arcanechat-android/res/layout/registration_activity.xml

<?xml version="1.0" encoding="utf-8"?>
<ScrollView 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="match_parent"
    android:background="@color/white"
    android:fillViewport="true"
    tools:context=".RegistrationActivity">

    <android.support.constraint.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:animateLayoutChanges="true">

        <android.support.constraint.Guideline
            android:id="@+id/guideline_root_start"
            android:layout_width="wrap_content"
            android:layout_height="16dp"
            android:orientation="vertical"
            app:layout_constraintGuide_begin="16dp" />

        <android.support.constraint.Guideline
            android:id="@+id/guideline_root_end"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            app:layout_constraintGuide_end="16dp" />

        <TextView
            android:id="@+id/header"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="@color/signal_primary"
            android:gravity="center"
            android:padding="16dp"
            android:text="@string/RegistrationActivity_header"
            android:textColor="@color/white"
            android:textSize="20sp"
            android:textStyle="bold" />

        <TextView
            android:id="@+id/sub_header"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:background="@color/signal_primary"
            android:gravity="center"
            android:paddingBottom="48dp"
            android:paddingLeft="16dp"
            android:paddingRight="16dp"
            android:text="@string/RegistrationActivity_subheader"
            android:textColor="@color/white"
            app:layout_constraintTop_toBottomOf="@id/header" />

        <android.support.v4.widget.Space
            android:id="@+id/fab_spacer"
            android:layout_width="wrap_content"
            android:layout_height="28dp"
            app:layout_constraintTop_toBottomOf="@id/sub_header" />

        <android.support.design.widget.FloatingActionButton
            android:id="@+id/fab"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/ic_forum_white_24dp"
            android:tint="@color/grey_700"
            app:backgroundTint="@color/white"
            app:elevation="1dp"
            app:fabSize="normal"
            app:layout_constraintBottom_toBottomOf="@id/fab_spacer"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent" />

        <android.support.design.widget.TextInputLayout
            android:id="@+id/email"
            android:layout_width="0dp"
            android:layout_height="58dp"
            app:errorEnabled="true"
            app:layout_constraintEnd_toEndOf="@id/guideline_root_end"
            app:layout_constraintStart_toStartOf="@id/guideline_root_start"
            app:layout_constraintTop_toBottomOf="@id/fab">

            <android.support.design.widget.TextInputEditText
                android:id="@+id/email_text"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:hint="@string/email_address"
                android:inputType="textEmailAddress" />

        </android.support.design.widget.TextInputLayout>

        <android.support.design.widget.TextInputLayout
            android:id="@+id/password"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            app:layout_constraintEnd_toEndOf="@id/guideline_root_end"
            app:layout_constraintStart_toStartOf="@id/guideline_root_start"
            app:layout_constraintTop_toBottomOf="@id/email"
            app:passwordToggleEnabled="true">

            <android.support.design.widget.TextInputEditText
                android:id="@+id/password_text"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:hint="@string/password"
                android:inputType="textPassword" />

        </android.support.design.widget.TextInputLayout>

        <android.support.constraint.Group
            android:id="@+id/advanced_group"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:visibility="gone"
            app:constraint_referenced_ids="inbox, imap_login, imap_server, imap_port, imap_security_label, imap_security, outbox_view_spacer_top,
            outbox, smtp_login, smtp_password, smtp_server, smtp_port, smtp_security_label, smtp_security, register_button_spacer_top" />

        <TextView
            android:id="@+id/advanced_text"
            android:layout_width="wrap_content"
            android:layout_height="48dp"
            android:gravity="center"
            android:text="@string/advanced"
            android:textColor="@color/blue_400"
            app:layout_constraintEnd_toStartOf="@+id/advanced_icon"
            app:layout_constraintHorizontal_chainStyle="packed"
            app:layout_constraintStart_toStartOf="@id/guideline_root_start"
            app:layout_constraintTop_toBottomOf="@id/password" />

