Add keyboard special key support for web content interaction

Enter, Backspace, Tab, Escape, Delete, arrow keys, Home, End,
PageUp, PageDown now forward to Servo. Previously only printable
characters reached the web engine, making forms unusable.

crates/ely_app/src/shell/web_surface_keyboard.rs

@@ -10,15 +10,21 @@ impl ElyShell {
         _window: &mut Window,
         cx: &mut Context<Self>,
     ) {
-        let Some(text) = typed_text_from_key_down(event) else {
-            return;
-        };
         let Some((tab_id, requested_url)) = self.active_external_tab_target() else {
             return;
         };
 
-        if self.type_text_in_external_web_viewport(tab_id, requested_url, text, cx) {
-            cx.stop_propagation();
+        if let Some(text) = printable_text_from_key_down(event) {
+            if self.type_text_in_external_web_viewport(tab_id, requested_url, text, cx) {
+                cx.stop_propagation();
+            }
+            return;
+        }
+
+        if let Some(text) = special_key_text(event) {
+            if self.type_text_in_external_web_viewport(tab_id, requested_url, text, cx) {
+                cx.stop_propagation();
+            }
         }
     }
 
@@ -36,7 +42,7 @@ impl ElyShell {
     }
 }
 
-fn typed_text_from_key_down(event: &KeyDownEvent) -> Option<&str> {
+fn printable_text_from_key_down(event: &KeyDownEvent) -> Option<&str> {
     let modifiers = &event.keystroke.modifiers;
     if modifiers.control || modifiers.platform || modifiers.function {
         return None;
@@ -52,17 +58,39 @@ fn typed_text_from_key_down(event: &KeyDownEvent) -> Option<&str> {
     Some(text)
 }
 
+fn special_key_text(event: &KeyDownEvent) -> Option<&'static str> {
+    if event.keystroke.modifiers.platform || event.keystroke.modifiers.control {
+        return None;
+    }
+    match event.keystroke.key.as_str() {
+        "enter" => Some("\n"),
+        "backspace" => Some("\x08"),
+        "tab" => Some("\t"),
+        "escape" => Some("\x1b"),
+        "delete" => Some("\x7f"),
+        "left" => Some("\u{F702}"),
+        "right" => Some("\u{F703}"),
+        "up" => Some("\u{F700}"),
+        "down" => Some("\u{F701}"),
+        "home" => Some("\u{F729}"),
+        "end" => Some("\u{F72B}"),
+        "pageup" => Some("\u{F72C}"),
+        "pagedown" => Some("\u{F72D}"),
+        _ => None,
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use gpui::{KeyDownEvent, Keystroke, Modifiers};
 
-    use super::typed_text_from_key_down;
+    use super::{printable_text_from_key_down, special_key_text};
 
     #[test]
     fn typed_text_uses_printable_key_char() {
         let event = key_down("e", Some("e"), Modifiers::none());
 
-        assert_eq!(typed_text_from_key_down(&event), Some("e"));
+        assert_eq!(printable_text_from_key_down(&event), Some("e"));
     }
 
     #[test]
@@ -71,7 +99,7 @@ mod tests {
         modifiers.shift = true;
         let event = key_down("1", Some("!"), modifiers);
 
-        assert_eq!(typed_text_from_key_down(&event), Some("!"));
+        assert_eq!(printable_text_from_key_down(&event), Some("!"));
     }
 
     #[test]
@@ -80,7 +108,36 @@ mod tests {
         modifiers.platform = true;
         let event = key_down("l", None, modifiers);
 
-        assert_eq!(typed_text_from_key_down(&event), None);
+        assert_eq!(printable_text_from_key_down(&event), None);
+    }
+
+    #[test]
+    fn special_key_enter() {
+        let event = key_down("enter", None, Modifiers::none());
+        assert_eq!(special_key_text(&event), Some("\n"));
+    }
+
+    #[test]
+    fn special_key_backspace() {
+        let event = key_down("backspace", None, Modifiers::none());
+        assert_eq!(special_key_text(&event), Some("\x08"));
+    }
+
+    #[test]
+    fn special_key_ignored_with_platform_modifier() {
+        let mut modifiers = Modifiers::none();
+        modifiers.platform = true;
+        let event = key_down("enter", None, modifiers);
+        assert_eq!(special_key_text(&event), None);
+    }
+
+    #[test]
+    fn special_key_arrows() {
+        let event = key_down("left", None, Modifiers::none());
+        assert_eq!(special_key_text(&event), Some("\u{F702}"));
+
+        let event = key_down("right", None, Modifiers::none());
+        assert_eq!(special_key_text(&event), Some("\u{F703}"));
     }
 
     fn key_down(key: &str, key_char: Option<&str>, modifiers: Modifiers) -> KeyDownEvent {