Auto merge of #19358 - jonleighton:issue-19171-3, r=KiChjang

Move selection to end when textarea value is assigned

Issue #19171

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components/script/dom/htmltextareaelement.rs

@@ -34,7 +34,7 @@ use std::default::Default;
 use std::ops::Range;
 use style::attr::AttrValue;
 use style::element_state::ElementState;
-use textinput::{KeyReaction, Lines, SelectionDirection, TextInput};
+use textinput::{Direction, KeyReaction, Lines, Selection, SelectionDirection, TextInput};
 
 #[dom_struct]
 pub struct HTMLTextAreaElement {
@@ -232,10 +232,25 @@ impl HTMLTextAreaElementMethods for HTMLTextAreaElement {
 
     // https://html.spec.whatwg.org/multipage/#dom-textarea-value
     fn SetValue(&self, value: DOMString) {
-        // TODO move the cursor to the end of the field
-        self.textinput.borrow_mut().set_content(value);
+        let mut textinput = self.textinput.borrow_mut();
+
+        // Step 1
+        let old_value = textinput.get_content();
+        let old_selection = textinput.selection_begin;
+
+        // Step 2
+        textinput.set_content(value);
+
+        // Step 3
         self.value_changed.set(true);
 
+        if old_value != textinput.get_content() {
+            // Step 4
+            textinput.adjust_horizontal_to_limit(Direction::Forward, Selection::NotSelected);
+        } else {
+            textinput.selection_begin = old_selection;
+        }
+
         self.upcast::<Node>().dirty(NodeDamage::OtherNodeDamage);
     }
 

components/script/dom/textcontrol.rs

@@ -21,7 +21,16 @@ pub trait TextControl: DerivedFrom<EventTarget> + DerivedFrom<Node> {
 
     // https://html.spec.whatwg.org/multipage/#dom-textarea/input-selectionstart
     fn set_dom_selection_start(&self, start: u32) {
-        self.set_selection_range(start, self.dom_selection_end(), self.selection_direction());
+        // Step 2
+        let mut end = self.dom_selection_end();
+
+        // Step 3
+        if end < start {
+            end = start;
+        }
+
+        // Step 4
+        self.set_selection_range(start, end, self.selection_direction());
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-textarea/input-selectionend

components/script/textinput.rs

@@ -770,7 +770,11 @@ impl<T: ClipboardProvider> TextInput<T> {
     /// any \n encountered will be stripped and force a new logical line.
     pub fn set_content(&mut self, content: DOMString) {
         self.lines = if self.multiline {
-            content.split('\n').map(DOMString::from).collect()
+            // https://html.spec.whatwg.org/multipage/#textarea-line-break-normalisation-transformation
+            content.replace("\r\n", "\n")
+                   .split(|c| c == '\n' || c == '\r')
+                   .map(DOMString::from)
+                   .collect()
         } else {
             vec!(content)
         };