GestureDetector class

A widget that detects gestures.

Attempts to recognize gestures that correspond to its non-null callbacks.

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

By default a GestureDetector with an invisible child ignores touches; this behavior can be controlled with behavior.

GestureDetector also listens for accessibility events and maps them to the callbacks. To ignore accessibility events, set excludeFromSemantics to true.

See flutter.dev/gestures/ for additional information.

Material design applications typically react to touches with ink splash effects. The InkWell class implements this effect and can be used in place of a GestureDetector for handling taps.

This example of a Container contains a black light bulb wrapped in a GestureDetector. It turns the light bulb yellow when the "turn lights on" button is tapped by setting the _lights field. Above animation shows the code in use:

Container(
  alignment: FractionalOffset.center,
  color: Colors.white,
  child: Column(
    mainAxisAlignment: MainAxisAlignment.center,
    children: <Widget>[
      Padding(
        padding: const EdgeInsets.all(8.0),
        child: Icon(
          Icons.lightbulb_outline,
          color: _lights ? Colors.yellow.shade600 : Colors.black,
          size: 60,
        ),
      ),
      GestureDetector(
        onTap: () {
          setState(() {
            _lights = true;
          });
        },
        child: Container(
          color: Colors.yellow.shade600,
          padding: const EdgeInsets.all(8),
          child: const Text('TURN LIGHTS ON'),
        ),
      ),
    ],
  ),
)

This example of a Container wraps a GestureDetector widget. Since the GestureDetector does not have a child it takes on the size of its parent making the entire area of the surrounding Container clickable. When tapped the Container turns yellow by setting the _color field:

Container(
  color: _color,
  height: 200.0,
  width: 200.0,
  child: GestureDetector(
    onTap: () {
      setState(() {
        _color = Colors.yellow;
      });
    },
  ),
)

Debugging

To see how large the hit test box of a GestureDetector is for debugging purposes, set debugPaintPointersEnabled to true.

Constructors

GestureDetector({Key key, Widget child, void onTapDown(TapDownDetails details), void onTapUp(TapUpDetails details), GestureTapCallback onTap, GestureTapCancelCallback onTapCancel, GestureTapCallback onSecondaryTap, void onSecondaryTapDown(TapDownDetails details), void onSecondaryTapUp(TapUpDetails details), GestureTapCancelCallback onSecondaryTapCancel, void onTertiaryTapDown(TapDownDetails details), void onTertiaryTapUp(TapUpDetails details), GestureTapCancelCallback onTertiaryTapCancel, void onDoubleTapDown(TapDownDetails details), GestureTapCallback onDoubleTap, GestureTapCancelCallback onDoubleTapCancel, GestureLongPressCallback onLongPress, void onLongPressStart(LongPressStartDetails details), void onLongPressMoveUpdate(LongPressMoveUpdateDetails details), GestureLongPressUpCallback onLongPressUp, void onLongPressEnd(LongPressEndDetails details), GestureLongPressCallback onSecondaryLongPress, void onSecondaryLongPressStart(LongPressStartDetails details), void onSecondaryLongPressMoveUpdate(LongPressMoveUpdateDetails details), GestureLongPressUpCallback onSecondaryLongPressUp, void onSecondaryLongPressEnd(LongPressEndDetails details), void onVerticalDragDown(DragDownDetails details), void onVerticalDragStart(DragStartDetails details), void onVerticalDragUpdate(DragUpdateDetails details), void onVerticalDragEnd(DragEndDetails details), GestureDragCancelCallback onVerticalDragCancel, void onHorizontalDragDown(DragDownDetails details), void onHorizontalDragStart(DragStartDetails details), void onHorizontalDragUpdate(DragUpdateDetails details), void onHorizontalDragEnd(DragEndDetails details), GestureDragCancelCallback onHorizontalDragCancel, void onForcePressStart(ForcePressDetails details), void onForcePressPeak(ForcePressDetails details), void onForcePressUpdate(ForcePressDetails details), void onForcePressEnd(ForcePressDetails details), void onPanDown(DragDownDetails details), void onPanStart(DragStartDetails details), void onPanUpdate(DragUpdateDetails details), void onPanEnd(DragEndDetails details), GestureDragCancelCallback onPanCancel, void onScaleStart(ScaleStartDetails details), void onScaleUpdate(ScaleUpdateDetails details), void onScaleEnd(ScaleEndDetails details), HitTestBehavior behavior, bool excludeFromSemantics: false, DragStartBehavior dragStartBehavior: DragStartBehavior.start}): Creates a widget that detects gestures. [...]

