MouseRegion class

A widget that tracks the movement of mice, even when no button is pressed.

It does not listen to events that can construct gestures, such as when the pointer is pressed, moved, then released or canceled. For these events, use Listener, or more preferably, GestureDetector.

Layout behavior

See BoxConstraints for an introduction to box layout models.

If it has a child, this widget defers to the child for sizing behavior. If it does not have a child, it grows to fit the parent instead.

This example makes a Container react to being entered by a mouse pointer, showing a count of the number of entries and exits.

import 'package:flutter/widgets.dart';

// ...

int _enterCounter = 0;
int _exitCounter = 0;
double x = 0.0;
double y = 0.0;

void _incrementEnter(PointerEvent details) {
  setState(() {
    _enterCounter++;
  });
}
void _incrementExit(PointerEvent details) {
  setState(() {
    _exitCounter++;
  });
}
void _updateLocation(PointerEvent details) {
  setState(() {
    x = details.position.dx;
    y = details.position.dy;
  });
}

@override
Widget build(BuildContext context) {
  return ConstrainedBox(
    constraints: new BoxConstraints.tight(Size(300.0, 200.0)),
    child: MouseRegion(
      onEnter: _incrementEnter,
      onHover: _updateLocation,
      onExit: _incrementExit,
      child: Container(
        color: Colors.lightBlueAccent,
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text('You have entered or exited this box this many times:'),
            Text(
              '$_enterCounter Entries\n$_exitCounter Exits',
              style: Theme.of(context).textTheme.display1,
            ),
            Text(
              'The cursor is here: (${x.toStringAsFixed(2)}, ${y.toStringAsFixed(2)})',
            ),
          ],
        ),
      ),
    ),
  );
}

To create a sample project with this code snippet, run:
flutter create --sample=widgets.MouseRegion.1 mysample

// Flutter code sample for MouseRegion

// This example makes a [Container] react to being entered by a mouse
// pointer, showing a count of the number of entries and exits.

import 'package:flutter/material.dart';

import 'package:flutter/widgets.dart';

void main() => runApp(MyApp());

/// This Widget is the main application widget.
class MyApp extends StatelessWidget {
  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: _title,
      home: Scaffold(
        appBar: AppBar(title: const Text(_title)),
        body: Center(
          child: MyStatefulWidget(),
        ),
      ),
    );
  }
}

class MyStatefulWidget extends StatefulWidget {
  MyStatefulWidget({Key key}) : super(key: key);

  @override
  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
}

class _MyStatefulWidgetState extends State<MyStatefulWidget> {
  int _enterCounter = 0;
  int _exitCounter = 0;
  double x = 0.0;
  double y = 0.0;

  void _incrementEnter(PointerEvent details) {
    setState(() {
      _enterCounter++;
    });
  }

  void _incrementExit(PointerEvent details) {
    setState(() {
      _exitCounter++;
    });
  }

  void _updateLocation(PointerEvent details) {
    setState(() {
      x = details.position.dx;
      y = details.position.dy;
    });
  }

  @override
  Widget build(BuildContext context) {
    return ConstrainedBox(
      constraints: BoxConstraints.tight(Size(300.0, 200.0)),
      child: MouseRegion(
        onEnter: _incrementEnter,
        onHover: _updateLocation,
        onExit: _incrementExit,
        child: Container(
          color: Colors.lightBlueAccent,
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              Text('You have entered or exited this box this many times:'),
              Text(
                '$_enterCounter Entries\n$_exitCounter Exits',
                style: Theme.of(context).textTheme.display1,
              ),
              Text(
                'The cursor is here: (${x.toStringAsFixed(2)}, ${y.toStringAsFixed(2)})',
              ),
            ],
          ),
        ),
      ),
    );
  }
}

Constructors

MouseRegion({Key key, PointerEnterEventListener onEnter, PointerExitEventListener onExit, PointerHoverEventListener onHover, bool opaque: true, Widget child}): Creates a widget that forwards mouse events to callbacks.
const

Properties

onEnter → PointerEnterEventListener: Called when a mouse pointer (with or without buttons pressed) enters the region defined by this widget, or when the widget appears under the pointer.
final
onExit → PointerExitEventListener: Called when a mouse pointer (with or without buttons pressed) leaves the region defined by this widget, or when the widget disappears from under the pointer.
final
onHover → PointerHoverEventListener: Called when a mouse pointer (with or without buttons pressed) changes position, and the new position is within the region defined by this widget.
final
opaque → bool: Whether this widget should prevent other MouseRegions visually behind it from detecting the pointer, thus affecting how their onHover, onEnter, and onExit behave. [...]
final
child → Widget: The widget below this widget in the tree. [...]
final, inherited
hashCode → int: The hash code for this object. [...]
read-only, inherited
key → Key: Controls how one widget replaces another widget in the tree. [...]
final, inherited
runtimeType → Type: A representation of the runtime type of the object.
read-only, inherited

Methods

createElement() → _MouseRegionElement: RenderObjectWidgets always inflate to a RenderObjectElement subclass.
override
createRenderObject(BuildContext context) → RenderMouseRegion: Creates an instance of the RenderObject class that this RenderObjectWidget represents, using the configuration described by this RenderObjectWidget. [...]
override
debugFillProperties(DiagnosticPropertiesBuilder properties) → void: Add additional properties associated with the node. [...]
override
updateRenderObject(BuildContext context, covariant RenderMouseRegion renderObject) → void: Copies the configuration described by this RenderObjectWidget to the given RenderObject, which will be of the same type as returned by this object's createRenderObject. [...]
override
debugDescribeChildren() → List<DiagnosticsNode>: Returns a list of DiagnosticsNode objects describing this node's children.
@protected, inherited
didUnmountRenderObject(covariant RenderObject renderObject) → void: A render object previously associated with this widget has been removed from the tree. The given RenderObject will be of the same type as returned by this object's createRenderObject.
@protected, inherited
noSuchMethod(Invocation invocation) → dynamic: Invoked when a non-existent method or property is accessed. [...]
inherited
toDiagnosticsNode({String name, DiagnosticsTreeStyle style}) → DiagnosticsNode: Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.
inherited
toString({DiagnosticLevel minLevel: DiagnosticLevel.debug}) → String: Returns a string representation of this object.
inherited
toStringDeep({String prefixLineOne: '', String prefixOtherLines, DiagnosticLevel minLevel: DiagnosticLevel.debug}) → String: Returns a string representation of this node and its descendants.
inherited
toStringShallow({String joiner: ', ', DiagnosticLevel minLevel: DiagnosticLevel.debug}) → String: Returns a one-line detailed description of the object.
inherited
toStringShort() → String: A short, textual description of this widget.
inherited

Operators

operator ==(dynamic other) → bool: The equality operator. [...]
inherited