1 /*
2  * Copyright 2018 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package androidx.navigation.ui
17 
18 import android.graphics.drawable.Drawable
19 import android.os.Bundle
20 import androidx.annotation.StringRes
21 import androidx.appcompat.widget.Toolbar
22 import androidx.navigation.NavController
23 import androidx.navigation.NavDestination
24 import androidx.transition.TransitionManager
25 import com.google.android.material.appbar.CollapsingToolbarLayout
26 import java.lang.ref.WeakReference
27 
28 /**
29  * The OnDestinationChangedListener specifically for keeping a CollapsingToolbarLayout+Toolbar
30  * updated. This handles both updating the title and updating the Up Indicator, transitioning
31  * between the drawer icon and up arrow as needed.
32  */
33 internal class CollapsingToolbarOnDestinationChangedListener(
34     collapsingToolbarLayout: CollapsingToolbarLayout,
35     toolbar: Toolbar,
36     configuration: AppBarConfiguration
37 ) : AbstractAppBarOnDestinationChangedListener(collapsingToolbarLayout.context, configuration) {
38 
39     private val mCollapsingToolbarLayoutWeakReference: WeakReference<CollapsingToolbarLayout> =
40         WeakReference(collapsingToolbarLayout)
41     private val mToolbarWeakReference: WeakReference<Toolbar> = WeakReference(toolbar)
42 
onDestinationChangednull43     override fun onDestinationChanged(
44         controller: NavController,
45         destination: NavDestination,
46         arguments: Bundle?
47     ) {
48         val collapsingToolbarLayout = mCollapsingToolbarLayoutWeakReference.get()
49         val toolbar = mToolbarWeakReference.get()
50         if (collapsingToolbarLayout == null || toolbar == null) {
51             controller.removeOnDestinationChangedListener(this)
52             return
53         }
54         super.onDestinationChanged(controller, destination, arguments)
55     }
56 
setTitlenull57     override fun setTitle(title: CharSequence?) {
58         val collapsingToolbarLayout = mCollapsingToolbarLayoutWeakReference.get()
59         if (collapsingToolbarLayout != null) {
60             collapsingToolbarLayout.title = title
61         }
62     }
63 
setNavigationIconnull64     override fun setNavigationIcon(icon: Drawable?, @StringRes contentDescription: Int) {
65         val toolbar = mToolbarWeakReference.get()
66         if (toolbar != null) {
67             val useTransition = icon == null && toolbar.navigationIcon != null
68             toolbar.navigationIcon = icon
69             toolbar.setNavigationContentDescription(contentDescription)
70             if (useTransition) {
71                 TransitionManager.beginDelayedTransition(toolbar)
72             }
73         }
74     }
75 }
76