feat: display file chosen for input file (#35789)

Signed-off-by: DK Liao <dklassic@gmail.com>

3 files changed, 53 insertions, 5 deletions

diff --git a/components/script/dom/filelist.rs b/components/script/dom/filelist.rs
index d526b54b99b..8942ec92239 100644
--- a/components/script/dom/filelist.rs
+++ b/components/script/dom/filelist.rs
@@ -6,6 +6,7 @@ use std::slice::Iter;
 
 use dom_struct::dom_struct;
 
+use super::bindings::root::{LayoutDom, ToLayout};
 use crate::dom::bindings::codegen::Bindings::FileListBinding::FileListMethods;
 use crate::dom::bindings::reflector::{Reflector, reflect_dom_object};
 use crate::dom::bindings::root::{Dom, DomRoot};
@@ -69,3 +70,23 @@ impl FileListMethods<crate::DomTypeHolder> for FileList {
         self.Item(index)
     }
 }
+
+pub(crate) trait LayoutFileListHelpers<'dom> {
+    fn file_for_layout(&self, index: u32) -> Option<&File>;
+    fn len(&self) -> usize;
+}
+
+#[allow(unsafe_code)]
+impl<'dom> LayoutFileListHelpers<'dom> for LayoutDom<'dom, FileList> {
+    fn len(&self) -> usize {
+        self.unsafe_get().list.len()
+    }
+    fn file_for_layout(&self, index: u32) -> Option<&File> {
+        let list = &self.unsafe_get().list;
+        if (index as usize) < list.len() {
+            Some(unsafe { list[index as usize].to_layout().unsafe_get() })
+        } else {
+            None
+        }
+    }
+}
diff --git a/components/script/dom/htmlinputelement.rs b/components/script/dom/htmlinputelement.rs
index 66fef852ffd..1cbf386e03e 100644
--- a/components/script/dom/htmlinputelement.rs
+++ b/components/script/dom/htmlinputelement.rs
@@ -57,7 +57,7 @@ use crate::dom::element::{AttributeMutation, Element, LayoutElementHelpers};
 use crate::dom::event::{Event, EventBubbles, EventCancelable};
 use crate::dom::eventtarget::EventTarget;
 use crate::dom::file::File;
-use crate::dom::filelist::FileList;
+use crate::dom::filelist::{FileList, LayoutFileListHelpers};
 use crate::dom::globalscope::GlobalScope;
 use crate::dom::htmldatalistelement::HTMLDataListElement;
 use crate::dom::htmlelement::HTMLElement;
@@ -90,6 +90,7 @@ use crate::textinput::{
 const DEFAULT_SUBMIT_VALUE: &str = "Submit";
 const DEFAULT_RESET_VALUE: &str = "Reset";
 const PASSWORD_REPLACEMENT_CHAR: char = '●';
+const DEFAULT_FILE_INPUT_VALUE: &str = "No file chosen";
 
 /// <https://html.spec.whatwg.org/multipage/#attr-input-type>
 #[derive(Clone, Copy, Default, JSTraceable, PartialEq)]
@@ -1037,6 +1038,9 @@ impl<'dom> LayoutDom<'dom, HTMLInputElement> {
                 .get_content()
         }
     }
+    fn get_filelist(self) -> Option<LayoutDom<'dom, FileList>> {
+        unsafe { self.unsafe_get().filelist.get_inner_as_layout() }
+    }
 
     fn placeholder(self) -> &'dom str {
         unsafe { self.unsafe_get().placeholder.borrow_for_layout() }
@@ -1070,8 +1074,27 @@ impl<'dom> LayoutHTMLInputElementHelpers<'dom> for LayoutDom<'dom, HTMLInputElem
         }
 
         match self.input_type() {
-            InputType::Checkbox | InputType::Radio => "".into(),
-            InputType::File | InputType::Image => "".into(),
+            InputType::Checkbox | InputType::Radio | InputType::Image => "".into(),
+            InputType::File => {
+                let filelist = self.get_filelist();
+                match filelist {
+                    Some(filelist) => {
+                        let length = filelist.len();
+                        if length == 0 {
+                            return DEFAULT_FILE_INPUT_VALUE.into();
+                        }
+                        if length == 1 {
+                            match filelist.file_for_layout(0) {
+                                Some(file) => return file.name().to_string().into(),
+                                None => return DEFAULT_FILE_INPUT_VALUE.into(),
+                            }
+                        }
+
+                        format!("{} files", length).into()
+                    },
+                    None => DEFAULT_FILE_INPUT_VALUE.into(),
+                }
+            },
             InputType::Button => get_raw_attr_value(self, ""),
             InputType::Submit => get_raw_attr_value(self, DEFAULT_SUBMIT_VALUE),
             InputType::Reset => get_raw_attr_value(self, DEFAULT_RESET_VALUE),
diff --git a/resources/servo.css b/resources/servo.css
index ee2aca1f66f..d9f0366c217 100644
--- a/resources/servo.css
+++ b/resources/servo.css
@@ -74,13 +74,17 @@ input[type="radio"]:checked::before { content: "●"; line-height: 1em; }
 
 input[type="file"]::before {
   content: "Choose File";
+  background: lightgrey;
+  border-top: solid 1px #EEEEEE;
+  border-left: solid 1px #CCCCCC;
+  border-right: solid 1px #999999;
+  border-bottom: solid 1px #999999;
 }
 
 input[type="file"] {
-  background: lightgrey;
   text-align: center;
-  vertical-align: middle;
   color: black;
+  border-style: none;
 }
 
 select {