        <ImageView
            android:id="@+id/advanced_icon"
            android:layout_width="40dp"
            android:layout_height="40dp"
            android:contentDescription="@string/icon"
            android:padding="8dp"
            android:src="@drawable/ic_menu_remove_holo_light"
            android:tint="@color/blue_400"
            app:layout_constraintBottom_toTopOf="@+id/inbox"
            app:layout_constraintEnd_toStartOf="@+id/guideline_root_end"
            app:layout_constraintHorizontal_chainStyle="packed"
            app:layout_constraintStart_toEndOf="@id/advanced_text"
            app:layout_constraintTop_toBottomOf="@id/password" />

        <TextView
            android:id="@+id/inbox"
            android:layout_width="wrap_content"
            android:layout_height="24dp"
            android:gravity="center"
            android:text="@string/RegistrationActivity_inbox"
            app:layout_constraintStart_toStartOf="@id/guideline_root_start"
            app:layout_constraintTop_toBottomOf="@id/advanced_text" />

        <android.support.design.widget.TextInputLayout
            android:id="@+id/imap_login"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            app:layout_constraintEnd_toEndOf="@id/guideline_root_end"
            app:layout_constraintStart_toStartOf="@id/guideline_root_start"
            app:layout_constraintTop_toBottomOf="@id/inbox">

            <android.support.design.widget.TextInputEditText
                android:id="@+id/imap_login_text"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:hint="@string/RegistrationActivity_imap_login" />

        </android.support.design.widget.TextInputLayout>

        <android.support.design.widget.TextInputLayout
            android:id="@+id/imap_server"
            android:layout_width="0dp"
            android:layout_height="58dp"
            app:errorEnabled="true"
            app:layout_constraintEnd_toEndOf="@id/guideline_root_end"
            app:layout_constraintStart_toStartOf="@id/guideline_root_start"
            app:layout_constraintTop_toBottomOf="@id/imap_login">

            <android.support.design.widget.TextInputEditText
                android:id="@+id/imap_server_text"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:hint="@string/RegistrationActivity_imap_server" />

        </android.support.design.widget.TextInputLayout>

        <android.support.design.widget.TextInputLayout
            android:id="@+id/imap_port"
            android:layout_width="0dp"
            android:layout_height="58dp"
            app:errorEnabled="true"
            app:layout_constraintEnd_toEndOf="@id/guideline_root_end"
            app:layout_constraintStart_toStartOf="@id/guideline_root_start"
            app:layout_constraintTop_toBottomOf="@id/imap_server">

            <android.support.design.widget.TextInputEditText
                android:id="@+id/imap_port_text"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:hint="@string/RegistrationActivity_imap_port"
                android:inputType="number" />

        </android.support.design.widget.TextInputLayout>

        <TextView
            android:id="@+id/imap_security_label"
            style="@style/TextAppearance.AppCompat.Caption"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/RegistrationActivity_imap_security"
            app:layout_constraintEnd_toEndOf="@id/guideline_root_end"
            app:layout_constraintStart_toStartOf="@id/guideline_root_start"
            app:layout_constraintTop_toBottomOf="@id/imap_port" />

        <Spinner
            android:id="@+id/imap_security"
            android:layout_width="0dp"
            android:layout_height="48dp"
            android:entries="@array/server_security"
            app:layout_constraintEnd_toEndOf="@id/guideline_root_end"
            app:layout_constraintStart_toStartOf="@id/guideline_root_start"
            app:layout_constraintTop_toBottomOf="@id/imap_security_label" />

        <android.support.v4.widget.Space
            android:id="@+id/outbox_view_spacer_top"
            android:layout_width="wrap_content"
            android:layout_height="16dp"
            app:layout_constraintTop_toBottomOf="@id/imap_security" />

        <TextView
            android:id="@+id/outbox"
            android:layout_width="wrap_content"
            android:layout_height="24dp"
            android:gravity="center"
            android:text="@string/RegistrationActivity_outbox"
            app:layout_constraintStart_toStartOf="@id/guideline_root_start"
            app:layout_constraintTop_toBottomOf="@id/outbox_view_spacer_top" />

        <android.support.design.widget.TextInputLayout
            android:id="@+id/smtp_login"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            app:layout_constraintEnd_toEndOf="@id/guideline_root_end"
            app:layout_constraintStart_toStartOf="@id/guideline_root_start"
            app:layout_constraintTop_toBottomOf="@id/outbox">

