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// Copyright 2016 The Chromium 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/foundation.dart';
import 'basic.dart';
import 'framework.dart';
import 'layout_builder.dart';
import 'media_query.dart';
/// Signature for a function that builds a widget given an [Orientation].
///
/// Used by [OrientationBuilder.builder].
typedef Widget OrientationWidgetBuilder(BuildContext context, Orientation orientation);
/// Builds a widget tree that can depend on the parent widget's orientation.
///
/// See also:
///
/// * [LayoutBuilder], which exposes the complete constraints, not just the
/// orientation.
/// * [CustomSingleChildLayout], which positions its child during layout.
/// * [CustomMultiChildLayout], with which you can define the precise layout
/// of a list of children during the layout phase.
class OrientationBuilder extends StatelessWidget {
/// Creates an orientation builder.
///
/// The [builder] argument must not be null.
OrientationBuilder({
Key key,
@required this.builder,
}) : super(key: key) {
assert(builder != null);
}
/// Builds the widgets below this widget given this widget's orientation.
final OrientationWidgetBuilder builder;
Widget _buildWithConstraints(BuildContext context, BoxConstraints constraints) {
// If the constraints are fully unbounded (i.e., maxWidth and maxHeight are
// both infinite), we prefer Orientation.portrait because its more common to
// scroll vertially than horizontally.
final Orientation orientation = constraints.maxWidth > constraints.maxHeight ? Orientation.landscape : Orientation.portrait;
return builder(context, orientation);
}
@override
Widget build(BuildContext context) {
return new LayoutBuilder(builder: _buildWithConstraints);
}
}