# Svelte Material UI - Shape

Shapes direct attention, identify components, communicate state, and express brand.

> Currently shape system for web only supports rounded corners.

# Design

https://m2.material.io/design/shape/about-shape.html

# Basic Usage

## Styles

```scss
@use '@smui/common/shape';
```

# Style Customization

## Sass Variables

Components are categorized as small, medium, and large in the Material shape system. Overriding the below Sass variables will change all components in their respective categories.

| Variable                   | Description                                                           |
| -------------------------- | --------------------------------------------------------------------- |
| `$small-component-radius`  | Rounded shape radius size for small components. Default value `4px`.  |
| `$medium-component-radius` | Rounded shape radius size for medium components. Default value `4px`. |
| `$large-component-radius`  | Rounded shape radius size for large components. Default value `0`.    |

Please refer [Material Design guidelines: Shape](https://m2.material.io/go/design-shape) to learn about how components are categorized.

**Note: Only rounded shape designs are currently supported.**

## CSS Custom Properties

| CSS Custom Property  | Description                                                          |
| -------------------- | -------------------------------------------------------------------- |
| `--mdc-shape-small`  | Rounded shape radius size for small components. Default value `4px`. |
| `--mdc-shape-medium` | Rounded shape radius size for small components. Default value `4px`. |
| `--mdc-shape-large`  | Rounded shape radius size for small components. Default value `0`.   |

**Note: Do not use percentage values with custom properties, since they cannot be resolved by `shape.radius()` at runtime.**

## Sass Mixins

| Mixin                             | Description                                                                                                                                                                                                                            |
| --------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `radius($radius, $rtl-reflexive)` | Shape API used by all other components to apply radius to appropriate corners. `$radius` can be single value or list of up to 4 radius corner values. Set `$rtl-reflexive` to true to flip the radius in RTL case, `false` by default. |

## Sass Functions

| Function                                     | Description                                                                                                                                                                                                                                                                           |
| -------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `resolve-radius($radius, $component-height)` | Returns the resolved radius value of a shape category - `large`, `medium`, or `small`. If $radius is not a category, this function returns the value itself if valid. Valid values are numbers or percentages. `$component-height`should be provided if`$radius` may be a percentage. |
| `flip-radius($radius)`                       | Flips the radius values in RTL context. `$radius` is list of 2-4 corner values.                                                                                                                                                                                                       |
| `mask-radius($radius, $masked-corners)`      | Accepts radius number or list of 2-4 radius values and returns 4 value list with masked corners as mentioned in `$masked-corners`.                                                                                                                                                    |
| `unpack-radius($radius)`                     | Unpacks shorthand values for border-radius (i.e. lists of 1-3 values). If a list of 4 values is given, it is returned as-is.                                                                                                                                                          |

## Additional Information

### Shapes for fixed height components

Styles for applying shape to a fixed height component such as button looks like this:

```scss
@use '@smui/button';

@include shape.radius($radius, $component-height: button.$height);
```

Where `button.$height` is the height of standard button and `$radius` is the size of the shape. `shape.radius()` will resolve any percentage unit value to an absolute radius value based on the component's height.

### Shapes for dynamic height components

Styles for applying shapes to dynamic height component such as card looks like this:

```scss
@include shape.radius($radius);
```

Where `$radius` is an absolute value only.

### Shapes for components on specific corners

Styles for applying shapes for specific corners such as drawer looks like this:

```scss
@include shape.radius(0 $radius $radius 0, $rtl-reflexive: true);
```

Where only top-right & bottom-right corners are customizable. `shape.radius()` will automatically flip radius values based on RTL context if `$rtl-reflexive` is set to true.

### Component theming

The styles for applying custom shape to a button component looks like this:

```scss
@use '@smui/button';

.my-custom-button {
  @include button.shape-radius(50%);
}
```

In this example, the above style applies a 50% pill shape to the button. It could also be an absolute value (e.g., `8px`);

> The Shape API is typically used indirectly through each respective component's mixin, which takes care of setting height and applying radius to applicable corners for all of its variants.