在运行时更改xamarin.forms颜色

我正在使用xamarin.forms制作应用程序，并且我已经设置了一种配色方案，现在我希望能够在设置中将其更改为深色样式或浅色样式，但所有这些都可以正常工作，除了我每次都要重新启动应用程序在我选择了不同的配色方案之后。

这是我试图在运行时更改它的地方

   private void DarkThemeClick(object sender, EventArgs e)
    {
        database.DropTable(new StyleModel());
        database.CreateTable(new StyleModel());
        database.SaveItem(new StyleModel() { ThemeNum = 1 });
        App.ActiveStyle = new DarkStyle();
    }

    private void LightThemeClick(object sender, EventArgs e)
    {
        database.DropTable(new StyleModel());
        database.CreateTable(new StyleModel());
        database.SaveItem(new StyleModel() { ThemeNum = 0 });
        App.ActiveStyle = new LightStyle();
    }

这是我正在使用的要更改颜色的项目的示例

    using System;
using TestXamForms.Style;
using Xamarin.Forms;

namespace TestXamForms.Helpers
{
class EntryValueCell : StackLayout
{

    public EntryValueCell(string key,int FieldIdx, string value = "",  bool isNumber = false)
    {
        Entry entry;
        Label label = new Label()
        {
            TextColor = App.ActiveStyle.LabelTextColor,
            Text = key,
            HorizontalOptions = LayoutOptions.End
        };
        if (isNumber)
        {
            entry = new Entry()
            {
                ClassId = FieldIdx.ToString(),
                TextColor = App.ActiveStyle.LabelTextColor,
                HorizontalOptions = LayoutOptions.FillAndExpand,
                Keyboard = Keyboard.Numeric,
                Text = value, 


            };
        }
        else
        {
            entry = new Entry()
            {
                ClassId = FieldIdx.ToString(),
                TextColor = App.ActiveStyle.LabelTextColor,
                HorizontalOptions = LayoutOptions.FillAndExpand,
                Keyboard = Keyboard.Text,
                Text = value
            };
        }

        BackgroundColor = App.ActiveStyle.StackLayoutBackground;
        Orientation = StackOrientation.Horizontal;
        VerticalOptions = LayoutOptions.FillAndExpand;
        Children.Add(label);
        Children.Add(entry);
    }
}
}

这是其中一种配色方案的示例

    using Xamarin.Forms;

   namespace TestXamForms.Style
 {
     public  class LightStyle : StyleBase
    {
       public LightStyle()
        {
        LabelTextColor = Color.Black;
        ButtonColor = Color.FromHex("337ab7");
        StackLayoutBackground = Color.FromHex("eff0f1");
        InputBackgroundColor = Color.White;
        PlaceHolderColor = Color.Gray;
        TableColor = Color.FromHex("e6e6e6");
        StacklayoutBorderColor = Color.Black;
       }
      }
     }

这是上面文件正在继承的styleBase

using TestXamForms.Models;
using Xamarin.Forms;

namespace TestXamForms.Style
{
public class StyleBase : ModelBase
{
    public enum ThemeNum : int
    {
        Light = 0, Dark = 1
    }
    public Color LabelTextColor { get; set; }
    public Color ButtonColor { get; set; }
    public Color StackLayoutBackground { get; set; }
    public Color InputBackgroundColor { get; set; }
    public Color PlaceHolderColor { get; set; }

    public Color StacklayoutBorderColor { get; set; }

    public Color TableColor { get; set; }

    public int ThemeNums { get; set; }

}
}

这是App.cs文件的一部分，该文件在应用启动时加载配色方案

    static StyleBase activeStyle { get; set; }


    public static StyleBase ActiveStyle
    {
        get
        {
            if (activeStyle == null)
            {
                StyleModel styleBase = database.GetItems(new     StyleModel()).First();
                if (styleBase == null)
                {
                    database.SaveItem(new StyleModel() { ThemeNum = 0 }); //sets the default color scheme to light style 
                    styleBase = database.GetItems(new StyleModel()).First();
                }
                int themeNum = styleBase.ThemeNum;
                switch (themeNum)
                {
                    case (int)StyleBase.ThemeNum.Dark:
                        activeStyle = new DarkStyle();
                        break;
                    case (int)StyleBase.ThemeNum.Light:
                        activeStyle = new LightStyle();
                        break;
                }
            }
            return activeStyle;
        }
        set { } }