在我的程序中,我想contentPresenter
在其他人contentPresenter
获得关注时禁用a 。每个演示者由位于my中的一个属性表示MainWindowViewModel
。这也是IsEnabled
两位主持人所在的属性。
两者均contentPresenters
采用以下结构创建:UserControl-> ViewModel->数据模型。
现在,我试图contentPresenter
通过IsEnabled
从contentPresenter
获得焦点的代码的后面更改主窗口的ViewModel中的属性来禁用必要的功能。
contentPresenter
背后的用户控制代码:
public partial class EditBlockUC : UserControl
{
public EditBlockViewModel ViewModel { get { return DataContext as EditBlockViewModel; } }
public EditBlockUC()
{
InitializeComponent();
}
//Runs when the user control gets focus
private void UserControl_GotFocus(object sender, RoutedEventArgs e)
{
//This UserControl has access to MainWindowViewModel through
//it's own ViewModel, EditBlockViewModel
ViewModel.MainViewModel.LeftWidgetEnabled = false;
}
}
这行:ViewModel.MainViewModel.LeftWidgetEnabled = false;
成功更改了“主”窗口的视图模型中的属性,但视图不受影响。我可以通过查找呼叫方式来解决此问题NotifyPropertyChange()
吗?如果是这样,我该怎么做?
如果这是完全错误的解决方案,请告诉我,并帮助我修复它。
谢谢
更新1:
我完整的基础课:
public class PropertyChangedBase : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
}
public virtual void NotifyPropertyChange<TProperty>(Expression<Func<TProperty>> property)
{
var lambda = (LambdaExpression)property;
MemberExpression memberExpression;
if (lambda.Body is UnaryExpression)
{
var unaryExpression = (UnaryExpression)lambda.Body;
memberExpression = (MemberExpression)unaryExpression.Operand;
}
else
memberExpression = (MemberExpression)lambda.Body;
OnPropertyChanged(memberExpression.Member.Name);
}
protected bool SetField<T>(ref T field, T value, string propertyName)
{
if (EqualityComparer<T>.Default.Equals(field, value)) return false;
field = value;
OnPropertyChanged(propertyName);
return true;
}
}
更新2:
我的LeftWidgetEnabled
财产:
public bool LeftWidgetEnabled
{
get { return _leftWidgetEnabled; }
set { SetField(ref _leftWidgetEnabled, value, "LeftWidgetEnabled"); }
}
在LeftWidgetEnabled
你的ViewModel.MainViewModel
类必须是这样的:
private bool leftWidgetEnabled;
public bool LeftWidgetEnabled
{
get { return leftWidgetEnabled; }
set { SetField(ref leftWidgetEnabled, value, "LeftWidgetEnabled"); }
}
另外,您MainViewModel
必须实现INotifyPropertyChanged。
您最好允许MainViewModel
继承自aViewModelBase
并ViewModelBase
实现INotifyPropertyChanged。
public class MainViewModel : ViewModelBase
{
private bool leftWidgetEnabled;
public bool LeftWidgetEnabled
{
get { return leftWidgetEnabled; }
set { SetField(ref leftWidgetEnabled, value, "LeftWidgetEnabled"); }
}
}
public class ViewModelBase : INotifyPropertyChanged
{
// boiler-plate
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
}
protected bool SetField<T>(ref T field, T value, string propertyName)
{
if (EqualityComparer<T>.Default.Equals(field, value)) return false;
field = value;
OnPropertyChanged(propertyName);
return true;
}
}
更新1
然后,您的ContentPresenter应该绑定为:
<ContentPresenter IsEnabled="{Binding Path=LeftWidgetEnabled}" />
而DataContext
您的UserControl
(ContentPresenter
位于上的)应该是的实例MainViewModel
。
例如:
<UserControl
x:Class="MyApplication.UserControl1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:viewModels="**PATH TO YOUR VIEWMODELS-ASSEMBLY**"
mc:Ignorable="d">
<UserControl.DataContext>
<viewModels:MainViewModel />
</UserControl.DataContext>
<ContentPresenter IsEnabled="{Binding Path=LeftWidgetEnabled}" />
</UserControl>
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