core: Prevent pasting empty string when the clipboard is empty

Author: kjarosh

core/src/backend/ui.rs

@@ -73,6 +73,11 @@ pub trait UiBackend: Downcast {
     /// Get the clipboard content
     fn clipboard_content(&mut self) -> String;
 
+    /// Check if the clipboard is available and not empty
+    fn clipboard_available(&mut self) -> bool {
+        !self.clipboard_content().is_empty()
+    }
+
     /// Sets the clipboard to the given content.
     fn set_clipboard_content(&mut self, content: String);
 

core/src/context_menu.rs

@@ -11,7 +11,6 @@ use crate::display_object::{EditText, Stage};
 use crate::display_object::{InteractiveObject, TDisplayObject};
 use crate::events::TextControlCode;
 use crate::i18n::core_text;
-use fluent_templates::LanguageIdentifier;
 use gc_arena::Collect;
 use ruffle_render::quality::StageQuality;
 use serde::Serialize;
@@ -54,7 +53,7 @@ impl<'gc> ContextMenuState<'gc> {
         // show the copy/paste menu.
         if let Some(text) = context.focus_tracker.get_as_edit_text() {
             if InteractiveObject::option_ptr_eq(context.mouse_data.hovered, text.as_interactive()) {
-                self.build_text_items(text, language);
+                self.build_text_items(text, context);
                 return;
             }
         }
@@ -139,8 +138,9 @@ impl<'gc> ContextMenuState<'gc> {
         }
     }
 
-    fn build_text_items(&mut self, text: EditText<'gc>, language: &LanguageIdentifier) {
-        let flags = TextItemFlags::for_edit_text(text);
+    fn build_text_items(&mut self, text: EditText<'gc>, context: &mut UpdateContext<'_, 'gc>) {
+        let language = &context.ui.language();
+        let flags = TextItemFlags::for_edit_text(text, context);
         self.push(
             ContextMenuItem {
                 enabled: flags.cut,
@@ -292,16 +292,17 @@ struct TextItemFlags {
 }
 
 impl TextItemFlags {
-    pub fn for_edit_text(text: EditText<'_>) -> Self {
+    pub fn for_edit_text<'gc>(text: EditText<'gc>, context: &mut UpdateContext<'_, 'gc>) -> Self {
         let editable = text.is_editable();
         let selectable = text.is_selectable();
         let any_text_selected = selectable && text.selection().is_some_and(|s| !s.is_caret());
         let pastable = editable && text.selection().is_some();
+        let clipboard_available = context.ui.clipboard_available();
 
         Self {
             cut: any_text_selected && editable,
             copy: any_text_selected,
-            paste: pastable,
+            paste: pastable && clipboard_available,
             delete: any_text_selected && editable,
             select_all: selectable,
         }

core/src/display_object/edit_text.rs

@@ -1502,8 +1502,16 @@ impl<'gc> EditText<'gc> {
                         context.ui.set_clipboard_content(text.to_string());
                     }
                 }
-                TextControlCode::Paste => {
+                TextControlCode::Paste => 'paste: {
                     let text = context.ui.clipboard_content();
+                    if text.is_empty() {
+                        // When the clipboard is empty, nothing is pasted
+                        // and the already selected text is not removed.
+                        // Note that if the clipboard is not empty, but does not have
+                        // any allowed characters, the selected text is removed.
+                        break 'paste;
+                    }
+
                     let mut text = self.0.read().restrict.filter_allowed(&text);
 
                     if text.len() > self.available_chars() && self.available_chars() > 0 {

web/src/ui.rs

@@ -222,6 +222,12 @@ impl UiBackend for WebUiBackend {
         self.clipboard_content.to_owned()
     }
 
+    fn clipboard_available(&mut self) -> bool {
+        // On web, we have to assume that the clipboard
+        // is available due to the JS `paste` event.
+        true
+    }
+
     fn set_clipboard_content(&mut self, content: String) {
         self.clipboard_content = content.to_owned();
         // We use `document.execCommand("copy")` as `navigator.clipboard.writeText("string")`