FragmentTransition.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.fragment.app
import android.os.Build
import android.view.View
import androidx.collection.ArrayMap
/**
* Contains the Fragment Transition functionality.
*/
internal object FragmentTransition {
@JvmField
val PLATFORM_IMPL: FragmentTransitionImpl? =
if (Build.VERSION.SDK_INT >= 21) FragmentTransitionCompat21() else null
@JvmField
val SUPPORT_IMPL = resolveSupportImpl()
@Suppress("UNCHECKED_CAST")
private fun resolveSupportImpl(): FragmentTransitionImpl? = try {
val impl = Class.forName(
"androidx.transition.FragmentTransitionSupport"
) as Class<FragmentTransitionImpl>
impl.getDeclaredConstructor().newInstance()
} catch (ignored: Exception) {
// support-transition is not loaded; ignore
null
}
/**
* Utility to find the String key in [map] that maps to [value].
*/
@JvmStatic
fun ArrayMap<String, String>.findKeyForValue(
value: String
): String? = filter { entry ->
// Find the entries with the given value
entry.value == value
}.map { entry ->
// And get the key associated with that value
entry.key
}.firstOrNull()
/**
* A utility to retain only the mappings in the map that have a value
* that has a key in [namedViews]. This is a useful equivalent to
* [ArrayMap.retainAll] for values.
*/
@JvmStatic
fun ArrayMap<String, String>.retainValues(namedViews: ArrayMap<String, View>) {
for (i in (size - 1) downTo 0) {
val targetName = valueAt(i)
if (!namedViews.containsKey(targetName)) {
removeAt(i)
}
}
}
/**
* Calls the [android.app.SharedElementCallback.onSharedElementStart] or
* [android.app.SharedElementCallback.onSharedElementEnd] on the appropriate
* incoming or outgoing fragment.
*
* @param inFragment The incoming fragment
* @param outFragment The outgoing fragment
* @param isPop Is the incoming fragment part of a pop transaction?
* @param sharedElements The shared element Views
* @param isStart Call the start or end call on the SharedElementCallback
*/
@JvmStatic
fun callSharedElementStartEnd(
inFragment: Fragment,
outFragment: Fragment,
isPop: Boolean,
sharedElements: ArrayMap<String, View>,
isStart: Boolean
) {
val sharedElementCallback = if (isPop) {
outFragment.enterTransitionCallback
} else {
inFragment.enterTransitionCallback
}
if (sharedElementCallback != null) {
val views = sharedElements.map { it.value }
val names = sharedElements.map { it.key }
if (isStart) {
sharedElementCallback.onSharedElementStart(names, views, null)
} else {
sharedElementCallback.onSharedElementEnd(names, views, null)
}
}
}
/**
* Sets the visibility of all Views in [views] to [visibility].
*/
@JvmStatic
fun setViewVisibility(views: List<View>, visibility: Int) {
views.forEach { view ->
view.visibility = visibility
}
}
@JvmStatic
fun supportsTransition(): Boolean {
return PLATFORM_IMPL != null || SUPPORT_IMPL != null
}
}