[Framework] Add Share to selection controls (#132599)

In native iOS, users are able to select text and initiate a share menu, which provides several standard services, such as copy, sharing to social media, direct ability to send to various contacts through messaging apps, etc. 

https://github.com/flutter/engine/assets/36148254/d0af7034-31fd-412e-8636-a06bbff54765

This PR is the framework portion of the changes that will allow Share to be implemented.
The corresponding merged engine PR is [here](flutter/engine#44554)
This PR addresses #107578
More details are available in this [design doc](https://github.com/flutter/engine/pull/flutter.dev/go/add-missing-features-to-selection-controls)

Author: LouiseHsu

packages/flutter/lib/src/cupertino/adaptive_text_selection_toolbar.dart

@@ -96,6 +96,7 @@ class CupertinoAdaptiveTextSelectionToolbar extends StatelessWidget {
     required VoidCallback? onSelectAll,
     required VoidCallback? onLookUp,
     required VoidCallback? onSearchWeb,
+    required VoidCallback? onShare,
     required VoidCallback? onLiveTextInput,
     required this.anchors,
   }) : children = null,
@@ -107,6 +108,7 @@ class CupertinoAdaptiveTextSelectionToolbar extends StatelessWidget {
          onSelectAll: onSelectAll,
          onLookUp: onLookUp,
          onSearchWeb: onSearchWeb,
+         onShare: onShare,
          onLiveTextInput: onLiveTextInput
        );
 

packages/flutter/lib/src/cupertino/localizations.dart

@@ -253,6 +253,10 @@ abstract class CupertinoLocalizations {
   // The global version uses the translated string from the arb file.
   String get searchWebButtonLabel;
 
+  /// The term used for launching a web search on a selection.
+  // The global version uses the translated string from the arb file.
+  String get shareButtonLabel;
+
   /// The default placeholder used in [CupertinoSearchTextField].
   // The global version uses the translated string from the arb file.
   String get searchTextFieldPlaceholderLabel;
@@ -469,6 +473,9 @@ class DefaultCupertinoLocalizations implements CupertinoLocalizations {
   @override
   String get searchWebButtonLabel => 'Search Web';
 
+  @override
+  String get shareButtonLabel => 'Share...';
+
   @override
   String get searchTextFieldPlaceholderLabel => 'Search';
 

packages/flutter/lib/src/cupertino/text_selection_toolbar_button.dart

@@ -109,6 +109,8 @@ class CupertinoTextSelectionToolbarButton extends StatefulWidget {
         return localizations.lookUpButtonLabel;
       case ContextMenuButtonType.searchWeb:
         return localizations.searchWebButtonLabel;
+      case ContextMenuButtonType.share:
+        return localizations.shareButtonLabel;
       case ContextMenuButtonType.liveTextInput:
       case ContextMenuButtonType.delete:
       case ContextMenuButtonType.custom:
@@ -195,6 +197,7 @@ class _CupertinoTextSelectionToolbarButtonState extends State<CupertinoTextSelec
       case ContextMenuButtonType.delete:
       case ContextMenuButtonType.lookUp:
       case ContextMenuButtonType.searchWeb:
+      case ContextMenuButtonType.share:
       case ContextMenuButtonType.custom:
         return textWidget;
       case ContextMenuButtonType.liveTextInput:

packages/flutter/lib/src/material/adaptive_text_selection_toolbar.dart

@@ -105,6 +105,7 @@ class AdaptiveTextSelectionToolbar extends StatelessWidget {
     required VoidCallback? onSelectAll,
     required VoidCallback? onLookUp,
     required VoidCallback? onSearchWeb,
+    required VoidCallback? onShare,
     required VoidCallback? onLiveTextInput,
     required this.anchors,
   }) : children = null,
@@ -116,6 +117,7 @@ class AdaptiveTextSelectionToolbar extends StatelessWidget {
          onSelectAll: onSelectAll,
          onLookUp: onLookUp,
          onSearchWeb: onSearchWeb,
+         onShare: onShare,
          onLiveTextInput: onLiveTextInput
        );
 
@@ -223,6 +225,8 @@ class AdaptiveTextSelectionToolbar extends StatelessWidget {
             return localizations.lookUpButtonLabel;
           case ContextMenuButtonType.searchWeb:
             return localizations.searchWebButtonLabel;
+          case ContextMenuButtonType.share:
+            return localizations.searchWebButtonLabel;
           case ContextMenuButtonType.liveTextInput:
             return localizations.scanTextButtonLabel;
           case ContextMenuButtonType.custom:

packages/flutter/lib/src/material/material_localizations.dart

@@ -121,6 +121,9 @@ abstract class MaterialLocalizations {
   /// Label for "search web" edit buttons and menu items.
   String get searchWebButtonLabel;
 
+  /// Label for "share" edit buttons and menu items.
+  String get shareButtonLabel;
+
   /// Label for the [AboutDialog] button that shows the [LicensePage].
   String get viewLicensesButtonLabel;
 
@@ -1190,6 +1193,9 @@ class DefaultMaterialLocalizations implements MaterialLocalizations {
   @override
   String get searchWebButtonLabel => 'Search Web';
 
+  @override
+  String get shareButtonLabel => 'Share...';
+
   @override
   String get viewLicensesButtonLabel => 'View licenses';
 

packages/flutter/lib/src/services/text_input.dart

@@ -1038,24 +1038,27 @@ mixin TextSelectionDelegate {
   /// input.
   void bringIntoView(TextPosition position);
 
-  /// Whether cut is enabled, must not be null.
+  /// Whether cut is enabled.
   bool get cutEnabled => true;
 
