topic Re: .NET MAUI, Android: Map is not shown when navigated back to map-page in .NET Maps SDK Questions

.NET MAUI, Android: Map is not shown when navigated back to map-page

SokoFromNZ — Tue, 27 Jun 2023 17:34:50 GMT

Hi,

Since day one I have basically the same issue as described here: https://community.esri.com/t5/net-maps-sdk-questions/net-maui-map-not-loading-for-the-second-time/m-p/1191435

The issue persits on Android (emulator and real device). On Windows it is OK. iOS I cannot test.

See the attached example solution for your convenience (I'm using latest VS v17.6.4).

Please provide a valid license and Apikey in MauiProgram.cs before starting...

The app starts like this:

Then use the lower tab buttons to switch to the "Note" page:

Switching back to the "Map" page shows the watermark, but now map:

If you just move the finger on the "empty" map, it appears again.

I reckon it is a Maui bug...as most of the issues we are having 😞

But I haven't found any workaround yet and my customer gets really annoyed by this bug now as it is in our app since day one and Maui does not seem to improve.

Would be great if you can give me a little insight on this behaviour and maybe let me know a workaround.

Thanks

Soko

Re: .NET MAUI, Android: Map is not shown when navigated back to map-page

SokoFromNZ — Thu, 17 Aug 2023 13:49:20 GMT

@MatveiStefarov : As you drew the attention of the developer to the KML pixelation bug I would like to ask you to have a look here too as this bug is imho way more severe and nobody has had a look at it yet.

Thanks in advance.

Re: .NET MAUI, Android: Map is not shown when navigated back to map-page

dotMorten_esri — Tue, 22 Aug 2023 17:35:09 GMT

I'm able to reproduce your issue. Still investigating the root cause, but I was able to work around it with this bit of code in MainPage.xaml:

protected override void OnAppearing() { #if ANDROID if (MyMapView.GetCurrentViewpoint(ViewpointType.CenterAndScale) is Viewpoint vp) MyMapView.SetViewpoint(vp); #endif }

Re: .NET MAUI, Android: Map is not shown when navigated back to map-page

SokoFromNZ — Tue, 22 Aug 2023 17:39:44 GMT

Thanks @dotMorten_esri for taking the time!

I will give your workaround a try.

There has been related news though since I've opened this topic.

The workaround for the user was to just to move the finger a little over the map and it appeared again.

But now they experience a different (more severe) issue:
After a couple of page changes (back an forth) the "move-finger-fix" does not work anymore. But only if GPS tracking is active! Only a complete restart of the app brings it to life again.

Unfortunately I haven't found a reproducable workflow for this issue. But maybe your developers can have this in mind when looking for the issue above...

thx Soko

PS: By GPS tracking active i mean:

MapView.LocationDisplay.IsEnabled = true; MapView.LocationDisplay.AutoPanMode = DefaultAutoPanMode; await MapView.LocationDisplay.DataSource!.StartAsync();

Re: .NET MAUI, Android: Map is not shown when navigated back to map-page

SokoFromNZ — Wed, 23 Aug 2023 08:32:24 GMT

Hi again,

I've tried your workaround and it worked. So the users don't have to move the map a little with their finger anymore to see it again.

But the issue with GPS active is still there even with your code snipped in place 😞

Re: .NET MAUI, Android: Map is not shown when navigated back to map-page

SokoFromNZ — Tue, 29 Aug 2023 07:45:36 GMT

Hi again,

After a couple of days with try & error I was able to create a workaround for the disappearance of the map when GPS is active.

It seems that setting the ViewPoint as @dotMorten_esri suggested above is not enough.

Instead I have to resize a little the MapView like this:

// -1 means in .NET MAUI apparently "not set". So everytime the page comes into view I toggle between "not set" and the last height of "not set" + 0.1 MyMapView.HeightRequest = Math.Abs(MyMapView.HeightRequest - (-1)) < 0.001 && MyMapView.Height > 0 ? MyMapView.Height + 0.1d : -1;

I've also tried forcing a new Measure round and/or Layout with `IView.InvalidateMeasure()` or `Page.ForceLaout()` on the MyMapView, the Grid containing it, or the whole Page...but nothing helped...only the above.

I hope this helps somehow to find the root issue of this.

Ohh...and maybe it also has something to do with this other issue where the Map also stayed empty...

Soko

Re: .NET MAUI, Android: Map is not shown when navigated back to map-page

esp1rl — Fri, 17 Nov 2023 12:45:00 GMT

Hi, I'm experiencing this issue on Windows, iOS and Android. With both .NET 7 and .NET 8 RTM. I'm using Esri.ArcGISRuntime.Maui v200.2.0

I found this issue to be linked with the use of location tracking and the MAUI shell tab pages. I think something goes haywire when the user spend time on another tab (not having the map) and the location tracker is still updating the MapView which is out of view.

It is a very reproducible issue, but there is some randomness to it. I have not been able to make a step by step process to reproduce it.

