Android背景填充半个屏幕

public class HalfScreenBackgroundView extends View {
    private Paint paint;

    public HalfScreenBackgroundView(Context context) {
        super(context);
        init();
    }

    public HalfScreenBackgroundView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    private void init() {
        paint = new Paint();
        paint.setColor(Color.BLUE); // 设置背景颜色
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        int height = getHeight();
        int width = getWidth();
        canvas.drawRect(0, 0, width, height / 2, paint); // 绘制半个屏幕的背景
    }
}

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.example.yourapp.HalfScreenBackgroundView
        android:id="@+id/halfScreenBackground"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toTopOf="@+id/contentView" />

    <LinearLayout
        android:id="@+id/contentView"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:orientation="vertical"
        app:layout_constraintTop_toBottomOf="@id/halfScreenBackground"
        app:layout_constraintBottom_toBottomOf="parent">

        <!-- 这里放置你的内容视图 -->

    </LinearLayout>

</androidx.constraintlayout.widget.ConstraintLayout>