1// Copyright 2014 The Flutter Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5/// @docImport 'package:flutter/cupertino.dart';
6/// @docImport 'package:flutter/material.dart';
7///
8/// @docImport 'text_selection_toolbar_layout_delegate.dart';
9library;
10
11import 'package:flutter/rendering.dart';
12
13/// Positions the toolbar at [anchor] if it fits, otherwise moves it so that it
14/// just fits fully on-screen.
15///
16/// See also:
17///
18/// * [desktopTextSelectionControls], which uses this to position
19/// itself.
20/// * [cupertinoDesktopTextSelectionControls], which uses this to position
21/// itself.
22/// * [TextSelectionToolbarLayoutDelegate], which does a similar layout for
23/// the mobile text selection toolbars.
24class DesktopTextSelectionToolbarLayoutDelegate extends SingleChildLayoutDelegate {
25 /// Creates an instance of TextSelectionToolbarLayoutDelegate.
26 DesktopTextSelectionToolbarLayoutDelegate({required this.anchor});
27
28 /// The point at which to render the menu, if possible.
29 ///
30 /// Should be provided in local coordinates.
31 final Offset anchor;
32
33 @override
34 BoxConstraints getConstraintsForChild(BoxConstraints constraints) {
35 return constraints.loosen();
36 }
37
38 @override
39 Offset getPositionForChild(Size size, Size childSize) {
40 final Offset overhang = Offset(
41 anchor.dx + childSize.width - size.width,
42 anchor.dy + childSize.height - size.height,
43 );
44 return Offset(
45 overhang.dx > 0.0 ? anchor.dx - overhang.dx : anchor.dx,
46 overhang.dy > 0.0 ? anchor.dy - overhang.dy : anchor.dy,
47 );
48 }
49
50 @override
51 bool shouldRelayout(DesktopTextSelectionToolbarLayoutDelegate oldDelegate) {
52 return anchor != oldDelegate.anchor;
53 }
54}
55