MediaQueryData.fromView constructor
- FlutterView view, {
- MediaQueryData? platformData,
Creates data for a MediaQuery based on the given view.
If provided, the platformData is used to fill in the platform-specific
aspects of the newly created MediaQueryData. If platformData is null,
the view's PlatformDispatcher is consulted to construct the
platform-specific data.
Data which is exposed directly on the FlutterView is considered view-specific. Data which is only exposed via the FlutterView.platformDispatcher property is considered platform-specific.
Callers of this method should ensure that they also register for notifications so that the MediaQueryData can be updated when any data used to construct it changes. Notifications to consider are:
- WidgetsBindingObserver.didChangeMetrics or dart:ui.PlatformDispatcher.onMetricsChanged,
- WidgetsBindingObserver.didChangeAccessibilityFeatures or dart:ui.PlatformDispatcher.onAccessibilityFeaturesChanged,
- WidgetsBindingObserver.didChangeTextScaleFactor or dart:ui.PlatformDispatcher.onTextScaleFactorChanged,
- WidgetsBindingObserver.didChangePlatformBrightness or dart:ui.PlatformDispatcher.onPlatformBrightnessChanged.
The last three notifications are only relevant if no platformData is
provided. If platformData is provided, callers should ensure to call
this method again when it changes to keep the constructed MediaQueryData
updated.
In general, MediaQuery.of, and its associated "...Of" methods, are the
appropriate way to obtain MediaQueryData from a widget. This fromView
constructor is primarily for use in the implementation of the framework
itself.
See also:
- MediaQuery.fromView, which constructs MediaQueryData from a provided FlutterView, makes it available to descendant widgets, and sets up the appropriate notification listeners to keep the data updated.
Implementation
MediaQueryData.fromView(ui.FlutterView view, {MediaQueryData? platformData})
: size = view.physicalSize / view.devicePixelRatio,
devicePixelRatio = view.devicePixelRatio,
_textScaleFactor = 1.0, // _textScaler is the source of truth.
_textScaler = _textScalerFromView(view, platformData),
platformBrightness = platformData?.platformBrightness ?? view.platformDispatcher.platformBrightness,
padding = EdgeInsets.fromViewPadding(view.padding, view.devicePixelRatio),
viewPadding = EdgeInsets.fromViewPadding(view.viewPadding, view.devicePixelRatio),
viewInsets = EdgeInsets.fromViewPadding(view.viewInsets, view.devicePixelRatio),
systemGestureInsets = EdgeInsets.fromViewPadding(view.systemGestureInsets, view.devicePixelRatio),
accessibleNavigation = platformData?.accessibleNavigation ?? view.platformDispatcher.accessibilityFeatures.accessibleNavigation,
invertColors = platformData?.invertColors ?? view.platformDispatcher.accessibilityFeatures.invertColors,
disableAnimations = platformData?.disableAnimations ?? view.platformDispatcher.accessibilityFeatures.disableAnimations,
boldText = platformData?.boldText ?? view.platformDispatcher.accessibilityFeatures.boldText,
highContrast = platformData?.highContrast ?? view.platformDispatcher.accessibilityFeatures.highContrast,
onOffSwitchLabels = platformData?.onOffSwitchLabels ?? view.platformDispatcher.accessibilityFeatures.onOffSwitchLabels,
alwaysUse24HourFormat = platformData?.alwaysUse24HourFormat ?? view.platformDispatcher.alwaysUse24HourFormat,
navigationMode = platformData?.navigationMode ?? NavigationMode.traditional,
gestureSettings = DeviceGestureSettings.fromView(view),
displayFeatures = view.displayFeatures,
supportsShowingSystemContextMenu = platformData?.supportsShowingSystemContextMenu ?? view.platformDispatcher.supportsShowingSystemContextMenu;