core: Fix TextField.maxChars handling and address other reviews

Author: n0samu

core/src/display_object/edit_text.rs

@@ -1174,19 +1174,21 @@ impl<'gc> EditText<'gc> {
         None
     }
 
+    /// The number of characters that currently can be inserted, considering `TextField.maxChars`
+    /// constraint, current text length, and current text selection length.
     fn available_chars(self) -> usize {
         let read = self.0.read();
         let max_chars = read.max_chars;
         if max_chars == 0 {
             usize::MAX
         } else {
-            let text_len = read.text_spans.text().len();
+            let text_len = read.text_spans.text().len() as i32;
             let selection_len = if let Some(selection) = self.selection() {
-                selection.end() - selection.start()
+                (selection.end() - selection.start()) as i32
             } else {
                 0
             };
-            max_chars.max(0) as usize - (text_len - selection_len)
+            0.max(max_chars.max(0) - (text_len - selection_len)) as usize
         }
     }
 

core/src/events.rs

@@ -336,7 +336,7 @@ impl<'gc> ClipEvent<'gc> {
 /// Control inputs to a text field
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 pub enum TextControlCode {
-    // TODO: Extend this
+    // TODO: Add control codes for Ctrl+Arrows and Home/End keys
     MoveLeft,
     MoveRight,
     SelectLeft,

desktop/src/main.rs

@@ -915,6 +915,7 @@ fn winit_key_to_char(key_code: VirtualKeyCode, is_shift_down: bool) -> Option<ch
 
 /// Converts a `VirtualKeyCode` and `ModifiersState` to a Ruffle `TextControlCode`.
 /// Returns `None` if there is no match.
+/// TODO: Handle Ctrl+Arrows and Home/End keys
 fn winit_to_ruffle_text_control(
     key: VirtualKeyCode,
     modifiers: ModifiersState,

web/src/lib.rs

@@ -843,12 +843,12 @@ impl Ruffle {
                             let is_ctrl_cmd = js_event.ctrl_key() || js_event.meta_key();
                             core.handle_event(PlayerEvent::KeyDown { key_code, key_char });
 
-                            if let Some(control_code) = web_to_text_control(
+                            if let Some(control_code) = web_to_ruffle_text_control(
                                 &js_event.key(),
                                 is_ctrl_cmd,
                                 js_event.shift_key(),
                             ) {
-                                core.handle_event(PlayerEvent::TextControl { code: control_code })
+                                core.handle_event(PlayerEvent::TextControl { code: control_code });
                             } else if let Some(codepoint) = key_char {
                                 core.handle_event(PlayerEvent::TextInput { codepoint });
                             }
@@ -1748,14 +1748,20 @@ fn web_key_to_codepoint(key: &str) -> Option<char> {
     }
 }
 
-pub fn web_to_text_control(key: &str, ctrl_key: bool, shift_key: bool) -> Option<TextControlCode> {
+/// Convert a web `KeyboardEvent.key` value to a Ruffle `TextControlCode`,
+/// given the states of the modifier keys. Return `None` if there is no match.
+/// TODO: Handle Ctrl+Arrows and Home/End keys
+pub fn web_to_ruffle_text_control(
+    key: &str,
+    ctrl_key: bool,
+    shift_key: bool,
+) -> Option<TextControlCode> {
     let mut chars = key.chars();
     let (c1, c2) = (chars.next(), chars.next());
     if c2.is_none() {
         // Single character.
         if ctrl_key {
             match c1 {
-                // TODO: Extend this
                 Some('a') => Some(TextControlCode::SelectAll),
                 Some('c') => Some(TextControlCode::Copy),
                 Some('v') => Some(TextControlCode::Paste),