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// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "ui/accessibility/ax_tree_combiner.h"
#include "ui/accessibility/ax_enums.mojom.h"
#include "ui/accessibility/ax_tree.h"
#include "ui/gfx/geometry/rect_f.h"
namespace ui {
AXTreeCombiner::AXTreeCombiner() = default;
AXTreeCombiner::~AXTreeCombiner() = default;
void AXTreeCombiner::AddTree(AXTreeUpdate& tree, bool is_root) {
if (tree.tree_data.tree_id == AXTreeIDUnknown()) {
LOG(WARNING) << "Skipping AXTreeID because its tree ID is unknown";
return;
}
if (is_root) {
DCHECK_EQ(root_tree_id_, AXTreeIDUnknown());
root_tree_id_ = tree.tree_data.tree_id;
}
trees_.emplace_back(std::move(tree));
}
bool AXTreeCombiner::Combine() {
// `Combine` should only ever be called once.
CHECK(!combined_.has_value());
if (trees_.size() == 1) {
// Nothing to combine -- only one tree.
DCHECK(root_tree_id_ == trees_[0].tree_data.tree_id);
combined_ = std::move(trees_[0]);
return true;
}
combined_ = AXTreeUpdate();
// First create a map from tree ID to tree update.
std::map<AXTreeID, AXTreeUpdate*> tree_id_map;
for (auto& tree : trees_) {
AXTreeID tree_id = tree.tree_data.tree_id;
if (tree_id_map.find(tree_id) != tree_id_map.end()) {
return false;
}
tree_id_map[tree.tree_data.tree_id] = &tree;
}
// Make sure the root tree ID is in the map, otherwise fail.
if (tree_id_map.find(root_tree_id_) == tree_id_map.end()) {
return false;
}
// Process the nodes recursively, starting with the root tree.
AXTreeUpdate* root = tree_id_map.find(root_tree_id_)->second;
ProcessTree(root, tree_id_map);
// Set the root id.
combined_->root_id = combined_->nodes.size() > 0 ? combined_->nodes[0].id : 0;
// Finally, handle the tree ID, taking into account which subtree might
// have focus and mapping IDs from the tree data appropriately.
combined_->has_tree_data = true;
combined_->tree_data = root->tree_data;
AXTreeID focused_tree_id = root->tree_data.focused_tree_id;
const AXTreeUpdate* focused_tree = root;
if (tree_id_map.find(focused_tree_id) != tree_id_map.end()) {
focused_tree = tree_id_map[focused_tree_id];
}
combined_->tree_data.focus_id =
MapId(focused_tree_id, focused_tree->tree_data.focus_id);
combined_->tree_data.sel_is_backward =
MapId(focused_tree_id, focused_tree->tree_data.sel_is_backward);
combined_->tree_data.sel_anchor_object_id =
MapId(focused_tree_id, focused_tree->tree_data.sel_anchor_object_id);
combined_->tree_data.sel_focus_object_id =
MapId(focused_tree_id, focused_tree->tree_data.sel_focus_object_id);
combined_->tree_data.sel_anchor_offset =
focused_tree->tree_data.sel_anchor_offset;
combined_->tree_data.sel_focus_offset =
focused_tree->tree_data.sel_focus_offset;
// Debug-mode check that the resulting combined tree is valid.
AXTree tree;
DCHECK(tree.Unserialize(*combined_)) << combined_->ToString() << "\n"
<< tree.error();
return true;
}
AXNodeID AXTreeCombiner::MapId(AXTreeID tree_id, AXNodeID node_id) {
auto tree_id_node_id = std::make_pair(tree_id, node_id);
if (tree_id_node_id_map_[tree_id_node_id] == 0)
tree_id_node_id_map_[tree_id_node_id] = next_id_++;
return tree_id_node_id_map_[tree_id_node_id];
}
void AXTreeCombiner::ProcessTree(
AXTreeUpdate* tree,
const std::map<AXTreeID, AXTreeUpdate*>& tree_id_map) {
AXTreeID tree_id = tree->tree_data.tree_id;
for (auto& node : tree->nodes) {
AXTreeID child_tree_id = AXTreeID::FromString(
node.GetStringAttribute(ax::mojom::StringAttribute::kChildTreeId));
// Map the node's ID.
node.id = MapId(tree_id, node.id);
// Map the node's child IDs.
for (int& child_id : node.child_ids) {
child_id = MapId(tree_id, child_id);
}
// Map the container id.
if (node.relative_bounds.offset_container_id > 0) {
node.relative_bounds.offset_container_id =
MapId(tree_id, node.relative_bounds.offset_container_id);
}
// Map other int attributes that refer to node IDs.
for (auto& attr : node.int_attributes) {
if (IsNodeIdIntAttribute(attr.first)) {
attr.second = MapId(tree_id, attr.second);
}
}
// Map other int list attributes that refer to node IDs.
for (auto& node_int_list : node.intlist_attributes) {
if (IsNodeIdIntListAttribute(node_int_list.first)) {
for (int& attr : node_int_list.second) {
attr = MapId(tree_id, attr);
}
}
}
// Remove the ax::mojom::StringAttribute::kChildTreeId attribute.
for (auto& attr : node.string_attributes) {
if (attr.first == ax::mojom::StringAttribute::kChildTreeId) {
attr.first = ax::mojom::StringAttribute::kNone;
attr.second = "";
}
}
// See if this node has a child tree. As a confidence check, make sure the
// child tree lists this tree as its parent tree id.
AXTreeUpdate* child_tree = nullptr;
if (tree_id_map.find(child_tree_id) != tree_id_map.end()) {
child_tree = tree_id_map.find(child_tree_id)->second;
if (child_tree->tree_data.parent_tree_id != tree_id) {
child_tree = nullptr;
}
if (child_tree && child_tree->nodes.empty()) {
child_tree = nullptr;
}
if (child_tree) {
node.child_ids.push_back(MapId(child_tree_id, child_tree->nodes[0].id));
}
}
// Put the rewritten AXNodeData into the output data structure.
combined_->nodes.emplace_back(std::move(node));
// Recurse into the child tree now, if any.
if (child_tree) {
ProcessTree(child_tree, tree_id_map);
}
}
}
} // namespace ui
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