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il...@google.com
ma...@gmail.com
Verified library version is `1.0.0-beta02`
ap...@google.com
I investigated the sample: https://github.com/marbat87/ScrollingViewPager2.git
See attached video:
1) no scrolling issues as long as angle is kept very close to x or y axis (0 -- 13s)
2) when scroll angle changes during a scroll, that is respected; if you remove NestedScrollView from the layout hierarchy (in fragment_main.xml) and have RecyclerView there directly, scroll orientation locking happens and makes for a better user experience
3) threshold / angle exploration (29s -- end) -- clearly the threshold angle is too narrow (touch slop not respected); it's worse with AppBarLayout collapsed than when it's expanded -- it confirms the issue; we'll investigate further
See attached video:
1) no scrolling issues as long as angle is kept very close to x or y axis (0 -- 13s)
2) when scroll angle changes during a scroll, that is respected; if you remove NestedScrollView from the layout hierarchy (in fragment_main.xml) and have RecyclerView there directly, scroll orientation locking happens and makes for a better user experience
3) threshold / angle exploration (29s -- end) -- clearly the threshold angle is too narrow (touch slop not respected); it's worse with AppBarLayout collapsed than when it's expanded -- it confirms the issue; we'll investigate further
Description
android.arch.navigation:navigation-fragment-ktx
android.arch.navigation:navigation-ui-ktx
Version used:
1.0.0-alpha05
Devices/Android versions reproduced on:
-SM-A510F, Android 7.0
-Emulator x86_64 API 28
Sample project:
Description:
Having this structure:
nav_graph.xml
<navigation
android:id="@+id/nav_graph"
app:startDestination="@id/startFragment">
<fragment
android:id="@+id/startFragment"
android:name="com.example.navbug.StartFragment"
android:label="StartFragment"
tools:layout="@layout/fragment_start">
<action
android:id="@+id/action_startFragment_to_nested_nav_graph"
app:destination="@id/nested_nav_graph" />
</fragment>
<include app:graph="@navigation/nested_nav_graph" />
</navigation>
nested_nav_graph.xml
<navigation
android:id="@+id/nested_nav_graph"
app:startDestination="@id/nestedStartFragment">
<fragment
android:id="@+id/nestedStartFragment"
android:name="com.example.navbug.NestedStartFragment"
android:label="NestedStartFragment">
<action
android:id="@+id/action_nestedStartFragment_to_nestedSecondFragment"
app:destination="@id/nestedSecondFragment"
app:popUpTo="@+id/nestedStartFragment"
app:popUpToInclusive="true" />
</fragment>
<fragment
android:id="@+id/nestedSecondFragment"
android:name="com.example.navbug.NestedSecondFragment"
android:label="NestedSecondFragment" />
</navigation>
I want to achieve this navigation pattern:
StartFragment => NestedStartFragment => NestedSecondFragment =(back)=> StartFragment
I'm trying to implement this by setting the action NestedStartFragment=>NestedSecondFragment with the options [popUpTo=NestedStartFragment, popUpToInclusive=true], so that the resulting stack would be:
0. NestedSecondFragment
1. NestedNavGraph
2. StartFragment
3. NavGraph
When navigating from NestedStartFragment to NestedSecondFragment, the following execption occurs:
java.lang.IllegalArgumentException: Navigator androidx.navigation.fragment.FragmentNavigator@ccc9092 reported navigation to unknown destination id com.example.navbug:id/nestedSecondFragment
at androidx.navigation.NavController$2.onNavigatorNavigated(NavController.java:142)
at androidx.navigation.Navigator.dispatchOnNavigatorNavigated(Navigator.java:217)
at androidx.navigation.fragment.FragmentNavigator.navigate(FragmentNavigator.java:207)
at androidx.navigation.fragment.FragmentNavigator.navigate(FragmentNavigator.java:45)
at androidx.navigation.NavDestination.navigate(NavDestination.java:407)
at androidx.navigation.NavController.navigate(NavController.java:683)
at androidx.navigation.NavController.navigate(NavController.java:630)
at androidx.navigation.NavController.navigate(NavController.java:618)
at com.example.navbug.NestedStartFragment$onViewCreated$1.onClick(Fragments.kt:31)
at android.view.View.performClick(View.java:6597)
at android.view.View.performClickInternal(View.java:6574)
at android.view.View.access$3100(View.java:778)
at android.view.View$PerformClick.run(View.java:25885)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Right before the navigation, the stack is:
0. NestedStartFragment
1. NestedNavGraph
2. StartFragment
3. NavGraph
When NestedStartFragment is popped on my request, NestedNavGraph is also popped because
"// We never want to leave NavGraphs on the top of the stack" (from NavController.onNavigatorNavigated)
with the effect that eventually the requested destination NestedSecondFragment is pruned from the graph and cannot be reached anymore.
Unless I'm doing something wrong, it seems that NavGraph automatic popping should be avoided if the final destination actually belongs to it.