Customizing a Progress Bar appearance in Xamarin.Forms

问题

I used Drawable to customize the rendering of the ProgressBar in Android as answered to this question but the solution is not working with iOS.

Below is how it renders in Android.

Below is how it renders in iOS

Below is the code for my iOS CustomRenderer

[assembly: ExportRenderer(typeof(CustomProgressbar), typeof(CustomProgressBarRenderer))]
namespace Demo.iOS.Renderers
{
public class CustomProgressBarRenderer : ProgressBarRenderer
{
    protected override void OnElementChanged(ElementChangedEventArgs<ProgressBar> e)
    {
        try
        {
            base.OnElementChanged(e);

            if (Control != null)
            {                
               Control.ProgressTintColor = Color.FromHex("#ff0000").ToUIColor();                       
               Control.TrackTintColor = Color.FromHex("#3489cc").ToUIColor();
             } 
        }
        catch (Exception ex)
        {

        }
    }

    public override void LayoutSubviews()
    {
        base.LayoutSubviews();
        var X = 1.0f;
        var Y = 15.0f;
        CGAffineTransform _transform = CGAffineTransform.MakeScale(X, Y);
        this.Transform = _transform;
        this.ClipsToBounds = true;
        this.Layer.MasksToBounds = true;
        this.Layer.CornerRadius = 5;
    }
}

}

How do I accomplish this?

回答1:

According to @SushiHangover's answer, we can make a ViewRenderer to achieve your effect.

Firstly, create our own ProgressView, make sure it is inherited from ContentView. also add a BindableProperty to present the value:

public partial class ProgressView : ContentView
{
    public double Progress
    {
        set { SetValue(ProgressProperty, value); }
        get { return (double)GetValue(ProgressProperty); }
    }

    public readonly static BindableProperty ProgressProperty = BindableProperty.Create("Progress", typeof(double), typeof(ProgressView), 0.0);

    ...
}

Then, We can make the Custom renderer like:

protected override void OnElementChanged(ElementChangedEventArgs<View> e)
{
    base.OnElementChanged(e);

    //You can refer to @SushiHangover's method for detail's code, here I use the same name.
    Setup();
    Complete = ((ProgressView)Element).Progress;
}

protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
    base.OnElementPropertyChanged(sender, e);

    if (e.PropertyName == "Progress")
    {
        Complete = ((ProgressView)Element).Progress;
    }
}

Because this is in renderer, we should refresh our label's frame:

public override void Draw(CGRect rect)
{
    base.Draw(rect);
    ...
    label.Frame = Bounds;
}

At last we can use it on Forms like:

<local:ProgressView x:Name="MyProgress" HeightRequest="50"/>

来源：https://stackoverflow.com/questions/48703637/customizing-a-progress-bar-appearance-in-xamarin-forms

标签

ios

Xamarin

xamarin.forms