LibWeb+Browser: Add a barebones LayoutTreeModel to the inspector window

This allows you to inspect the layout tree, along side the DOM tree.
It will need more functionality to be truly useful, but it's a start.

Libraries/LibWeb/LayoutTreeModel.cpp

@@ -0,0 +1,162 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "LayoutTreeModel.h"
+#include <AK/StringBuilder.h>
+#include <LibWeb/DOM/Document.h>
+#include <LibWeb/DOM/Element.h>
+#include <LibWeb/DOM/Text.h>
+#include <LibWeb/Layout/LayoutText.h>
+#include <ctype.h>
+#include <stdio.h>
+
+namespace Web {
+
+LayoutTreeModel::LayoutTreeModel(Document& document)
+    : m_document(document)
+{
+    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"));
+}
+
+LayoutTreeModel::~LayoutTreeModel()
+{
+}
+
+GUI::ModelIndex LayoutTreeModel::index(int row, int column, const GUI::ModelIndex& parent) const
+{
+    if (!parent.is_valid())
+        return create_index(row, column, m_document->layout_node());
+    auto& parent_node = *static_cast<LayoutNode*>(parent.internal_data());
+    return create_index(row, column, parent_node.child_at_index(row));
+}
+
+GUI::ModelIndex LayoutTreeModel::parent_index(const GUI::ModelIndex& index) const
+{
+    if (!index.is_valid())
+        return {};
+    auto& node = *static_cast<LayoutNode*>(index.internal_data());
+    if (!node.parent())
+        return {};
+
+    // No grandparent? Parent is the document!
+    if (!node.parent()->parent()) {
+        return create_index(0, 0, m_document->layout_node());
+    }
+
+    // Walk the grandparent's children to find the index of node's parent in its parent.
+    // (This is needed to produce the row number of the GUI::ModelIndex corresponding to node's parent.)
+    int grandparent_child_index = 0;
+    for (auto* grandparent_child = node.parent()->parent()->first_child(); grandparent_child; grandparent_child = grandparent_child->next_sibling()) {
+        if (grandparent_child == node.parent())
+            return create_index(grandparent_child_index, 0, node.parent());
+        ++grandparent_child_index;
+    }
+
+    ASSERT_NOT_REACHED();
+    return {};
+}
+
+int LayoutTreeModel::row_count(const GUI::ModelIndex& index) const
+{
+    if (!index.is_valid())
+        return 1;
+    auto& node = *static_cast<LayoutNode*>(index.internal_data());
+    return node.child_count();
+}
+
+int LayoutTreeModel::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 LayoutTreeModel::data(const GUI::ModelIndex& index, Role role) const
+{
+    auto& node = *static_cast<LayoutNode*>(index.internal_data());
+    if (role == Role::Icon) {
+        if (node.is_root())
+            return m_document_icon;
+        if (node.is_text())
+            return m_text_icon;
+        return m_element_icon;
+    }
+    if (role == Role::Display) {
+        if (node.is_text())
+            return String::format("LayoutText: %s", with_whitespace_collapsed(to<LayoutText>(node).text_for_rendering()).characters());
+        StringBuilder builder;
+        builder.append(node.class_name());
+        builder.append(' ');
+        if (node.is_anonymous()) {
+            builder.append("[anonymous]");
+        } else if (!node.node()->is_element()) {
+            builder.append(node.node()->tag_name());
+        } else {
+            auto& element = to<Element>(*node.node());
+            builder.append('<');
+            builder.append(element.tag_name());
+            element.for_each_attribute([&](auto& name, auto& value) {
+                builder.append(' ');
+                builder.append(name);
+                builder.append('=');
+                builder.append('"');
+                builder.append(value);
+                builder.append('"');
+            });
+            builder.append('>');
+        }
+        return builder.to_string();
+    }
+    return {};
+}
+
+void LayoutTreeModel::update()
+{
+    did_update();
+}
+
+}