(AXNode* node) = 0; |
| |
| // Called at the end of an update operation when the root node changes. |
| virtual void OnRootChanged(AXNode* new_root) = 0; |
| }; |
| |
| // AXTree is a live, managed tree of AXNode objects that can receive |
| // updates from another AXTreeSource via AXTreeUpdates, and it can be |
| // used as a source for sending updates to another client tree. |
| // It's designed to be subclassed to implement support for native |
| // accessibility APIs on a specific platform. |
| class AX_EXPORT AXTree { |
| public: |
| AXTree(); |
| explicit AXTree(const AXTreeUpdate& initial_state); |
| virtual ~AXTree(); |
| |
| virtual void SetDelegate(AXTreeDelegate* delegate); |
| |
| virtual AXNode* GetRoot() const; |
| virtual AXNode* GetFromId(int32 id) const; |
| |
| // Returns true on success. If it returns false, it's a fatal error |
| // and this tree should be destroyed, and the source of the tree update |
| // should not be trusted any longer. |
| virtual bool Unserialize(const AXTreeUpdate& update); |
| |
| // Return a multi-line indented string representation, for logging. |
| std::string ToString() const; |
| |
| // A string describing the error from an unsuccessful Unserialize, |
| // for testing and debugging. |
| const std::string& error() { return error_; } |
| |
| private: |
| AXNode* CreateNode(AXNode* parent, int32 id, int32 index_in_parent); |
| |
| // This is called from within Unserialize(), it returns true on success. |
| bool UpdateNode(const AXNodeData& src, AXTreeUpdateState* update_state); |
| |
| void OnRootChanged(); |
| |
| // Call Destroy() on |node|, and delete it from the id map, and then |
| // call recursively on all nodes in its subtree. |
| void DestroyNodeAndSubtree(AXNode* node); |
| |
| // Iterate over the children of |node| and for each child, destroy the |
| // child and its subtree if its id is not in |new_child_ids|. Returns |
| // true on success, false on fatal error. |
| bool DeleteOldChildren(AXNode* node, |
| const std::vector<int32> new_child_ids); |
| |
| // Iterate over |new_child_ids| and populate |new_children| with |
| // pointers to child nodes, reusing existing nodes already in the tree |
| // if they exist, and creating otherwise. Reparenting is disallowed, so |
| // if the id already exists as the child of another node, that's an |
| // error. Returns true on success, false on fatal error. |
| bool CreateNewChildVector(AXNode* node, |
| const std::vector<int32> new_child_ids, |
| std::vector<AXNode*>* new_children, |
| AXTreeUpdateState* update_state); |
| |
| AXTreeDelegate* delegate_; |
| AXNode* root_; |
| base::hash_map<int32, AXNode*> id_map_; |
| std::string error_; |
| }; |
| |
| } // namespace ui |
| |
| #endif // UI_ACCESSIBILITY_AX_TREE_H_ |