core: Use Cow<str> for FullscreenError in UI backend, as it can't ever be anything else

core/src/backend/ui.rs

@@ -1,7 +1,8 @@
 use crate::events::{KeyCode, PlayerEvent};
+use std::borrow::Cow;
 use std::collections::HashSet;
 
-pub type Error = Box<dyn std::error::Error>;
+pub type FullscreenError = Cow<'static, str>;
 
 pub trait UiBackend {
     fn mouse_visible(&self) -> bool;
@@ -14,7 +15,7 @@ pub trait UiBackend {
     /// Sets the clipboard to the given content.
     fn set_clipboard_content(&mut self, content: String);
 
-    fn set_fullscreen(&mut self, is_full: bool) -> Result<(), Error>;
+    fn set_fullscreen(&mut self, is_full: bool) -> Result<(), FullscreenError>;
 
     /// Displays a warning about unsupported content in Ruffle.
     /// The user can still click an "OK" or "run anyway" message to dismiss the warning.
@@ -138,7 +139,7 @@ impl UiBackend for NullUiBackend {
 
     fn set_clipboard_content(&mut self, _content: String) {}
 
-    fn set_fullscreen(&mut self, _is_full: bool) -> Result<(), Error> {
+    fn set_fullscreen(&mut self, _is_full: bool) -> Result<(), FullscreenError> {
         Ok(())
     }
 

desktop/src/ui.rs

@@ -1,6 +1,6 @@
 use clipboard::{ClipboardContext, ClipboardProvider};
 use rfd::{MessageButtons, MessageDialog, MessageLevel};
-use ruffle_core::backend::ui::{Error, MouseCursor, UiBackend};
+use ruffle_core::backend::ui::{FullscreenError, MouseCursor, UiBackend};
 use std::rc::Rc;
 use winit::window::{Fullscreen, Window};
 
@@ -55,7 +55,7 @@ impl UiBackend for DesktopUiBackend {
         self.clipboard.set_contents(content).unwrap();
     }
 
-    fn set_fullscreen(&mut self, is_full: bool) -> Result<(), Error> {
+    fn set_fullscreen(&mut self, is_full: bool) -> Result<(), FullscreenError> {
         self.window.set_fullscreen(if is_full {
             Some(Fullscreen::Borderless(None))
         } else {

web/src/ui.rs

@@ -1,25 +1,9 @@
 use super::JavascriptPlayer;
-use ruffle_core::backend::ui::{Error, MouseCursor, UiBackend};
+use ruffle_core::backend::ui::{FullscreenError, MouseCursor, UiBackend};
 use ruffle_web_common::JsResult;
+use std::borrow::Cow;
 use web_sys::HtmlCanvasElement;
 
-#[derive(Debug)]
-struct FullScreenError {
-    jsval: String,
-}
-
-impl std::fmt::Display for FullScreenError {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.write_str(&self.jsval)
-    }
-}
-
-impl std::error::Error for FullScreenError {
-    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
-        None
-    }
-}
-
 /// An implementation of `UiBackend` utilizing `web_sys` bindings to input APIs.
 pub struct WebUiBackend {
     js_player: JavascriptPlayer,
@@ -75,14 +59,13 @@ impl UiBackend for WebUiBackend {
         log::warn!("set clipboard not implemented");
     }
 
-    fn set_fullscreen(&mut self, is_full: bool) -> Result<(), Error> {
+    fn set_fullscreen(&mut self, is_full: bool) -> Result<(), FullscreenError> {
         match self.js_player.set_fullscreen(is_full) {
             Ok(_) => Ok(()),
-            Err(jsval) => Err(Box::new(FullScreenError {
-                jsval: jsval
-                    .as_string()
-                    .unwrap_or_else(|| "Failed to change full screen state".to_string()),
-            })),
+            Err(jsval) => Err(jsval
+                .as_string()
+                .map(Cow::Owned)
+                .unwrap_or_else(|| Cow::Borrowed("Failed to change full screen state"))),
         }
     }