display input caret for textarea. fixes #7758

components/layout/text.rs

@@ -431,9 +431,19 @@ fn split_first_fragment_at_newline_if_necessary(fragments: &mut LinkedList<Fragm
 
             string_before =
                 unscanned_text_fragment_info.text[..(position + 1)].to_owned();
-            insertion_point_before = unscanned_text_fragment_info.insertion_point;
             unscanned_text_fragment_info.text =
                 unscanned_text_fragment_info.text[(position + 1)..].to_owned().into_boxed_str();
+            let offset = CharIndex(string_before.char_indices().count() as isize);
+            match unscanned_text_fragment_info.insertion_point {
+                Some(insertion_point) if insertion_point >= offset => {
+                    insertion_point_before = None;
+                    unscanned_text_fragment_info.insertion_point = Some(insertion_point - offset);
+                }
+                Some(_) | None => {
+                    insertion_point_before = unscanned_text_fragment_info.insertion_point;
+                    unscanned_text_fragment_info.insertion_point = None;
+                }
+            };
         }
         first_fragment.transform(first_fragment.border_box.size,
                                  SpecificFragmentInfo::UnscannedText(

components/layout/wrapper.rs

@@ -71,7 +71,7 @@ use style::node::TElementAttributes;
 use style::properties::ComputedValues;
 use style::properties::{PropertyDeclaration, PropertyDeclarationBlock};
 use url::Url;
-use util::str::is_whitespace;
+use util::str::{is_whitespace, search_index};
 
 /// A wrapper so that layout can access only the methods that it should have access to. Layout must
 /// only ever see these and must never see instances of `LayoutJS`.
@@ -918,24 +918,17 @@ impl<'ln> ThreadSafeLayoutNode<'ln> {
         let this = unsafe {
             self.get_jsmanaged()
         };
-        let input = this.downcast();
-        if let Some(input) = input {
-            let insertion_point = unsafe {
-                input.get_insertion_point_for_layout()
-            };
-            if let Some(insertion_point) = insertion_point {
-                let text = unsafe {
-                    input.get_value_for_layout()
-                };
 
-                let mut character_count = 0;
-                for (character_index, _) in text.char_indices() {
-                    if character_index == insertion_point.index {
-                        return Some(CharIndex(character_count))
-                    }
-                    character_count += 1
-                }
-                return Some(CharIndex(character_count))
+        if let Some(area) = this.downcast::<HTMLTextAreaElement>() {
+            let insertion_point = unsafe { area.get_absolute_insertion_point_for_layout() };
+            let text = unsafe { area.get_value_for_layout() };
+            return Some(CharIndex(search_index(insertion_point, text.char_indices())));
+        }
+        if let Some(input) = this.downcast::<HTMLInputElement>() {
+            let insertion_point = unsafe { input.get_insertion_point_for_layout() };
+            if let Some(insertion_point) = insertion_point {
+                let text = unsafe { input.get_value_for_layout() };
+                return Some(CharIndex(search_index(insertion_point.index, text.char_indices())));
             }
         }
         None

components/script/dom/htmltextareaelement.rs

@@ -46,6 +46,8 @@ pub struct HTMLTextAreaElement {
 pub trait LayoutHTMLTextAreaElementHelpers {
     #[allow(unsafe_code)]
     unsafe fn get_value_for_layout(self) -> String;
+    #[allow(unsafe_code)]
+    unsafe fn get_absolute_insertion_point_for_layout(self) -> usize;
 }
 
 pub trait RawLayoutHTMLTextAreaElementHelpers {
@@ -61,6 +63,12 @@ impl LayoutHTMLTextAreaElementHelpers for LayoutJS<HTMLTextAreaElement> {
     unsafe fn get_value_for_layout(self) -> String {
         (*self.unsafe_get()).textinput.borrow_for_layout().get_content()
     }
+
+    #[allow(unrooted_must_root)]
+    #[allow(unsafe_code)]
+    unsafe fn get_absolute_insertion_point_for_layout(self) -> usize {
+        (*self.unsafe_get()).textinput.borrow_for_layout().get_absolute_insertion_point()
+    }
 }
 
 impl<'a> RawLayoutHTMLTextAreaElementHelpers for &'a HTMLTextAreaElement {

components/script/textinput.rs

@@ -455,4 +455,14 @@ impl<T: ClipboardProvider> TextInput<T> {
         self.edit_point.line = min(self.edit_point.line, self.lines.len() - 1);
         self.edit_point.index = min(self.edit_point.index, self.current_line_length());
     }
+
+    pub fn get_absolute_insertion_point(&self) -> usize {
+        self.lines.iter().enumerate().fold(0, |acc, (i, val)| {
+            if i < self.edit_point.line {
+                acc + val.len() + 1 // +1 for the \n
+            } else {
+                acc
+            }
+        }) + self.edit_point.index
+    }
 }

components/util/str.rs

@@ -11,7 +11,7 @@ use std::borrow::ToOwned;
 use std::ffi::CStr;
 use std::iter::{Filter, Peekable};
 use std::ops::Deref;
-use std::str::{FromStr, Split, from_utf8};
+use std::str::{CharIndices, FromStr, Split, from_utf8};
 
 pub type DOMString = String;
 pub type StaticCharVec = &'static [char];
@@ -420,3 +420,16 @@ pub fn slice_chars(s: &str, begin: usize, end: usize) -> &str {
         (Some(a), Some(b)) => unsafe { s.slice_unchecked(a, b) }
     }
 }
+
+// searches a character index in CharIndices
+// returns indices.count if not found
+pub fn search_index(index: usize, indices: CharIndices) -> isize {
+    let mut character_count = 0;
+    for (character_index, _) in indices {
+        if character_index == index {
+            return character_count;
+        }
+        character_count += 1
+    }
+    character_count
+}

tests/unit/util/str.rs

@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use util::str::{split_html_space_chars, str_join};
+use util::str::{search_index, split_html_space_chars, str_join};
 
 
 #[test]
@@ -34,3 +34,15 @@ pub fn test_str_join_many() {
     let expected = "-alpha--beta-gamma-";
     assert_eq!(actual, expected);
 }
+
+#[test]
+pub fn test_search_index() {
+    let tuples = [("", 1, 0),
+                  ("foo", 8, 3),
+                  ("føo", 8, 3),
+                  ("foo", 2, 2),
+                  ("føo", 2, 3)];
+    for t in tuples.iter() {
+        assert_eq!(search_index(t.1, t.0.char_indices()), t.2);
+    };
+}