Fully support <input type=color> (#36992)

This change adds a shadow-tree widget for `<input type=color>` elements.
It also involves some changes to the way layout interacts with the DOM,
because currently all `input` and `textarea` elements are rendered as
plain text and their descendants are ignored. This obviously doesn't
work for `<input type={color, date, range, etc}>`.


![image](https://github.com/user-attachments/assets/4f16c3b0-1f79-4095-b19d-1153f5853dd5)

<details><summary>HTML used for the screenshot above</summary>

```html
<input type=color>
```

</details>



Testing: I doubt that this affects WPT tests, because the appearance and
behaviour of the widget is almost entirely unspecified.

---------

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

components/constellation/tracing.rs

@@ -239,7 +239,7 @@ mod from_script {
                 Self::StopGamepadHapticEffect(..) => target_variant!("StopGamepadHapticEffect"),
                 Self::ShutdownComplete => target_variant!("ShutdownComplete"),
                 Self::ShowNotification(..) => target_variant!("ShowNotification"),
-                Self::ShowSelectElementMenu(..) => target_variant!("ShowSelectElementMenu"),
+                Self::ShowFormControl(..) => target_variant!("ShowFormControl"),
                 Self::FinishJavaScriptEvaluation(..) => {
                     target_variant!("FinishJavaScriptEvaluation")
                 },

components/layout/dom_traversal.rs

@@ -201,17 +201,7 @@ fn traverse_children_of<'dom>(
 ) {
     traverse_eager_pseudo_element(PseudoElement::Before, parent_element, context, handler);
 
-    let is_text_input_element = matches!(
-        parent_element.type_id(),
-        LayoutNodeType::Element(LayoutElementType::HTMLInputElement)
-    );
-
-    let is_textarea_element = matches!(
-        parent_element.type_id(),
-        LayoutNodeType::Element(LayoutElementType::HTMLTextAreaElement)
-    );
-
-    if is_text_input_element || is_textarea_element {
+    if parent_element.is_text_input() {
         let info = NodeAndStyleInfo::new(
             parent_element,
             parent_element.style(context.shared_context()),
@@ -229,9 +219,7 @@ fn traverse_children_of<'dom>(
         } else {
             handler.handle_text(&info, node_text_content);
         }
-    }
-
-    if !is_text_input_element && !is_textarea_element {
+    } else {
         for child in iter_child_nodes(parent_element) {
             if child.is_text_node() {
                 let info = NodeAndStyleInfo::new(child, child.style(context.shared_context()));

components/layout/stylesheets/servo.css

@@ -87,6 +87,15 @@ input[type="file"] {
   border-style: none;
 }
 
+input[type="color"] {
+  padding: 6px;
+  width: 64px;
+  height: 32px;
+  border-radius: 2px;
+  background: lightgrey;
+  border: 1px solid gray;
+}
+
 td[align="left"]    { text-align: left; }
 td[align="center"]  { text-align: center; }
 td[align="right"]   { text-align: right; }

components/script/dom/htmlinputelement.rs

@@ -12,9 +12,13 @@ use std::str::FromStr;
 use std::{f64, ptr};
 
 use dom_struct::dom_struct;
-use embedder_traits::{FilterPattern, InputMethodType};
+use embedder_traits::{
+    EmbedderMsg, FilterPattern, FormControl as EmbedderFormControl, InputMethodType, RgbColor,
+};
 use encoding_rs::Encoding;
+use euclid::{Point2D, Rect, Size2D};
 use html5ever::{LocalName, Prefix, local_name, ns};
+use ipc_channel::ipc;
 use js::jsapi::{
     ClippedTime, DateGetMsecSinceEpoch, Handle, JS_ClearPendingException, JSObject, NewDateObject,
     NewUCRegExpObject, ObjectIsDate, RegExpFlag_UnicodeSets, RegExpFlags,
@@ -25,7 +29,9 @@ use js::rust::{HandleObject, MutableHandleObject};
 use net_traits::blob_url_store::get_blob_origin;
 use net_traits::filemanager_thread::FileManagerThreadMsg;
 use net_traits::{CoreResourceMsg, IpcSend};
-use profile_traits::ipc;
+use script_bindings::codegen::GenericBindings::ShadowRootBinding::{
+    ShadowRootMode, SlotAssignmentMode,
+};
 use style::attr::AttrValue;
 use style::str::{split_commas, str_join};
 use stylo_atoms::Atom;
@@ -33,12 +39,12 @@ use stylo_dom::ElementState;
 use time::{Month, OffsetDateTime, Time};
 use unicode_bidi::{BidiClass, bidi_class};
 use url::Url;
+use webrender_api::units::DeviceIntRect;
 
