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