UserControl Fire属性更改时发生事件 [英] UserControl Fire Event when a property changes

问题描述

DocField 具有公共bool属性 IsSelected

DocField 实现INotifyPropertyChanged

DocField has a public bool property IsSelected
DocField implements INotifyPropertyChanged

当$ <$ c $时，我需要在 UserControlDocFieldBaseB 中触发的事件c> DocField.IsSelected 更改。

I need an event that fires in UserControlDocFieldBaseB when DocField.IsSelected changes.

我该怎么做？

public partial class UserControlDocFieldBaseB : UserControl
{
    private DocField docField = null;

    public UserControlDocFieldBaseB(DocField DocField)
    {
        InitializeComponent();
        docField = DocField;
    }

根据dkozl的评论，这是我如何连接它

UserControlDocFieldString是一个相当昂贵的，所以我只想加载它根据需要

Based on the comment from dkozl this is how I wired it up
UserControlDocFieldString is a fairly expensive so I only want to load it on demand

我怀疑我可以使用Loaded事件而不是UserControl1_DataContextChanged，但这似乎工作

它也适用于加载的事件

I suspect I could use the Loaded event rather than the UserControl1_DataContextChanged but this seems to work
It also works with the Loaded event

public UserControlDocFieldBaseB()
{
    InitializeComponent();
    DataContextChanged += new DependencyPropertyChangedEventHandler(UserControl1_DataContextChanged);
}
void UserControl1_DataContextChanged(object sender, DependencyPropertyChangedEventArgs e)
{
    if (sender is UserControlDocFieldBaseB)
    {
        UserControlDocFieldBaseB uc = (UserControlDocFieldBaseB)sender;
        if (uc.DataContext is DocFieldString)
        {
            if (docFieldString == null)
            {
                docFieldString = (DocFieldString)uc.DataContext;
                docFieldString.PropertyChanged += DocFieldString_PropertyChanged;
            } 
        }
    }
}
void DocFieldString_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
    switch (e.PropertyName)
    {
        case "IsSelected":
            //MessageBox.Show(docFieldString.Name + " docFieldString.IsSelected " + docFieldString.IsSelected.ToString());
            if (userControlDocFieldString == null && docFieldString != null && docFieldString.IsSelected)
            {
                userControlDocFieldString = new UserControlDocFieldString(docFieldString);
                this.frmEdit.Content = userControlDocFieldString;
            }
            break;
    }
}

推荐答案

DocField 实现 INotifyPropertyChanged for IsSelected 属性，您可以简单地订阅 PropertyChanged 事件 DocField ，例如加载控件或 DocField property is changed and pass on the event if it is for'IsSelected property

Since DocField implements INotifyPropertyChanged for IsSelected property you can simply subscribe to PropertyChanged event of DocField, for example when control is loaded or DocField property is changed and pass on the event if it's for `IsSelected property

private void PropertyChanged(object sender, PropertyChangedEventArgs e)
{
    if (String.IsNullOrEmpty(e.PropertyName) || e.PropertyName == "IsSelected")
    {
        //pass on the event
    }
}

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