com.facebook.litho.annotations

Annotation Type MountSpec

@Retention(value=RUNTIME)
 @Documented
public @interface MountSpec

A class that is annotated with this annotation will be used to create a component that renders something, in the form of either a Drawable or a View.

A class that is annotated with MountSpec must implement a method with the OnCreateMountContent annotation. It may also implement methods with the following annotations:

• OnLoadStyle
• OnEvent
• OnPrepare
• OnMeasure
• OnBoundsDefined
• OnMount
• OnBind
• OnUnbind
• OnUnmount
• ShouldUpdate

If you wish to create a component that is a composition of other components, then use LayoutSpec instead.

For example:

 @MountSpec
 public class MyComponentSpec {

   @OnCreateMountContent
   MyDrawable onCreateMountContent(Context context) {
     return new MyDrawable(context);
   }

   @OnMount
   void onMount(
       ComponentContext c,
       MyDrawable myDrawable,
       @Prop MyProp prop) {
     myDrawable.setMyProp(prop);
   }
 }

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
boolean	canPreallocate
java.lang.Class<?>[]	events
boolean	hasChildLithoViews
boolean	isPublic
boolean	isPureRender
int	poolSize
java.lang.Class<?>[]	triggers
java.lang.String	value Class name of the generated component.

Element Detail

value

public abstract java.lang.String value

Class name of the generated component. When not provided defaults to name of the annotated class sans the "Spec" suffix. E.g. "MyComponentSpec" to "MyComponent".

In order to avoid confusion, this should only be used if you have a very good reason for it. For instance to avoid naming collisions.

Default:

""

isPublic

public abstract boolean isPublic

Returns:

Boolean indicating whether the generated class should be public. If not, it will be package-private.

Default:

true

isPureRender

public abstract boolean isPureRender

Returns:

Boolean indicating whether the component implements a pure render function. If this is true and the Component didn't change during an update of the ComponentTree measurements and LayoutOutputs will be reused instead of being calculated again.

Default:

false

hasChildLithoViews

public abstract boolean hasChildLithoViews

Returns:

boolean indicating whether this mount spec has child LithoViews. If this is true then we need to ensure that these child views are correctly incrementally mounted.

Default:

false

events

public abstract java.lang.Class<?>[] events

Returns:

List of event POJOs this component can dispatch. Used to generate event dispatch methods.

Default:

{}

poolSize

public abstract int poolSize

Returns:

The max number of preallocated Mount objects we want to keep in the pools for this type of MountSpec

Default:

3

canPreallocate

public abstract boolean canPreallocate

Returns:

whether the component generated from this MountSpec will be preallocated.

Default:

false

triggers

public abstract java.lang.Class<?>[] triggers

Returns:

List of trigger POJOs this component can dispatch. Used to generate trigger creation methods.

Default:

{}