zoukankan      html  css  js  c++  java
  • (转)WPF Custom Control Dependency Property Gotcha

    原文地址:http://geekswithblogs.net/thibbard/archive/2008/04/22/wpf-custom-control-dependency-property-gotcha.aspx

     

    Let's say you have a custom WPF control called SearchTextBox.  It has a textbox and a button labeled "search".  Simple enough, you reuse it in your application when you want to provide search. 

    Then one day, you decide you need this control needs to be bindable.  So you expose a public property Text and map it to textSearch just like you would in WinForms.

    Well, that doesn't work, so you google around and stumble upon Dependency Properties and learn how to create your own (VS snippet shortcut propdb) and create a Text DP.

    Now you spend 30 minutes trying to map your Text DP to your textSearch.Text until you finally figure out that your DP snippet lead you astray and there is one more step that didn't get included in the shortcut.  In the UIPropertyMetaData, you need to specify a function to call when the property changes - so you can set textSearch.Text.

    The function looks like this:

    static void textChangedCallBack(DependencyObject property, DependencyPropertyChangedEventArgs args) { SearchTextBox searchTextBox = (SearchTextBox)property; searchTextBox.textSearch.Text= (string)args.NewValue; }

    And the rest of the DP looks like this:

    public string Text { get { return (string)GetValue(TextProperty); } set { SetValue(TextProperty, value); } } public static readonly DependencyProperty TextProperty = DependencyProperty.Register( "Text", typeof(string), typeof(SearchTextBox), new UIPropertyMetadata(string.Empty, new PropertyChangedCallback(textChangedCallBack)));

    The important part here is what wasn't created by the VS snippet :

    new UIPropertyMetadata(string.Empty, new PropertyChangedCallback(textChangedCallBack))

    Now you are binding to your custom control and all is good.

  • 相关阅读:
    Java面试基础 -- Git篇
    Java面试基础
    如何避免死锁?
    如何减少上下文切换?
    Java中的volatile变量有什么作用?
    Thread类中start()方法喝run()方法有什么不同?
    (一)java异常处理的几个问题
    SUSE CaaS Platform 4
    SUSE CaaS Platform 4
    SUSE Ceph 增加节点、减少节点、 删除OSD磁盘等操作
  • 原文地址:https://www.cnblogs.com/default/p/1944328.html
Copyright © 2011-2022 走看看