为何给BottomSheetDialogFragment设置样式后，键盘平滑动画消失？

问题背景 #

我实现了一个带有平滑键盘动画的BottomSheetDialogFragment，重要说明：为实现该平滑动画，应用主题使用了Theme.MaterialComponents.DayNight.DarkActionBar。

带有平滑键盘动画的实现代码 #

import android.app.Dialog
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.view.WindowManager
import com.google.android.material.bottomsheet.BottomSheetDialogFragment
import com.yocto.wetodo.databinding.TodoInputDialogFragmentBinding

class TodoInputDialogFragment : BottomSheetDialogFragment() {

    private var _binding: TodoInputDialogFragmentBinding? = null

    // 该属性仅在onCreateView和onDestroyView之间有效
    private val binding get() = _binding!!

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
    }

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        _binding = TodoInputDialogFragmentBinding.inflate(inflater, container, false)
        val root: View = binding.root

        return root
    }

    override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
        val dialog = super.onCreateDialog(savedInstanceState)

        dialog.window?.also {
            it.setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE)
        }

        return dialog
    }

    override fun onDestroyView() {
        super.onDestroyView()
        _binding = null
    }
}

平滑键盘动画效果 #

但当给BottomSheetDialogFragment设置自定义样式后，平滑动画消失了。

带有非平滑键盘动画的实现代码 #

import android.app.Dialog
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.view.WindowManager
import androidx.fragment.app.DialogFragment
import com.google.android.material.bottomsheet.BottomSheetDialogFragment
import com.yocto.wetodo.R
import com.yocto.wetodo.databinding.TodoInputDialogFragmentBinding

class TodoInputDialogFragment : BottomSheetDialogFragment() {

    private var _binding: TodoInputDialogFragmentBinding? = null

    // 该属性仅在onCreateView和onDestroyView之间有效
    private val binding get() = _binding!!

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        setStyle(DialogFragment.STYLE_NORMAL, R.style.TodoInputDialogFragment)
    }

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        _binding = TodoInputDialogFragmentBinding.inflate(inflater, container, false)
        val root: View = binding.root

        return root
    }

    override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
        val dialog = super.onCreateDialog(savedInstanceState)

        dialog.window?.also {
            it.setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE)
        }

        return dialog
    }

    override fun onDestroyView() {
        super.onDestroyView()
        _binding = null
    }
}

对应的styles.xml代码 #

<resources xmlns:tools="http://schemas.android.com/tools">
    <style name="TodoInputDialogFragment" parent="Theme.MaterialComponents.Light.BottomSheetDialog">
        <item name="android:windowIsFloating">false</item>
        <item name="android:statusBarColor">@android:color/transparent</item>
        <item name="android:windowSoftInputMode">adjustResize</item>
    </style>
</resources>

非平滑键盘动画效果 #

问题原因 #

动画消失的核心是自定义样式的父主题与原应用主题不兼容：

• 原应用主题Theme.MaterialComponents.DayNight.DarkActionBar继承自Material的DayNight主题，内置了键盘调整的平滑动画逻辑。
• 自定义样式使用的父主题Theme.MaterialComponents.Light.BottomSheetDialog，其内部的窗口动画配置覆盖了原主题的平滑过渡行为，导致系统无法触发原本的键盘动画。

解决方法 #

方案1：修改自定义样式的父主题 #

将自定义样式的父主题改为与应用主题匹配的DayNight版本，继承自Theme.MaterialComponents.DayNight.BottomSheetDialog：

<resources xmlns:tools="http://schemas.android.com/tools">
    <style name="TodoInputDialogFragment" parent="Theme.MaterialComponents.DayNight.BottomSheetDialog">
        <item name="android:windowIsFloating">false</item>
        <item name="android:statusBarColor">@android:color/transparent</item>
        <item name="android:windowSoftInputMode">adjustResize</item>
        <!-- 保留其他自定义属性 -->
    </style>
</resources>

方案2：显式指定动画样式 #

如果需要保留Light主题，可在自定义样式中显式引用原主题的窗口动画样式：

<resources xmlns:tools="http://schemas.android.com/tools">
    <style name="TodoInputDialogFragment" parent="Theme.MaterialComponents.Light.BottomSheetDialog">
        <item name="android:windowIsFloating">false</item>
        <item name="android:statusBarColor">@android:color/transparent</item>
        <item name="android:windowSoftInputMode">adjustResize</item>
        <item name="android:windowAnimationStyle">@style/Animation.MaterialComponents.DayNight.Dialog</item>
    </style>
</resources>

方案3：代码中兼容主题配置 #

若不想修改样式，可在onCreateDialog中手动从应用主题获取动画样式并设置：

override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
    val dialog = super.onCreateDialog(savedInstanceState)
    dialog.window?.also {
        it.setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE)
        // 从应用主题中获取动画样式
        val animStyle = requireContext().theme.obtainStyledAttributes(
            intArrayOf(android.R.attr.windowAnimationStyle)
        ).getResourceId(0, 0)
        it.setWindowAnimations(animStyle)
    }
    return dialog
}

验证 #

修改后重新运行，BottomSheetDialogFragment会保留自定义样式的同时，恢复平滑的键盘弹出/收起动画。

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