desktop_text_selection.dart

// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:flutter/gestures.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/widgets.dart';

import 'button.dart';
import 'colors.dart';
import 'localizations.dart';
import 'theme.dart';

// Minimal padding from all edges of the selection toolbar to all edges of the
// screen.
const double _kToolbarScreenPadding = 8.0;

// These values were measured from a screenshot of TextEdit on MacOS 10.15.7 on
// a Macbook Pro.
const double _kToolbarWidth = 222.0;
const Radius _kToolbarBorderRadius = Radius.circular(4.0);

// These values were measured from a screenshot of TextEdit on MacOS 10.16 on a
// Macbook Pro.
const CupertinoDynamicColor _kToolbarBorderColor = CupertinoDynamicColor.withBrightness(
  color: Color(0xFFBBBBBB),
  darkColor: Color(0xFF505152),
);
const CupertinoDynamicColor _kToolbarBackgroundColor = CupertinoDynamicColor.withBrightness(
  color: Color(0xffECE8E6),
  darkColor: Color(0xff302928),
);


class _CupertinoDesktopTextSelectionControls extends TextSelectionControls {
  /// Desktop has no text selection handles.
  @override
  Size getHandleSize(double textLineHeight) {
    return Size.zero;
  }

  /// Builder for the Mac-style copy/paste text selection toolbar.
  @override
  Widget buildToolbar(
    BuildContext context,
    Rect globalEditableRegion,
    double textLineHeight,
    Offset selectionMidpoint,
    List<TextSelectionPoint> endpoints,
    TextSelectionDelegate delegate,
    ClipboardStatusNotifier clipboardStatus,
    Offset? lastSecondaryTapDownPosition,
  ) {
    return _CupertinoDesktopTextSelectionControlsToolbar(
      clipboardStatus: clipboardStatus,
      endpoints: endpoints,
      globalEditableRegion: globalEditableRegion,
      handleCut: canCut(delegate) ? () => handleCut(delegate) : null,
      handleCopy: canCopy(delegate) ? () => handleCopy(delegate, clipboardStatus) : null,
      handlePaste: canPaste(delegate) ? () => handlePaste(delegate) : null,
      handleSelectAll: canSelectAll(delegate) ? () => handleSelectAll(delegate) : null,
      selectionMidpoint: selectionMidpoint,
      lastSecondaryTapDownPosition: lastSecondaryTapDownPosition,
      textLineHeight: textLineHeight,
    );
  }

  /// Builds the text selection handles, but desktop has none.
  @override
  Widget buildHandle(BuildContext context, TextSelectionHandleType type, double textLineHeight) {
    return const SizedBox.shrink();
  }

  /// Gets the position for the text selection handles, but desktop has none.
  @override
  Offset getHandleAnchor(TextSelectionHandleType type, double textLineHeight) {
    return Offset.zero;
  }
}

/// Text selection controls that follows Mac design conventions.
final TextSelectionControls cupertinoDesktopTextSelectionControls =
    _CupertinoDesktopTextSelectionControls();

// Generates the child that's passed into CupertinoDesktopTextSelectionToolbar.
class _CupertinoDesktopTextSelectionControlsToolbar extends StatefulWidget {
  const _CupertinoDesktopTextSelectionControlsToolbar({
    Key? key,
    required this.clipboardStatus,
    required this.endpoints,
    required this.globalEditableRegion,
    required this.handleCopy,
    required this.handleCut,
    required this.handlePaste,
    required this.handleSelectAll,
    required this.selectionMidpoint,
    required this.textLineHeight,
    required this.lastSecondaryTapDownPosition,
  }) : super(key: key);

  final ClipboardStatusNotifier? clipboardStatus;
  final List<TextSelectionPoint> endpoints;
  final Rect globalEditableRegion;
  final VoidCallback? handleCopy;
  final VoidCallback? handleCut;
  final VoidCallback? handlePaste;
  final VoidCallback? handleSelectAll;
  final Offset? lastSecondaryTapDownPosition;
  final Offset selectionMidpoint;
  final double textLineHeight;

  @override
  _CupertinoDesktopTextSelectionControlsToolbarState createState() => _CupertinoDesktopTextSelectionControlsToolbarState();
}

class _CupertinoDesktopTextSelectionControlsToolbarState extends State<_CupertinoDesktopTextSelectionControlsToolbar> {
  ClipboardStatusNotifier? _clipboardStatus;

  void _onChangedClipboardStatus() {
    setState(() {
      // Inform the widget that the value of clipboardStatus has changed.
    });
  }

