display a timer using progressBar xamarin forms - xaml

Question

how to add a nice timer
xaml :
<ProgressBar x:Name="progressBar" Grid.Row="2" Grid.ColumnSpan="5"
IsVisible="true"
Progress="0.0"
WidthRequest="300"
HeightRequest="20"
VerticalOptions="Center"
HorizontalOptions="Center">
</ProgressBar>
behind code:
progressBar.Progress = 0;
await progressBar.ProgressTo(1.0, 90000, Easing.Linear);

Answer 1

You can use a timer to increment the ProgressBar:
var updateRate = 1000 / 30f; // 30Hz
double step = updateRate / (2 * 30 * 1000f);
Device.StartTimer(TimeSpan.FromMilliseconds(updateRate), () =>
{
if (progressBar.Progress < 100)
{
Device.BeginInvokeOnMainThread(() => progressBar.Progress += step );
return true;
}
return false;
});
Then you can use an IValueConverter to convert the progress to a minute:second style format:
public class CountDownConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
double time = 0;
double.TryParse(parameter.ToString(), out var totalTime);
double.TryParse(value.ToString(), out var progress);
time = progress <= double.Epsilon ? totalTime : (totalTime - (totalTime * progress));
var timeSpan = TimeSpan.FromMilliseconds(time);
return $"{timeSpan.Minutes:00;00}:{timeSpan.Seconds:00;00}";
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
Tying it together with XAML:
<Label
BindingContext="{x:Reference progressBar}"
Text = "{Binding Progress, StringFormat='{0:P0}'}"
HorizontalOptions ="Center"
FontSize="20"
FontFamily = "Helvetica Neue"
TextColor ="Red" />
<ProgressBar x:Name="progressBar"
IsVisible="true"
Progress="0.0"
WidthRequest="300"
HorizontalOptions="Center">
</ProgressBar>
<Label Text="{Binding Source={x:Reference progressBar},
Path=Progress,
Converter={StaticResource countDownTime},
ConverterParameter=120000}}"
HorizontalOptions ="Center"
FontSize="20"
FontFamily = "Helvetica Neue"
TextColor = "Red" />
Output:
Update:
You have to define a ResourceDictionary to have an instance of the CountDownConverter class created and named so you can reference it in XAML:
<ContentPage.Resources>
<ResourceDictionary>
<tools:CountDownConverter x:Key="countDownTime"/>
</ResourceDictionary>
</ContentPage.Resources>
And the tools: namespace reference is based upon the C# namespace and assembly that contains the CountDownConverter. I have a bunch of these IValueConverter classes in a separate library and thus my xmlns:tools looks like:
xmlns:tools="clr-namespace:Converters;assembly=Converters"
re: Resource Dictionaries