I added a deepLink to `NavGraphBuilder.scrollable`...

# compose-wear

[Yingding Wang]

I added a deepLink to NavGraphBuilder.scrollable , called the deepLink with a PendingIntent from complication, and got java.lang.IllegalArgumentException: The WearNavigator backstack is empty, there is no navigation destination to display. Is this normal?

[Yingding Wang]

The first time as I clicked on my complication, the IllegalArgumentException raised, but i can still see the composable open. Close the MainActivty and tap on the complication second time, the whole watchface was then dead by the same java.lang.IllegalArgumentException: The WearNavigator backstack is empty, there is no navigation destination to display.

My deep link intent:

val deepLinkIntent = Intent(
    Intent.ACTION_VIEW,
    DeepLinkHelper.historyLink.toUri(),
    ctx,
    HomeActivity::class.java, // there is navHost defined in HomeActivity
    )
// adding the complication flag
// <https://stackoverflow.com/questions/2232238/how-to-bring-an-activity-to-foreground-top-of-stack/2235130#2235130>
deepLinkIntent.flags = Intent.FLAG_ACTIVITY_NEW_TASK

My PendingIntent:

val deepLinkPendingIntent: PendingIntent? =
return TaskStackBuilder.create(ctx).run {
    addNextIntentWithParentStack(intent)
    getPendingIntent(requestCode, PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE)
}

I also tried building PendingIntent with:

PendingIntent.getActivity(
    ctx,
    requestCode,
    intent, // buildHistoryDeepLinkIntent(ctx),
    PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE // Immutable is necessary due to a security fix
)

and the same result, IllegalArgumentException: The WearNavigator backstack is empty

[Yingding Wang]

I created the navController in the onCreate() of HomeActivity,

override fun onCreate(savedInstanceState: Bundle?) {
    mAmbientCallback = HomeActivityAmbientCallback()
    super.onCreate(savedInstanceState)
    setContent {
        WearAppTheme {
            navController = rememberSwipeDismissableNavController()
            WearApp(
                navController = navController!!,

I noticed that navController is null while onResume() of the HomeActivity is called, it seems to me the composable code is called later then onResume() ? Any hints are really appreciated.

[stevebower]

When we see "The WearNavigator backstack is empty, there is no navigation destination to display" it usually means that the ComposeNavigator is being used to add destinations rather than the WearNavigator - hence the Wear navigation backstack is empty. But here, it looks like you are using the correct one (worth checking the imports though).

[stevebower]

You don't show it - have you defined a navigation graph, as well as creating a deep link for the Intent?

[Yingding Wang]

I defined the <data> in the <intent-filter>

<activity
    android:name=".ui.home.HomeActivity"
    android:launchMode="singleInstance"
    android:theme="@style/composeWearAppTheme"
    android:label="@string/wear_menu_activity_label"
    android:exported="true">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
        <!-- implicit deeplink -->
        <data android:scheme="https" android:host="www.example.com"/>
    </intent-filter>

I used the NavGraphBuilder from the horologist.WearNavScaffold , but I don’t have a nav_graph.xml
The DeepLinkHelper.historyLink = "<http://www.example.com/my_route|www.example.com/my_route>"

[Yingding Wang]

The NavGraphBuilder code is

WearNavScaffold(
     …
     builder = {
          scrollable(
              route = "my_route",
              deepLinks = listOf(navDeepLink { 
                    uriPattern = "<http://www.example.com/my_route|www.example.com/my_route>" })
          ) { ... }
})

[Yingding Wang]

@stevebower You might be right with the Navigator and import statement. I am NOT using androidx.wear.compose.navigation.NavGraphBuilder , but with com.google.android.horologist.compose.navscaffold.NavGraphBuilder from`horologist` . Could this be the issue? Where can i found out which Navigator i have imported?

[stevebower]

I'm sure horologist is using the correct one - @yschimke

[Yingding Wang]

What really strange is that, the deep link seem to work only for the first time. It does shown up with an exception.

[Yingding Wang]

@stevebower @yschimke Oh, I found the issue, it is the uriPattern, <http://www.example.com/my_route|www.example.com/my_route> doesn’t work, but <http://www.example.com|www.example.com> works.

deepLinks = listOf(navDeepLink { 
                    uriPattern = "<http://www.example.com/my_route|www.example.com/my_route>" })

But why it is the case, how can i define multiple deep links with the same host <http://www.example.com|www.example.com>

[Yingding Wang]

@stevebower @yschimke I am not sure, but it might have something to do with my activity android:launchMode="singleInstance" thus the deepLinks with subpath uriPattern “www.example.com/my_route”, doesn’t work.

I added navController.handleDeepLink(intent) to my activity

override fun onNewIntent(intent: Intent?) {
    super.onNewIntent(intent)
    navController.handleDeepLink(intent)
}

now it works.
Referen: https://stackoverflow.com/questions/69781886/deep-links-navigation-in-jetpack-compose/70276252#70276252

We shall document this also on the wear navi doc, if it is the root cause. Can any of you double check my assumption. Thanks in advance.

[stevebower]

Yes, I would expect that you need to add NavArguments in order to build a URL like <http://www.example.com/my_route|www.example.com/my_route> so I think you've found the answer.

