Thursday, April 4, 2019

ConstraintLayout 2.0.0 alpha 4

We just released ConstraintLayout 2.0.0 alpha 4. It’s available from the google maven repository:
dependencies {
  implementation 'com.android.support.constraint:constraint-layout:2.0.0-alpha4'
}
or if using the AndroidX packages:
dependencies {
   implementation 'androidx.constraintlayout:constraintlayout:2.0.0-alpha4'
}

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

Changes

This release contains various bug fixes and performance improvements:

ConstraintLayout

  • Dynamic feature modules fix when using barriers and helpers
  • Chain fixes (bias with gone elements, RTL fixes)
  • Barrier fixes (RTL behavior, now can use a margin on a Barrier)
  • match_constraints fixes (max support, bias, percent…)
  • setTag/getTag on Group was fixed
  • ConstraintSet::setGoneMargin() for Top/Bottom
  • baseline behavior on gone
  • wrap behavior fixes

MotionLayout

  • Visibility fixes
  • Flickering issues / jump issues fixed
  • Various match_constraints issues fixed
  • Custom color interpolation (alpha was incorrectly handled)
  • Better barrier / helpers support

New Features


We also added several new features to MotionLayout:
  • Richer behaviors for OnClick actions
  • CustomAttributes support for customPixelDimensions
  • ImageFilterView overlay support
  • KeyTrigger collision support
  • Attributes rename

OnClick

OnClick now supports a richer set of behaviours
  • Toggle -  animate back and forth ( = transitionToEnd|transitionToStart)
  • transitionToEnd - animate to the end state
  • transitionToStart - animate to the start state
  • jumpToEnd - Jump to the end state
  • jumpToStart - Jump to the start state
These can be combined to allow jumping to the end but smooth transition to the start.
<OnClick motion:targetId="@id/button_west"
  motion:clickAction="transitionToEnd|transitionToStart"/>
<OnClick motion:targetId="@id/button_south"
  motion:clickAction="jumpToStart|transitionToEnd"/>

CustomPixelDimensions

Used when the method takes pixels such as setTextSize(...)
<CustomAttribute
  motion:attributeName="textSize"
  motion:customPixelDimension="2dp" />

ImageFilterView


New tag overlay - true(default) / false affects crossfade behaviour set to false to crossfade transparent objects.

KeyTrigger collision support


You can fire a  KeyTrigger on collision with another view.
<KeyTrigger
  motion:motionTarget="@id/button"
  motion:motion_triggerOnCollision ="@id/button2"
  motion:onPositiveCross="callOnClick"
  motion:motion_postLayoutCollision="true"
  />
  • motion_triggerOnCollision - Id of view to check collision with
  • motion_postLayoutCollision tested including layout or layout+transform
  • onPositiveCross Trigger on entering collision state
  • onNegativeCross Trigger on leaving the collision state
  • onCross Trigger on entering or leaving the collision state

Rename

To minimize the chance of name clashes with 3p libraries we have renamed attributes that were clashing or had a good chance of clashing.

Old
New
<OnClick
  app:mode="toggle"
  app:target="@+id/button" />
<OnClick
  app:clickAction="toggle"
  app:targetId="@+id/button" />
<Transition
  motion:constraintSetStart="@+id/start"
  motion:constraintSetEnd="@+id/end"
  motion:nterpolator="easeIn"
  motion:duration="1000">
<Transition
  motion:constraintSetStart="@+id/start"
  motion:constraintSetEnd="@+id/end"
  motion:motionInterpolator="easeIn"
  motion:duration="1000">
  motion:duration="123"
  motion:defaultDuration="123"
  motion:interpolator="easeInOut"
  motion:motionInterpolator="easeInOut"
  motion:progress="0.3"
  motion:motionProgress="0.3"
 In <OnClick>
 motion:target="@+id/button"
In <OnClick>
motion:targetId="@+id/button"
 In <Key*
 motion:target="0.3"
  In <Key*
motion:motionTarget="0.3"
  motion:elevation="0.3"
  motion:rotation="0.3"
  motion:rotationX="0.3"
  motion:rotationY="0.3"
  motion:scaleX="0.3"
  motion:scaleY="0.3"
  motion:transformPivotX="0.3"
  motion:transformPivotY="0.3"
  motion:translationX="0.3"
  motion:translationY="0.3"
  motion:translationZ="0.3"
  android:elevation="0.3"
  android:rotation="0.3"
  android:rotationX="0.3"
  android:rotationY="0.3"
  android:scaleX="0.3"
  android:scaleY="0.3"
  android:transformPivotX="0.3"
  android:transformPivotY="0.3"
  android:translationX="0.3"
  android:translationY="0.3"
  android:translationZ="0.3"
  motion:transitionPathRotate="0.3"
  motion:motionPathRotate="0.3"