core: Prevent pasting empty string when the clipboard is empty

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

@@ -142,7 +142,7 @@ impl<'gc> ContextMenuState<'gc> {
         let language = &context.ui.language();
         self.push(
             ContextMenuItem {
-                enabled: text.is_text_control_applicable(TextControlCode::Cut),
+                enabled: text.is_text_control_applicable(TextControlCode::Cut, context),
                 separator_before: true,
                 caption: core_text(language, "context-menu-cut"),
                 checked: false,
@@ -154,7 +154,7 @@ impl<'gc> ContextMenuState<'gc> {
         );
         self.push(
             ContextMenuItem {
-                enabled: text.is_text_control_applicable(TextControlCode::Copy),
+                enabled: text.is_text_control_applicable(TextControlCode::Copy, context),
                 separator_before: false,
                 caption: core_text(language, "context-menu-copy"),
                 checked: false,
@@ -166,7 +166,7 @@ impl<'gc> ContextMenuState<'gc> {
         );
         self.push(
             ContextMenuItem {
-                enabled: text.is_text_control_applicable(TextControlCode::Paste),
+                enabled: text.is_text_control_applicable(TextControlCode::Paste, context),
                 separator_before: false,
                 caption: core_text(language, "context-menu-paste"),
                 checked: false,
@@ -178,7 +178,7 @@ impl<'gc> ContextMenuState<'gc> {
         );
         self.push(
             ContextMenuItem {
-                enabled: text.is_text_control_applicable(TextControlCode::Delete),
+                enabled: text.is_text_control_applicable(TextControlCode::Delete, context),
                 separator_before: false,
                 caption: core_text(language, "context-menu-delete"),
                 checked: false,
@@ -190,7 +190,7 @@ impl<'gc> ContextMenuState<'gc> {
         );
         self.push(
             ContextMenuItem {
-                enabled: text.is_text_control_applicable(TextControlCode::SelectAll),
+                enabled: text.is_text_control_applicable(TextControlCode::SelectAll, context),
                 separator_before: true,
                 caption: core_text(language, "context-menu-select-all"),
                 checked: false,

core/src/display_object/edit_text.rs

@@ -1420,7 +1420,11 @@ impl<'gc> EditText<'gc> {
         }
     }
 
-    pub fn is_text_control_applicable(self, control_code: TextControlCode) -> bool {
+    pub fn is_text_control_applicable(
+        self,
+        control_code: TextControlCode,
+        context: &mut UpdateContext<'_, 'gc>,
+    ) -> bool {
         if !self.is_editable() && control_code.is_edit_input() {
             return false;
         }
@@ -1439,7 +1443,10 @@ impl<'gc> EditText<'gc> {
             | TextControlCode::SelectRightLine
             | TextControlCode::SelectRightDocument
             | TextControlCode::SelectAll => self.is_selectable(),
-            TextControlCode::Copy | TextControlCode::Cut => !selection.is_caret(),
+            TextControlCode::Copy | TextControlCode::Cut => {
+                !selection.is_caret()
+            }
+            TextControlCode::Paste => context.ui.clipboard_available(),
             _ => true,
         }
     }
@@ -1449,7 +1456,7 @@ impl<'gc> EditText<'gc> {
         control_code: TextControlCode,
         context: &mut UpdateContext<'_, 'gc>,
     ) {
-        if !self.is_text_control_applicable(control_code) {
+        if !self.is_text_control_applicable(control_code, context) {
             return;
         }
 
@@ -1525,8 +1532,15 @@ impl<'gc> EditText<'gc> {
                 let text = &self.text()[selection.start()..selection.end()];
                 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);
 

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")`