element-android/vector/src/main/res/layout/composer_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<merge 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:layout_width="match_parent"
    android:layout_height="wrap_content"
    tools:constraintSet="@layout/composer_layout_constraint_set_compact"
    tools:parentTag="androidx.constraintlayout.widget.ConstraintLayout">

    <!-- ========================
        /!\ Constraints for this layout are defined in external layout files that are used as constraint set for animation.
        /!\ These 3 files must be modified to stay coherent!
    ======================== -->
    <View
        android:id="@+id/related_message_background"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="?riotx_bottom_nav_background_color"
        tools:ignore="MissingConstraints" />

    <View
        android:id="@+id/related_message_background_top_separator"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="?riotx_bottom_nav_background_border_color"
        tools:ignore="MissingConstraints" />

    <View
        android:id="@+id/related_message_background_bottom_separator"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="?riotx_bottom_nav_background_border_color"
        tools:ignore="MissingConstraints" />

    <ImageView
        android:id="@+id/composerRelatedMessageAvatar"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:contentDescription="@string/avatar"
        tools:ignore="MissingConstraints"
        tools:src="@tools:sample/avatars" />

    <TextView
        android:id="@+id/composerRelatedMessageTitle"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:textStyle="bold"
        tools:ignore="MissingConstraints"
        tools:text="@tools:sample/first_names"
        tools:visibility="gone" />

    <TextView
        android:id="@+id/composerRelatedMessageContent"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:ellipsize="end"
        android:maxLines="3"
        android:textColor="?vctr_message_text_color"
        tools:ignore="MissingConstraints"
        tools:text="@tools:sample/lorem"
        tools:visibility="gone" />

    <ImageView
        android:id="@+id/composerRelatedMessageActionIcon"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:importantForAccessibility="no"
        app:tint="?riotx_text_primary"
        tools:ignore="MissingConstraints,MissingPrefix" />

    <ImageButton
        android:id="@+id/composerRelatedMessageCloseButton"
        android:layout_width="22dp"
        android:layout_height="22dp"
        android:background="?android:attr/selectableItemBackground"
        android:contentDescription="@string/cancel"
        android:src="@drawable/ic_close_round"
        android:tint="@color/riotx_notice"
        tools:ignore="MissingConstraints" />

    <androidx.constraintlayout.widget.Barrier
        android:id="@+id/composer_preview_barrier"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:barrierDirection="bottom"
        app:barrierMargin="8dp"
        app:constraint_referenced_ids="composerRelatedMessageContent,composerRelatedMessageActionIcon"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <ImageButton
        android:id="@+id/attachmentButton"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="?android:attr/selectableItemBackground"
        android:contentDescription="@string/option_send_files"
        android:src="@drawable/ic_attachment"
        tools:ignore="MissingConstraints" />

    <im.vector.app.core.ui.views.ShieldImageView
        android:id="@+id/composerShieldImageView"
        android:layout_width="0dp"
        android:layout_height="0dp"
        tools:ignore="MissingConstraints"
        tools:src="@drawable/ic_shield_black" />

    <im.vector.app.features.home.room.detail.composer.ComposerEditText
        android:id="@+id/composerEditText"
        style="@style/ComposerEditTextStyle"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:nextFocusLeft="@id/composerEditText"
        android:nextFocusUp="@id/composerEditText"
        tools:hint="@string/room_message_placeholder_not_encrypted"
        tools:ignore="MissingConstraints" />

    <ImageButton
        android:id="@+id/composerEmojiButton"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="?android:attr/selectableItemBackground"
        android:contentDescription="@string/a11y_open_emoji_picker"
        android:src="@drawable/ic_insert_emoji"
        tools:ignore="MissingConstraints" />

    <ImageButton
        android:id="@+id/sendButton"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="@drawable/bg_send"
        android:contentDescription="@string/send"
        android:src="@drawable/ic_send"
        tools:ignore="MissingConstraints" />

</merge>