-use super::bindings::str::{FromInputValueString, ToInputValueString};
 use crate::clipboard_provider::EmbedderClipboardProvider;
 use crate::dom::activation::Activatable;
 use crate::dom::attr::Attr;
-use crate::dom::bindings::cell::DomRefCell;
+use crate::dom::bindings::cell::{DomRefCell, Ref};
 use crate::dom::bindings::codegen::Bindings::ElementBinding::ElementMethods;
 use crate::dom::bindings::codegen::Bindings::EventBinding::EventMethods;
 use crate::dom::bindings::codegen::Bindings::FileListBinding::FileListMethods;
@@ -48,30 +54,33 @@ use crate::dom::bindings::codegen::Bindings::NodeBinding::{GetRootNodeOptions, N
 use crate::dom::bindings::error::{Error, ErrorResult};
 use crate::dom::bindings::inheritance::Castable;
 use crate::dom::bindings::reflector::DomGlobal;
-use crate::dom::bindings::root::{DomRoot, LayoutDom, MutNullableDom};
-use crate::dom::bindings::str::{DOMString, USVString};
+use crate::dom::bindings::root::{Dom, DomRoot, LayoutDom, MutNullableDom};
+use crate::dom::bindings::str::{DOMString, FromInputValueString, ToInputValueString, USVString};
 use crate::dom::clipboardevent::ClipboardEvent;
 use crate::dom::compositionevent::CompositionEvent;
 use crate::dom::document::Document;
-use crate::dom::element::{AttributeMutation, Element, LayoutElementHelpers};
+use crate::dom::element::{AttributeMutation, Element, ElementCreator, LayoutElementHelpers};
 use crate::dom::event::{Event, EventBubbles, EventCancelable};
 use crate::dom::eventtarget::EventTarget;
 use crate::dom::file::File;
 use crate::dom::filelist::{FileList, LayoutFileListHelpers};
 use crate::dom::globalscope::GlobalScope;
 use crate::dom::htmldatalistelement::HTMLDataListElement;
+use crate::dom::htmldivelement::HTMLDivElement;
 use crate::dom::htmlelement::HTMLElement;
 use crate::dom::htmlfieldsetelement::HTMLFieldSetElement;
 use crate::dom::htmlformelement::{
     FormControl, FormDatum, FormDatumValue, FormSubmitterElement, HTMLFormElement, ResetFrom,
     SubmittedFrom,
 };
+use crate::dom::htmlstyleelement::HTMLStyleElement;
 use crate::dom::keyboardevent::KeyboardEvent;
 use crate::dom::mouseevent::MouseEvent;
 use crate::dom::node::{
     BindContext, CloneChildrenFlag, Node, NodeDamage, NodeTraits, ShadowIncluding, UnbindContext,
 };
 use crate::dom::nodelist::NodeList;
+use crate::dom::shadowroot::{IsUserAgentWidget, ShadowRoot};
 use crate::dom::textcontrol::{TextControlElement, TextControlSelection};
 use crate::dom::validation::{Validatable, is_barred_by_datalist_ancestor};
 use crate::dom::validitystate::{ValidationFlags, ValidityState};
@@ -92,6 +101,34 @@ const DEFAULT_RESET_VALUE: &str = "Reset";
 const PASSWORD_REPLACEMENT_CHAR: char = '●';
 const DEFAULT_FILE_INPUT_VALUE: &str = "No file chosen";
 
+#[derive(Clone, JSTraceable, MallocSizeOf)]
+#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
+/// Contains references to the elements in the shadow tree for `<input type=range>`.
+///
+/// The shadow tree consists of a single div with the currently selected color as
+/// the background.
+struct InputTypeColorShadowTree {
+    color_value: Dom<HTMLDivElement>,
+}
+
+#[derive(Clone, JSTraceable, MallocSizeOf)]
+#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
+#[non_exhaustive]
+enum ShadowTree {
+    Color(InputTypeColorShadowTree),
+    // TODO: Add shadow trees for other input types (range etc) here
+}
+
+const COLOR_TREE_STYLE: &str = "
+#color-value {
+    width: 100%;
+    height: 100%;
+    box-sizing: border-box;
+    border: 1px solid gray;
+    border-radius: 2px;
+}
+";
+
 /// <https://html.spec.whatwg.org/multipage/#attr-input-type>
 #[derive(Clone, Copy, Default, JSTraceable, PartialEq)]
 #[allow(dead_code)]
@@ -172,8 +209,7 @@ impl InputType {
     fn is_textual(&self) -> bool {
         matches!(
             *self,
-            InputType::Color |
-                InputType::Date |
+            InputType::Date |
                 InputType::DatetimeLocal |
                 InputType::Email |
                 InputType::Hidden |
@@ -277,9 +313,16 @@ impl From<&Atom> for InputType {
 
 #[derive(Debug, PartialEq)]
 enum ValueMode {
+    /// <https://html.spec.whatwg.org/multipage/#dom-input-value-value>
     Value,
+
+    /// <https://html.spec.whatwg.org/multipage/#dom-input-value-default>
     Default,
+
+    /// <https://html.spec.whatwg.org/multipage/#dom-input-value-default-on>
     DefaultOn,
+
+    /// <https://html.spec.whatwg.org/multipage/#dom-input-value-filename>
     Filename,
 }
 
@@ -314,6 +357,7 @@ pub(crate) struct HTMLInputElement {
     form_owner: MutNullableDom<HTMLFormElement>,
     labels_node_list: MutNullableDom<NodeList>,
     validity_state: MutNullableDom<ValidityState>,
+    shadow_tree: DomRefCell<Option<ShadowTree>>,
 }
 
 #[derive(JSTraceable)]
@@ -372,6 +416,7 @@ impl HTMLInputElement {
             form_owner: Default::default(),
             labels_node_list: MutNullableDom::new(None),
             validity_state: Default::default(),
+            shadow_tree: Default::default(),
         }
     }
 
@@ -803,7 +848,7 @@ impl HTMLInputElement {
             .map(DomRoot::from_ref)
     }
 
-    // https://html.spec.whatwg.org/multipage/#suffering-from-being-missing
+    /// <https://html.spec.whatwg.org/multipage/#suffering-from-being-missing>
     fn suffers_from_being_missing(&self, value: &DOMString) -> bool {
         match self.input_type() {
             // https://html.spec.whatwg.org/multipage/#checkbox-state-(type%3Dcheckbox)%3Asuffering-from-being-missing
@@ -958,9 +1003,9 @@ impl HTMLInputElement {
         failed_flags
     }
 
