ImmLeaksCleaner.kt
/*
* Copyright 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.activity
import android.annotation.SuppressLint
import android.app.Activity
import android.content.Context
import android.view.View
import android.view.inputmethod.InputMethodManager
import androidx.lifecycle.Lifecycle
import androidx.lifecycle.LifecycleEventObserver
import androidx.lifecycle.LifecycleOwner
import java.lang.reflect.Field
internal class ImmLeaksCleaner(private val activity: Activity) : LifecycleEventObserver {
override fun onStateChanged(source: LifecycleOwner, event: Lifecycle.Event) {
if (event != Lifecycle.Event.ON_DESTROY) {
return
}
val inputMethodManager =
activity.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
with(cleaner) {
val lock = inputMethodManager.lock ?: return
val success = synchronized(lock) {
val servedView = inputMethodManager.servedView ?: return
if (servedView.isAttachedToWindow) {
return
}
// Here we have a detached mServedView. Set null to mNextServedViewField so that
// everything will be cleared in the next InputMethodManager#checkFocus().
inputMethodManager.clearNextServedView()
}
if (success) {
// Assume that InputMethodManager#isActive() internally triggers
// InputMethodManager#checkFocus().
inputMethodManager.isActive()
}
}
}
sealed class Cleaner {
abstract val InputMethodManager.lock: Any?
abstract val InputMethodManager.servedView: View?
/**
* @return Whether the next served view was successfully cleared
*/
abstract fun InputMethodManager.clearNextServedView(): Boolean
}
/**
* Cleaner that is used when reading the [InputMethodManager] fields via
* reflection failed.
*/
object FailedInitialization : Cleaner() {
override val InputMethodManager.lock: Any?
get() = null
override val InputMethodManager.servedView: View?
get() = null
override fun InputMethodManager.clearNextServedView(): Boolean = false
}
/**
* Cleaner that provides access to hidden fields via reflection
*/
class ValidCleaner(
private val hField: Field,
private val servedViewField: Field,
private val nextServedViewField: Field,
) : Cleaner() {
override val InputMethodManager.lock: Any?
get() = try {
hField.get(this)
} catch (e: IllegalAccessException) {
null
}
override val InputMethodManager.servedView: View?
get() = try {
servedViewField.get(this) as View?
} catch (e: IllegalAccessException) {
null
} catch (e: ClassCastException) {
null
}
override fun InputMethodManager.clearNextServedView() = try {
nextServedViewField.set(this, null)
true
} catch (e: IllegalAccessException) {
false
}
}
@SuppressLint("SoonBlockedPrivateApi") // This class is only used API <=23
companion object {
val cleaner by lazy {
try {
val immClass = InputMethodManager::class.java
val servedViewField = immClass.getDeclaredField("mServedView").apply {
isAccessible = true
}
val nextServedViewField = immClass.getDeclaredField("mNextServedView").apply {
isAccessible = true
}
val hField = immClass.getDeclaredField("mH").apply {
isAccessible = true
}
ValidCleaner(hField, servedViewField, nextServedViewField)
} catch (e: NoSuchFieldException) {
// very oem much custom ¯\_(ツ)_/¯
FailedInitialization
}
}
}
}