# Shape theming Material Design encourages brand expression through shapes. The Material Components library offers a `shape` library that can be used to create non-standard shapes using a `MaterialShapeDrawable`, a `Drawable` that can draw custom shapes while taking shadows, elevation, scale and color into account. On top of the shape library, the Material Components library provides a mechanism with which to easily customize component shapes at the theme level. Shape theming offers a new dimension with which to customize the look and feel of your app. ## Design and API Documentation - [Material Design 3 guidelines: Shape](https://m3.material.io/styles/shape/overview) ## How it works ### `MaterialShapeDrawable` and `ShapeAppearanceModel` `MaterialShapeDrawable` begins with a path generated by a `ShapeAppearanceModel`. A `ShapeAppearanceModel` is made of `CornerTreatment`s and `EdgeTreatment`s that combine to create a custom shape path, and is usually passed to a MaterialShapeDrawable's constructor. The `shape` library provides some subclassed `CornerTreatment`s and `EdgeTreatment`s to make it easy to build new shapes: - [`CutCornerTreatment`](https://developer.android.com/reference/com/google/android/material/shape/CutCornerTreatment) - [`RoundedCornerTreatment`](https://developer.android.com/reference/com/google/android/material/shape/RoundedCornerTreatment) - [`TriangleEdgeTreatment`](https://developer.android.com/reference/com/google/android/material/shape/TriangleEdgeTreatment) Both `CornerTreatment` and `EdgeTreatment` can be subclassed to create custom corners and edges. **Note:** When subclassing `CornerTreatment` or `EdgeTreatment`, make sure to implement the `Cloneable` interface to ensure that the `ShapeAppearanceModel` can create deep copies of the corner and edge treatments. ### Theming `MaterialShapeDrawable`s Components backed by `MaterialShapeDrawable`s can use themes across an application. #### Shape styles Style Name | Description | Corner Sizes ------------------------------------------------------ | ----------------------------------------------------------------------------------------------- | ------------ `ShapeAppearance.Material3.Corner.None` | No corners (i.e., fully rectangular) | 0dp `ShapeAppearance.Material3.Corner.ExtraSmall` | Shape with extra small corner size | 4dp `ShapeAppearance.Material3.Corner.Small` | Shape with small corner size | 8dp `ShapeAppearance.Material3.Corner.Medium` | Shape with medium corner size | 12dp `ShapeAppearance.Material3.Corner.Large` | Shape with large corner size | 16dp `ShapeAppearance.Material3.Corner.LargeIncreased` | Shape with increased large corner size | 20dp `ShapeAppearance.Material3.Corner.ExtraLarge` | Shape with extra large corner size | 28dp `ShapeAppearance.Material3.Corner.ExtraLargeIncreased` | Shape with increased extra large corner size | 32dp `ShapeAppearance.Material3.Corner.ExtraExtraLarge` | Shape with extra extra large corner size | 48dp `ShapeAppearance.Material3.Corner.Full` | Shape with full corner size
i.e., circle with rounded corners or rhombus with cut corners | 50% These are the shape styles providing the Material 3 shape scale. The shape families in these styles (i.e., `cornerFamily`) are mapped to the theme attribute `?attr/shapeCornerFamily`. See the section below for more details. #### Shape theme attributes Theme attributes can be set at the theme level to change the shape values that components use to set their shapes. Attribute Name | Description | Default Value ------------------------------------------ | ---------------------------------------------------------------------------------------------- | ------------- `shapeCornerFamily` | The corner family for all shape appearance styles | `rounded` `shapeAppearanceCornerExtraSmall` | The style reference that contains shape appearance with extra small corners | `ShapeAppearance.Material3.Corner.ExtraSmall` `shapeAppearanceCornerSmall` | The style reference that contains shape appearance with small corners | `ShapeAppearance.Material3.Corner.Small` `shapeAppearanceCornerMedium` | The style reference that contains shape appearance with medium corners | `ShapeAppearance.Material3.Corner.Medium` `shapeAppearanceCornerLarge` | The style reference that contains shape appearance with large corners | `ShapeAppearance.Material3.Corner.Large` `shapeAppearanceCornerLargeIncreased` | The