ConstraintSets in MotionLayout without copy-pasting attributes

Question

I want to use MotionLayout for animations without any code, just XML.

When I make a ConstraintSets it works fine, if I use all constraint attributes (like layout_width, layout_constraintEnd_toEndOf etc), but I don't change them. Can I use the attributes, which I really change in animation only?

Another question connected to this: can I make a transition from any state? Fоr example I want to manage three case with three buttons. I can do it in six transitions (each state to others), but may be it is possible to make only three ones?

Answer 1

Short answer is yes & mostly.

Long answer...

In a MotionScene CostraitnSets are "derived" from the layout. You can also derive from another ConstraintSet. You can override attributes at various levels of granularity.

Simple:

<ConstraintSet>
<Constraint androdi:id="@+id/a 
  motion:top_margin="23dp"
  ...
  />
</ConstraintSet>

Simple only defined Constraint tags override the layout

Sectioned:

<ConstraintSet>
<Constraint androdi:id="@+id/a">
  <Layout motion:top_margin="23dp" ...\>
  <PropertySet android:alpha="0.3" ...\>
  <Transform android:scaleX="1.3" ...\>
  <Motion motion:transitionEasing="linear ...\>
 
  </ConstraintSet>
</ConstraintSet>

Only sections are replace if you have a section all layout tags are replaced

ConstraintOverrid:

<ConstraintSet>
<ConstraintOVerride androdi:id="@+id/a" 
      motion:top_margin="23dp" 
      android:alpha="0.3"...\>
 
  </ConstraintSet>
</ConstraintSet>

Individual attributes are changed but you cannot use "anchor attributes" such as layout_constraintTop_ToTopOf

Second Question Medium answer: you can transition to any State Typically transition are given to and from

 <Transition
        motion:constraintSetEnd="@+id/end"
        motion:constraintSetStart="@id/start"
        motion:duration="6000">
        <OnClick motion:targetId="@+id/button1" />

You can leave out the motion:constraintSetStart.

 <Transition
        motion:constraintSetEnd="@+id/end"
        motion:duration="6000">
        <OnClick motion:targetId="@+id/button1" />

Which will mean on click can go to this state from any state. Even in transition between states! You can see code like this here