Re: .NET MAUI, Android: Map is not shown when navigated back to map-page

esp1rl — Wed, 22 Nov 2023 15:01:02 GMT

After debugging for a while I managed to discover the nature of this issue. FYI @dotMorten_esri

Listening to MapView.DrawStatusChanged I found that it would get stuck in InProgress when switching tabs. See code comments below.

protected override void OnDisappearing() { /* This is a workaround for a bug in ArcGIS Maps SDK where the internal rendering engine freezes * if the map is not fully rendered when the page disappears. * * It is easier to reproduce when using LocationDisplay which is within view as that * will cause the map to be constantly re-rendered. */ while (MapView.DrawStatus == DrawStatus.InProgress) { // occupy the UI thread for a while, waiting for the map to finish rendering Thread.Sleep(TimeSpan.FromMilliseconds(10)); } base.OnDisappearing(); }

Re: .NET MAUI, Android: Map is not shown when navigated back to map-page

SokoFromNZ — Wed, 22 Nov 2023 06:51:19 GMT

Looks like a great find, thanks! I will give it a try intead of my workaround once I find the time.

PS: This is the OnDisappearing() of the page, correct? Code is in the CodeBehind-CS-File of the page...

Re: .NET MAUI, Android: Map is not shown when navigated back to map-page

esp1rl — Wed, 22 Nov 2023 15:02:16 GMT

That's correct. I found this issue to occur for all Android, iOS and Windows

Re: .NET MAUI, Android: Map is not shown when navigated back to map-page

esp1rl — Wed, 22 Nov 2023 15:49:57 GMT

Setting LocationDisplay.ShowPingAnimationSymbol = false also reduces the chance of this issue occuring as the renders are completed much faster.

I also suggest adding a time based exit to the while loop so that one doesn't risk locking the UI thread forever.

Re: .NET MAUI, Android: Map is not shown when navigated back to map-page

SokoFromNZ — Wed, 22 Nov 2023 18:24:02 GMT

The original issue of my opening post is not solved by this though. It is for the GPS issue only.

Re: .NET MAUI, Android: Map is not shown when navigated back to map-page

esp1rl — Sun, 26 Nov 2023 20:56:14 GMT

I use this one to fix the fact that the MapView isn't redrawn when COMING from another tab. This is a separate issue from the rendering engine locking up when switching TO another tab.

private void PageNavigatedTo(object _, NavigatedToEventArgs __) { #if ANDROID /* ISSUE: This is a workaround for a bug in ArcGIS Maps SDK where the MapView is not redrawn on tab change * * https://community.esri.com/t5/net-maps-sdk-questions/net-maui-android-map-is-not-shown-when-navigated/m-p/1303488 */ MapView.InvalidateMeasureNonVirtual(Microsoft.Maui.Controls.Internals.InvalidationTrigger.Undefined); #endif }

Re: .NET MAUI, Android: Map is not shown when navigated back to map-page

SokoFromNZ — Tue, 12 Dec 2023 11:39:19 GMT

@esp1rl wrote:
I also suggest adding a time based exit to the while loop so that one doesn't risk locking the UI thread forever.

Thats exactly what my user are reporting at the moment: The UI thread freezes as DrawStatus never changes anymore.

Did you implement a time based exit yet? Having such a thing prevents the lock of course, but after that the map is still white/empty once going back to the page.

So I'm not sure if this solution of yours does help in the end...

Re: .NET MAUI, Android: Map is not shown when navigated back to map-page

dotMorten_esri — Tue, 12 Dec 2023 19:48:41 GMT

Could you please retry with the latest v200.3. I believe this issue should be fixed in that release.

Re: .NET MAUI, Android: Map is not shown when navigated back to map-page

dotMorten_esri — Tue, 12 Dec 2023 19:56:39 GMT

This workaround should no longer be needed with 200.3

Re: .NET MAUI, Android: Map is not shown when navigated back to map-page

SokoFromNZ — Wed, 13 Dec 2023 05:45:14 GMT

Is there a way to use v200.3 with .NET7? Why do you force .NET8 on us with this update? We cannot move to .NET8 at the moment with our product.

Re: .NET MAUI, Android: Map is not shown when navigated back to map-page

dotMorten_esri — Wed, 13 Dec 2023 16:57:19 GMT

We made the decision to move to .NET 8, because .NET 7 support lifecycle ends already in Spring 2024, and we've observed numerous critical bug fixes in the new version of MAUI.

This is also on par with the plans announced over the last few years, where we always move to the latest LTS version of .NET (which meant two years on .NET 3.1, then two years on .NET 6, now two years on .NET 8, before moving to .NET 10 etc. Also note that .NET MAUI by itself is on a more aggressive support lifecycle than the rest of .NET is, and for instance already dropped support for .NET 6 in the spring).

Re: .NET MAUI, Android: Map is not shown when navigated back to map-page

SokoFromNZ — Wed, 13 Dec 2023 17:18:20 GMT

"...numerous critical bug fixes..." tell me about it 😉

So there is no trick (or beta version of your v200.3) which I can use on .NET7, am I right?

We will upgrade to .NET8 in Q1 of 2024. W've tried already but there where a lot of breaking changes (.NET8 and MAUI8) so we could not do it without a week of additional labour to go into it...which we can not spent at the moment.

So lets hope MAUI8 is not so much beta anymore as v7 was

Re: .NET MAUI, Android: Map is not shown when navigated back to map-page

dotMorten_esri — Wed, 13 Dec 2023 17:24:17 GMT

Sorry there's no trick to support NET7.

I'm not going to promise you MAUI is now perfect but definitely has been greatly improved. It's another reason we weren't too worried about moving quickly to .NET 8, because we knew the benefit of moving to .NET 8 will be big enough that we expect most of our .NET MAUI users to move fairly quickly.

Only breaking changes I personally know of were actually bug fixes, and people seemed to rely on wrong behavior, which naturally no longer works.