InkWell class Null safety

A rectangular area of a Material that responds to touch.

For a variant of this widget that does not clip splashes, see InkResponse.

The following diagram shows how an InkWell looks when tapped, when using default values.

The highlight is a rectangle the size of the box.

The InkWell widget must have a Material widget as an ancestor. The Material widget is where the ink reactions are actually painted. This matches the material design premise wherein the Material is what is actually reacting to touches by spreading ink.

If a Widget uses this class directly, it should include the following line at the top of its build function to call debugCheckHasMaterial:

assert(debugCheckHasMaterial(context));

Troubleshooting

The ink splashes aren't visible!

If there is an opaque graphic, e.g. painted using a Container, Image, or DecoratedBox, between the Material widget and the InkWell widget, then the splash won't be visible because it will be under the opaque graphic. This is because ink splashes draw on the underlying Material itself, as if the ink was spreading inside the material.

The Ink widget can be used as a replacement for Image, Container, or DecoratedBox to ensure that the image or decoration also paints in the Material itself, below the ink.

If this is not possible for some reason, e.g. because you are using an opaque CustomPaint widget, alternatively consider using a second Material above the opaque widget but below the InkWell (as an ancestor to the ink well). The MaterialType.transparency material kind can be used for this purpose.

The ink splashes don't track the size of an animated container

If the size of an InkWell's Material ancestor changes while the InkWell's splashes are expanding, you may notice that the splashes aren't clipped correctly. This can't be avoided.

An example of this situation is as follows:

Tap the container to cause it to grow. Then, tap it again and hold before the widget reaches its maximum size to observe the clipped ink splash.

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

Tap the container to cause it to grow. Then, tap it again and hold before the widget reaches its maximum size to observe the clipped ink splash.

double sideLength = 50;

@override
Widget build(BuildContext context) {
  return AnimatedContainer(
    height: sideLength,
    width: sideLength,
    duration: const Duration(seconds: 2),
    curve: Curves.easeIn,
    child: Material(
      color: Colors.yellow,
      child: InkWell(
        onTap: () {
          setState(() {
            sideLength == 50 ? sideLength = 100 : sideLength = 50;
          });
        },
      ),
    ),
  );
}

An InkWell's splashes will not properly update to conform to changes if the size of its underlying Material, where the splashes are rendered, changes during animation. You should avoid using InkWells within Material widgets that are changing size.

Constructors

InkWell({Key? key, Widget? child, GestureTapCallback? onTap, GestureTapCallback? onDoubleTap, GestureLongPressCallback? onLongPress, GestureTapDownCallback? onTapDown, GestureTapCancelCallback? onTapCancel, ValueChanged<bool>? onHighlightChanged, ValueChanged<bool>? onHover, MouseCursor? mouseCursor, Color? focusColor, Color? hoverColor, Color? highlightColor, MaterialStateProperty<Color?>? overlayColor, Color? splashColor, InteractiveInkFeatureFactory? splashFactory, double? radius, BorderRadius? borderRadius, ShapeBorder? customBorder, bool? enableFeedback = true, bool excludeFromSemantics = false, FocusNode? focusNode, bool canRequestFocus = true, ValueChanged<bool>? onFocusChange, bool autofocus = false}): Creates an ink well. [...]
const

Properties

autofocus → bool: True if this widget will be selected as the initial focus when no other node in its scope is currently focused. [...]
final, inherited
borderRadius → BorderRadius?: The clipping radius of the containing rect. This is effective only if customBorder is null. [...]
final, inherited
canRequestFocus → bool: If true, this widget may request the primary focus. [...]
final, inherited
child → Widget?: The widget below this widget in the tree. [...]
final, inherited
containedInkWell → bool: Whether this ink response should be clipped its bounds. [...]
final, inherited
customBorder → ShapeBorder?: The custom clip border which overrides borderRadius.
final, inherited
enableFeedback → bool: Whether detected gestures should provide acoustic and/or haptic feedback. [...]
final, inherited
excludeFromSemantics → bool: Whether to exclude the gestures introduced by this widget from the semantics tree. [...]
final, inherited
focusColor → Color?: The color of the ink response when the parent widget is focused. If this property is null then the focus color of the theme, ThemeData.focusColor, will be used. [...]
final, inherited
focusNode → FocusNode?: An optional focus node to use as the focus node for this widget. [...]
final, inherited
hashCode → int: The hash code for this object. [...]
@nonVirtual, read-only, inherited
highlightColor → Color?: The highlight color of the ink response when pressed. If this property is null then the highlight color of the theme, ThemeData.highlightColor, will be used. [...]
final, inherited
highlightShape → BoxShape: The shape (e.g., circle, rectangle) to use for the highlight drawn around this part of the material when pressed, hovered over, or focused. [...]
final, inherited
hoverColor → Color?: The color of the ink response when a pointer is hovering over it. If this property is null then the hover color of the theme, ThemeData.hoverColor, will be used. [...]
final, inherited
key → Key?: Controls how one widget replaces another widget in the tree. [...]
final, inherited
mouseCursor → MouseCursor?: The cursor for a mouse pointer when it enters or is hovering over the widget. [...]
final, inherited
onDoubleTap → GestureTapCallback?: Called when the user double taps this part of the material.
final, inherited
onFocusChange → ValueChanged<bool>?: Handler called when the focus changes. [...]
final, inherited
onHighlightChanged → ValueChanged<bool>?: Called when this part of the material either becomes highlighted or stops being highlighted. [...]
final, inherited
onHover → ValueChanged<bool>?: Called when a pointer enters or exits the ink response area. [...]
final, inherited
onLongPress → GestureLongPressCallback?: Called when the user long-presses on this part of the material.
final, inherited
onTap → GestureTapCallback?: Called when the user taps this part of the material.
final, inherited
onTapCancel → GestureTapCallback?: Called when the user cancels a tap that was started on this part of the material.
final, inherited
onTapDown → GestureTapDownCallback?: Called when the user taps down this part of the material.
final, inherited
overlayColor → MaterialStateProperty<Color?>?: Defines the ink response focus, hover, and splash colors. [...]
final, inherited
radius → double?: The radius of the ink splash. [...]
final, inherited
runtimeType → Type: A representation of the runtime type of the object.
read-only, inherited
splashColor → Color?: The splash color of the ink response. If this property is null then the splash color of the theme, ThemeData.splashColor, will be used. [...]
final, inherited
splashFactory → InteractiveInkFeatureFactory?: Defines the appearance of the splash. [...]
final, inherited

Methods

build(BuildContext context) → Widget: Describes the part of the user interface represented by this widget. [...]
inherited
createElement() → StatelessElement: Creates a StatelessElement to manage this widget's location in the tree. [...]
inherited
debugCheckContext(BuildContext context) → bool: Asserts that the given context satisfies the prerequisites for this class. [...]
@mustCallSuper, 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. [...]
inherited
getRectCallback(RenderBox referenceBox) → RectCallback?: The rectangle to use for the highlight effect and for clipping the splash effects if containedInkWell is true. [...]
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.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