Android Studio Release Updates: ConstraintLayout 2.0.0 beta 1

We are happy to announce the release of ConstraintLayout 2.0 beta 1. APIs are now considered stable for the remaining of the 2.0 release cycle.

It’s available from the google maven repository:

dependencies {

implementation 'com.android.support.constraint:constraint-layout:2.0.0-beta1'

}

or if using the AndroidX packages:

dependencies {

implementation 'androidx.constraintlayout:constraintlayout:2.0.0-beta1'

}

Documentation is available on https://developer.android.com/reference/android/support/constraint/classes.html

Examples are available on https://github.com/googlesamples/android-ConstraintLayoutExamples

New in Beta1

Flow virtual layout

bug fixes (padding behavior + wrap content behavior)
addition of addView()/removeView() on ConstraintHelper, allowing runtime addition/removal of refrenced views

MotionLayout

Enhanced Staggered API

Previously staggered had just one attributes in <Transition>: staggered=”float”. It would stagger the animation transition of all objects based on their Manhattan distance from the top left corner.

You can now define in a ConstraintSet:

<Constraint

android:id="@id/view1">

<Motion

motion:motionStagger="1"/>

</Constraint>

<Constraint

android:id="@id/view2"

….

motion:motionStagger="1" />

</ConstraintSet>

This assigns a floating point stagger value to each view tagged with motionStagger (Views not tagged are ignored). The view with the lowest floating point value (V0) is started first. The view with the highest floating point value (Vn) is started last.

Let

The motionStagger value is S(Vi)
The overall stagger value is stagger (from 0.0 - 1.0)
The duration of the animation is duration

The views animation duration = duration * (1 - stagger)
The view starts animating at duration * (stagger - stagger * (S(Vi) - S(V0)) / (S(Vn) - S(V0)))

OnSwipe onTouchUp Modes

We changed removed the attribute “autoComplete” and changed to onTouchUp

motion:onTouchUp=”mode"

onTouchUp has the following modes:

autoComplete - normal default behavior
autoCompleteToStart - same as normal engine but always goes to start.
autoCompleteToEnd - same as normal engine but always goes to start.
stop - stop where you are
decelerate - linear drop in velocity allowing hitting the start or end with velocity
decelerateAndComplete - like decelerate but if insufficient velocity to end switch to autoComplete

motion:onTouchUp="decelerateAndComplete"

visibilityMode

We added the ability to ignore the visibility of a view. This allows the applications to control the visibility and not have MotionLayout set it.

motion:visibilityMode="ignore"

TransitionListener Callback interface change

One new API was added to the callback to allow you to programmatically block a transition.

public interface TransitionListener {

public void onTransitionStarted(MotionLayout motionLayout,

int startId, int endId);

void onTransitionChange(MotionLayout motionLayout,

int startId, int endId,

float progress);

void onTransitionCompleted(MotionLayout motionLayout, int currentId);

public void onTransitionTrigger(MotionLayout motionLayout, int triggerId, boolean positive,

float progress);

boolean allowsTransition(MotionScene.Transition transition);

}

Attribute changes

In general we adopted a policy that if there is an android attribute we use it.

Old	new
app:layout_width app:layout_height app:layout_marginStart app:layout_marginBottom app:layout_marginTop app:layout_marginEnd app:layout_marginLeft app:layout_marginRight app:visibility app:alpha	android:layout_width android:layout_height android:layout_marginBottom android:layout_marginBottom android:layout_marginTop android:layout_marginEnd android:layout_marginLeft android:layout_marginRight android:visibility android:alpha

Thursday, May 9, 2019

ConstraintLayout 2.0.0 beta 1