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// Copyright 2013 The Chromium Authors
// 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_SOURCE_H_
#define UI_ACCESSIBILITY_AX_TREE_SOURCE_H_
#include <stdint.h>
#include <string>
#include <vector>
#include "base/notreached.h"
#include "third_party/skia/include/core/SkBitmap.h"
#include "ui/accessibility/ax_node_id_forward.h"
#include "ui/accessibility/ax_tree_source_observer.h"
namespace ui {
// An AXTreeSource is an abstract interface for a serializable
// accessibility tree. The tree may be in some other format or
// may be computed dynamically, but maintains the properties that
// it's a strict tree, it has a unique id for each node, and all
// of the accessibility information about a node can be serialized
// as an AXNodeData. This is the primary interface to use when
// an accessibility tree will be sent over an IPC before being
// consumed.
template <typename AXNodeSource,
typename AXTreeDataType,
typename AXNodeDataType>
class AXTreeSource {
public:
virtual ~AXTreeSource() = default;
// Get the tree data and returns true if there is any data to copy.
virtual bool GetTreeData(AXTreeDataType data) const = 0;
// Get the root of the tree.
virtual AXNodeSource GetRoot() const = 0;
// Get a node by its id. If no node by that id exists in the tree, return a
// null node.
virtual AXNodeSource GetFromId(AXNodeID id) const = 0;
AXNodeSource EnsureGetFromId(AXNodeID id) const {
AXNodeSource node = GetFromId(id);
DCHECK(node);
return node;
}
// Return the id of a node. All ids must be positive integers; 0 is not a
// valid ID. IDs are unique only across the current tree source, not across
// tree sources.
virtual AXNodeID GetId(AXNodeSource node) const = 0;
virtual void CacheChildrenIfNeeded(AXNodeSource) = 0;
virtual size_t GetChildCount(AXNodeSource) const = 0;
virtual AXNodeSource ChildAt(AXNodeSource, size_t) const = 0;
virtual void ClearChildCache(AXNodeSource) = 0;
// Get the parent of |node|.
virtual AXNodeSource GetParent(AXNodeSource node) const = 0;
// Returns true if |node| is an ignored node
virtual bool IsIgnored(AXNodeSource node) const = 0;
// Returns true if two nodes are equal.
virtual bool IsEqual(AXNodeSource node1,
AXNodeSource node2) const = 0;
// Return a AXNodeSource representing null.
virtual AXNodeSource GetNull() const = 0;
// Serialize one node in the tree.
virtual void SerializeNode(AXNodeSource node,
AXNodeDataType* out_data) const = 0;
// Return a string useful for debugging a node.
virtual std::string GetDebugString(AXNodeSource node) const {
AXNodeDataType node_data;
SerializeNode(node, &node_data);
return node_data.ToString();
}
// The following methods should be overridden in order to add or remove an
// `AXTreeSourceObserver`, which is notified when nodes are added, removed or
// updated in this tree source.
virtual void AddObserver(
AXTreeSourceObserver<AXNodeSource, AXTreeDataType, AXNodeDataType>*
observer) {
NOTIMPLEMENTED();
}
virtual void RemoveObserver(
AXTreeSourceObserver<AXNodeSource, AXTreeDataType, AXNodeDataType>*
observer) {
NOTIMPLEMENTED();
}
protected:
AXTreeSource() {}
};
} // namespace ui
#endif // UI_ACCESSIBILITY_AX_TREE_SOURCE_H_
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