如何为iOS和Android更改步进器的颜色? [英] How can I change the colors of a stepper for iOS and Android?

问题描述

我的代码使用一个步进器，如下所示:

My code uses a stepper which looks like this:

:

有人知道如何通过在XAML中设置新颜色来将iOS和Android版本的步进器的颜色从蓝色更改为红色吗?请注意，这最后一个需求已添加到赏金文字中.谢谢

Does anyone know how I could change the color Blue to Red for the iOS and Android versions of the stepper by setting the new color in XAML? Note this last need was added to the text of the bounty. Thanks

推荐答案

这可以使用我在这里创建了一个示例应用程序: https://github.com/brminnick/CustomStepper

I've created a sample app here: https://github.com/brminnick/CustomStepper

<?xml version="1.0" encoding="UTF-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" 
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
    x:Class="CustomStepper.StepperPage"
    xmlns:local="clr-namespace:CustomStepper">
    
    <ContentPage.Content>
        <Stepper
            HorizontalOptions="Center"
            VerticalOptions="Center"
            local:StepperColorEffect.Color="Red"/>
    </ContentPage.Content>
</ContentPage>

步进颜色效果

using System.Linq;

using Xamarin.Forms;

namespace CustomStepper
{
    public static class StepperColorEffect
    {
        public static readonly BindableProperty ColorProperty =
            BindableProperty.CreateAttached(nameof(Color),
                typeof(Color),
                typeof(Stepper),
                Color.Gray,
                propertyChanged: OnStepperColorChanged);

        public static Color GetColor(BindableObject view) => (Color)view.GetValue(ColorProperty);

        public static void SetColor(BindableObject view, Color value) => view.SetValue(ColorProperty, value);

        static void OnStepperColorChanged(BindableObject bindable, object oldValue, object newValue) => UpdateEffect(bindable);

        static void UpdateEffect(BindableObject bindable)
        {
            var stepper = (Stepper)bindable:
            RemoveEffect(stepper);
            stepper.Effects.Add(new StepperColorRoutingEffect());
        }

        static void RemoveEffect(Stepper entry)
        {
            var effectToRemoveList = entry.Effects.OfType<StepperColorRoutingEffect>();

            foreach (var entryReturnTypeEffect in effectToRemoveList)
                entry.Effects.Remove(entryReturnTypeEffect);
        }
    }

    class StepperColorRoutingEffect : RoutingEffect
    {
        public StepperColorRoutingEffect() : base("CustomStepper.StepperColorEffect")
        {
        }
    }
}

iOS PlatformEffect

using UIKit;

using Xamarin.Forms;
using Xamarin.Forms.Platform.iOS;

using CustomStepper.iOS;

[assembly: ResolutionGroupName("CustomStepper")]
[assembly: ExportEffect(typeof(StepperColorEffect), nameof(StepperColorEffect))]
namespace CustomStepper.iOS
{
    public class StepperColorEffect : PlatformEffect
    {
        protected override void OnAttached()
        {
            if (Element is Stepper element && Control is UIStepper control)
            {
                control.TintColor = CustomStepper.StepperColorEffect.GetColor(element).ToUIColor();
                control.SetIncrementImage(Control.GetIncrementImage(UIControlState.Normal), UIControlState.Normal);
                control.SetDecrementImage(Control.GetDecrementImage(UIControlState.Normal), UIControlState.Normal);
            }
        }

        protected override void OnDetached()
        {
            if (Element is Stepper element && Control is UIStepper control)
            {
                control.TintColor = UIColor.Blue;
                control.SetIncrementImage(Control.GetIncrementImage(UIControlState.Normal), UIControlState.Normal);
                control.SetDecrementImage(Control.GetDecrementImage(UIControlState.Normal), UIControlState.Normal);
            }
        }
    }
}

Android PlatformEffect

using Android.Widget;
using Android.Graphics;

using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;

using CustomStepper.Droid;

[assembly: ResolutionGroupName("CustomStepper")]
[assembly: ExportEffect(typeof(StepperColorEffect), nameof(StepperColorEffect))]
namespace CustomStepper.Droid
{
    public class StepperColorEffect : PlatformEffect
    {
        protected override void OnAttached()
        {
            if (Element is Stepper element && Control is LinearLayout control)
            {
                control.GetChildAt(0).Background.SetColorFilter(CustomStepper.StepperColorEffect.GetColor(element).ToAndroid(), PorterDuff.Mode.Multiply);
                control.GetChildAt(1).Background.SetColorFilter(CustomStepper.StepperColorEffect.GetColor(element).ToAndroid(), PorterDuff.Mode.Multiply);
            }
        }

        protected override void OnDetached()
        {
            if (Element is Stepper element && Control is LinearLayout control)
            {
                control.GetChildAt(0).Background.SetColorFilter(Xamarin.Forms.Color.Gray.ToAndroid(), PorterDuff.Mode.Multiply);
                control.GetChildAt(1).Background.SetColorFilter(Xamarin.Forms.Color.Gray.ToAndroid(), PorterDuff.Mode.Multiply);
            }
        }
    }
}

屏幕截图

Android

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