如何解决软键盘交互时EditText滚动导致的界面跳动问题

需求 #

• 必须使用android:windowSoftInputMode="adjustPan"
• 通过ViewCompat.setWindowInsetsAnimationCallback和ViewCompat.setOnApplyWindowInsetsListener实现软键盘显示/隐藏的平滑动画交互

问题现象 #

当前实现的代码在EditText不可滚动时，软键盘显示与隐藏的动画效果表现正常，但当EditText内容可滚动时，界面出现跳动问题。

实现代码 #

MainActivity.java #

public class MainActivity extends AppCompatActivity {
    EditText editText;
    LinearLayout toolbar;
    FrameLayout keyboardView;

    private int systemBarsHeight = 0;
    private int keyboardHeightWhenVisible = 0;
    private boolean keyboardVisible = false;

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

        editText = findViewById(R.id.edit_text);
        toolbar = findViewById(R.id.toolbar);
        keyboardView = findViewById(R.id.keyboard_view);

        final View rootView = getWindow().getDecorView().getRootView();

        ViewCompat.setOnApplyWindowInsetsListener(rootView, (v, insets) -> {
            boolean imeVisible = insets.isVisible(WindowInsetsCompat.Type.ime());

            systemBarsHeight = insets.getInsets(WindowInsetsCompat.Type.systemBars()).bottom;

            keyboardVisible = imeVisible;

            if (keyboardVisible) {
                keyboardHeightWhenVisible = insets.getInsets(WindowInsetsCompat.Type.ime()).bottom;
            }

            return ViewCompat.onApplyWindowInsets(v, insets);
        });

        WindowInsetsAnimationCompat.Callback callback = new WindowInsetsAnimationCompat.Callback(
                WindowInsetsAnimationCompat.Callback.DISPATCH_MODE_STOP
        ) {
            @NonNull
            @Override
            public WindowInsetsCompat onProgress(@NonNull WindowInsetsCompat insets, @NonNull List<WindowInsetsAnimationCompat> runningAnimations) {
                // Find an IME animation.
                WindowInsetsAnimationCompat imeAnimation = null;
                for (WindowInsetsAnimationCompat animation : runningAnimations) {
                    if ((animation.getTypeMask() & WindowInsetsCompat.Type.ime()) != 0) {
                        imeAnimation = animation;
                        break;
                    }
                }
                if (imeAnimation != null) {
                    int keyboardViewHeight;
                    if (keyboardVisible) {
                        keyboardViewHeight = (int) (keyboardHeightWhenVisible * imeAnimation.getInterpolatedFraction()) - systemBarsHeight;
                    } else {
                        keyboardViewHeight = (int) (keyboardHeightWhenVisible * (1.0-imeAnimation.getInterpolatedFraction())) - systemBarsHeight;
                    }

                    keyboardViewHeight = Math.max(0, keyboardViewHeight);

                    ViewGroup.LayoutParams params = keyboardView.getLayoutParams();
                    params.height = keyboardViewHeight;
                    keyboardView.setLayoutParams(params);

                    Log.i("CHEOK", "keyboardVisible = " + keyboardVisible + ", keyboardViewHeight = " + keyboardViewHeight);
                }
                return insets;

            }
        };

        ViewCompat.setWindowInsetsAnimationCallback(rootView, callback);
    }
}

activity_main.xml #

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <EditText
        android:id="@+id/edit_text"

        android:padding="16dp"
        android:scrollbars="vertical"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:gravity="top" />

    <LinearLayout
        android:id="@+id/toolbar"

        android:layout_width="match_parent"
        android:layout_height="48dp"
        android:orientation="horizontal"
        android:background="#ffff00" />

    <FrameLayout
        android:id="@+id/keyboard_view"

        android:background="#ff0000"
        android:layout_width="match_parent"
        android:layout_height="0dp" />
</LinearLayout>

效果展示 #

• EditText不可滚动时，软键盘动画正常：
  
• EditText可滚动时，界面出现跳动：
  

问题咨询 #

请问该问题的根本原因是什么，如何解决？

内容的提问来源于stack exchange，提问作者Cheok Yan Cheng