avm2: Implement TextField.getLineIndexOfChar()

core/src/avm2/globals/flash/text/TextField.as

@@ -170,10 +170,7 @@ package flash.text {
             return 0;
         }
 
-        public function getLineIndexOfChar(charIndex:int):int {
-            stub_method("flash.text.TextField", "getLineIndexOfChar");
-            return 0;
-        }
+        public native function getLineIndexOfChar(charIndex:int):int;
 
         public function getParagraphLength(charIndex:int):int {
             stub_method("flash.text.TextField", "getParagraphLength");

core/src/avm2/globals/flash/text/text_field.rs

@@ -1164,11 +1164,11 @@ pub fn get_line_length<'gc>(
         return Err(make_error_2006(activation));
     }
 
-    return if let Some(length) = this.line_length(line_num as usize) {
+    if let Some(length) = this.line_length(line_num as usize) {
         Ok(length.into())
     } else {
         Err(make_error_2006(activation))
-    };
+    }
 }
 
 pub fn get_line_text<'gc>(
@@ -1208,11 +1208,11 @@ pub fn get_line_offset<'gc>(
         return Err(make_error_2006(activation));
     }
 
-    return if let Some(offset) = this.line_offset(line_num as usize) {
+    if let Some(offset) = this.line_offset(line_num as usize) {
         Ok(offset.into())
     } else {
         Err(make_error_2006(activation))
-    };
+    }
 }
 
 pub fn get_bottom_scroll_v<'gc>(
@@ -1444,3 +1444,28 @@ pub fn get_selected_text<'gc>(
     }
     Ok("".into())
 }
+
+pub fn get_line_index_of_char<'gc>(
+    activation: &mut Activation<'_, 'gc>,
+    this: Object<'gc>,
+    args: &[Value<'gc>],
+) -> Result<Value<'gc>, Error<'gc>> {
+    let Some(this) = this
+        .as_display_object()
+        .and_then(|this| this.as_edit_text())
+    else {
+        return Ok(Value::Undefined);
+    };
+
+    let index = args.get_i32(activation, 0)?;
+    if index < 0 {
+        // Docs say "throw RangeError", reality says "return -1".
+        return Ok(Value::Number(-1f64));
+    }
+
+    if let Some(line) = this.line_index_of_char(index as usize) {
+        Ok(line.into())
+    } else {
+        Ok(Value::Number(-1f64))
+    }
+}

core/src/display_object/edit_text.rs

@@ -1931,6 +1931,10 @@ impl<'gc> EditText<'gc> {
         Some(first_box.start())
     }
 
+    pub fn line_index_of_char(self, index: usize) -> Option<usize> {
+        self.0.read().layout.find_line_index_by_position(index)
+    }
+
     fn execute_avm1_asfunction(
         self,
         context: &mut UpdateContext<'_, 'gc>,

core/src/html/layout.rs

@@ -10,7 +10,7 @@ use crate::tag_utils::SwfMovie;
 use crate::DefaultFont;
 use gc_arena::Collect;
 use ruffle_render::shape_utils::DrawCommand;
-use std::cmp::{max, min};
+use std::cmp::{max, min, Ordering};
 use std::fmt::{Debug, Formatter};
 use std::mem;
 use std::ops::{Deref, Range};
@@ -773,6 +773,19 @@ impl<'gc> Layout<'gc> {
             boxes_iter: None,
         }
     }
+
+    pub fn find_line_index_by_position(&self, position: usize) -> Option<usize> {
+        let result = self.lines.binary_search_by(|probe| {
+            if probe.end <= position {
+                Ordering::Less
+            } else if position < probe.start {
+                Ordering::Greater
+            } else {
+                Ordering::Equal
+            }
+        });
+        result.ok()
+    }
 }
 
 /// A `LayoutLine` represents a single line of text.

tests/tests/swfs/avm2/edittext_get_line_index_of_char/Test.as

@@ -0,0 +1,35 @@
+package {
+import flash.display.Sprite;
+import flash.text.TextField;
+
+public class Test extends Sprite {
+    private var text1: TextField;
+    private var text2: TextField;
+    private var text3: TextField;
+
+    public function Test() {
+        text1 = new TextField();
+        text1.text = "line 1\n line2\n\n line 4\n";
+        text2 = new TextField();
+        text2.htmlText = "<p>line 1 </p><br/><li>line 2 </li>\n\n<li> line 4</li>";
+        text3 = new TextField();
+        text3.wordWrap = true;
+        text3.width = 50;
+        text3.text = "first second\nthird";
+
+        addChild(text1);
+        addChild(text2);
+        addChild(text3);
+        printValues("text1", text1, 25);
+        printValues("text2", text2, 25);
+        printValues("text3", text3, 20);
+    }
+
+    private function printValues(name:String, text:TextField, len: int):void {
+        trace("Field: " + name);
+        for (var i = -1; i < len; ++i) {
+            trace("  " + name + ".getLineIndexOfChar(" + i + ") = " + text.getLineIndexOfChar(i));
+        }
+    }
+}
+}