-    // https://html.spec.whatwg.org/multipage/#suffering-from-an-underflow
-    // https://html.spec.whatwg.org/multipage/#suffering-from-an-overflow
-    // https://html.spec.whatwg.org/multipage/#suffering-from-a-step-mismatch
+    /// * <https://html.spec.whatwg.org/multipage/#suffering-from-an-underflow>
+    /// * <https://html.spec.whatwg.org/multipage/#suffering-from-an-overflow>
+    /// * <https://html.spec.whatwg.org/multipage/#suffering-from-a-step-mismatch>
     fn suffers_from_range_issues(&self, value: &DOMString) -> ValidationFlags {
         if value.is_empty() || !self.does_value_as_number_apply() {
             return ValidationFlags::empty();
@@ -1014,9 +1059,109 @@ impl HTMLInputElement {
 
         failed_flags
     }
+
+    /// Return a reference to the ShadowRoot that this element is a host of,
+    /// or create one if none exists.
+    fn shadow_root(&self, can_gc: CanGc) -> DomRoot<ShadowRoot> {
+        self.upcast::<Element>().shadow_root().unwrap_or_else(|| {
+            self.upcast::<Element>()
+                .attach_shadow(
+                    IsUserAgentWidget::Yes,
+                    ShadowRootMode::Closed,
+                    false,
+                    false,
+                    false,
+                    SlotAssignmentMode::Manual,
+                    can_gc,
+                )
+                .expect("Attaching UA shadow root failed")
+        })
+    }
+
+    fn create_color_shadow_tree(&self, can_gc: CanGc) {
+        let document = self.owner_document();
+        let shadow_root = self.shadow_root(can_gc);
+        Node::replace_all(None, shadow_root.upcast::<Node>(), can_gc);
+
+        let color_value = HTMLDivElement::new(local_name!("div"), None, &document, None, can_gc);
+        color_value
+            .upcast::<Element>()
+            .SetId(DOMString::from("color-value"), can_gc);
+        shadow_root
+            .upcast::<Node>()
+            .AppendChild(color_value.upcast::<Node>(), can_gc)
+            .unwrap();
+
+        let style = HTMLStyleElement::new(
+            local_name!("style"),
+            None,
+            &document,
+            None,
+            ElementCreator::ScriptCreated,
+            can_gc,
+        );
+        style
+            .upcast::<Node>()
+            .SetTextContent(Some(DOMString::from(COLOR_TREE_STYLE)), can_gc);
+        shadow_root
+            .upcast::<Node>()
+            .AppendChild(style.upcast::<Node>(), can_gc)
+            .unwrap();
+
+        let _ = self
+            .shadow_tree
+            .borrow_mut()
+            .insert(ShadowTree::Color(InputTypeColorShadowTree {
+                color_value: color_value.as_traced(),
+            }));
+    }
+
+    /// Get a handle to the shadow tree for this input, assuming it's [InputType] is `Color`.
+    ///
+    /// If the input is not currently a shadow host, a new shadow tree will be created.
+    ///
+    /// If the input is a shadow host for a different kind of shadow tree then the old
+    /// tree will be removed and a new one will be created.
+    fn color_shadow_tree(&self, can_gc: CanGc) -> Ref<InputTypeColorShadowTree> {
+        let has_color_shadow_tree = self
+            .shadow_tree
+            .borrow()
+            .as_ref()
+            .is_some_and(|shadow_tree| matches!(shadow_tree, ShadowTree::Color(_)));
+        if !has_color_shadow_tree {
+            self.create_color_shadow_tree(can_gc);
+        }
+
+        let shadow_tree = self.shadow_tree.borrow();
+        Ref::filter_map(shadow_tree, |shadow_tree| {
+            let shadow_tree = shadow_tree.as_ref()?;
+            let ShadowTree::Color(color_tree) = shadow_tree;
+            Some(color_tree)
+        })
+        .ok()
+        .expect("UA shadow tree was not created")
+    }
+
+    fn update_shadow_tree_if_needed(&self, can_gc: CanGc) {
+        if self.input_type() == InputType::Color {
+            let color_shadow_tree = self.color_shadow_tree(can_gc);
+            let mut value = self.Value();
+            if value.str().is_valid_simple_color_string() {
+                value.make_ascii_lowercase();
+            } else {
+                value = DOMString::from("#000000");
+            }
+            let style = format!("background-color: {value}");
+            color_shadow_tree
+                .color_value
+                .upcast::<Element>()
+                .set_string_attribute(&local_name!("style"), style.into(), can_gc);
+        }
+    }
 }
 