style reference that contains shape appearance with slightly increased large corners | `ShapeAppearance.Material3.Corner.LargeIncreased` `shapeAppearanceCornerExtraLarge` | The style reference that contains shape appearance with extra large corners | `ShapeAppearance.Material3.Corner.ExtraLarge` `shapeAppearanceCornerExtraLargeIncreased` | The style reference that contains shape appearance with slightly increased extra large corners | `ShapeAppearance.Material3.Corner.ExtraLargeIncreased` `shapeAppearanceCornerExtraExtraLarge` | The style reference that contains shape appearance with extra extra large corners | `ShapeAppearance.Material3.Corner.ExtraExtraLarge` ### Corner family and corner sizes Shape role | Android attribute | values --------------------------------- | ---------------------------------- | ------- Corner Family | shapeCornerFamily | Rounded Corner Size Extra Small | shapeCornerSizeExtraSmall | 4dp Corner Size Small | shapeCornerSizeSmall | 8dp Corner Size Medium | shapeCornerSizeMedium | 12dp Corner Size Large | shapeCornerSizeLarge | 16dp Corner Size Large Increased | shapeCornerSizeLargeIncreased | 20dp Corner Size Extra Large | shapeCornerSizeExtraLarge | 28dp Corner Size Extra Large Increased | shapeCornerSizeExtraLargeIncreased | 32dp Corner Size Extra Extra Large | shapeCornerSizeExtraExtraLarge | 48dp Aside from defining these attributes in your theme, you likely will not need to reference these attributes at all; the widget styles are already mapped to the appropriate theme attribute to create a seamless shape theming experience. To change individual shapes throughout your app, you should use the [shapeAppearance and shapeAppearanceOverlay](#shapeappearance-and-shapeappearanceoverlay-attributes) attributes rather than redefining theme level attributes. **Note**: There is no sanity check for the shape values mapped to these theme attributes. It is the developer's responsibility to guarantee the relative correctness, for example, "medium" is smaller than "large", etc. ## Usage ### Building a shape appearance Component shapes are backed by "shape appearances", which are style references that define aspects of the shape. `ShapeAppearanceModel` uses the `shapeAppearance` style and creates corner and edge treatments out of the `shapeAppearance` values. The following attributes can be used in a `shapeAppearance` style: Attribute Name | Format | Description | Supported Values ------------------------- |---------------------| ---------------------------------------------------- | ---------------- `cornerFamily` | enum | corner family to be used for all four corners | `rounded`, `cut` `cornerFamilyTopLeft` | enum | corner family to be used for the top left corner | `rounded`, `cut` `cornerFamilyTopRight` | enum | corner family to be used for the top right corner | `rounded`, `cut` `cornerFamilyBottomRight` | enum | corner family to be used for the bottom right corner | `rounded`, `cut` `cornerFamilyBottomLeft` | enum | corner family to be used for the bottom left corner | `rounded`, `cut` `cornerSize` | dimension\|fraction | corner size to be used for all four corners | dimension values, percentage `cornerSizeTopLeft` | dimension\|fraction | corner size to be used for the top left corner | dimension values, percentage `cornerSizeTopRight` | dimension\|fraction | corner size to be used for the top right corner | dimension values, percentage `cornerSizeBottomRight` | dimension\|fraction | corner size to be used for the bottom right corner | dimension values, percentage `cornerSizeBottomLeft` | dimension\|fraction | corner size to be used for the bottom left corner | dimension values, percentage To build a `shapeAppearance`, you need at least a **`cornerSize`** and **`cornerFamily`** value specified for each corner. #### `ShapeAppearance` and `shapeAppearanceOverlay` attributes Two attributes are provided to set a component's shape style, `shapeAppearance` and `shapeAppearanceOverlay`: Attribute Name | Description ------------------------ | -------------------------------------- `shapeAppearance` | Style reference that contains shape values that are used to style the component. Should point to a theme attribute style reference such as `?attr/shapeAppearanceCornerExtraSmall`. `shapeAppearanceOverlay` | Style reference that