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

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.

See also:

Inheritance

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
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