 pub(crate) trait LayoutHTMLInputElementHelpers<'dom> {
+    /// Return a string that represents the contents of the element for layout.
     fn value_for_layout(self) -> Cow<'dom, str>;
     fn size_for_layout(self) -> u32;
     fn selection_for_layout(self) -> Option<Range<usize>>;
@@ -1075,16 +1220,15 @@ impl<'dom> LayoutHTMLInputElementHelpers<'dom> for LayoutDom<'dom, HTMLInputElem
                     Some(filelist) => {
                         let length = filelist.len();
                         if length == 0 {
-                            return DEFAULT_FILE_INPUT_VALUE.into();
-                        }
-                        if length == 1 {
+                            DEFAULT_FILE_INPUT_VALUE.into()
+                        } else if length == 1 {
                             match filelist.file_for_layout(0) {
-                                Some(file) => return file.name().to_string().into(),
-                                None => return DEFAULT_FILE_INPUT_VALUE.into(),
+                                Some(file) => file.name().to_string().into(),
+                                None => DEFAULT_FILE_INPUT_VALUE.into(),
                             }
+                        } else {
+                            format!("{} files", length).into()
                         }
-
-                        format!("{} files", length).into()
                     },
                     None => DEFAULT_FILE_INPUT_VALUE.into(),
                 }
@@ -1103,6 +1247,9 @@ impl<'dom> LayoutHTMLInputElementHelpers<'dom> for LayoutDom<'dom, HTMLInputElem
                     self.placeholder().into()
                 }
             },
+            InputType::Color => {
+                unreachable!("Input type color is explicitly not rendered as text");
+            },
             _ => {
                 let text = self.get_raw_textinput_value();
                 if !text.is_empty() {
@@ -1178,11 +1325,11 @@ impl TextControlElement for HTMLInputElement {
             InputType::Week |
             InputType::Time |
             InputType::DatetimeLocal |
-            InputType::Number |
-            InputType::Color => true,
+            InputType::Number => true,
 
             InputType::Button |
             InputType::Checkbox |
+            InputType::Color |
             InputType::File |
             InputType::Hidden |
             InputType::Image |
@@ -1257,7 +1404,7 @@ impl HTMLInputElementMethods<crate::DomTypeHolder> for HTMLInputElement {
     // https://html.spec.whatwg.org/multipage/#dom-input-checked
     fn SetChecked(&self, checked: bool) {
         self.update_checked_state(checked, true);
-        update_related_validity_states(self, CanGc::note())
+        self.value_changed(CanGc::note());
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-input-readonly
@@ -1349,7 +1496,7 @@ impl HTMLInputElementMethods<crate::DomTypeHolder> for HTMLInputElement {
             },
         }
 
-        update_related_validity_states(self, can_gc);
+        self.value_changed(can_gc);
         self.upcast::<Node>().dirty(NodeDamage::OtherNodeDamage);
         Ok(())
     }
@@ -1724,18 +1871,6 @@ fn perform_radio_group_validation(elem: &HTMLInputElement, group: Option<&Atom>,
     }
 }
 
-fn update_related_validity_states(elem: &HTMLInputElement, can_gc: CanGc) {
-    match elem.input_type() {
-        InputType::Radio => {
-            perform_radio_group_validation(elem, elem.radio_group_name().as_ref(), can_gc)
-        },
-        _ => {
-            elem.validity_state()
-                .perform_validation_and_update(ValidationFlags::all(), can_gc);
-        },
-    }
-}
-
 // https://html.spec.whatwg.org/multipage/#radio-button-group
 fn in_same_group(
     other: &HTMLInputElement,
@@ -1905,7 +2040,7 @@ impl HTMLInputElement {
             InputType::Radio | InputType::Checkbox => {
                 self.update_checked_state(self.DefaultChecked(), false);
                 self.checked_changed.set(false);
-                update_related_validity_states(self, can_gc);
+                self.value_changed(can_gc);
             },
             InputType::Image => (),
             _ => (),
@@ -1949,8 +2084,9 @@ impl HTMLInputElement {
                     .collect()
             });
 
-            let (chan, recv) = ipc::channel(self.global().time_profiler_chan().clone())
-                .expect("Error initializing channel");
+            let (chan, recv) =
+                profile_traits::ipc::channel(self.global().time_profiler_chan().clone())
+                    .expect("Error initializing channel");
             let msg =
                 FileManagerThreadMsg::SelectFiles(webview_id, filter, chan, origin, opt_test_paths);
             resource_threads
@@ -1977,8 +2113,9 @@ impl HTMLInputElement {
                 None => None,
             };
 
-            let (chan, recv) = ipc::channel(self.global().time_profiler_chan().clone())
-                .expect("Error initializing channel");
+            let (chan, recv) =
+                profile_traits::ipc::channel(self.global().time_profiler_chan().clone())
+                    .expect("Error initializing channel");
             let msg =
                 FileManagerThreadMsg::SelectFile(webview_id, filter, chan, origin, opt_test_path);
             resource_threads
@@ -2348,6 +2485,70 @@ impl HTMLInputElement {
             },
         })
     }
+
+    fn update_related_validity_states(&self, can_gc: CanGc) {
+        match self.input_type() {
+            InputType::Radio => {
+                perform_radio_group_validation(self, self.radio_group_name().as_ref(), can_gc)
+            },
+            _ => {
+                self.validity_state()
+                    .perform_validation_and_update(ValidationFlags::all(), can_gc);
+            },
+        }
+    }
+
+    fn value_changed(&self, can_gc: CanGc) {
+        self.update_related_validity_states(can_gc);
+        self.update_shadow_tree_if_needed(can_gc);
+    }
+
+    /// <https://html.spec.whatwg.org/multipage/#show-the-picker,-if-applicable>
+    fn show_the_picker_if_applicable(&self, can_gc: CanGc) {
+        // FIXME: Implement most of this algorithm
+
+        // Step 2. If element is not mutable, then return.
+        if !self.is_mutable() {
+            return;
+        }
+
+        // Step 6. Otherwise, the user agent should show the relevant user interface for selecting a value for element,
+        // in the way it normally would when the user interacts with the control.
+        if self.input_type() == InputType::Color {
+            let (ipc_sender, ipc_receiver) =
+                ipc::channel::<Option<RgbColor>>().expect("Failed to create IPC channel!");
+            let document = self.owner_document();
+            let rect = self.upcast::<Node>().bounding_content_box_or_zero(can_gc);
+            let rect = Rect::new(
+                Point2D::new(rect.origin.x.to_px(), rect.origin.y.to_px()),
+                Size2D::new(rect.size.width.to_px(), rect.size.height.to_px()),
+            );
+            let current_value = self.Value();
+            let current_color = RgbColor {
+                red: u8::from_str_radix(&current_value[1..3], 16).unwrap(),
+                green: u8::from_str_radix(&current_value[3..5], 16).unwrap(),
+                blue: u8::from_str_radix(&current_value[5..7], 16).unwrap(),
+            };
+            document.send_to_embedder(EmbedderMsg::ShowFormControl(
+                document.webview_id(),
+                DeviceIntRect::from_untyped(&rect.to_box2d()),
+                EmbedderFormControl::ColorPicker(current_color, ipc_sender),
+            ));
+
+            let Ok(response) = ipc_receiver.recv() else {
+                log::error!("Failed to receive response");
+                return;
+            };
+
+            if let Some(selected_color) = response {
+                let formatted_color = format!(
+                    "#{:0>2x}{:0>2x}{:0>2x}",
+                    selected_color.red, selected_color.green, selected_color.blue
+                );
+                let _ = self.SetValue(formatted_color.into(), can_gc);
+            }
+        }
+    }
 }
 
