# SurfaceCallback

Artifact: [androidx.car.app:app](https://developer.android.com/jetpack/androidx/releases/car-app) [View Source](https://cs.android.com/search?q=file:androidx/car/app/SurfaceCallback.java+class:androidx.car.app.SurfaceCallback) Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/car-app#1.0.0)

*** ** * ** ***


```
public interface SurfaceCallback
```

<br />

*** ** * ** ***

A callback for changes on the `https://developer.android.com/reference/androidx/car/app/SurfaceContainer` and its attributes.

## Summary

| ### Public methods |
|---|---|
| `default void` | `@https://developer.android.com/reference/androidx/car/app/annotations/RequiresCarApi(value = 5) https://developer.android.com/reference/androidx/car/app/SurfaceCallback#onClick(float,float)(float x, float y)` Provides information about a click event on the car screen. |
| `default void` | `@https://developer.android.com/reference/androidx/car/app/annotations/RequiresCarApi(value = 2) https://developer.android.com/reference/androidx/car/app/SurfaceCallback#onFling(float,float)(float velocityX, float velocityY)` Provides information about a fling touch event on the car screen. |
| `default void` | `@https://developer.android.com/reference/androidx/car/app/annotations/RequiresCarApi(value = 2) https://developer.android.com/reference/androidx/car/app/SurfaceCallback#onScale(float,float,float)(float focusX, float focusY, float scaleFactor)` Provides information about a scale touch event on the car screen. |
| `default void` | `@https://developer.android.com/reference/androidx/car/app/annotations/RequiresCarApi(value = 2) https://developer.android.com/reference/androidx/car/app/SurfaceCallback#onScroll(float,float)(float distanceX, float distanceY)` Provides information about a scroll touch event on the car screen. |
| `default void` | `https://developer.android.com/reference/androidx/car/app/SurfaceCallback#onStableAreaChanged(android.graphics.Rect)(@https://jspecify.dev/docs/api/org/jspecify/annotations/NonNull.html https://developer.android.com/reference/android/graphics/Rect.html stableArea)` Indicates that the stable area provided by the host has changed. |
| `default void` | `https://developer.android.com/reference/androidx/car/app/SurfaceCallback#onSurfaceAvailable(androidx.car.app.SurfaceContainer)(@https://jspecify.dev/docs/api/org/jspecify/annotations/NonNull.html https://developer.android.com/reference/androidx/car/app/SurfaceContainer surfaceContainer)` Provides a `https://developer.android.com/reference/androidx/car/app/SurfaceContainer` from the host which is ready for drawing. |
| `default void` | `https://developer.android.com/reference/androidx/car/app/SurfaceCallback#onSurfaceDestroyed(androidx.car.app.SurfaceContainer)(@https://jspecify.dev/docs/api/org/jspecify/annotations/NonNull.html https://developer.android.com/reference/androidx/car/app/SurfaceContainer surfaceContainer)` Indicates that the `https://developer.android.com/reference/androidx/car/app/SurfaceContainer` provided by the host will be destroyed after this callback. |
| `default void` | `https://developer.android.com/reference/androidx/car/app/SurfaceCallback#onVisibleAreaChanged(android.graphics.Rect)(@https://jspecify.dev/docs/api/org/jspecify/annotations/NonNull.html https://developer.android.com/reference/android/graphics/Rect.html visibleArea)` Indicates that the visible area provided by the host has changed. |

## Public methods

### onClick

Added in [1.2.0](https://developer.android.com/jetpack/androidx/releases/car-app#1.2.0)

```
@RequiresCarApi(value = 5)
default void onClick(float x, float y)
```

Provides information about a click event on the car screen.

See `https://developer.android.com/reference/androidx/car/app/navigation/model/NavigationTemplate` class description for more details on how to receive this callback.

This method may not be called in some car systems.

| Parameters |
|---|---|
| `float x` | x coordinate of the click in pixels |
| `float y` | y coordinate of the click in pixels |

### onFling

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/car-app#1.1.0)

```
@RequiresCarApi(value = 2)
default void onFling(float velocityX, float velocityY)
```

Provides information about a fling touch event on the car screen.

See `https://developer.android.com/reference/androidx/car/app/navigation/model/NavigationTemplate` class description for more details on how to receive this callback.

This method may not be called in some car systems.

| Parameters |
|---|---|
| `float velocityX` | the velocity of this fling measured in pixels per second along the x axis |
| `float velocityY` | the velocity of this fling measured in pixels per second along the y axis |

### onScale

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/car-app#1.1.0)

```
@RequiresCarApi(value = 2)
default void onScale(float focusX, float focusY, float scaleFactor)
```

Provides information about a scale touch event on the car screen.

