MouseRegion class Null safety

A widget that tracks the movement of mice.

MouseRegion is used when it is needed to compare the list of objects that a mouse pointer is hovering over between this frame and the last frame. This means entering events, exiting events, and mouse cursors.

To listen to general pointer 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.

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

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.headline4,
            ),
            Text(
              'The cursor is here: (${x.toStringAsFixed(2)}, ${y.toStringAsFixed(2)})',
            ),
          ],
        ),
      ),
    ),
  );
}

Constructors

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

Properties

child → Widget?: The widget below this widget in the tree. [...]
final
cursor → MouseCursor: The mouse cursor for mouse pointers that are hovering over the region. [...]
final
hashCode → int: The hash code for this object. [...]
@nonVirtual, read-only, inherited
key → Key?: Controls how one widget replaces another widget in the tree. [...]
final, inherited
onEnter → PointerEnterEventListener?: Triggered when a mouse pointer has entered this widget. [...]
final
onExit → PointerExitEventListener?: Triggered when a mouse pointer has exited this widget when the widget is still mounted. [...]
final
onHover → PointerHoverEventListener?: Triggered when a pointer moves into a position within this widget without buttons pressed. [...]
final
opaque → bool: Whether this widget should prevent other MouseRegions visually behind it from detecting the pointer. [...]
final
runtimeType → Type: A representation of the runtime type of the object.
read-only, inherited

Methods

createElement() → StatefulElement: Creates a StatefulElement to manage this widget's location in the tree. [...]
inherited
createState() → _MouseRegionState: Creates the mutable state for this widget at a given location in the tree. [...]
override
debugDescribeChildren() → List<DiagnosticsNode>: Returns a list of DiagnosticsNode objects describing this node's children. [...]
@protected, inherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void: Add additional properties associated with the node. [...]
override
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.info}) → String: 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 ==(Object other) → bool: The equality operator. [...]
@nonVirtual, inherited