ladybird/Userland/Libraries/LibWeb/DOMTreeJSONModel.cpp
Timothy Flynn 447ecc2155 LibWeb: Maintain a map of child-to-parent nodes in OOPWV DOM Inspector
Currently, each time parent_index() is invoked, two depth-first searches
are incurred to find the node's parent and grandparent. This becomes
particularly expensive, for example, when trying to scroll through a
large <ul> list.

Instead, upon creation, traverse the DOM JSON and create a map of child
nodes to their parent. Then those two lookups become hash map lookups
rather than a DFS traversal.
2021-07-01 19:19:46 +02:00

175 lines
5.3 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2018-2020, Adam Hodgen <ant1441@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "DOMTreeJSONModel.h"
#include <AK/JsonObject.h>
#include <AK/StringBuilder.h>
#include <ctype.h>
namespace Web {
DOMTreeJSONModel::DOMTreeJSONModel(JsonObject dom_tree)
: m_dom_tree(move(dom_tree))
{
m_document_icon.set_bitmap_for_size(16, Gfx::Bitmap::load_from_file("/res/icons/16x16/filetype-html.png"));
m_element_icon.set_bitmap_for_size(16, Gfx::Bitmap::load_from_file("/res/icons/16x16/inspector-object.png"));
m_text_icon.set_bitmap_for_size(16, Gfx::Bitmap::load_from_file("/res/icons/16x16/filetype-unknown.png"));
map_dom_nodes_to_parent(nullptr, &m_dom_tree);
}
DOMTreeJSONModel::~DOMTreeJSONModel()
{
}
GUI::ModelIndex DOMTreeJSONModel::index(int row, int column, const GUI::ModelIndex& parent) const
{
if (!parent.is_valid()) {
return create_index(row, column, &m_dom_tree);
}
auto const& parent_node = *static_cast<JsonObject const*>(parent.internal_data());
auto const* children = get_children(parent_node);
if (!children)
return create_index(row, column, &m_dom_tree);
auto const& child_node = children->at(row).as_object();
return create_index(row, column, &child_node);
}
GUI::ModelIndex DOMTreeJSONModel::parent_index(const GUI::ModelIndex& index) const
{
// FIXME: Handle the template element (child elements are not stored in it, all of its children are in its document fragment "content")
// Probably in the JSON generation in Node.cpp?
if (!index.is_valid())
return {};
auto const& node = *static_cast<JsonObject const*>(index.internal_data());
auto const* parent_node = get_parent(node);
if (!parent_node)
return {};
// If the parent is the root document, we know it has index 0, 0
if (parent_node == &m_dom_tree) {
return create_index(0, 0, parent_node);
}
// Otherwise, we need to find the grandparent, to find the index of parent within that
auto const* grandparent_node = get_parent(*parent_node);
VERIFY(grandparent_node);
auto const* grandparent_children = get_children(*grandparent_node);
if (!grandparent_children)
return {};
for (size_t grandparent_child_index = 0; grandparent_child_index < grandparent_children->size(); ++grandparent_child_index) {
auto const& child = grandparent_children->at(grandparent_child_index).as_object();
if (&child == parent_node)
return create_index(grandparent_child_index, 0, parent_node);
}
return {};
}
int DOMTreeJSONModel::row_count(const GUI::ModelIndex& index) const
{
if (!index.is_valid())
return 1;
auto const& node = *static_cast<JsonObject const*>(index.internal_data());
auto const* children = get_children(node);
return children ? children->size() : 0;
}
int DOMTreeJSONModel::column_count(const GUI::ModelIndex&) const
{
return 1;
}
static String with_whitespace_collapsed(const StringView& string)
{
StringBuilder builder;
for (size_t i = 0; i < string.length(); ++i) {
if (isspace(string[i])) {
builder.append(' ');
while (i < string.length()) {
if (isspace(string[i])) {
++i;
continue;
}
builder.append(string[i]);
break;
}
continue;
}
builder.append(string[i]);
}
return builder.to_string();
}
GUI::Variant DOMTreeJSONModel::data(const GUI::ModelIndex& index, GUI::ModelRole role) const
{
auto const& node = *static_cast<JsonObject const*>(index.internal_data());
auto node_name = node.get("name").as_string();
auto type = node.get("type").as_string_or("unknown");
if (role == GUI::ModelRole::Icon) {
if (type == "document")
return m_document_icon;
if (type == "element")
return m_element_icon;
// FIXME: More node type icons?
return m_text_icon;
}
if (role == GUI::ModelRole::Display) {
if (type == "text")
return with_whitespace_collapsed(node.get("text").as_string());
if (type != "element")
return node_name;
StringBuilder builder;
builder.append('<');
builder.append(node_name.to_lowercase());
if (node.has("attributes")) {
auto attributes = node.get("attributes").as_object();
attributes.for_each_member([&builder](auto& name, JsonValue const& value) {
builder.append(' ');
builder.append(name);
builder.append('=');
builder.append('"');
builder.append(value.to_string());
builder.append('"');
});
}
builder.append('>');
return builder.to_string();
}
return {};
}
void DOMTreeJSONModel::update()
{
did_update();
}
void DOMTreeJSONModel::map_dom_nodes_to_parent(JsonObject const* parent, JsonObject const* node)
{
m_dom_node_to_parent_map.set(node, parent);
auto const* children = get_children(*node);
if (!children)
return;
children->for_each([&](auto const& child) {
auto const& child_node = child.as_object();
map_dom_nodes_to_parent(node, &child_node);
});
}
}