<?xml version="1.0" encoding="utf-8"?>
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"
tools:context=".MainActivity">
android:id="@+id/c_view1"
android:layout_height="wrap_content"
android:layout_width="match_parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:layout_gravity="fill"
android:gravity="end"
android:layout_marginStart="5dp"
android:layout_marginEnd="5dp"
android:layout_marginTop="5dp"
android:background="#FFCCCC"
android:text="0"
android:textSize="50sp" />
android:layout_height="wrap_content"
android:layout_width="0dp"
app:layout_constraintTop_toBottomOf="@id/c_view1"
app:layout_constraintStart_toStartOf="@id/c_view1"
app:layout_constraintEnd_toStartOf="@id/btn_qk"
android:layout_marginEnd="5dp"
android:textSize="40sp"
android:id="@+id/btn_ht"
android:text="回退" />
android:id="@+id/btn_qk"
android:layout_height="0dp"
android:layout_width="0dp"
app:layout_constraintEnd_toEndOf="@id/c_view1"
app:layout_constraintStart_toEndOf="@id/btn_ht"
app:layout_constraintTop_toBottomOf="@id/c_view1"
app:layout_constraintBottom_toBottomOf="@id/btn_ht"
android:textSize="40sp"
android:text="清空" />
