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我实现了一个自定义文本选择控件，在高亮显示的文本上的默认复制/粘贴/selectAll旁边添加一个打开Map按钮，如下所示：

class MapTextSelectionControls extends MaterialTextSelectionControls {
  // Padding between the toolbar and the anchor.
  static const double _toolbarContentDistanceBelow = 20.0;
  static const double _toolbarContentDistance = 8.0;

  MapTextSelectionControls();

  @override
  Widget buildToolbar(
      BuildContext context,
      Rect globalEditableRegion,
      double textLineHeight,
      Offset selectionMidpoint,
      List<TextSelectionPoint> endpoints,
      TextSelectionDelegate delegate,
      ClipboardStatusNotifier? clipboardStatus,
      Offset? lastSecondaryTapDownPosition,
      ) {
    //.. some code here

    return MapSelectionToolbar(
      anchorAbove: anchorAbove,
      anchorBelow: anchorBelow,
      clipboardStatus: clipboardStatus,
      handleCopy: canCopy(delegate)
          ? () => handleCopy(delegate, clipboardStatus)
          : null,
      handleMap: selectedText.isNotEmpty
          ? () {
        openLink(generateLocationLinkFromQuery(selectedText));
        delegate.hideToolbar();
      }
          : null,
      handleCut: canCut(delegate) ? () => handleCut(delegate) : null,
      handlePaste: canPaste(delegate) ? () => handlePaste(delegate) : null,
      handleSelectAll:
      canSelectAll(delegate) ? () => handleSelectAll(delegate) : null,
    );
  }
}

class MapSelectionToolbar extends StatefulWidget { ....

SelectableRegion(
        selectionControls: MapTextSelectionControls(),
        focusNode: _selectableRegionFocusNode, ....)

然而，Flutter警告说，我现在实现它的方式即将被弃用，但我无法找出或找到足够的资源来实现相同的结果。