[yschimke]

Sounds like you have this covered. If it's still an issue and a bug with WearNavScaffold, I can dig into it when I'm back from holidays on Monday

[Yingding Wang]

I am all good now. Will report back should i found any further issue regarding deep link with wear navigation.

[yschimke]

Any feedback on WearNavScaffold/scrollable? Is it laying out well automatically?

[Yingding Wang]

I like WearNavScaffold/scrollable very much 🙂 A couple of things I noticed:
• The timeTextMode, positionIndicatorMode, etc in ScrollableScaffoldContext is really great, it makes more fun to build app.
• While using the default autoCentering itemIndex=1, for two 3 items in SLC, the first items can be very close to the time text.
• Using the AnimatedVisibility(visible = expanded) sometimes the time text in WearNavScaffold/scrollable jumps a little bit.
Overall, WearNavScaffold is really a bless, thanks for making it.

[yschimke]

While using the default autoCentering itemIndex=1, for two items in SLC, the first items can be very close to the time text.

Is it text or a Chip?

[Yingding Wang]

Is it text or a Chip?

Text, I add sometimes an empty item without spacer, things goes better.

[yschimke]

You shouldn't have to. If you can make a repro as a small @ Preview, I can see why it's going wrong.

[yschimke]

This is with scrollable, right

[Yingding Wang]

yes.

[yschimke]

It should place it sensibly for a list header of text, you can override if you have a full width item like a Chip, and it places it 20 dp lower.

[Yingding Wang]

Will put something together for tomorrow.

[yschimke]

Perfect. the whole point is you shouldn't have to add that spacer, so I'd love to dig into why you do. Thanks, no rush, just like to respond to early users.

[Yingding Wang]

You are the best.

[yschimke]

One thing I'm confused about...

autoCentering itemIndex=1, for two items in SLC

the scrollable fun has a param defaulted to ScalingLazyColumnDefaults.belowTimeText() that stops is using itemIndex=1, offset = 0, you end up with itemIndex = 0 and offset = screenHeightPx / 2 - topPaddingPx

[Yingding Wang]

I may mistaken it, could also be 3 items 😞

[yschimke]

No prob, when you have time I'll take a look.

[Yingding Wang]

I have a three item from the picture, the time text can not be scrolled down any more.

[yschimke]

Yep, looks like a bug.

[Yingding Wang]

Another one is better

[yschimke]

That still doesn't look right. It shouldn't be cut off on sides. That one, might just need to pass in

ScalingLazyColumnDefaults.belowTimeText(firstItemIsFullWidth = true)

[John Nichol]

If you can't scroll your time text down then typically you have you offsets for Modifier.scrollAway(),ScalingLazyListState and/or AutoCentering inconsistent

[yschimke]

Yep, unfortunately it's probably my buggy library code :)

[John Nichol]

Regarding the clipping if the content is in a ScalingLazyColumn then it looks like the the normal horizontal padding has been overridden

[Yingding Wang]

Sorry for confusion, regarding the clipping of chips, I was the one overridden the contentPadding in SLC

contentPadding = PaddingValues(horizontal = 6.dp), // to make less padding

[Yingding Wang]

@yschimke I opened an issue at horologist repo https://github.com/google/horologist/issues/919, also attached the sample repo reproducing two issues:
1. Time Text not scroll down
2. Time Text overlap with head text
Thanks again for looking into these.

[yschimke]

I'm travelling so it might be monday

[yschimke]

Think this is down to poor documentation on this very new code. Sorry!

[yschimke]

PR to update your usage https://github.com/yingding/timeText/pull/1

[yschimke]

timetext.mp4

timetext.mp4

[Yingding Wang]

Oh, I missed the columnStateFactory as you have already posted. Sorry for that. 🙂
https://kotlinlang.slack.com/archives/C02GBABJUAF/p1672277001696559?thread_ts=1672146428.263589&amp;cid=C02GBABJUAF

[Yingding Wang]

@yschimke How do you think about this implementation change https://github.com/google/horologist/issues/931
I need to change the contentPadding of SLC without duplicating your factory code.

[yschimke]

It can't be a var, it needs to be immutable. So we should pass it in. I'd prefer to add an optional param. I'm happy to do that.

[yschimke]

Before jumping to that, can you give a screenshot, or show in that existing sample project, what you need it for.

[yschimke]

The idea of ScalingLazyColumnDefaults.belowTimeText is meant to be that it does the right thing without a lot of tuning params. Any counter examples, I'd like to understand why it's breaking.

[yschimke]

I'm also seeing the original exception "IllegalArgumentException: The WearNavigator backstack is empty, there is no navigation destination to display" https://issuetracker.google.com/issues/277700155

[Yingding Wang]

Yes, can you check if the launchMode android:launchMode="singleInstance" is set for your activity, and does adding onNewIntent to trigger navController.handleDeepLink manually works for you?

override fun onNewIntent(intent: Intent?) {
    super.onNewIntent(intent)
    navController.handleDeepLink(intent)
}

Update: this also happens, as i call the startActivity() with FLAG_ACTIVITY_SINGLE_TOP , if the activity is already created. It will not trigger the navController.handleDeepLink.

[yschimke]

Reproduced on https://buganizer.corp.google.com/issues/277700155

[yschimke]

@Hardik Khandelwal nice fix!