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// 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 '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 OrientationWidgetBuilder = Widget Function(BuildContext context, Orientation orientation);
/// Builds a widget tree that can depend on the parent widget's orientation
/// (distinct from the device 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.
/// * [MediaQueryData.orientation], which exposes whether the device is in
/// landscape or portrait mode.
class OrientationBuilder extends StatelessWidget {
/// Creates an orientation builder.
///
/// The [builder] argument must not be null.
const OrientationBuilder({
Key key,
@required this.builder,
}) : assert(builder != null),
super(key: key);
/// Builds the widgets below this widget given this widget's orientation.
///
/// A widget's orientation is simply a factor of its width relative to its
/// height. For example, a [Column] widget will have a landscape orientation
/// if its width exceeds its height, even though it displays its children in
/// a vertical array.
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 vertically then horizontally.
final Orientation orientation = constraints.maxWidth > constraints.maxHeight ? Orientation.landscape : Orientation.portrait;
return builder(context, orientation);
}
@override
Widget build(BuildContext context) {
return LayoutBuilder(builder: _buildWithConstraints);
}
}