 impl VirtualMethods for HTMLInputElement {
@@ -2359,6 +2560,7 @@ impl VirtualMethods for HTMLInputElement {
         self.super_type()
             .unwrap()
             .attribute_mutated(attr, mutation, can_gc);
+
         match *attr.local_name() {
             local_name!("disabled") => {
                 let disabled_state = match mutation {
@@ -2553,7 +2755,7 @@ impl VirtualMethods for HTMLInputElement {
             _ => {},
         }
 
-        update_related_validity_states(self, can_gc);
+        self.value_changed(can_gc);
     }
 
     fn parse_plain_attribute(&self, name: &LocalName, value: DOMString) -> AttrValue {
@@ -2584,7 +2786,8 @@ impl VirtualMethods for HTMLInputElement {
         if self.input_type() == InputType::Radio {
             self.radio_group_updated(self.radio_group_name().as_ref());
         }
-        update_related_validity_states(self, can_gc);
+
+        self.value_changed(can_gc);
     }
 
     fn unbind_from_tree(&self, context: &UnbindContext, can_gc: CanGc) {
@@ -2730,7 +2933,7 @@ impl VirtualMethods for HTMLInputElement {
             }
         }
 
-        update_related_validity_states(self, can_gc);
+        self.value_changed(can_gc);
     }
 
     // https://html.spec.whatwg.org/multipage/#the-input-element%3Aconcept-node-clone-ext
@@ -2752,7 +2955,7 @@ impl VirtualMethods for HTMLInputElement {
         elem.textinput
             .borrow_mut()
             .set_content(self.textinput.borrow().get_content());
-        update_related_validity_states(self, can_gc);
+        self.value_changed(can_gc);
     }
 }
 
@@ -2861,7 +3064,8 @@ impl Activatable for HTMLInputElement {
             },
             // https://html.spec.whatwg.org/multipage/#checkbox-state-(type=checkbox):input-activation-behavior
             // https://html.spec.whatwg.org/multipage/#radio-button-state-(type=radio):input-activation-behavior
-            InputType::Checkbox | InputType::Radio => true,
+            // https://html.spec.whatwg.org/multipage/#color-state-(type=color):input-activation-behavior
+            InputType::Checkbox | InputType::Radio | InputType::Color => true,
             _ => false,
         }
     }
@@ -2907,7 +3111,7 @@ impl Activatable for HTMLInputElement {
         };
 
         if activation_state.is_some() {
-            update_related_validity_states(self, can_gc);
+            self.value_changed(can_gc);
         }
 
         activation_state
@@ -2966,7 +3170,7 @@ impl Activatable for HTMLInputElement {
             _ => (),
         }
 
-        update_related_validity_states(self, can_gc);
+        self.value_changed(can_gc);
     }
 
     /// <https://html.spec.whatwg.org/multipage/#input-activation-behavior>
@@ -3028,6 +3232,10 @@ impl Activatable for HTMLInputElement {
             },
             // https://html.spec.whatwg.org/multipage/#file-upload-state-(type=file):input-activation-behavior
             InputType::File => self.select_files(None, can_gc),
+            // https://html.spec.whatwg.org/multipage/#color-state-(type=color):input-activation-behavior
+            InputType::Color => {
+                self.show_the_picker_if_applicable(can_gc);
+            },
             _ => (),
         }
     }

components/script/dom/htmlselectelement.rs

@@ -14,7 +14,7 @@ use style::attr::AttrValue;
 use stylo_dom::ElementState;
 use embedder_traits::{SelectElementOptionOrOptgroup, SelectElementOption};
 use euclid::{Size2D, Point2D, Rect};
-use embedder_traits::EmbedderMsg;
+use embedder_traits::{FormControl as EmbedderFormControl, EmbedderMsg};
 
