Xamarin.Forms BoxView arrondi avec couleur de fond sélectionnable


Exemple

Première étape: partie PCL

public class RoundedBoxView : BoxView
{
    public static readonly BindableProperty CornerRadiusProperty =
        BindableProperty.Create("CornerRadius", typeof(double), typeof(RoundedEntry), default(double));

    public double CornerRadius
    {
        get
        {
            return (double)GetValue(CornerRadiusProperty);
        }
        set
        {
            SetValue(CornerRadiusProperty, value);
        }
    }

    public static readonly BindableProperty FillColorProperty =
        BindableProperty.Create("FillColor", typeof(string), typeof(RoundedEntry), default(string));

    public string FillColor
    {
        get 
        {
            return (string) GetValue(FillColorProperty);
        }
        set 
        {
            SetValue(FillColorProperty, value);
        }
    }
}

Deuxième étape: partie Droid

[assembly: ExportRenderer(typeof(RoundedBoxView), typeof(RoundedBoxViewRenderer))]
namespace MyNamespace.Droid
{
    public class RoundedBoxViewRenderer : VisualElementRenderer<BoxView>
    {
        protected override void OnElementChanged(ElementChangedEventArgs<BoxView> e)
        {
            base.OnElementChanged(e);
            SetWillNotDraw(false);
            Invalidate();
        }

        protected override void OnElementPropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
        {
            base.OnElementPropertyChanged(sender, e);
            SetWillNotDraw(false);
            Invalidate();
        }

        public override void Draw(Canvas canvas)
        {
            var box = Element as RoundedBoxView;
            var rect = new Rect();
            var paint = new Paint
            {
                Color = Xamarin.Forms.Color.FromHex(box.FillColor).ToAndroid(),
                AntiAlias = true,
            };

            GetDrawingRect(rect);

            var radius = (float)(rect.Width() / box.Width * box.CornerRadius);

            canvas.DrawRoundRect(new RectF(rect), radius, radius, paint);
        }
    }
}

Troisième étape: partie iOS

[assembly: ExportRenderer(typeof(RoundedBoxView), typeof(RoundedBoxViewRenderer))]
namespace MyNamespace.iOS
{
    public class RoundedBoxViewRenderer : BoxRenderer
    {
        protected override void OnElementChanged(ElementChangedEventArgs<BoxView> e)
        {
            base.OnElementChanged(e);

            if (Element != null) 
            {
                Layer.CornerRadius = (float)(Element as RoundedBoxView).CornerRadius;
                Layer.BackgroundColor = Color.FromHex((Element as RoundedBoxView).FillColor).ToCGColor();
            }
        }

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

            if (Element != null) 
            {
                Layer.CornerRadius = (float)(Element as RoundedBoxView).CornerRadius;
                Layer.BackgroundColor = (Element as RoundedBoxView).FillColor.ToCGColor();
            }
        }
    }
}