  @override
  void initState() {
    super.initState();
    if (widget.handlePaste != null) {
      _clipboardStatus = widget.clipboardStatus ?? ClipboardStatusNotifier();
      _clipboardStatus!.addListener(_onChangedClipboardStatus);
      _clipboardStatus!.update();
    }
  }

  @override
  void didUpdateWidget(_CupertinoDesktopTextSelectionControlsToolbar oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (oldWidget.clipboardStatus != widget.clipboardStatus) {
      if (_clipboardStatus != null) {
        _clipboardStatus!.removeListener(_onChangedClipboardStatus);
        _clipboardStatus!.dispose();
      }
      _clipboardStatus = widget.clipboardStatus ?? ClipboardStatusNotifier();
      _clipboardStatus!.addListener(_onChangedClipboardStatus);
      if (widget.handlePaste != null) {
        _clipboardStatus!.update();
      }
    }
  }

  @override
  void dispose() {
    super.dispose();
    // When used in an Overlay, this can be disposed after its creator has
    // already disposed _clipboardStatus.
    if (_clipboardStatus != null && !_clipboardStatus!.disposed) {
      _clipboardStatus!.removeListener(_onChangedClipboardStatus);
      if (widget.clipboardStatus == null) {
        _clipboardStatus!.dispose();
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    // Don't render the menu until the state of the clipboard is known.
    if (widget.handlePaste != null && _clipboardStatus!.value == ClipboardStatus.unknown) {
      return const SizedBox(width: 0.0, height: 0.0);
    }

    assert(debugCheckHasMediaQuery(context));
    final MediaQueryData mediaQuery = MediaQuery.of(context);

    final Offset midpointAnchor = Offset(
      (widget.selectionMidpoint.dx - widget.globalEditableRegion.left).clamp(
        mediaQuery.padding.left,
        mediaQuery.size.width - mediaQuery.padding.right,
      ),
      widget.selectionMidpoint.dy - widget.globalEditableRegion.top,
    );

    final List<Widget> items = <Widget>[];
    final CupertinoLocalizations localizations = CupertinoLocalizations.of(context);
    final Widget onePhysicalPixelVerticalDivider =
        SizedBox(width: 1.0 / MediaQuery.of(context).devicePixelRatio);

    void addToolbarButton(
      String text,
      VoidCallback onPressed,
    ) {
      if (items.isNotEmpty) {
        items.add(onePhysicalPixelVerticalDivider);
      }

      items.add(_CupertinoDesktopTextSelectionToolbarButton.text(
        context: context,
        onPressed: onPressed,
        text: text,
      ));
    }

    if (widget.handleCut != null) {
      addToolbarButton(localizations.cutButtonLabel, widget.handleCut!);
    }
    if (widget.handleCopy != null) {
      addToolbarButton(localizations.copyButtonLabel, widget.handleCopy!);
    }
    if (widget.handlePaste != null
        && _clipboardStatus!.value == ClipboardStatus.pasteable) {
      addToolbarButton(localizations.pasteButtonLabel, widget.handlePaste!);
    }
    if (widget.handleSelectAll != null) {
      addToolbarButton(localizations.selectAllButtonLabel, widget.handleSelectAll!);
    }

    // If there is no option available, build an empty widget.
    if (items.isEmpty) {
      return const SizedBox(width: 0.0, height: 0.0);
    }

    return _CupertinoDesktopTextSelectionToolbar(
      anchor: widget.lastSecondaryTapDownPosition ?? midpointAnchor,
      children: items,
    );
  }
}

/// A Mac-style text selection toolbar.
///
/// Typically displays buttons for text manipulation, e.g. copying and pasting
/// text.
///
/// Tries to position itself as closesly as possible to [anchor] while remaining
/// fully on-screen.
///
/// See also:
///
///  * [TextSelectionControls.buildToolbar], where this is used by default to
///    build a Mac-style toolbar.
///  * [TextSelectionToolbar], which is similar, but builds an Android-style
///    toolbar.
class _CupertinoDesktopTextSelectionToolbar extends StatelessWidget {
  /// Creates an instance of CupertinoTextSelectionToolbar.
  const _CupertinoDesktopTextSelectionToolbar({
    Key? key,
    required this.anchor,
    required this.children,
    this.toolbarBuilder = _defaultToolbarBuilder,
  }) : assert(children.length > 0),
       super(key: key);

  /// The point at which the toolbar will attempt to position itself as closely
  /// as possible.
  final Offset anchor;

  /// {@macro flutter.material.TextSelectionToolbar.children}
  ///
  /// See also:
  ///   * [CupertinoDesktopTextSelectionToolbarButton], which builds a default
  ///     Mac-style text selection toolbar text button.
  final List<Widget> children;