 use crate::dom::bindings::codegen::GenericBindings::HTMLOptGroupElementBinding::HTMLOptGroupElement_Binding::HTMLOptGroupElementMethods;
 use crate::dom::activation::Activatable;
@@ -406,12 +406,10 @@ impl HTMLSelectElement {
         let selected_index = self.list_of_options().position(|option| option.Selected());
 
         let document = self.owner_document();
-        document.send_to_embedder(EmbedderMsg::ShowSelectElementMenu(
+        document.send_to_embedder(EmbedderMsg::ShowFormControl(
             document.webview_id(),
-            options,
-            selected_index,
             DeviceIntRect::from_untyped(&rect.to_box2d()),
-            ipc_sender,
+            EmbedderFormControl::SelectElement(options, selected_index, ipc_sender),
         ));
 
         let Ok(response) = ipc_receiver.recv() else {

components/script/dom/node.rs

@@ -50,7 +50,6 @@ use style::stylesheets::{Stylesheet, UrlExtraData};
 use uuid::Uuid;
 use xml5ever::serialize as xml_serialize;
 
-use super::globalscope::GlobalScope;
 use crate::conversions::Convert;
 use crate::document_loader::DocumentLoader;
 use crate::dom::attr::Attr;
@@ -92,13 +91,14 @@ use crate::dom::documenttype::DocumentType;
 use crate::dom::element::{CustomElementCreationMode, Element, ElementCreator, SelectorWrapper};
 use crate::dom::event::{Event, EventBubbles, EventCancelable};
 use crate::dom::eventtarget::EventTarget;
+use crate::dom::globalscope::GlobalScope;
 use crate::dom::htmlbodyelement::HTMLBodyElement;
 use crate::dom::htmlcanvaselement::{HTMLCanvasElement, LayoutHTMLCanvasElementHelpers};
 use crate::dom::htmlcollection::HTMLCollection;
 use crate::dom::htmlelement::HTMLElement;
 use crate::dom::htmliframeelement::{HTMLIFrameElement, HTMLIFrameElementLayoutMethods};
 use crate::dom::htmlimageelement::{HTMLImageElement, LayoutHTMLImageElementHelpers};
-use crate::dom::htmlinputelement::{HTMLInputElement, LayoutHTMLInputElementHelpers};
+use crate::dom::htmlinputelement::{HTMLInputElement, InputType, LayoutHTMLInputElementHelpers};
 use crate::dom::htmllinkelement::HTMLLinkElement;
 use crate::dom::htmlslotelement::{HTMLSlotElement, Slottable};
 use crate::dom::htmlstyleelement::HTMLStyleElement;
@@ -1612,6 +1612,8 @@ pub(crate) trait LayoutNodeHelpers<'dom> {
     /// attempting to read or modify the opaque layout data of this node.
     unsafe fn clear_style_and_layout_data(self);
 
+    /// Whether this element is a `<input>` rendered as text or a `<textarea>`.
+    fn is_text_input(&self) -> bool;
     fn text_content(self) -> Cow<'dom, str>;
     fn selection(self) -> Option<Range<usize>>;
     fn image_url(self) -> Option<ServoUrl>;
@@ -1776,6 +1778,25 @@ impl<'dom> LayoutNodeHelpers<'dom> for LayoutDom<'dom, Node> {
         self.unsafe_get().layout_data.borrow_mut_for_layout().take();
     }
 
+    fn is_text_input(&self) -> bool {
+        let type_id = self.type_id_for_layout();
+        if type_id ==
+            NodeTypeId::Element(ElementTypeId::HTMLElement(
+                HTMLElementTypeId::HTMLInputElement,
+            ))
+        {
+            let input = self.unsafe_get().downcast::<HTMLInputElement>().unwrap();
+
+            // FIXME: All the non-color input types currently render as text
+            input.input_type() != InputType::Color
+        } else {
+            type_id ==
+                NodeTypeId::Element(ElementTypeId::HTMLElement(
+                    HTMLElementTypeId::HTMLTextAreaElement,
+                ))
+        }
+    }
+
     fn text_content(self) -> Cow<'dom, str> {
         if let Some(text) = self.downcast::<Text>() {
             return text.upcast().data_for_layout().into();

components/script/layout_dom/node.rs

@@ -96,6 +96,10 @@ impl<'dom> ServoLayoutNode<'dom> {
             .map(LayoutDom::upcast)
             .map(ServoLayoutElement::from_layout_js)
     }
+
+    pub fn is_text_input(&self) -> bool {
+        self.node.is_text_input()
+    }
 }
 
 impl style::dom::NodeInfo for ServoLayoutNode<'_> {

components/servo/lib.rs

@@ -66,6 +66,7 @@ use constellation::{
 };
 use constellation_traits::{EmbedderToConstellationMessage, ScriptToConstellationChan};
 use crossbeam_channel::{Receiver, Sender, unbounded};
+use embedder_traits::FormControl as EmbedderFormControl;
 use embedder_traits::user_content_manager::UserContentManager;
 pub use embedder_traits::*;
 use env_logger::Builder as EnvLoggerBuilder;
@@ -125,8 +126,8 @@ pub use crate::servo_delegate::{ServoDelegate, ServoError};
 use crate::webrender_api::FrameReadyParams;
 pub use crate::webview::{WebView, WebViewBuilder};
 pub use crate::webview_delegate::{
-    AllowOrDenyRequest, AuthenticationRequest, FormControl, NavigationRequest, PermissionRequest,
-    SelectElement, WebResourceLoad, WebViewDelegate,
+    AllowOrDenyRequest, AuthenticationRequest, ColorPicker, FormControl, NavigationRequest,
+    PermissionRequest, SelectElement, WebResourceLoad, WebViewDelegate,
 };
 
