From 29a2aac89ab4eb9d369d4094d7a851ca5c2faee8 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Wed, 10 Feb 2021 18:26:07 +0100
Subject: [PATCH] LibWeb: Start implementing <input type=text> using a shadow
 DOM

Text <input> fields will now generate a basic shadow DOM and attach it
to the input element.

The shadow DOM contains a <div> with some inline style, and an always-
editable text node inside it. Accessing the "value" attribute on such
an input element will get/set the value from that text node.

This is really cool, although not super stable since HTML editing is
not super stable. But it's a start! :^)
---
 Userland/Libraries/LibWeb/CSS/Default.css     |  7 +++
 .../LibWeb/HTML/HTMLInputElement.cpp          | 44 ++++++++++++++++++-
 .../Libraries/LibWeb/HTML/HTMLInputElement.h  |  8 +++-
 .../LibWeb/HTML/HTMLInputElement.idl          |  2 +
 4 files changed, 58 insertions(+), 3 deletions(-)

diff --git a/Userland/Libraries/LibWeb/CSS/Default.css b/Userland/Libraries/LibWeb/CSS/Default.css
index a63c7873ef2..e151de6b5fb 100644
--- a/Userland/Libraries/LibWeb/CSS/Default.css
+++ b/Userland/Libraries/LibWeb/CSS/Default.css
@@ -194,3 +194,10 @@ ul,
 ol {
     padding-left: 20px;
 }
+
+/* FIXME: This is a temporary hack until we can render a native-looking frame for these. */
+input[type=text] {
+    border: 1px solid black;
+    min-width: 80px;
+    min-height: 16px;
+}
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp
index 27db0a94c9e..c46e841723c 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp
+++ b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp
@@ -27,10 +27,13 @@
 #include <LibGfx/FontDatabase.h>
 #include <LibWeb/DOM/Document.h>
 #include <LibWeb/DOM/Event.h>
+#include <LibWeb/DOM/ShadowRoot.h>
+#include <LibWeb/DOM/Text.h>
 #include <LibWeb/HTML/EventNames.h>
 #include <LibWeb/HTML/HTMLFormElement.h>
 #include <LibWeb/HTML/HTMLInputElement.h>
 #include <LibWeb/InProcessWebView.h>
+#include <LibWeb/Layout/BlockBox.h>
 #include <LibWeb/Layout/ButtonBox.h>
 #include <LibWeb/Layout/CheckBox.h>
 #include <LibWeb/Page/Frame.h>
@@ -74,8 +77,10 @@ RefPtr<Layout::Node> HTMLInputElement::create_layout_node()
     if (type() == "checkbox")
         return adopt(*new Layout::CheckBox(document(), *this, move(style)));
 
-    // FIXME: Implement <input type=text> in terms of LibWeb primitives.
-    return nullptr;
+    create_shadow_tree_if_needed();
+    auto layout_node = adopt(*new Layout::BlockBox(document(), this, move(style)));
+    layout_node->set_inline(true);
+    return layout_node;
 }
 
 void HTMLInputElement::set_checked(bool checked)
@@ -94,4 +99,39 @@ bool HTMLInputElement::enabled() const
     return !has_attribute(HTML::AttributeNames::disabled);
 }
 
+String HTMLInputElement::value() const
+{
+    if (m_text_node)
+        return m_text_node->data();
+    return default_value();
+}
+
+void HTMLInputElement::set_value(String value)
+{
+    if (m_text_node) {
+        m_text_node->set_data(move(value));
+        return;
+    }
+    set_attribute(HTML::AttributeNames::value, move(value));
+}
+
+void HTMLInputElement::create_shadow_tree_if_needed()
+{
+    if (shadow_root())
+        return;
+
+    // FIXME: This assumes that we want a text box. Is that always true?
+    auto shadow_root = adopt(*new DOM::ShadowRoot(document(), *this));
+    auto initial_value = attribute(HTML::AttributeNames::value);
+    if (initial_value.is_null())
+        initial_value = String::empty();
+    auto element = document().create_element(HTML::TagNames::div);
+    element->set_attribute(HTML::AttributeNames::style, "white-space: pre");
+    m_text_node = adopt(*new DOM::Text(document(), initial_value));
+    m_text_node->set_always_editable(true);
+    element->append_child(*m_text_node);
+    shadow_root->append_child(move(element));
+    set_shadow_root(move(shadow_root));
+}
+
 }
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.h b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.h
index d4f66b3e833..51387371df4 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.h
+++ b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.h
@@ -40,9 +40,12 @@ public:
     virtual RefPtr<Layout::Node> create_layout_node() override;
 
     String type() const { return attribute(HTML::AttributeNames::type); }
-    String value() const { return attribute(HTML::AttributeNames::value); }
+    String default_value() const { return attribute(HTML::AttributeNames::value); }
     String name() const { return attribute(HTML::AttributeNames::name); }
 
+    String value() const;
+    void set_value(String);
+
     bool checked() const { return m_checked; }
     void set_checked(bool);
 
@@ -51,6 +54,9 @@ public:
     void did_click_button(Badge<Layout::ButtonBox>);
 
 private:
+    void create_shadow_tree_if_needed();
+
+    RefPtr<DOM::Text> m_text_node;
     bool m_checked { false };
 };
 
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.idl b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.idl
index 037b65c280f..1fe526d6cc4 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.idl
+++ b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.idl
@@ -11,6 +11,8 @@ interface HTMLInputElement : HTMLElement {
     [Reflect=dirname] attribute DOMString dirName;
     [Reflect=value] attribute DOMString defaultValue;
 
+    [LegacyNullToEmptyString] attribute DOMString value;
+
     attribute boolean checked;
 
     [Reflect] attribute boolean disabled;