See `https://developer.android.com/reference/androidx/car/app/navigation/model/NavigationTemplate` class description for more details on how to receive this callback.

This method may not be called in some car systems.

| Parameters |
|---|---|
| `float focusX` | x coordinate of the focal point in pixels. A negative value indicates that the focal point is unavailable. |
| `float focusY` | y coordinate of the focal point in pixels. A negative value indicates that the focal point is unavailable. |
| `float scaleFactor` | the scaling factor from the previous state to the current state during the scale event. This value is defined as (current state) / (previous state) |

### onScroll

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/car-app#1.1.0)

```
@RequiresCarApi(value = 2)
default void onScroll(float distanceX, float distanceY)
```

Provides information about a scroll touch event on the car screen.

See `https://developer.android.com/reference/androidx/car/app/navigation/model/NavigationTemplate` class description for more details on how to receive this callback.

| Parameters |
|---|---|
| `float distanceX` | the distance in pixels along the X axis that has been scrolled since the last touch position during the scroll event |
| `float distanceY` | the distance in pixels along the Y axis that has been scrolled since the last touch position during the scroll event |

### onStableAreaChanged

Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/car-app#1.0.0)

```
default void onStableAreaChanged(@NonNull Rect stableArea)
```

Indicates that the stable area provided by the host has changed.

The surface may be occluded for several reasons including status bar changes, overlays from other apps or dynamic UI within the template (also see `https://developer.android.com/reference/androidx/car/app/SurfaceCallback#onVisibleAreaChanged(android.graphics.Rect)`). The stable area is the visual area that accounts for these occlusions as if they were always present. If the app needs to show more persistent data that do not necessarily adjust based on these dynamic content changes, it should be bounded by this area.

| Parameters |
|---|---|
| `@https://jspecify.dev/docs/api/org/jspecify/annotations/NonNull.html https://developer.android.com/reference/android/graphics/Rect.html stableArea` | inset rectangle of the surface space designated as stable. If `https://developer.android.com/reference/android/graphics/Rect.html#isEmpty()` returns `true` for the stable area, then it is currently unknown |

### onSurfaceAvailable

Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/car-app#1.0.0)

```
default void onSurfaceAvailable(@NonNull SurfaceContainer surfaceContainer)
```

Provides a `https://developer.android.com/reference/androidx/car/app/SurfaceContainer` from the host which is ready for drawing.

This method may be called multiple times if the surface changes characteristics. For instance, the size or DPI may change without the underlying surface being destroyed.

This method is guaranteed to be called before any other methods on this listener.

**Important:** every instance of `https://developer.android.com/reference/android/view/Surface.html` received through this method must be released by calling `https://developer.android.com/reference/android/view/Surface.html#release()`.

| Parameters |
|---|---|
| `@https://jspecify.dev/docs/api/org/jspecify/annotations/NonNull.html https://developer.android.com/reference/androidx/car/app/SurfaceContainer surfaceContainer` | the `https://developer.android.com/reference/androidx/car/app/SurfaceContainer` that is ready for drawing |

### onSurfaceDestroyed

Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/car-app#1.0.0)

```
default void onSurfaceDestroyed(@NonNull SurfaceContainer surfaceContainer)
```

Indicates that the `https://developer.android.com/reference/androidx/car/app/SurfaceContainer` provided by the host will be destroyed after this callback.

| Parameters |
|---|---|
| `@https://jspecify.dev/docs/api/org/jspecify/annotations/NonNull.html https://developer.android.com/reference/androidx/car/app/SurfaceContainer surfaceContainer` | the `https://developer.android.com/reference/androidx/car/app/SurfaceContainer` being destroyed |

### onVisibleAreaChanged

Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/car-app#1.0.0)

```
default void onVisibleAreaChanged(@NonNull Rect visibleArea)
```

Indicates that the visible area provided by the host has changed.

The surface may be occluded for several reasons including status bar changes, overlays from other apps or dynamic UI within a template. `visibleArea` is the area currently guaranteed to not be occluded by any other UI. If the app needs to show critical data, it should be bounded by this area.

| Parameters |
|---|---|
| `@https://jspecify.dev/docs/api/org/jspecify/annotations/NonNull.html https://developer.android.com/reference/android/graphics/Rect.html visibleArea` | the rectangle set to the surface area guaranteed to be visible. If `https://developer.android.com/reference/android/graphics/Rect.html#isEmpty()` returns `true` for the visible area, then it is currently unknown |