如何使用 java 代码了解 android 活动中 DecorView 的深度？

Question

我知道我们可以通过视觉在 View Hierachy 中看到它，但是如何在代码中获取它？

在布局视图的过程中可以看到如下代码： LayoutInflater.java http://androidxref.com/6.0.1_r10/xref/frameworks/base/core/java/android/view/LayoutInflater.java // Gets the current parser pointer where the node is at the layout level final int depth = parser.getDepth();

我也发中文版的github，https://github.com/JackyAndroid/AndroidInterview-Q-A/issues/22

Answer 1

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ViewGroup decorView = (ViewGroup) getWindow().getDecorView();
        final FrameLayout frameLayout = decorView.findViewById(android.R.id.content);

        View main = frameLayout.getChildAt(0);

        View main1 = findViewById(R.id.main_layout);

        int[] maxDepth = {0};

        dfs(decorView, 1, maxDepth);

        Log.d("gzl", "" + maxDepth[0]);

    }

    private void dfs(View root, int level, int[] maxDepth) {
        maxDepth[0] = Math.max(level, maxDepth[0]);
        if (root instanceof ViewGroup) {
            ViewGroup viewGroup = (ViewGroup) root;
            for (int i = 0; i < viewGroup.getChildCount(); i++) {
                View child = viewGroup.getChildAt(i);
                dfs(child, level + 1, maxDepth);
            }
        }
    }

}

布局/activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
    android:id="@+id/main_layout"
    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"
    tools:context="com.example.gongzelong.decorviewdepthdemo.MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <FrameLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Hello World!"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintLeft_toLeftOf="parent"
                app:layout_constraintRight_toRightOf="parent"
                app:layout_constraintTop_toTopOf="parent"/>

        </FrameLayout>

    </LinearLayout>

</android.support.constraint.ConstraintLayout>