InkResponse class Null safety

An area of a Material that responds to touch. Has a configurable shape and can be configured to clip splashes that extend outside its bounds or not.

For a variant of this widget that is specialized for rectangular areas that always clip splashes, see InkWell.

An InkResponse widget does two things when responding to a tap:

  • It starts to animate a highlight. The shape of the highlight is determined by highlightShape. If it is a BoxShape.circle, the default, then the highlight is a circle of fixed size centered in the InkResponse. If it is BoxShape.rectangle, then the highlight is a box the size of the InkResponse itself, unless getRectCallback is provided, in which case that callback defines the rectangle. The color of the highlight is set by highlightColor.

  • Simultaneously, it starts to animate a splash. This is a growing circle initially centered on the tap location. If this is a containedInkWell, the splash grows to the radius while remaining centered at the tap location. Otherwise, the splash migrates to the center of the box as it grows.

The following two diagrams show how InkResponse looks when tapped if the highlightShape is BoxShape.circle (the default) and containedInkWell is false (also the default).

The first diagram shows how it looks if the InkResponse is relatively large:

The highlight is a disc centered in the box, smaller than the child widget.

The second diagram shows how it looks if the InkResponse is small:

The highlight is a disc overflowing the box, centered on the child.

The main thing to notice from these diagrams is that the splashes happily exceed the bounds of the widget (because containedInkWell is false).

The following diagram shows the effect when the InkResponse has a highlightShape of BoxShape.rectangle with containedInkWell set to true. These are the values used by InkWell.

The highlight is a rectangle the size of the box.

The InkResponse 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 InkResponse 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 InkResponse (as an ancestor to the ink response). The MaterialType.transparency material kind can be used for this purpose.

See also:

Inheritance
Implementers

Constructors

InkResponse({Key? key, Widget? child, GestureTapCallback? onTap, GestureTapDownCallback? onTapDown, GestureTapCallback? onTapCancel, GestureTapCallback? onDoubleTap, GestureLongPressCallback? onLongPress, ValueChanged<bool>? onHighlightChanged, ValueChanged<bool>? onHover, MouseCursor? mouseCursor, bool containedInkWell, BoxShape highlightShape, double? radius, BorderRadius? borderRadius, ShapeBorder? customBorder, Color? focusColor, Color? hoverColor, Color? highlightColor, MaterialStateProperty<Color?>? overlayColor, Color? splashColor, InteractiveInkFeatureFactory? splashFactory, bool enableFeedback, bool excludeFromSemantics, FocusNode? focusNode, bool canRequestFocus, ValueChanged<bool>? onFocusChange, bool autofocus})
Creates an area of a Material that responds to touch. [...]
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
borderRadius BorderRadius?
The clipping radius of the containing rect. This is effective only if customBorder is null. [...]
final
canRequestFocus bool
If true, this widget may request the primary focus. [...]
final
child Widget?
The widget below this widget in the tree. [...]
final
containedInkWell bool
Whether this ink response should be clipped its bounds. [...]
final
customBorder ShapeBorder?
The custom clip border which overrides borderRadius.
final
enableFeedback bool
Whether detected gestures should provide acoustic and/or haptic feedback. [...]
final
excludeFromSemantics bool
Whether to exclude the gestures introduced by this widget from the semantics tree. [...]
final
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
focusNode FocusNode?
An optional focus node to use as the focus node for this widget. [...]
final
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
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
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
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
onDoubleTap GestureTapCallback?
Called when the user double taps this part of the material.
final
onFocusChange ValueChanged<bool>?
Handler called when the focus changes. [...]
final
onHighlightChanged ValueChanged<bool>?
Called when this part of the material either becomes highlighted or stops being highlighted. [...]
final
onHover ValueChanged<bool>?
Called when a pointer enters or exits the ink response area. [...]
final
onLongPress GestureLongPressCallback?
Called when the user long-presses on this part of the material.
final
onTap GestureTapCallback?
Called when the user taps this part of the material.
final
onTapCancel GestureTapCallback?
Called when the user cancels a tap that was started on this part of the material.
final
onTapDown GestureTapDownCallback?
Called when the user taps down this part of the material.
final
overlayColor MaterialStateProperty<Color?>?
Defines the ink response focus, hover, and splash colors. [...]
final
radius double?
The radius of the ink splash. [...]
final
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
splashFactory InteractiveInkFeatureFactory?
Defines the appearance of the splash. [...]
final

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
debugCheckContext(BuildContext context) bool
Asserts that the given context satisfies the prerequisites for this class. [...]
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. [...]
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