-  /// Whether copy is enabled, must not be null.
+  /// Whether copy is enabled.
   bool get copyEnabled => true;
 
-  /// Whether paste is enabled, must not be null.
+  /// Whether paste is enabled.
   bool get pasteEnabled => true;
 
-  /// Whether select all is enabled, must not be null.
+  /// Whether select all is enabled.
   bool get selectAllEnabled => true;
 
-  /// Whether look up is enabled, must not be null.
+  /// Whether look up is enabled.
   bool get lookUpEnabled => true;
 
-  /// Whether search web is enabled, must not be null.
+  /// Whether search web is enabled.
   bool get searchWebEnabled => true;
 
+  /// Whether share is enabled.
+  bool get shareEnabled => true;
+
   /// Whether Live Text input is enabled.
   ///
   /// See also:

packages/flutter/lib/src/widgets/context_menu_button_item.dart

@@ -32,6 +32,9 @@ enum ContextMenuButtonType {
   /// A button that launches a web search for the current text selection.
   searchWeb,
 
+  /// A button that displays the share screen for the current text selection.
+  share,
+
   /// A button for starting Live Text input.
   ///
   /// See also:

packages/flutter/lib/src/widgets/editable_text.dart

@@ -1874,6 +1874,7 @@ class EditableText extends StatefulWidget {
     required final VoidCallback? onSelectAll,
     required final VoidCallback? onLookUp,
     required final VoidCallback? onSearchWeb,
+    required final VoidCallback? onShare,
     required final VoidCallback? onLiveTextInput,
   }) {
     final List<ContextMenuButtonItem> resultButtonItem = <ContextMenuButtonItem>[];
@@ -1914,6 +1915,11 @@ class EditableText extends StatefulWidget {
             onPressed: onSearchWeb,
             type: ContextMenuButtonType.searchWeb,
           ),
+        if (onShare != null)
+          ContextMenuButtonItem(
+            onPressed: onShare,
+            type: ContextMenuButtonType.share,
+          ),
       ]);
     }
 
@@ -2291,6 +2297,17 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
         && textEditingValue.selection.textInside(textEditingValue.text).trim() != '';
   }
 
+  @override
+  bool get shareEnabled {
+    if (defaultTargetPlatform != TargetPlatform.iOS) {
+      return false;
+    }
+
+    return !widget.obscureText
+        && !textEditingValue.selection.isCollapsed
+        && textEditingValue.selection.textInside(textEditingValue.text).trim() != '';
+  }
+
   @override
   bool get liveTextInputEnabled {
     return _liveTextInputStatus?.value == LiveTextInputStatus.enabled &&
@@ -2456,8 +2473,11 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
     }
   }
 
-  /// Look up the current selection, as in the "Look Up" edit menu button on iOS.
+  /// Look up the current selection,
+  /// as in the "Look Up" edit menu button on iOS.
+  ///
   /// Currently this is only implemented for iOS.
+  ///
   /// Throws an error if the selection is empty or collapsed.
   Future<void> lookUpSelection(SelectionChangedCause cause) async {
     assert(!widget.obscureText);
@@ -2473,9 +2493,10 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
   }
 
   /// Launch a web search on the current selection,
-  ///   as in the "Search Web" edit menu button on iOS.
+  /// as in the "Search Web" edit menu button on iOS.
   ///
   /// Currently this is only implemented for iOS.
+  ///
   /// When 'obscureText' is true or the selection is empty,
   /// this function will not do anything
   Future<void> searchWebForSelection(SelectionChangedCause cause) async {
@@ -2493,6 +2514,28 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
     }
   }
 
+  /// Launch the share interface for the current selection,
+  /// as in the "Share" edit menu button on iOS.
+  ///
+  /// Currently this is only implemented for iOS.
+  ///
+  /// When 'obscureText' is true or the selection is empty,
+  /// this function will not do anything
+  Future<void> shareSelection(SelectionChangedCause cause) async {
+    assert(!widget.obscureText);
+    if (widget.obscureText) {
+      return;
+    }
+
+    final String text = textEditingValue.selection.textInside(textEditingValue.text);
+    if (text.isNotEmpty) {
+      await SystemChannels.platform.invokeMethod(
+        'Share.invoke',
+        text,
+      );
+    }
+  }
+
   void _startLiveTextInput(SelectionChangedCause cause) {
     if (!liveTextInputEnabled) {
       return;
@@ -2725,6 +2768,9 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
       onSearchWeb: searchWebEnabled
           ? () => searchWebForSelection(SelectionChangedCause.toolbar)
           : null,
+      onShare: shareEnabled
+          ? () => shareSelection(SelectionChangedCause.toolbar)
+          : null,
       onLiveTextInput: liveTextInputEnabled
           ? () => _startLiveTextInput(SelectionChangedCause.toolbar)
           : null,

packages/flutter/test/cupertino/adaptive_text_selection_toolbar_test.dart

@@ -177,6 +177,7 @@ void main() {
           onLiveTextInput: () {},
           onLookUp: () {},
           onSearchWeb: () {},
+          onShare: () {},
         ),
       ),
     ));
@@ -202,7 +203,7 @@ void main() {
       case TargetPlatform.macOS:
       case TargetPlatform.linux:
       case TargetPlatform.windows:
-        expect(find.byType(CupertinoDesktopTextSelectionToolbarButton), findsNWidgets(7));
+        expect(find.byType(CupertinoDesktopTextSelectionToolbarButton), findsNWidgets(8));
     }
   },
     skip: kIsWeb, // [intended] on web the browser handles the context menu.