Properties

behavior → HitTestBehavior: How this gesture detector should behave during hit testing. [...]
final
child → Widget: The widget below this widget in the tree. [...]
final
dragStartBehavior → DragStartBehavior: Determines the way that drag start behavior is handled. [...]
final
excludeFromSemantics → bool: Whether to exclude these gestures from the semantics tree. For example, the long-press gesture for showing a tooltip is excluded because the tooltip itself is included in the semantics tree directly and so having a gesture to show it would result in duplication of information.
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
onDoubleTap → GestureTapCallback: The user has tapped the screen with a primary button at the same location twice in quick succession. [...]
final
onDoubleTapCancel → GestureTapCancelCallback: The pointer that previously triggered onDoubleTapDown will not end up causing a double tap. [...]
final
onDoubleTapDown → void Function(TapDownDetails details): A pointer that might cause a double tap has contacted the screen at a particular location. [...]
final
onForcePressEnd → void Function(ForcePressDetails details): The pointer is no longer in contact with the screen. [...]
final
onForcePressPeak → void Function(ForcePressDetails details): The pointer is in contact with the screen and has pressed with the maximum force. The amount of force is at least ForcePressGestureRecognizer.peakPressure. [...]
final
onForcePressStart → void Function(ForcePressDetails details): The pointer is in contact with the screen and has pressed with sufficient force to initiate a force press. The amount of force is at least ForcePressGestureRecognizer.startPressure. [...]
final
onForcePressUpdate → void Function(ForcePressDetails details): A pointer is in contact with the screen, has previously passed the ForcePressGestureRecognizer.startPressure and is either moving on the plane of the screen, pressing the screen with varying forces or both simultaneously. [...]
final
onHorizontalDragCancel → GestureDragCancelCallback: The pointer that previously triggered onHorizontalDragDown did not complete. [...]
final
onHorizontalDragDown → void Function(DragDownDetails details): A pointer has contacted the screen with a primary button and might begin to move horizontally. [...]
final
onHorizontalDragEnd → void Function(DragEndDetails details): A pointer that was previously in contact with the screen with a primary button and moving horizontally is no longer in contact with the screen and was moving at a specific velocity when it stopped contacting the screen. [...]
final
onHorizontalDragStart → void Function(DragStartDetails details): A pointer has contacted the screen with a primary button and has begun to move horizontally. [...]
final
onHorizontalDragUpdate → void Function(DragUpdateDetails details): A pointer that is in contact with the screen with a primary button and moving horizontally has moved in the horizontal direction. [...]
final
onLongPress → GestureLongPressCallback: Called when a long press gesture with a primary button has been recognized. [...]
final
onLongPressEnd → void Function(LongPressEndDetails details): A pointer that has triggered a long-press with a primary button has stopped contacting the screen. [...]
final
onLongPressMoveUpdate → void Function(LongPressMoveUpdateDetails details): A pointer has been drag-moved after a long press with a primary button. [...]
final
onLongPressStart → void Function(LongPressStartDetails details): Called when a long press gesture with a primary button has been recognized. [...]
final
onLongPressUp → GestureLongPressUpCallback: A pointer that has triggered a long-press with a primary button has stopped contacting the screen. [...]
final
onPanCancel → GestureDragCancelCallback: The pointer that previously triggered onPanDown did not complete. [...]
final
onPanDown → void Function(DragDownDetails details): A pointer has contacted the screen with a primary button and might begin to move. [...]
final
onPanEnd → void Function(DragEndDetails details): A pointer that was previously in contact with the screen with a primary button and moving is no longer in contact with the screen and was moving at a specific velocity when it stopped contacting the screen. [...]
final
onPanStart → void Function(DragStartDetails details): A pointer has contacted the screen with a primary button and has begun to move. [...]
final
