Material class Null safety

A piece of material.

The Material widget is responsible for:

  1. Clipping: If clipBehavior is not Clip.none, Material clips its widget sub-tree to the shape specified by shape, type, and borderRadius. By default, clipBehavior is Clip.none for performance considerations. See Ink for an example of how this affects clipping Ink widgets.
  2. Elevation: Material elevates its widget sub-tree on the Z axis by elevation pixels, and draws the appropriate shadow.
  3. Ink effects: Material shows ink effects implemented by InkFeatures like InkSplash and InkHighlight below its children.

The Material Metaphor

Material is the central metaphor in Material Design. Each piece of material exists at a given elevation, which influences how that piece of material visually relates to other pieces of material and how that material casts shadows.

Most user interface elements are either conceptually printed on a piece of material or themselves made of material. Material reacts to user input using InkSplash and InkHighlight effects. To trigger a reaction on the material, use a MaterialInkController obtained via Material.of.

In general, the features of a Material should not change over time (e.g. a Material should not change its color, shadowColor or type). Changes to elevation, shadowColor and surfaceTintColor are animated for animationDuration. Changes to shape are animated if type is not MaterialType.transparency and ShapeBorder.lerp between the previous and next shape values is supported. Shape changes are also animated for animationDuration.

Shape

The shape for material is determined by shape, type, and borderRadius.

Border

If shape is not null, then its border will also be painted (if any).

Layout change notifications

If the layout changes (e.g. because there's a list on the material, and it's been scrolled), a LayoutChangedNotification must be dispatched at the relevant subtree. This in particular means that transitions (e.g. SlideTransition) should not be placed inside Material widgets so as to move subtrees that contain InkResponses, InkWells, Inks, or other widgets that use the InkFeature mechanism. Otherwise, in-progress ink features (e.g., ink splashes and ink highlights) won't move to account for the new layout.

Painting over the material

Material widgets will often trigger reactions on their nearest material ancestor. For example, ListTile.hoverColor triggers a reaction on the tile's material when a pointer is hovering over it. These reactions will be obscured if any widget in between them and the material paints in such a way as to obscure the material (such as setting a BoxDecoration.color on a DecoratedBox). To avoid this behavior, use InkDecoration to decorate the material itself.

See also:

Inheritance

Constructors

Material({Key? key, MaterialType type = MaterialType.canvas, double elevation = 0.0, Color? color, Color? shadowColor, Color? surfaceTintColor, TextStyle? textStyle, BorderRadiusGeometry? borderRadius, ShapeBorder? shape, bool borderOnForeground = true, Clip clipBehavior = Clip.none, Duration animationDuration = kThemeChangeDuration, Widget? child})
Creates a piece of material.
const

Properties

animationDuration → Duration
Defines the duration of animated changes for shape, elevation, shadowColor, surfaceTintColor and the elevation overlay if it is applied.
final
borderOnForeground → bool
Whether to paint the shape border in front of the child.
final
borderRadius → BorderRadiusGeometry?
If non-null, the corners of this box are rounded by this BorderRadiusGeometry value.
final
child → Widget?
The widget below this widget in the tree.
final
clipBehavior → Clip
The content will be clipped (or not) according to this option.
final
color → Color?
The color to paint the material.
final
elevation → double
The z-coordinate at which to place this material relative to its parent.
final
hashCode → int
The hash code for this object.
nonVirtual">@nonVirtualread-onlyinherited
key → Key?
Controls how one widget replaces another widget in the tree.
finalinherited
runtimeType → Type
A representation of the runtime type of the object.
read-onlyinherited
shadowColor → Color?
The color to paint the shadow below the material.
final
shape → ShapeBorder?
Defines the material's shape as well its shadow.
final
surfaceTintColor → Color?
The color of the surface tint overlay applied to the material color to indicate elevation.
final
textStyle → TextStyle?
The typographical style to use for text within this material.
final
type → MaterialType
The kind of material to show (e.g., card or canvas). This affects the shape of the widget, the roundness of its corners if the shape is rectangular, and the default color.
final

Methods

createElement() → StatefulElement
Creates a StatefulElement to manage this widget's location in the tree.
inherited
createState() → State<Material>
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">@protectedinherited
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">@nonVirtualinherited

Static Methods

of(BuildContext context) → MaterialInkController?
The ink controller from the closest instance of this class that encloses the given context.

Constants

defaultSplashRadius → const double
The default radius of an ink splash in logical pixels.
35.0