  /// {@macro flutter.material.TextSelectionToolbar.toolbarBuilder}
  ///
  /// The given anchor and isAbove can be used to position an arrow, as in the
  /// default Cupertino toolbar.
  final ToolbarBuilder toolbarBuilder;

  // Builds a toolbar just like the default Mac toolbar, with the right color
  // background, padding, and rounded corners.
  static Widget _defaultToolbarBuilder(BuildContext context, Widget child) {
    return Container(
      width: _kToolbarWidth,
      decoration: BoxDecoration(
        color: _kToolbarBackgroundColor.resolveFrom(context),
        border: Border.all(
          color: _kToolbarBorderColor.resolveFrom(context),
        ),
        borderRadius: const BorderRadius.all(_kToolbarBorderRadius),
      ),
      child: Padding(
        padding: const EdgeInsets.symmetric(
          horizontal: 0.0,
          // This value was measured from a screenshot of TextEdit on MacOS
          // 10.15.7 on a Macbook Pro.
          vertical: 3.0,
        ),
        child: child,
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    assert(debugCheckHasMediaQuery(context));
    final MediaQueryData mediaQuery = MediaQuery.of(context);

    final double paddingAbove = mediaQuery.padding.top + _kToolbarScreenPadding;
    final Offset localAdjustment = Offset(_kToolbarScreenPadding, paddingAbove);

    return Padding(
      padding: EdgeInsets.fromLTRB(
        _kToolbarScreenPadding,
        paddingAbove,
        _kToolbarScreenPadding,
        _kToolbarScreenPadding,
      ),
      child: CustomSingleChildLayout(
        delegate: DesktopTextSelectionToolbarLayoutDelegate(
          anchor: anchor - localAdjustment,
        ),
        child: toolbarBuilder(context, Column(
          mainAxisSize: MainAxisSize.min,
          children: children,
        )),
      ),
    );
  }
}

// These values were measured from a screenshot of TextEdit on MacOS 10.15.7 on
// a Macbook Pro.
const TextStyle _kToolbarButtonFontStyle = TextStyle(
  inherit: false,
  fontSize: 14.0,
  letterSpacing: -0.15,
  fontWeight: FontWeight.w400,
);

// This value was measured from a screenshot of TextEdit on MacOS 10.15.7 on a
// Macbook Pro.
const EdgeInsets _kToolbarButtonPadding = EdgeInsets.fromLTRB(
  20.0,
  0.0,
  20.0,
  3.0,
);

/// A button in the style of the Mac context menu buttons.
class _CupertinoDesktopTextSelectionToolbarButton extends StatefulWidget {
  /// Creates an instance of CupertinoDesktopTextSelectionToolbarButton.
  const _CupertinoDesktopTextSelectionToolbarButton({
    Key? key,
    required this.onPressed,
    required this.child,
  }) : super(key: key);

  /// Create an instance of [CupertinoDesktopTextSelectionToolbarButton] whose child is
  /// a [Text] widget styled like the default Mac context menu button.
  _CupertinoDesktopTextSelectionToolbarButton.text({
    Key? key,
    required BuildContext context,
    required this.onPressed,
    required String text,
  }) : child = Text(
         text,
         overflow: TextOverflow.ellipsis,
         style: _kToolbarButtonFontStyle.copyWith(
           color: const CupertinoDynamicColor.withBrightness(
             color: CupertinoColors.black,
             darkColor: CupertinoColors.white,
           ).resolveFrom(context),
         ),
       ),
       super(key: key);

  /// {@macro flutter.cupertino.CupertinoTextSelectionToolbarButton.onPressed}
  final VoidCallback onPressed;

  /// {@macro flutter.cupertino.CupertinoTextSelectionToolbarButton.child}
  final Widget child;

  @override
  _CupertinoDesktopTextSelectionToolbarButtonState createState() => _CupertinoDesktopTextSelectionToolbarButtonState();
}

class _CupertinoDesktopTextSelectionToolbarButtonState extends State<_CupertinoDesktopTextSelectionToolbarButton> {
  bool _isHovered = false;

  void _onEnter(PointerEnterEvent event) {
    setState(() {
      _isHovered = true;
    });
  }

  void _onExit(PointerExitEvent event) {
    setState(() {
      _isHovered = false;
    });
  }

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      width: double.infinity,
      child: MouseRegion(
        onEnter: _onEnter,
        onExit: _onExit,
        child: CupertinoButton(
          alignment: Alignment.centerLeft,
          borderRadius: null,
          color: _isHovered ? CupertinoTheme.of(context).primaryColor : null,
          minSize: 0.0,
          onPressed: widget.onPressed,
          padding: _kToolbarButtonPadding,
          pressedOpacity: 0.7,
          child: widget.child,
        ),
      ),
    );
  }
}