onPanUpdate → void Function(DragUpdateDetails details): A pointer that is in contact with the screen with a primary button and moving has moved again. [...]
final
onScaleEnd → void Function(ScaleEndDetails details): The pointers are no longer in contact with the screen.
final
onScaleStart → void Function(ScaleStartDetails details): The pointers in contact with the screen have established a focal point and initial scale of 1.0.
final
onScaleUpdate → void Function(ScaleUpdateDetails details): The pointers in contact with the screen have indicated a new focal point and/or scale.
final
onSecondaryLongPress → GestureLongPressCallback: Called when a long press gesture with a secondary button has been recognized. [...]
final
onSecondaryLongPressEnd → void Function(LongPressEndDetails details): A pointer that has triggered a long-press with a secondary button has stopped contacting the screen. [...]
final
onSecondaryLongPressMoveUpdate → void Function(LongPressMoveUpdateDetails details): A pointer has been drag-moved after a long press with a secondary button. [...]
final
onSecondaryLongPressStart → void Function(LongPressStartDetails details): Called when a long press gesture with a secondary button has been recognized. [...]
final
onSecondaryLongPressUp → GestureLongPressUpCallback: A pointer that has triggered a long-press with a secondary button has stopped contacting the screen. [...]
final
onSecondaryTap → GestureTapCallback: A tap with a secondary button has occurred. [...]
final
onSecondaryTapCancel → GestureTapCancelCallback: The pointer that previously triggered onSecondaryTapDown will not end up causing a tap. [...]
final
onSecondaryTapDown → void Function(TapDownDetails details): A pointer that might cause a tap with a secondary button has contacted the screen at a particular location. [...]
final
onSecondaryTapUp → void Function(TapUpDetails details): A pointer that will trigger a tap with a secondary button has stopped contacting the screen at a particular location. [...]
final
onTap → GestureTapCallback: A tap with a primary button has occurred. [...]
final
onTapCancel → GestureTapCancelCallback: The pointer that previously triggered onTapDown will not end up causing a tap. [...]
final
onTapDown → void Function(TapDownDetails details): A pointer that might cause a tap with a primary button has contacted the screen at a particular location. [...]
final
onTapUp → void Function(TapUpDetails details): A pointer that will trigger a tap with a primary button has stopped contacting the screen at a particular location. [...]
final
onTertiaryTapCancel → GestureTapCancelCallback: The pointer that previously triggered onTertiaryTapDown will not end up causing a tap. [...]
final
onTertiaryTapDown → void Function(TapDownDetails details): A pointer that might cause a tap with a tertiary button has contacted the screen at a particular location. [...]
final
onTertiaryTapUp → void Function(TapUpDetails details): A pointer that will trigger a tap with a tertiary button has stopped contacting the screen at a particular location. [...]
final
onVerticalDragCancel → GestureDragCancelCallback: The pointer that previously triggered onVerticalDragDown did not complete. [...]
final
onVerticalDragDown → void Function(DragDownDetails details): A pointer has contacted the screen with a primary button and might begin to move vertically. [...]
final
onVerticalDragEnd → void Function(DragEndDetails details): A pointer that was previously in contact with the screen with a primary button and moving vertically is no longer in contact with the screen and was moving at a specific velocity when it stopped contacting the screen. [...]
final
onVerticalDragStart → void Function(DragStartDetails details): A pointer has contacted the screen with a primary button and has begun to move vertically. [...]
final
onVerticalDragUpdate → void Function(DragUpdateDetails details): A pointer that is in contact with the screen with a primary button and moving vertically has moved in the vertical direction. [...]
final
runtimeType → Type: A representation of the runtime type of the object.
read-only, inherited

Methods

build(BuildContext context) → Widget: Describes the part of the user interface represented by this widget. [...]
override
createElement() → StatelessElement: Creates a StatelessElement to manage this widget's location in the tree. [...]
inherited
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: 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 ==(Object other) → bool: The equality operator. [...]
@nonVirtual, inherited