Xamarin Android ProgressBar

Question

I'm struggling to use the ProgressBar in the MVVMCross structure of Xamarin Android. Originally, I wanted to bind the visibility of the ProgressBar to a field in my ViewModel. That proved difficult, I tried several permutations and tried suggestions from here: How to set visibility for ProgressBar in android MvvmCross Xamarin

I do have other elements such as buttons I have been able to successfully bind else where in my project, so I'm not sure why that was such a big issue. After many tries I decided to try setting the Visibility pragmatically in the ViewModel. I've tried several methods but what I finally thought would for sure work doesn't.

Xaml:

<ProgressBar
    android:id="@+id/progressBarMap"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerInParent="true"
    android:visibility="gone"
    style="@android:style/Widget.ProgressBar.Large" />

I've tried with and without having a default visibility. I've tried the local:MvxBind with several normal methods of binding, and then using a custom converter or with the Visibility plugin.

In my Fragment I regretfully set a FragmentActivity property in my ViewModel just to see if I can get this to work in some form (OnCreateView):

ViewModel.FragActivity = this.Activity;
ViewModel.Progress = view.FindViewById<Android.Widget.ProgressBar>(Resource.Id.progressBarMap);

Notice I did also try setting the ProgressBar to a field called Progress, and use it in my ViewModel.

Here is where I'm manipulating the ProgressBar in my ViewModel:

private void AddOfflinePoints()
{
    try
    {
        FragActivity.RunOnUiThread(() => 
        {
            //I've also tried using the above Progress property. That wasn't null but did not update.
            ProgressBar barOfProgression = FragActivity.FindViewById<ProgressBar>(Resource.Id.progressBarMap);
            //barOfProgression is null :(
            barOfProgression.Visibility = ViewStates.Visible;
            barOfProgression.Enabled = true;
        });

        //Code to run while spinning the progress bar (It is inside Task.Run)
    }
    catch (Exception)
    {
        //Exception Handling code...
    }

    FragActivity.RunOnUiThread(() => Progress.Visibility = ViewStates.Gone);
}

What am I doing wrong? I've tried many permutations, anything on Google and consulted the limited Xamarin documentation. Any help or pointers is much appreciated.

Thank you.

You should be able to just bind Visibility. Remember to add the Visibility Plugin for that though. — Cheesebaron

jazzmasterkc jazzmasterkc · Accepted Answer · 2018-09-12T16:17:16

Turns out the issue was the Linker removing the Visibility property. I got the idea from this post: Visibility binding fails

I added the following code in LinkerPleaseInclude:

public static void Include(ProgressBar progressBar)
{
    progressBar.Click += (s, e) => progressBar.Visibility = progressBar.Visibility - 1;
}

If anyone is curious how I did it, below is the code:

Xaml:

<ProgressBar
    android:id="@+id/progressBarMap"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerInParent="true"
    local:MvxBind="Visibility Visibility(ShowProgress)"
    style="@android:style/Widget.ProgressBar.Large" />

ViewModel:

private bool _showProgress;
public bool ShowProgress
{
    get => _showProgress;
    set => SetProperty(ref _showProgress, value);
}

Where SetProperty is from MvxNotifyPropertyChanged class.

Xamarin Android ProgressBar

1 Answers