Material class
A piece of material.
The Material widget is responsible for:
- 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.
- Elevation: Material elevates its widget sub-tree on the Z axis by elevation pixels, and draws the appropriate shadow.
- 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.
- If shape is non null, it determines the shape.
- If shape is null and borderRadius is non null, the shape is a rounded rectangle, with corners specified by borderRadius.
- If shape and borderRadius are null, type determines the
shape as follows:
- MaterialType.canvas: the default material shape is a rectangle.
- MaterialType.card: the default material shape is a rectangle with rounded edges. The edge radii is specified by kMaterialEdges.
- MaterialType.circle: the default material shape is a circle.
- MaterialType.button: the default material shape is a rectangle with rounded edges. The edge radii is specified by kMaterialEdges.
- MaterialType.transparency: the default material shape is a rectangle.
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:
- MergeableMaterial, a piece of material that can split and re-merge.
- Card, a wrapper for a Material of type MaterialType.card.
- material-io.cn/design/
- m3.material-io.cn/styles/color/the-color-system/color-roles
- Inheritance
-
- Object
- DiagnosticableTree
- Widget
- StatefulWidget
- Material
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.
no setterinherited
- key → Key?
-
Controls how one widget replaces another widget in the tree.
finalinherited
- runtimeType → Type
-
A representation of the runtime type of the object.
no setterinherited
- 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
DiagnosticsNodeobjects describing this node's children.inherited -
debugFillProperties(
DiagnosticPropertiesBuilder properties) → void -
Add additional properties associated with the node.
override
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a nonexistent 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.
inherited
Static Methods
-
maybeOf(
BuildContext context) → MaterialInkController? - The ink controller from the closest instance of this class that encloses the given context within the closest LookupBoundary.
-
of(
BuildContext context) → MaterialInkController - The ink controller from the closest instance of Material that encloses the given context within the closest LookupBoundary.
Constants
- defaultSplashRadius → const double
- The default radius of an ink splash in logical pixels.