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// Copyright 2014 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/tree_generator.h"
#include "ui/accessibility/ax_serializable_tree.h"
#include "ui/accessibility/ax_tree.h"
#include "ui/accessibility/ax_tree_data.h"
#include "ui/accessibility/ax_tree_id.h"
namespace ui {
TreeGenerator::TreeGenerator(int max_node_count, bool permutations)
: max_node_count_(max_node_count),
permutations_(permutations),
total_unique_tree_count_(0) {
unique_tree_count_by_size_.push_back(0);
for (int i = 1; i <= max_node_count; ++i) {
int unique_tree_count = UniqueTreeCountForNodeCount(i, permutations);
unique_tree_count_by_size_.push_back(unique_tree_count);
total_unique_tree_count_ += unique_tree_count;
}
}
TreeGenerator::~TreeGenerator() {
}
int TreeGenerator::UniqueTreeCount() const {
return total_unique_tree_count_;
}
void TreeGenerator::BuildUniqueTree(int tree_index, AXTree* out_tree) const {
AXTreeUpdate update;
BuildUniqueTreeUpdate(tree_index, &update);
CHECK(out_tree->Unserialize(update)) << out_tree->error();
}
int TreeGenerator::IgnoredPermutationCountPerUniqueTree(int tree_index) const {
int unique_tree_count_so_far = 0;
for (int node_count = 1; node_count <= max_node_count_; ++node_count) {
int unique_tree_count = unique_tree_count_by_size_[node_count];
if (tree_index - unique_tree_count_so_far < unique_tree_count) {
// Each node other than the root can be either ignored or not,
// so return 2 ^ (node_count - 1)
return 1 << (node_count - 1);
}
unique_tree_count_so_far += unique_tree_count;
}
NOTREACHED();
return 0;
}
void TreeGenerator::BuildUniqueTreeWithIgnoredNodes(
int tree_index,
int ignored_index,
absl::optional<int> focused_node,
AXTree* out_tree) const {
// Enable the behavior whereby all focused nodes will be exposed to the
// platform accessibility layer. This behavior is currently disabled in
// production code, but is enabled in tests so that it could be tested
// thoroughly before it is turned on for all code.
//
// TODO(nektar): Turn this on in a followup patch.
// AXTree::SetFocusedNodeShouldNeverBeIgnored();
AXTreeUpdate update;
BuildUniqueTreeUpdate(tree_index, &update);
int node_count = static_cast<int>(update.nodes.size());
CHECK_GE(ignored_index, 0);
CHECK_LT(ignored_index, 1 << (node_count - 1));
CHECK(!focused_node || *focused_node >= 0);
CHECK(!focused_node || *focused_node < node_count);
for (int i = 0; i < node_count - 1; i++) {
if (ignored_index & (1 << i))
update.nodes[i + 1].AddState(ax::mojom::State::kIgnored);
}
if (focused_node) {
AXTreeData tree_data;
tree_data.tree_id = AXTreeID::CreateNewAXTreeID();
tree_data.focused_tree_id = tree_data.tree_id;
tree_data.focus_id = update.nodes[*focused_node].id;
update.has_tree_data = true;
update.tree_data = tree_data;
}
CHECK(out_tree->Unserialize(update)) << out_tree->error();
}
void TreeGenerator::BuildUniqueTreeUpdate(int tree_index,
AXTreeUpdate* out_update) const {
CHECK_LT(tree_index, total_unique_tree_count_);
int unique_tree_count_so_far = 0;
for (int node_count = 1; node_count <= max_node_count_; ++node_count) {
int unique_tree_count = unique_tree_count_by_size_[node_count];
if (tree_index - unique_tree_count_so_far < unique_tree_count) {
BuildUniqueTreeUpdateWithSize(
node_count, tree_index - unique_tree_count_so_far, out_update);
return;
}
unique_tree_count_so_far += unique_tree_count;
}
}
void TreeGenerator::BuildUniqueTreeUpdateWithSize(
int node_count,
int tree_index,
AXTreeUpdate* out_update) const {
std::vector<int> indices;
std::vector<int> permuted;
int unique_tree_count = unique_tree_count_by_size_[node_count];
CHECK_LT(tree_index, unique_tree_count);
if (permutations_) {
// Use the first few bits of |tree_index| to permute the indices.
for (int i = 0; i < node_count; ++i)
indices.push_back(i + 1);
for (int i = 0; i < node_count; ++i) {
int p = (node_count - i);
int index = tree_index % p;
tree_index /= p;
permuted.push_back(indices[index]);
indices.erase(indices.begin() + index);
}
} else {
for (int i = 0; i < node_count; ++i)
permuted.push_back(i + 1);
}
// Build an AXTreeUpdate. The first two nodes of the tree always
// go in the same place.
out_update->root_id = permuted[0];
out_update->nodes.resize(node_count);
out_update->nodes[0].id = permuted[0];
if (node_count > 1) {
out_update->nodes[0].child_ids.push_back(permuted[1]);
out_update->nodes[1].id = permuted[1];
}
// The remaining nodes are assigned based on their parent
// selected from the next bits from |tree_index|.
for (int i = 2; i < node_count; ++i) {
out_update->nodes[i].id = permuted[i];
int parent_index = (tree_index % i);
tree_index /= i;
out_update->nodes[parent_index].child_ids.push_back(permuted[i]);
}
}
} // namespace ui
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