            <android.support.design.widget.TextInputEditText
                android:id="@+id/smtp_login_text"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:hint="@string/RegistrationActivity_smtp_login" />

        </android.support.design.widget.TextInputLayout>

        <android.support.design.widget.TextInputLayout
            android:id="@+id/smtp_password"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            app:layout_constraintEnd_toEndOf="@id/guideline_root_end"
            app:layout_constraintStart_toStartOf="@id/guideline_root_start"
            app:layout_constraintTop_toBottomOf="@id/smtp_login"
            app:passwordToggleEnabled="true">

            <android.support.design.widget.TextInputEditText
                android:id="@+id/smtp_password_text"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:hint="@string/RegistrationActivity_smtp_password"
                android:inputType="textPassword" />

        </android.support.design.widget.TextInputLayout>

        <android.support.design.widget.TextInputLayout
            android:id="@+id/smtp_server"
            android:layout_width="0dp"
            android:layout_height="58dp"
            app:errorEnabled="true"
            app:layout_constraintEnd_toEndOf="@id/guideline_root_end"
            app:layout_constraintStart_toStartOf="@id/guideline_root_start"
            app:layout_constraintTop_toBottomOf="@id/smtp_password">

            <android.support.design.widget.TextInputEditText
                android:id="@+id/smtp_server_text"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:hint="@string/RegistrationActivity_smtp_server" />

        </android.support.design.widget.TextInputLayout>

        <android.support.design.widget.TextInputLayout
            android:id="@+id/smtp_port"
            android:layout_width="0dp"
            android:layout_height="58dp"
            app:errorEnabled="true"
            app:layout_constraintEnd_toEndOf="@id/guideline_root_end"
            app:layout_constraintStart_toStartOf="@id/guideline_root_start"
            app:layout_constraintTop_toBottomOf="@id/smtp_server">

            <android.support.design.widget.TextInputEditText
                android:id="@+id/smtp_port_text"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:hint="@string/RegistrationActivity_smtp_port"
                android:inputType="number" />

        </android.support.design.widget.TextInputLayout>

        <TextView
            android:id="@+id/smtp_security_label"
            style="@style/TextAppearance.AppCompat.Caption"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/RegistrationActivity_smtp_security"
            app:layout_constraintEnd_toEndOf="@id/guideline_root_end"
            app:layout_constraintStart_toStartOf="@id/guideline_root_start"
            app:layout_constraintTop_toBottomOf="@id/smtp_port" />

        <Spinner
            android:id="@+id/smtp_security"
            android:layout_width="0dp"
            android:layout_height="48dp"
            android:entries="@array/server_security"
            app:layout_constraintEnd_toEndOf="@id/guideline_root_end"
            app:layout_constraintStart_toStartOf="@id/guideline_root_start"
            app:layout_constraintTop_toBottomOf="@id/smtp_security_label" />

        <android.support.v4.widget.Space
            android:id="@+id/register_button_spacer_top"
            android:layout_width="wrap_content"
            android:layout_height="16dp"
            app:layout_constraintTop_toBottomOf="@id/smtp_security" />

        <com.dd.CircularProgressButton
            android:id="@+id/register_button"
            android:layout_width="0dp"
            android:layout_height="50dp"
            android:layout_marginEnd="16dp"
            android:layout_marginStart="16dp"
            android:background="@color/signal_primary"
            android:textColor="@color/white"
            app:cpb_colorIndicator="@color/white"
            app:cpb_colorProgress="@color/textsecure_primary"
            app:cpb_cornerRadius="50dp"
            app:cpb_selectorIdle="@drawable/progress_button_state"
            app:cpb_textIdle="@string/registration_activity__register"
            app:layout_constraintEnd_toEndOf="@id/guideline_root_end"
            app:layout_constraintStart_toStartOf="@id/guideline_root_start"
            app:layout_constraintTop_toBottomOf="@id/register_button_spacer_top" />

        <android.support.v4.widget.Space
            android:layout_width="wrap_content"
            android:layout_height="16dp"
            app:layout_constraintTop_toBottomOf="@id/register_button" />

    </android.support.constraint.ConstraintLayout>

</ScrollView>