c#绑定前更改属性值

Question

我不确定之前是否有人问过这个问题，但我目前处于将控件的属性绑定到 a 的情况。DependencyProperty但是，返回的值Property是类型Double。设置绑定时，如何20从属性中减去或给定值，然后绑定控件？我需要为此实施IValueConverter吗？我仍在学习 WPF，因此将不胜感激。依赖属性public static readonly DependencyProperty ProgressbarValueDependency = DependencyProperty.Register("PrValue", typeof(double),     typeof(LinearProgressBar));public double PrValue{    get    {        return System.Convert.ToDouble(GetValue(ProgressbarValueDependency));    }    set    {        SetValue(ProgressbarValueDependency, value);    }}绑定到属性 {MainGrid = GetTemplateChild("MainGrid");Binding MainGridWidthBinding = new Binding("PrValue"){    Source = this,    Mode = BindingMode.TwoWay};MainGrid.SetBinding(Grid.WidthProperty, MainGridWidthBinding);}

Answer 1

为了达到你的目的，你需要编写一个类实现IValueConverter接口。

public class MyConverter : IValueConverter

{

    public object Convert(object value, Type targetType, 

        object parameter, string language)

    {

        // Contain your source to target convertion logic. 

    }

    public object ConvertBack(object value, Type targetType, 

        object parameter, string language)

    {

        // Contain your target to source convertion logic.

        // Only needed if using TwoWay or OneWayToSource Binding Mode. 

    }

}

然后Binding.Converter在调用SetBinding方法之前将其实例设置为属性　。

Binding MainGridWidthBinding = new Binding("PrValue")

{

    Source = this,

    Mode = BindingMode.TwoWay,

    Converter = new MyConverter(),

};

MainGrid.SetBinding(Grid.WidthProperty, MainGridWidthBinding);