tests/tests/swfs/avm2/edittext_get_line_index_of_char/output.txt

@@ -0,0 +1,76 @@
+Field: text1
+  text1.getLineIndexOfChar(-1) = -1
+  text1.getLineIndexOfChar(0) = 0
+  text1.getLineIndexOfChar(1) = 0
+  text1.getLineIndexOfChar(2) = 0
+  text1.getLineIndexOfChar(3) = 0
+  text1.getLineIndexOfChar(4) = 0
+  text1.getLineIndexOfChar(5) = 0
+  text1.getLineIndexOfChar(6) = 0
+  text1.getLineIndexOfChar(7) = 1
+  text1.getLineIndexOfChar(8) = 1
+  text1.getLineIndexOfChar(9) = 1
+  text1.getLineIndexOfChar(10) = 1
+  text1.getLineIndexOfChar(11) = 1
+  text1.getLineIndexOfChar(12) = 1
+  text1.getLineIndexOfChar(13) = 1
+  text1.getLineIndexOfChar(14) = 2
+  text1.getLineIndexOfChar(15) = 3
+  text1.getLineIndexOfChar(16) = 3
+  text1.getLineIndexOfChar(17) = 3
+  text1.getLineIndexOfChar(18) = 3
+  text1.getLineIndexOfChar(19) = 3
+  text1.getLineIndexOfChar(20) = 3
+  text1.getLineIndexOfChar(21) = 3
+  text1.getLineIndexOfChar(22) = 3
+  text1.getLineIndexOfChar(23) = -1
+  text1.getLineIndexOfChar(24) = -1
+Field: text2
+  text2.getLineIndexOfChar(-1) = -1
+  text2.getLineIndexOfChar(0) = 0
+  text2.getLineIndexOfChar(1) = 0
+  text2.getLineIndexOfChar(2) = 0
+  text2.getLineIndexOfChar(3) = 0
+  text2.getLineIndexOfChar(4) = 0
+  text2.getLineIndexOfChar(5) = 0
+  text2.getLineIndexOfChar(6) = 0
+  text2.getLineIndexOfChar(7) = 0
+  text2.getLineIndexOfChar(8) = 0
+  text2.getLineIndexOfChar(9) = 0
+  text2.getLineIndexOfChar(10) = 0
+  text2.getLineIndexOfChar(11) = 0
+  text2.getLineIndexOfChar(12) = 0
+  text2.getLineIndexOfChar(13) = 0
+  text2.getLineIndexOfChar(14) = 0
+  text2.getLineIndexOfChar(15) = 1
+  text2.getLineIndexOfChar(16) = 2
+  text2.getLineIndexOfChar(17) = 2
+  text2.getLineIndexOfChar(18) = 2
+  text2.getLineIndexOfChar(19) = 2
+  text2.getLineIndexOfChar(20) = 2
+  text2.getLineIndexOfChar(21) = 2
+  text2.getLineIndexOfChar(22) = 2
+  text2.getLineIndexOfChar(23) = -1
+  text2.getLineIndexOfChar(24) = -1
+Field: text3
+  text3.getLineIndexOfChar(-1) = -1
+  text3.getLineIndexOfChar(0) = 0
+  text3.getLineIndexOfChar(1) = 0
+  text3.getLineIndexOfChar(2) = 0
+  text3.getLineIndexOfChar(3) = 0
+  text3.getLineIndexOfChar(4) = 0
+  text3.getLineIndexOfChar(5) = 0
+  text3.getLineIndexOfChar(6) = 1
+  text3.getLineIndexOfChar(7) = 1
+  text3.getLineIndexOfChar(8) = 1
+  text3.getLineIndexOfChar(9) = 1
+  text3.getLineIndexOfChar(10) = 1
+  text3.getLineIndexOfChar(11) = 1
+  text3.getLineIndexOfChar(12) = 1
+  text3.getLineIndexOfChar(13) = 2
+  text3.getLineIndexOfChar(14) = 2
+  text3.getLineIndexOfChar(15) = 2
+  text3.getLineIndexOfChar(16) = 2
+  text3.getLineIndexOfChar(17) = 2
+  text3.getLineIndexOfChar(18) = -1
+  text3.getLineIndexOfChar(19) = -1

tests/tests/swfs/avm2/edittext_get_line_index_of_char/test.toml

@@ -0,0 +1 @@
+num_ticks = 1