如何在具有C＃后端而不是XAML的模板上绑定XAML元素？

Question

Here's what I have right now:

I have this template that's simplified for the question:

<?xml version="1.0" encoding="UTF-8"?>
<Frame xmlns="http://xamarin.com/schemas/2014/forms" 
                      xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
   xmlns:t="clr-namespace:Japanese.Templates" 
   xmlns:local="clr-namespace:Japanese;assembly=Japanese" 
   x:Class="Japanese.Templates.RoundButtonText" x:Name="this">
   <Label Text="ABC"     
          TextColor="{Binding LabelTextColor, Source={x:Reference this}}"
   />
</Frame>

and this C#

using Xamarin.Forms;

namespace Japanese.Templates
{
    public partial class RoundButtonText : BaseFrameButtonTemplate
    {
        public RoundButtonText()
        {
            InitializeComponent();
            // I would like to put the Label TextColor binding here instead of in the XAML
        }

    }
}

Can someone help me by telling me how I can add the binding for the label TextColor in the C# back end so that it changes in exactly the same way as it currently does when it's written as:

 TextColor="{Binding LabelTextColor, Source={x:Reference this}}"

in XAML?

Answer 1

Remove the binding from the XAML and give the Label control an x:Name:

<?xml version="1.0" encoding="UTF-8"?>
<Frame xmlns="http://xamarin.com/schemas/2014/forms" 
       xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
       xmlns:t="clr-namespace:Japanese.Templates" 
       xmlns:local="clr-namespace:Japanese;assembly=Japanese" 
       x:Class="Japanese.Templates.RoundButtonText" x:Name="this">
    <Label x:Name="label" 
           Text="ABC" />
</Frame>

Set up the binding and the property to bind to in C# code behind:

using Xamarin.Forms;

namespace Japanese.Templates
{
    public partial class RoundButtonText : BaseFrameButtonTemplate
    {
        Color _labelTextColor;
        public Color LabelTextColor {
            get {
                return _labelTextColor;
            } 
            set {
                if (_labelTextColor != value) {
                    _labelTextColor = value;
                    OnPropertyChanged("LabelTextColor");
                } 
            }
        }

        public RoundButtonText()
        {
            InitializeComponent();
            label.BindingContext = this;
            label.SetBinding(Label.TextColorProperty, "LabelTextColor");
        }
    }
}

Now whenever the LabelTextColor property value is changed, the Label's TextColor property should change as well, just like with a XAML binding.