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// Copyright 2015 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 'dart:ui' as ui;
import 'package:flutter/foundation.dart';
import 'basic.dart';
import 'framework.dart';
/// Whether in portrait or landscape.
enum Orientation {
/// Taller than wide.
portrait,
/// Wider than tall.
landscape
}
/// Information about a piece of media (e.g., a window).
///
/// For example, the [MediaQueryData.size] property contains the width and
/// height of the current window.
///
/// To obtain the current [MediaQueryData] for a given [BuildContext], use the
/// [MediaQuery.of] function. For example, to obtain the size of the current
/// window, use `MediaQuery.of(context).size`.
///
/// If no [MediaQuery] is in scope then the [MediaQuery.of] method will throw an
/// exception, unless the `nullOk` argument is set to true, in which case it
/// returns null.
@immutable
class MediaQueryData {
/// Creates data for a media query with explicit values.
///
/// Consider using [MediaQueryData.fromWindow] to create data based on a
/// [Window].
const MediaQueryData({
this.size: Size.zero,
this.devicePixelRatio: 1.0,
this.textScaleFactor: 1.0,
this.padding: EdgeInsets.zero,
this.viewInsets: EdgeInsets.zero,
this.alwaysUse24HourFormat: false,
});
/// Creates data for a media query based on the given window.
///
/// If you use this, you should ensure that you also register for
/// notifications so that you can update your [MediaQueryData] when the
/// window's metrics change. For example, see
/// [WidgetsBindingObserver.didChangeMetrics] or [Window.onMetricsChanged].
MediaQueryData.fromWindow(ui.Window window)
: size = window.physicalSize / window.devicePixelRatio,
devicePixelRatio = window.devicePixelRatio,
textScaleFactor = window.textScaleFactor,
padding = new EdgeInsets.fromWindowPadding(window.padding, window.devicePixelRatio),
viewInsets = new EdgeInsets.fromWindowPadding(window.viewInsets, window.devicePixelRatio),
alwaysUse24HourFormat = window.alwaysUse24HourFormat;
/// The size of the media in logical pixel (e.g, the size of the screen).
///
/// Logical pixels are roughly the same visual size across devices. Physical
/// pixels are the size of the actual hardware pixels on the device. The
/// number of physical pixels per logical pixel is described by the
/// [devicePixelRatio].
final Size size;
/// The number of device pixels for each logical pixel. This number might not
/// be a power of two. Indeed, it might not even be an integer. For example,
/// the Nexus 6 has a device pixel ratio of 3.5.
final double devicePixelRatio;
/// The number of font pixels for each logical pixel.
///
/// For example, if the text scale factor is 1.5, text will be 50% larger than
/// the specified font size.
final double textScaleFactor;
/// The number of physical pixels on each side of the display rectangle into
/// which the application can render, but over which the operating system
/// will likely place system UI, such as the keyboard, that fully obscures
/// any content.
final EdgeInsets viewInsets;
/// The number of physical pixels on each side of the display rectangle into
/// which the application can render, but which may be partially obscured by
/// system UI (such as the system notification area), or or physical
/// intrusions in the display (e.g. overscan regions on television screens or
/// phone sensor housings).
final EdgeInsets padding;
/// Whether to use 24-hour format when formatting time.
///
/// The behavior of this flag is different across platforms:
///
/// - On Android this flag is reported directly from the user settings called
/// "Use 24-hour format". It applies to any locale used by the application,
/// whether it is the system-wide locale, or the custom locale set by the
/// application.
/// - On iOS this flag is set to true when the user setting called "24-Hour
/// Time" is set or the system-wide locale's default uses 24-hour
/// formatting.
final bool alwaysUse24HourFormat;
/// The orientation of the media (e.g., whether the device is in landscape or portrait mode).
Orientation get orientation {
return size.width > size.height ? Orientation.landscape : Orientation.portrait;
}
/// Creates a copy of this media query data but with the given fields replaced
/// with the new values.
MediaQueryData copyWith({
Size size,
double devicePixelRatio,
double textScaleFactor,
EdgeInsets padding,
EdgeInsets viewInsets,
}) {
return new MediaQueryData(
size: size ?? this.size,
devicePixelRatio: devicePixelRatio ?? this.devicePixelRatio,
textScaleFactor: textScaleFactor ?? this.textScaleFactor,
padding: padding ?? this.padding,
viewInsets: viewInsets ?? this.viewInsets,
);
}
/// Creates a copy of this media query data but with the given paddings
/// replaced with zero.
///
/// The `removeLeft`, `removeTop`, `removeRight`, and `removeBottom` arguments
/// must not be null. If all four are false (the default) then this
/// [MediaQueryData] is returned unmodified.
///
/// See also:
///
/// * [new MediaQuery.removePadding], which uses this method to remove padding
/// from the ambient [MediaQuery].
/// * [SafeArea], which both removes the padding from the [MediaQuery] and
/// adds a [Padding] widget.
