Question/Comment: FeatureFormView hangs up app - MAUI

[ramtechjoe]

I have been using the FeatureFormView and in general I find it an incredibly useful tool.

However, I am finding one problem that the binding process of the FeatureForm can really take a long time

var featureForm = new FeatureForm(feature);
Log.Debug("new FeatureForm");

FeatureForm = featureForm;
Log.Debug("Binding FeatureForm");  //This takes a long time

_ = await FeatureForm.EvaluateExpressionsAsync();
Log.Debug("EvaluateExpressionsAsync");

Can take 8 or more seconds with a larger form. Even with a relatively simple form it can take a couple seconds. And during this load time the app (UI Thread) really freezes up. I have played with a bunch of different ways to navigate to get around this without success.

[dotMorten]

@ramtechjoe Which platform are you testing on? Are you saying setting the featureform property takes a long time? What does assigning the FeatureForm property do?

[ramtechjoe]

We are using Maui on iOS

That is assigning the bound property. FeatureFormView is setup in Xaml and FeatureForm is bound to that control

  <Grid>
    <esri:FeatureFormView x:Name="FeatureFormView" Background="Transparent" Padding="12" Grid.ColumnSpan="2" VerticalScrollBarVisibility="Default"
                          FeatureForm="{Binding FeatureForm}" />
  </Grid>

IN the ViewModel the feature (update or create) is used to create a FeatureForm object and the it is assigned to the Bindable FeatureForm

In the code in the original post I broke out into each step so I could log the time each step took

[dotMorten]

Thanks. Is your form relatively complicated? I wonder if it's causing a lot of UI creation.
Also you don't need to evaluate expressions after - the featureform will do that for you. Having said that, it might help doing it prior to assigning the featureform - that might avoid some extra UI work.

[dotMorten]

I also wonder if this PR would improve things for you: #644

[ramtechjoe]

Having tried both the most current and 200.7 version. I think the PR might improve things, but for a large form it still takes a while to build. The hit is really just on the statement that sets the bound property to the FeatureForm

[dotMorten]

I'm seeing slow performance on Android in the v.next branch. One location that seem to take a lot of time are these two lines:

arcgis-maps-sdk-dotnet-toolkit/src/Toolkit/Toolkit.Maui/ContentControl.cs

Lines 44 to 45 in 9cbcdf9

	contentView.BindingContext = Content;
	presenter.Content = contentView;

[dotMorten]

Android nettrace / speedscope: Toolkit.SampleApp.Maui.zip

[dotMorten]

@ramtechjoe How many elements are in your FeatrueForm? (ie the FeatureForm.Elements property). The one I'm testing with is rather excessive with over 100 elements. A more reasonable amount seem to perform fairly well.

Unfortunately at this point I'm finding that MAUI is still is using some of the old Xamarin.Forms layout compatibility code which causes an excessive amount of measures, and they aren't looking to address that until .NET 10

I've only been able to make modest improvements (albeit huge improvements on subsequent loads if the FeatureFormDefinition/Elements stays the same, but only the feature itself changes).