在 Xamarin.Forms 中自定义进度栏外观

I used Drawable自定义渲染ProgressBar in Android正如对这个问题但该解决方案不适用于 iOS。

Below is how it renders in Android.

Below is how it renders in iOS

下面是我的代码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;
    }
}

}

我该如何实现这个目标？

根据@SushiHangover的回答，我们可以做一个ViewRenderer来达到你的效果。

首先，创建我们自己的ProgressView，确保它继承自ContentView。还添加一个BindableProperty呈现价值：

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);

    ...
}

然后，我们可以制作自定义渲染器，如下所示：

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;
    }
}

因为这是在渲染器中，所以我们应该刷新标签的框架：

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

最后我们可以在表单上使用它，例如：

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