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motionLayout.md

Android - MotionLayout tips and tricks

SOURCE, SOURCE, SOURCE

Make a custom collapsing toolbar with motion layout:

the main res/layout/fragment_product_category file:

<androidx.constraintlayout.motion.widget.MotionLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/fpc_root"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layoutDescription="@xml/fragment_product_category_scene">

    <androidx.appcompat.widget.AppCompatImageView
        android:id="@+id/fpc_back_iv"
        style="@style/NavBarButtonBackStyle2"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"/>

    <androidx.appcompat.widget.AppCompatImageView
        android:id="@+id/fpc_image_iv"
        android:layout_width="0dp"
        android:layout_height="300dp"
        android:scaleType="centerCrop"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/fpc_back_iv" />

    <androidx.appcompat.widget.AppCompatTextView
        android:id="@+id/fpc_title_tv"
        style="@style/Header1"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        app:layout_constraintHorizontal_bias="0"
        android:transformPivotX="0sp"
        app:layout_constraintEnd_toEndOf="@id/fpc_end_guideline"
        app:layout_constraintStart_toStartOf="@id/fpc_start_guideline"
        app:layout_constraintTop_toBottomOf="@id/fpc_back_iv"
        tools:text="Mother &amp; Baby Care"/>

    <androidx.cardview.widget.CardView
        android:id="@+id/fpc_filter_container_cv"
        style="@style/RippleAnimatedCardViewStyle"
        android:layout_width="0dp"
        android:layout_height="42dp"
        android:layout_marginTop="13dp"
        app:cardCornerRadius="5dp"
        app:layout_constraintEnd_toEndOf="@id/fpc_end_guideline"
        app:layout_constraintStart_toStartOf="@id/fpc_start_guideline"
        app:layout_constraintTop_toBottomOf="@id/fpc_image_iv">

        <androidx.constraintlayout.widget.ConstraintLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:paddingStart="15dp"
            android:paddingTop="10dp"
            android:paddingEnd="15dp"
            android:paddingBottom="10dp">

            <androidx.appcompat.widget.AppCompatImageView
                android:layout_width="14dp"
                android:layout_height="18dp"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintTop_toTopOf="parent"
                app:srcCompat="@drawable/ic_filter" />

            <androidx.appcompat.widget.AppCompatTextView
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:text="@string/filter"
                android:textColor="@color/headline"
                android:textSize="14sp"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent" />
        </androidx.constraintlayout.widget.ConstraintLayout>
    </androidx.cardview.widget.CardView>

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/fpc_start_guideline"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        app:layout_constraintGuide_begin="@dimen/common_guideline_start_end"
        app:layout_constraintStart_toStartOf="parent" />

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/fpc_end_guideline"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintGuide_end="@dimen/common_guideline_start_end" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/fpc_product_rv"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:clipChildren="false"
        android:clipToPadding="false"
        android:overScrollMode="never"
        android:paddingStart="14dp"
        android:paddingEnd="14dp"
        android:scrollbars="none"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/fpc_filter_container_cv"
        app:layout_constraintVertical_bias="0" />
</androidx.constraintlayout.motion.widget.MotionLayout>

You can either right click the root ConstraintLayout in design view and choose Convert to MotionLayout or manually create the res/xml/fragment_product_category_scene file:

<?xml version="1.0" encoding="utf-8"?>
<MotionScene 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:motion="http://schemas.android.com/apk/res-auto">

    <Transition
        motion:constraintSetEnd="@id/fpcs_end"
        motion:constraintSetStart="@id/fpcs_start"
        motion:motionInterpolator="easeInOut"
        motion:duration="1000">
        <OnSwipe motion:dragDirection="dragUp"
            motion:touchAnchorSide="top"
            motion:touchAnchorId="@+id/fpc_product_rv" />
    </Transition>

    <ConstraintSet android:id="@+id/fpcs_start">
    </ConstraintSet>

    <ConstraintSet android:id="@+id/fpcs_end">
        <Constraint
            android:id="@+id/fpc_title_tv"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:scaleX="0.58"
            android:scaleY="0.58"
            android:layout_marginStart="43dp"
            android:layout_marginTop="18dp"
            motion:layout_constraintHorizontal_bias="0"
            motion:layout_constraintTop_toTopOf="@id/fpc_back_iv"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintEnd_toEndOf="@id/fpc_end_guideline"/>

        <Constraint
            android:id="@+id/fpc_image_iv"
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:alpha="0"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toBottomOf="@id/fpc_back_iv"
            />

    </ConstraintSet>
</MotionScene>

additional logic to change the typeface of the title:

fpc_root.setTransitionListener(object : TransitionAdapter() {
            override fun onTransitionCompleted(motionLayout: MotionLayout?, currentId: Int) {
                fpc_title_tv.typeface = if (currentId == R.id.fpcs_end) {
                    ResourcesCompat.getFont(requireContext(), R.font.avenir_next_demi_bold)
                } else {
                    ResourcesCompat.getFont(requireContext(), R.font.avenir_next_bold)
                }
            }
        })

Some key notes:

  • Scale TextView works better that using CustomAttribute for textSize but it will mess up the constraint so we need to set the transformPivotX of the view in the layout xml.
  • transformPivotY doesn't works so well so we omit it.
  • center the title using constraint top and bottom to back button doesn't work so we use hard value for margin top.
  • the start scene in motion file can be left blank.
  • we must define every constraint of the animated view in the end scence as it will use it to replace the initial constraints (replace, not taking differences between 2 scenes).

Child View's Visibilty

SOURCE

By default MotionLayout controls the visibility of all views within it. But you can opt out child views by using the app:visibilityMode="ignore" attribute and defining the view in the <ConstraintSet>:

<?xml version="1.0" encoding="utf-8"?>
<MotionScene xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:motion="http://schemas.android.com/apk/res-auto"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <Transition
        ...
    </Transition>

    <ConstraintSet android:id="@+id/start">
        <Constraint android:id="@id/viewId">
            <PropertySet
                app:applyMotionScene="false"
                app:visibilityMode="ignore" />
        </Constraint>
    </ConstraintSet>

    <ConstraintSet
        android:id="@+id/end"
        motion:deriveConstraintsFrom="@id/start">
        ...
    </ConstraintSet>

</MotionScene>

Other Bugs

  1. onSwipe doesn't work with view that have onClick event -> remove onClick event. SOURCE
  2. why onSwipe does not handle correct drag event? -> either reverse the drag direction or introduce a dummy view as touchAnchorId. SOURCE
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