我试图为用户控件做一个简单的OneWay绑定,但老实说,我不明白为什么有些部分不起作用。 简单来说,我创建了一个带有一些依赖属性的WPF标准UserControl。 在我的主窗口中,我根据某些事件隐藏/显示UserControl,并将属性绑定到我的主窗口viewmodel数据。 但是,这样做不会让我的UserControl为某些部分刷新。例如,我的UserControl上有一个SearchString依赖项属性:
public static readonly DependencyProperty SearchStringProperty = DependencyProperty.Register("SearchString",
typeof(string), typeof(DisplayMailView), new UIPropertyMetadata(null));
public string SearchString
{
get { return (string)GetValue(SearchStringProperty); }
set
{
SetValue(SearchStringProperty, value);
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs("SearchString"));
}
var loFinds = richEditControl1.Document.FindAll(SearchString, SearchOptions.WholeWord);
foreach (var find in loFinds)
{
var oDoc = find.BeginUpdateDocument();
var oChars = oDoc.BeginUpdateCharacters(find);
oChars.BackColor = System.Drawing.Color.Yellow;
oDoc.EndUpdateCharacters(oChars);
find.EndUpdateDocument(oDoc);
}
}
}
UserControl中的这个绑定到我的主Window viewmodel
的SearchString成员<local:DisplayMailView SearchString="{Binding DataContext.SearchString, RelativeSource={RelativeSource AncestorType={x:Type Window}}, UpdateSourceTrigger=PropertyChanged, NotifyOnSourceUpdated=True,NotifyOnTargetUpdated=True,Mode=TwoWay}"/>
在我的ViewModel上:
public string SearchString
{
get
{
return _searchString;
}
set
{
_searchString = value;
if (!string.IsNullOrWhiteSpace(value))
DataGridService.FocusFirstRow();
RaisePropertyChanged();
}
}
我在主窗口viewmodel中设置了一个断点到我的SearchString,设置了值。但是,当我在UserControl上将一个断点放入我的SearchString集合时,它永远不会触发?
此外,我的UserControl的dataContext设置为:
(this.Content as FrameworkElement).DataContext = this;
我确切地说我的UserControl构造函数只在启动时调用一次,其他东西必须根据用户操作动态刷新。
有人有想法吗?我的输出窗口没有错误 感谢
答案 0 :(得分:4)
这是一种常见的误解。当DependencyProperty的值更改时,不会执行其CLR属性的set
中的代码。如果要在属性值更改时执行某些代码,则需要使用PropertyChanged回调。
您的UserControl代码应如下所示:
public static readonly DependencyProperty SearchStringProperty =
DependencyProperty.Register(
"SearchString",
typeof(string),
typeof(DisplayMailView),
new UIPropertyMetadata(null, OnSearchStringChanged));
// This sets OnSearchStringChanged as the PropertyChanged callback
public string SearchString
{
get { return (string)GetValue(SearchStringProperty); }
set
{
SetValue(SearchStringProperty, value);
// Any code you put here won't be executed
// when the DependencyProperty value changes
}
}
private static void OnSearchStringChanged(object sender, DependencyPropertyChangedEventArgs e)
{
// This part is not needed, DependencyProperties already
// notify of their changes automatically
//if (PropertyChanged != null)
//{
// PropertyChanged(this, new PropertyChangedEventArgs("SearchString"));
//}
var control = sender as DisplayMailView;
var loFinds = control.richEditControl1.Document.FindAll(SearchString, SearchOptions.WholeWord);
foreach (var find in loFinds)
{
var oDoc = find.BeginUpdateDocument();
var oChars = oDoc.BeginUpdateCharacters(find);
oChars.BackColor = System.Drawing.Color.Yellow;
oDoc.EndUpdateCharacters(oChars);
find.EndUpdateDocument(oDoc);
}
}