SurfaceCallback

public interface SurfaceCallback

A callback for changes on the SurfaceContainer and its attributes.

Summary

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

Provides information about a click event on the car screen.
default void
@RequiresCarApi(value = 2)
onFling(float velocityX, float velocityY)

Provides information about a fling touch event on the car screen.
default void
@RequiresCarApi(value = 2)
onScale(float focusX, float focusY, float scaleFactor)

Provides information about a scale touch event on the car screen.
default void
@RequiresCarApi(value = 2)
onScroll(float distanceX, float distanceY)

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

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

Provides a SurfaceContainer from the host which is ready for drawing.
default void

Indicates that the SurfaceContainer provided by the host will be destroyed after this callback.
default void

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

Public methods

onClick

Added in 1.2.0
@RequiresCarApi(value = 5)
default void onClick(float x, float y)

Provides information about a click event on the car screen.

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

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

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

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

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

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

See 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
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 onVisibleAreaChanged). 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
@NonNull Rect stableArea

inset rectangle of the surface space designated as stable. If isEmpty returns true for the stable area, then it is currently unknown

onSurfaceAvailable

Added in 1.0.0
default void onSurfaceAvailable(@NonNull SurfaceContainer surfaceContainer)

Provides a 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 android.view.Surface received through this method must be released by calling release.

Parameters
@NonNull SurfaceContainer surfaceContainer

the SurfaceContainer that is ready for drawing

onSurfaceDestroyed

Added in 1.0.0
default void onSurfaceDestroyed(@NonNull SurfaceContainer surfaceContainer)

Indicates that the SurfaceContainer provided by the host will be destroyed after this callback.

Parameters
@NonNull SurfaceContainer surfaceContainer

the SurfaceContainer being destroyed

onVisibleAreaChanged

Added in 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
@NonNull Rect visibleArea

the rectangle set to the surface area guaranteed to be visible. If isEmpty returns true for the visible area, then it is currently unknown