 #[cfg(feature = "webdriver")]
@@ -965,18 +966,30 @@ impl Servo {
                     None => self.delegate().show_notification(notification),
                 }
             },
-            EmbedderMsg::ShowSelectElementMenu(
-                webview_id,
-                options,
-                selected_option,
-                position,
-                ipc_sender,
-            ) => {
+            EmbedderMsg::ShowFormControl(webview_id, position, form_control) => {
                 if let Some(webview) = self.get_webview_handle(webview_id) {
-                    let prompt = SelectElement::new(options, selected_option, position, ipc_sender);
-                    webview
-                        .delegate()
-                        .show_form_control(webview, FormControl::SelectElement(prompt));
+                    let form_control = match form_control {
+                        EmbedderFormControl::SelectElement(
+                            options,
+                            selected_option,
+                            ipc_sender,
+                        ) => FormControl::SelectElement(SelectElement::new(
+                            options,
+                            selected_option,
+                            position,
+                            ipc_sender,
+                        )),
+                        EmbedderFormControl::ColorPicker(current_color, ipc_sender) => {
+                            FormControl::ColorPicker(ColorPicker::new(
+                                current_color,
+                                position,
+                                ipc_sender,
+                                self.servo_errors.sender(),
+                            ))
+                        },
+                    };
+
+                    webview.delegate().show_form_control(webview, form_control);
                 }
             },
         }

components/servo/webview_delegate.rs

@@ -9,7 +9,7 @@ use constellation_traits::EmbedderToConstellationMessage;
 use embedder_traits::{
     AllowOrDeny, AuthenticationResponse, ContextMenuResult, Cursor, FilterPattern,
     GamepadHapticEffectType, InputMethodType, LoadStatus, MediaSessionEvent, Notification,
-    PermissionFeature, ScreenGeometry, SelectElementOptionOrOptgroup, SimpleDialog,
+    PermissionFeature, RgbColor, ScreenGeometry, SelectElementOptionOrOptgroup, SimpleDialog,
     WebResourceRequest, WebResourceResponse, WebResourceResponseMsg,
 };
 use ipc_channel::ipc::IpcSender;
@@ -300,6 +300,8 @@ impl Drop for InterceptedWebResourceLoad {
 pub enum FormControl {
     /// The picker of a `<select>` element.
     SelectElement(SelectElement),
+    /// The picker of a `<input type=color>` element.
+    ColorPicker(ColorPicker),
 }
 
 /// Represents a dialog triggered by clicking a `<select>` element.
@@ -356,6 +358,48 @@ impl SelectElement {
     }
 }
 
+/// Represents a dialog triggered by clicking a `<input type=color>` element.
+pub struct ColorPicker {
+    pub(crate) current_color: RgbColor,
+    pub(crate) position: DeviceIntRect,
+    pub(crate) responder: IpcResponder<Option<RgbColor>>,
+    pub(crate) error_sender: ServoErrorSender,
+}
+
+impl ColorPicker {
+    pub(crate) fn new(
+        current_color: RgbColor,
+        position: DeviceIntRect,
+        ipc_sender: IpcSender<Option<RgbColor>>,
+        error_sender: ServoErrorSender,
+    ) -> Self {
+        Self {
+            current_color,
+            position,
+            responder: IpcResponder::new(ipc_sender, None),
+            error_sender,
+        }
+    }
+
+    /// Get the area occupied by the `<input>` element that triggered the prompt.
+    ///
+    /// The embedder should use this value to position the prompt that is shown to the user.
+    pub fn position(&self) -> DeviceIntRect {
+        self.position
+    }
+
+    /// Get the color that was selected before the prompt was opened.
+    pub fn current_color(&self) -> RgbColor {
+        self.current_color
+    }
+
+    pub fn select(&mut self, color: Option<RgbColor>) {
+        if let Err(error) = self.responder.send(color) {
+            self.error_sender.raise_response_send_error(error);
+        }
+    }
+}
+
 pub trait WebViewDelegate {
     /// Get the [`ScreenGeometry`] for this [`WebView`]. If this is unimplemented or returns `None`
     /// the screen will have the size of the [`WebView`]'s `RenderingContext` and `WebView` will be

components/shared/embedder/lib.rs

@@ -364,16 +364,8 @@ pub enum EmbedderMsg {
     ShutdownComplete,
     /// Request to display a notification.
     ShowNotification(Option<WebViewId>, Notification),
-    /// Indicates that the user has activated a `<select>` element.
-    ///
-    /// The embedder should respond with the new state of the `<select>` element.
-    ShowSelectElementMenu(
-        WebViewId,
-        Vec<SelectElementOptionOrOptgroup>,
-        Option<usize>,
-        DeviceIntRect,
-        IpcSender<Option<usize>>,
-    ),
+    /// Request to display a form control to the embedder.
+    ShowFormControl(WebViewId, DeviceIntRect, FormControl),
     /// Inform the embedding layer that a JavaScript evaluation has
     /// finished with the given result.
     FinishJavaScriptEvaluation(
@@ -389,6 +381,18 @@ impl Debug for EmbedderMsg {
     }
 }
 
