# Class Index # Class Index These are the API classes. See all[API packages](https://developer.android.com/reference/androidx/constraintlayout/packages). ## A |----------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------| | [Animatable](https://developer.android.com/reference/androidx/constraintlayout/motion/widget/Animatable) | A helper interface allowing MotionLayout to directly drive custom views | ## B |---------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------| | [Barrier](https://developer.android.com/reference/androidx/constraintlayout/widget/Barrier) | **Added in 1.1** A Barrier references multiple widgets as input, and creates a virtual guideline based on the most extreme widget on the specified side. | ## C |-----------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [Carousel](https://developer.android.com/reference/androidx/constraintlayout/helper/widget/Carousel) | Carousel works within a MotionLayout to provide a simple recycler like pattern. | | [Carousel.Adapter](https://developer.android.com/reference/androidx/constraintlayout/helper/widget/Carousel.Adapter) | Adapter for a Carousel | | [CircularFlow](https://developer.android.com/reference/androidx/constraintlayout/helper/widget/CircularFlow) | CircularFlow virtual layout. | | [ConstraintLayout](https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintLayout) | A`ConstraintLayout`is a[ViewGroup](https://developer.android.com/reference/android/view/ViewGroup.html)which allows you to position and size widgets in a flexible way. | | [ConstraintLayout.LayoutParams](https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintLayout.LayoutParams) | This class contains the different attributes specifying how a view want to be laid out inside a[ConstraintLayout](https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintLayout). | | [ConstraintProperties](https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintProperties) | **Added in 2.0** ConstraintProperties provides an easy to use api to update the layout params of[ConstraintLayout](https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintLayout)children | | [ConstraintsChangedListener](https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintsChangedListener) | **Added in 2.0** Callbacks on state change | | [ConstraintSet](https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintSet) | This class allows you to define programmatically a set of constraints to be used with[ConstraintLayout](https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintLayout). | | [CustomSupport](https://developer.android.com/reference/androidx/constraintlayout/motion/utils/CustomSupport) | | ## F |------------------------------------------------------------------------------------------------------------|-----------------------------------------------------| | [FloatLayout](https://developer.android.com/reference/androidx/constraintlayout/motion/widget/FloatLayout) | Add support to views that do floating point layout. | | [Flow](https://developer.android.com/reference/androidx/constraintlayout/helper/widget/Flow) | Flow VirtualLayout. | ## G |-------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [Group](https://developer.android.com/reference/androidx/constraintlayout/widget/Group) | Control the visibility and elevation of the referenced views**Added in 1.1** This class controls the visibility of a set of referenced widgets. | | [Guideline](https://developer.android.com/reference/androidx/constraintlayout/widget/Guideline) | Utility class representing a Guideline helper object for[ConstraintLayout](https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintLayout). | ## I |-----------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------| | [ImageFilterButton](https://developer.android.com/reference/androidx/constraintlayout/utils/widget/ImageFilterButton) | An AppCompatImageButton that can display, combine and filter images. | | [ImageFilterView](https://developer.android.com/reference/androidx/constraintlayout/utils/widget/ImageFilterView) | An ImageView that can display, combine and filter images. | ## L |------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [Layer](https://developer.android.com/reference/androidx/constraintlayout/helper/widget/Layer) | Layer adds the ability to move and rotate a group of views as if they were contained in a viewGroup**Added in 2.0**Methods such as setRotation(float) rotate all views about a common center. | ## M |----------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [MockView](https://developer.android.com/reference/androidx/constraintlayout/utils/widget/MockView) | A view that is useful for prototyping layouts. | | [MotionButton](https://developer.android.com/reference/androidx/constraintlayout/utils/widget/MotionButton) | A MotionButton is an AppCompatButton that can round its edges. | | [MotionEffect](https://developer.android.com/reference/androidx/constraintlayout/helper/widget/MotionEffect) | MotionHelper that automatically inserts keyframes for views moving in a given direction, out of: - NORTH - SOUTH - EAST - WEST By default, will pick the opposite of the dominant direction (e.g. | | [MotionHelperInterface](https://developer.android.com/reference/androidx/constraintlayout/motion/widget/MotionHelperInterface) | | | [MotionInterpolator](https://developer.android.com/reference/androidx/constraintlayout/motion/widget/MotionInterpolator) | | | [MotionLabel](https://developer.android.com/reference/androidx/constraintlayout/utils/widget/MotionLabel) | This class is designed to create complex animated single line text in MotionLayout. | | [MotionLayout](https://developer.android.com/reference/androidx/constraintlayout/motion/widget/MotionLayout) | A subclass of ConstraintLayout that supports animating between various states**Added in 2.0** A`MotionLayout`is a subclass of[ConstraintLayout](https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintLayout)which supports transitions between between various states ([ConstraintSet](https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintSet)) defined in[MotionScene](https://developer.android.com/reference/androidx/constraintlayout/motion/widget/MotionScene)s. | | [MotionLayout.MotionTracker](https://developer.android.com/reference/androidx/constraintlayout/motion/widget/MotionLayout.MotionTracker) | Subclasses can override to build test frameworks | | [MotionLayout.TransitionListener](https://developer.android.com/reference/androidx/constraintlayout/motion/widget/MotionLayout.TransitionListener) | Listener for monitoring events about TransitionLayout. | | [MotionPlaceholder](https://developer.android.com/reference/androidx/constraintlayout/helper/widget/MotionPlaceholder) | | | [MotionScene](https://developer.android.com/reference/androidx/constraintlayout/motion/widget/MotionScene) | The information to transition between multiple ConstraintSets This Class is meant to be used from XML | | [MotionScene.Transition](https://developer.android.com/reference/androidx/constraintlayout/motion/widget/MotionScene.Transition) | Transition defines the interaction from one state to another. | | [MotionScene.Transition.TransitionOnClick](https://developer.android.com/reference/androidx/constraintlayout/motion/widget/MotionScene.Transition.TransitionOnClick) | | | [MotionTelltales](https://developer.android.com/reference/androidx/constraintlayout/utils/widget/MotionTelltales) | A view that is useful for prototyping Views that will move in MotionLayout. | ## O |----------------------------------------------------------------------------------------------------|----------------------------------------| | [OnSwipe](https://developer.android.com/reference/androidx/constraintlayout/motion/widget/OnSwipe) | Container for holding swipe infomation | ## P |-----------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------| | [Placeholder](https://developer.android.com/reference/androidx/constraintlayout/widget/Placeholder) | **Added in 1.1** A`Placeholder`provides a virtual object which can position an existing object. | ## R |---------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [ReactiveGuide](https://developer.android.com/reference/androidx/constraintlayout/widget/ReactiveGuide) | Utility class representing a reactive Guideline helper object for[ConstraintLayout](https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintLayout). | ## S |-------------------------------------------------------------------------------------------------------------------------------------------------|---------------| | [SharedValues](https://developer.android.com/reference/androidx/constraintlayout/widget/SharedValues) | Shared values | | [SharedValues.SharedValuesListener](https://developer.android.com/reference/androidx/constraintlayout/widget/SharedValues.SharedValuesListener) | | ## T |------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [TransitionAdapter](https://developer.android.com/reference/androidx/constraintlayout/motion/widget/TransitionAdapter) | | | [TransitionBuilder](https://developer.android.com/reference/androidx/constraintlayout/motion/widget/TransitionBuilder) | Builder class for creating[MotionScene.Transition](https://developer.android.com/reference/androidx/constraintlayout/motion/widget/MotionScene.Transition)programmatically. | ## V |--------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [ViewSpline](https://developer.android.com/reference/androidx/constraintlayout/motion/utils/ViewSpline) | | | [ViewSpline.CustomSet](https://developer.android.com/reference/androidx/constraintlayout/motion/utils/ViewSpline.CustomSet) | | | [ViewSpline.PathRotate](https://developer.android.com/reference/androidx/constraintlayout/motion/utils/ViewSpline.PathRotate) | | | [ViewState](https://developer.android.com/reference/androidx/constraintlayout/motion/utils/ViewState) | Stores the bounds and rotation of a widget | | [ViewTransition](https://developer.android.com/reference/androidx/constraintlayout/motion/widget/ViewTransition) | Provides a support fortag it Parses tag it implement the transition it will update ConstraintSet or sets For asynchronous it will create and drive a MotionController. | | [ViewTransitionController](https://developer.android.com/reference/androidx/constraintlayout/motion/widget/ViewTransitionController) | Container for ViewTransitions. |