我正在开发一个 WPF 项目。这是我的 XAML 代码:
<Window x:Class="MyNamespace.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:l="clr-namespace:MyNamespace"
xmlns:p="clr-namespace:MyNamespace.Properties"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Height="500" Title="{x:Static p:Resources.Title}" Width="500"
WindowStartupLocation="CenterScreen">
<Window.Resources>
<l:BrowsersViewModel x:Key="BrowsersViewModel"/>
</Window.Resources>
<Canvas Background="{DynamicResource {x:Static SystemColors.ControlBrushKey}}"
DataContext="{StaticResource BrowsersViewModel}">
<ComboBox Canvas.Left="10" Canvas.Top="10" DisplayMemberPath="Name"
ItemsSource="{Binding Path=Items}"
SelectedItem="{Binding Mode=TwoWay, Path=SelectedItem}"
SelectedValuePath="Process" Width="379"/>
<Button Content="Repopulate" Canvas.Right="10"
Canvas.Top="10" Width="75"/>
</Canvas>
</Window>
这是我的 ViewModel 代码:
// BrowserInstance is a simple struct with two public fields:
// 1) System.Diagnostics.Process Process
// 2) System.String Name
public sealed class BrowsersViewModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private BrowserInstance m_SelectedItem;
public BrowserInstance SelectedItem
{
get { return m_SelectedItem; }
set
{
if (m_SelectedItem != value)
{
m_SelectedItem = value;
NotifyPropertyChanged("SelectedItem");
}
}
}
private ObservableCollection<BrowserInstance> m_Items;
public ObservableCollection<BrowserInstance> Items
{
get { return m_Items; }
set
{
if (m_Items != value)
{
m_Items = value;
NotifyPropertyChanged("Items");
}
}
}
public BrowsersViewModel()
{
m_Items = new ObservableCollection<BrowserInstance>();
Populate();
}
private void NotifyPropertyChanged(String propertyName)
{
if (PropertyChanged != null)
PropertyChanged(this, (new PropertyChangedEventArgs(propertyName)));
}
public void Populate()
{
foreach (Process process in Process.GetProcessesByName("chrome"))
{
BrowserInstance instance = new BrowserInstance();
instance.Process = process;
instance.Name = "[Chrome] "
+ process.Handle.ToString()
+ " " + ((process.MainWindowTitle.Length > 0) ?
process.MainWindowTitle : "NULL");
m_Items.Add(instance);
}
NotifyPropertyChanged("Items");
}
}
我真的很难让这个工作。我到处查看了大量示例,但仍然找不到使一切按预期工作的解决方案。
1) 我在 ComboBox 下拉列表中看到很多值,但它们都是空的。我想BrowserInstance.Name
在 ComboBox 内显示属性并在选择项目时检索BrowserInstance.Process
值。
2) 当应用程序启动时,会检查当前正在运行的浏览器进程以填充 ComboBox。如果没有找到正在运行的实例,我怎么能在我的 ComboBox 中显示一条消息,例如“没有找到实例!”?
3) 如果在应用统计时发现一个或多个浏览器实例,如何默认选择第一个?
4) Repopulate 按钮将用于重新检查用户正在运行的浏览器实例。假设之前选择的实例仍在运行……我怎样才能让那个实例保持选中状态?如果之前选择的实例不再运行,我如何再次默认选择第一个?
非常感谢!
编辑:这是我当前的代码
主窗口:
public MainWindow()
{
InitializeComponent();
DataContext = m_BrowserInstances = new BrowserInstancesViewModel();
}
private void OnClickButtonRefresh(Object sender, RoutedEventArgs e)
{
m_BrowserInstances.Populate();
}
BrowserInstancesViewModel:
public void Populate()
{
BrowserInstance selectedItem = m_SelectedItem;
List<BrowserInstance> items = new List<BrowserInstance>();
foreach (Process process in Process.GetProcessesByName("chrome"))
items.Add(new BrowserInstance(process));
if (items.Count > 0)
{
m_Items = new ObservableCollection<BrowserInstance>(items.OrderBy(x => x.Process.Id));
if ((selectedItem != null) && (m_Items.SingleOrDefault(NewMethod(selectedItem)) != null))
m_SelectedItem = selectedItem;
else
m_SelectedItem = m_Items[0];
m_Enabled = true;
}
else
{
m_Items = new ObservableCollection<BrowserInstance>() { (new BrowserInstance()) };
m_SelectedItem = m_Items[0];
m_Enabled = false;
}
NotifyPropertyChanged("Enabled");
NotifyPropertyChanged("Items");
NotifyPropertyChanged("SelectedItem");
}