+#[derive(Deserialize, Serialize)]
+pub enum FormControl {
+    /// Indicates that the user has activated a `<select>` element.
+    SelectElement(
+        Vec<SelectElementOptionOrOptgroup>,
+        Option<usize>,
+        IpcSender<Option<usize>>,
+    ),
+    /// Indicates that the user has activated a `<input type=color>` element.
+    ColorPicker(RgbColor, IpcSender<Option<RgbColor>>),
+}
+
 /// Filter for file selection;
 /// the `String` content is expected to be extension (e.g, "doc", without the prefixing ".")
 #[derive(Clone, Debug, Deserialize, Serialize)]
@@ -921,3 +925,10 @@ pub enum JavaScriptEvaluationError {
     /// value into a [`JSValue`].
     SerializationError,
 }
+
+#[derive(Clone, Copy, Debug, Deserialize, Serialize)]
+pub struct RgbColor {
+    pub red: u8,
+    pub green: u8,
+    pub blue: u8,
+}

ports/servoshell/desktop/app_state.rs

@@ -609,6 +609,15 @@ impl WebViewDelegate for RunningAppState {
                 let offset = self.inner().window.toolbar_height();
                 self.add_dialog(webview, Dialog::new_select_element_dialog(prompt, offset));
             },
+            FormControl::ColorPicker(color_picker) => {
+                // FIXME: Reading the toolbar height is needed here to properly position the select dialog.
+                // But if the toolbar height changes while the dialog is open then the position won't be updated
+                let offset = self.inner().window.toolbar_height();
+                self.add_dialog(
+                    webview,
+                    Dialog::new_color_picker_dialog(color_picker, offset),
+                );
+            },
         }
     }
 }

ports/servoshell/desktop/dialog.rs

@@ -12,9 +12,9 @@ use log::warn;
 use servo::ipc_channel::ipc::IpcSender;
 use servo::servo_geometry::DeviceIndependentPixel;
 use servo::{
-    AlertResponse, AuthenticationRequest, ConfirmResponse, FilterPattern, PermissionRequest,
-    PromptResponse, SelectElement, SelectElementOption, SelectElementOptionOrOptgroup,
-    SimpleDialog,
+    AlertResponse, AuthenticationRequest, ColorPicker, ConfirmResponse, FilterPattern,
+    PermissionRequest, PromptResponse, RgbColor, SelectElement, SelectElementOption,
+    SelectElementOptionOrOptgroup, SimpleDialog,
 };
 
 pub enum Dialog {
@@ -43,6 +43,11 @@ pub enum Dialog {
         maybe_prompt: Option<SelectElement>,
         toolbar_offset: Length<f32, DeviceIndependentPixel>,
     },
+    ColorPicker {
+        current_color: egui::Color32,
+        maybe_prompt: Option<ColorPicker>,
+        toolbar_offset: Length<f32, DeviceIndependentPixel>,
+    },
 }
 
 impl Dialog {
@@ -119,6 +124,22 @@ impl Dialog {
         }
     }
 
+    pub fn new_color_picker_dialog(
+        prompt: ColorPicker,
+        toolbar_offset: Length<f32, DeviceIndependentPixel>,
+    ) -> Self {
+        let current_color = egui::Color32::from_rgb(
+            prompt.current_color().red,
+            prompt.current_color().green,
+            prompt.current_color().blue,
+        );
+        Dialog::ColorPicker {
+            current_color,
+            maybe_prompt: Some(prompt),
+            toolbar_offset,
+        }
+    }
+
     pub fn update(&mut self, ctx: &egui::Context) -> bool {
         match self {
             Dialog::File {
@@ -485,6 +506,50 @@ impl Dialog {
                     maybe_prompt.take().unwrap().submit();
                 }
 
+                is_open
+            },
+            Dialog::ColorPicker {
+                current_color,
+                maybe_prompt,
+                toolbar_offset,
+            } => {
+                let Some(prompt) = maybe_prompt else {
+                    // Prompt was dismissed, so the dialog should be closed too.
+                    return false;
+                };
+                let mut is_open = true;
+
+                let mut position = prompt.position();
+                position.min.y += toolbar_offset.0 as i32;
+                position.max.y += toolbar_offset.0 as i32;
+                let area = egui::Area::new(egui::Id::new("select-window"))
+                    .fixed_pos(egui::pos2(position.min.x as f32, position.max.y as f32));
+
+                let modal = Modal::new("select_element_picker".into()).area(area);
+                modal.show(ctx, |ui| {
+                    egui::widgets::color_picker::color_picker_color32(
+                        ui,
+                        current_color,
+                        egui::widgets::color_picker::Alpha::Opaque,
+                    );
+
+                    ui.add_space(10.);
+
+                    if ui.button("Dismiss").clicked() {
+                        is_open = false;
+                        prompt.select(None);
+                    }
+                    if ui.button("Select").clicked() {
+                        is_open = false;
+                        let selected_color = RgbColor {
+                            red: current_color.r(),
+                            green: current_color.g(),
+                            blue: current_color.b(),
+                        };
+                        prompt.select(Some(selected_color));
+                    }
+                });
+
                 is_open
             },
         }

tests/wpt/meta/css/css-transforms/transform-input-016.html.ini

@@ -0,0 +1,2 @@
+[transform-input-016.html]
+  expected: FAIL

tests/wpt/meta/html/semantics/forms/form-submission-0/form-double-submit-input-type-change.html.ini

@@ -38,8 +38,5 @@
   [default submit action should supersede input onclick submit() and change the input type from range to submit]
     expected: FAIL
 
-  [default submit action should supersede input onclick submit() and change the input type from color to submit]
-    expected: FAIL
-
   [default submit action should supersede input onclick submit() and change the input type from button to submit]
     expected: FAIL