contains shape values that layer on top of a `shapeAppearance` style. This attribute is intended for overrides on top of the themed shapeAppearance shape values, and should map to a custom style reference rather than a themed style reference. The `shapeAppearanceOverlay` attribute is provided to override components on a case by case basis. This attribute stacks on top of the `shapeAppearance` attribute; the `shapeAppearance` is read first, and then if there is anything specified in the `shapeAppearanceOverlay` attribute, it overrides what’s set in the `shapeAppearance`. **Note:** `shapeAppearance` styles require both `cornerSize` and `cornerFamily` to be set, while `shapeAppearanceOverlay` does not. This means that when defining a custom `shapeAppearance` style, you should either inherit from a parent if one exists, or set both `cornerSize` and `cornerFamily`. However, when defining a style to be used as a `shapeAppearanceOverlay`, you should generally set an empty parent by setting `parent=""`. This is because `shapeAppearanceOverlay` stacks on top of `shapeAppearance`, so all values will be set in the `shapeAppearance.` ### Using `shapeAppearance` in the theme The Material Components library supports theming shapes at the application level. To apply theme shapes across your app, specify the shape theme attributes in your theme. This will allow [components that support shape theming](#supported-components) to read the customized values and change their shapes accordingly. If you want to change the small and medium corners in your app to cut corners, define the shape theme attributes to point to custom style references that contain shape values: ```xml ``` The shape theme attributes should point to custom `shapeAppearance` styles that define both `cornerSize` and `cornerFamily`. You can either define both attributes in a style from scratch or modify the corner family from a built-in shape style like this: ```xml ``` Material components that support shape theming use theme attributes according to the themed shape values. ### Customizing component shapes #### Theme-wide component overrides You can change a component's shape across the entire app by defining a custom `shapeAppearanceOverlay` in the component's style. If you want to modify `MaterialCardView` so that it uses 16dp rounded corners across the entire app, define your own card style to extend from the widget's style, and set the relevant attributes to the desired theme attributes: ```xml ``` And define `ShapeAppearanceOverlay.MyApp.CardView`: ```xml ``` Then make sure to set the component's style in your theme to your custom style: ```xml ``` All cards in your app should now have 16dp rounded corners. #### Individual component overrides You can also change an individual component's shape on a case by case basis. For example, if cards in your theme have 16dp rounded corners, but one card should have 16dp cut corners, you can change that card's `cornerFamily` by setting the `shapeAppearanceOverlay` attribute on the card in your layout. Define a custom `shapeAppearanceOverlay` style with just the attribute you want to overlay on top of the existing `shapeAppearance`. In this case, you would set `cornerFamily` to `cut`: ```xml ``` Then, set the card's `shapeAppearanceOverlay` attribute to that `ShapeAppearanceOverlay` style in your layout: ```xml ``` The `cornerFamily` attribute set in the `shapeAppearanceOverlay` will override the `cornerFamily` set in the card's `shapeAppearance`, so the card should now have 16dp cut corners instead of 16dp rounded corners. #### Supported components Components that support shape theming have a `shapeAppearance` attribute, a `shapeAppearanceOverlay` attribute, and are backed by a `MaterialShapeDrawable`: * [Bottom Sheet](../components/BottomSheet.md) * [Card](../components/Card.md) * [Chip](../components/Chip.md) * [Date Picker](../components/DatePicker.md) * [Dialog](../components/Dialog.md) * [Extended Floating Action Button](../components/FloatingActionButton.md?#extended-fabs) * [Floating Action Button](../components/FloatingActionButton.md) * [Button](../components/Button.md) * [Time Picker](../components/TimePicker.md) * [Navigation Drawer](../components/NavigationDrawer.md) * [Slider](../components/Slider.md) * [Snackbar](../components/Snackbar.md) * [Text Field](../components/TextField.md)