MediaQueryData removePadding({
bool removeLeft: false,
bool removeTop: false,
bool removeRight: false,
bool removeBottom: false,
}) {
if (!(removeLeft || removeTop || removeRight || removeBottom))
return this;
return new MediaQueryData(
size: size,
devicePixelRatio: devicePixelRatio,
textScaleFactor: textScaleFactor,
padding: padding.copyWith(
left: removeLeft ? 0.0 : null,
top: removeTop ? 0.0 : null,
right: removeRight ? 0.0 : null,
bottom: removeBottom ? 0.0 : null,
),
viewInsets: viewInsets.copyWith(
left: removeLeft ? 0.0 : null,
top: removeTop ? 0.0 : null,
right: removeRight ? 0.0 : null,
bottom: removeBottom ? 0.0 : null,
),
);
}
@override
bool operator ==(Object other) {
if (other.runtimeType != runtimeType)
return false;
final MediaQueryData typedOther = other;
return typedOther.size == size
&& typedOther.devicePixelRatio == devicePixelRatio
&& typedOther.textScaleFactor == textScaleFactor
&& typedOther.padding == padding
&& typedOther.viewInsets == viewInsets;
}
@override
int get hashCode => hashValues(size, devicePixelRatio, textScaleFactor, padding, viewInsets);
@override
String toString() {
return '$runtimeType(size: $size, devicePixelRatio: $devicePixelRatio, '
'textScaleFactor: $textScaleFactor, padding: $padding, viewInsets: $viewInsets)';
}
}
/// Establishes a subtree in which media queries resolve to the given data.
///
/// For example, to learn the size of the current media (e.g., the window
/// containing your app), you can read the [MediaQueryData.size] property from
/// the [MediaQueryData] returned by [MediaQuery.of]:
/// `MediaQuery.of(context).size`.
///
/// Querying the current media using [MediaQuery.of] will cause your widget to
/// rebuild automatically whenever the [MediaQueryData] changes (e.g., if the
/// user rotates their device).
///
/// If no [MediaQuery] is in scope then the [MediaQuery.of] method will throw an
/// exception, unless the `nullOk` argument is set to true, in which case it
/// returns null.
///
/// See also:
///
/// * [WidgetsApp] and [MaterialApp], which introduce a [MediaQuery] and keep
/// it up to date with the current screen metrics as they change.
/// * [MediaQueryData], the data structure that represents the metrics.
class MediaQuery extends InheritedWidget {
/// Creates a widget that provides [MediaQueryData] to its descendants.
///
/// The [data] and [child] arguments must not be null.
const MediaQuery({
Key key,
@required this.data,
@required Widget child,
}) : assert(child != null),
assert(data != null),
super(key: key, child: child);
/// Creates a new [MediaQuery] that inherits from the ambient [MediaQuery] from
/// the given context, but removes the specified paddings.
///
/// The [context] argument is required, must not be null, and must have a
/// [MediaQuery] in scope.
///
/// The `removeLeft`, `removeTop`, `removeRight`, and `removeBottom` arguments
/// must not be null. If all four are false (the default) then the returned
/// [MediaQuery] reuses the ambient [MediaQueryData] unmodified, which is not
/// particularly useful.
///
/// The [child] argument is required and must not be null.
///
/// See also:
///
/// * [SafeArea], which both removes the padding from the [MediaQuery] and
/// adds a [Padding] widget.
factory MediaQuery.removePadding({
Key key,
@required BuildContext context,
bool removeLeft: false,
bool removeTop: false,
bool removeRight: false,
bool removeBottom: false,
@required Widget child,
}) {
return new MediaQuery(
key: key,
data: MediaQuery.of(context).removePadding(
removeLeft: removeLeft,
removeTop: removeTop,
removeRight: removeRight,
removeBottom: removeBottom,
),
child: child,
);
}
/// Contains information about the current media.
///
/// For example, the [MediaQueryData.size] property contains the width and
/// height of the current window.
final MediaQueryData data;
/// The data from the closest instance of this class that encloses the given
/// context.
///
/// You can use this function to query the size an orientation of the screen.
/// When that information changes, your widget will be scheduled to be rebuilt,
/// keeping your widget up-to-date.
///
/// Typical usage is as follows:
///
/// ```dart
/// MediaQueryData media = MediaQuery.of(context);
/// ```
///
/// If there is no [MediaQuery] in scope, then this will throw an exception.
/// To return null if there is no [MediaQuery], then pass `nullOk: true`.
///
/// If you use this from a widget (e.g. in its build function), consider
/// calling [debugCheckHasMediaQuery].
static MediaQueryData of(BuildContext context, { bool nullOk: false }) {
assert(context != null);
assert(nullOk != null);
final MediaQuery query = context.inheritFromWidgetOfExactType(MediaQuery);
if (query != null)
return query.data;
if (nullOk)
return null;
throw new FlutterError(
'MediaQuery.of() called with a context that does not contain a MediaQuery.\n'
'No MediaQuery ancestor could be found starting from the context that was passed '
'to MediaQuery.of(). This can happen because you do not have a WidgetsApp or '
'MaterialApp widget (those widgets introduce a MediaQuery), or it can happen '
'if the context you use comes from a widget above those widgets.\n'
'The context used was:\n'
' $context'
);
}
@override
bool updateShouldNotify(MediaQuery old) => data != old.data;
@override
void debugFillProperties(DiagnosticPropertiesBuilder description) {
super.debugFillProperties(description);
description.add(new DiagnosticsProperty<MediaQueryData>('data', data, showName: false));
}
}