我已經將一個小型應用程式與一個控制臺視窗集成在一起，該視窗將資訊傳遞給用戶。
在 meiner view habe ich ein ItemControl und im Template ein TextBlock, welches den "ConsoleText" anzeigt in der gewünschten Farbe "FontColour":
<Window x:Class="MyApplication.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:helper="clr-namespace:MyApplication.Helpers"
mc:Ignorable="d"
Title="MainWindow" Height="600" Width="800" MinHeight="600" MinWidth="800">
<Grid>
<DockPanel Grid.Row="0" Grid.Column="1" Grid.ColumnSpan="3" Grid.RowSpan="4" Background="Black">
<ScrollViewer HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto" helper:ScrollViewerExtension.AutoScroll="True">
<ItemsControl ItemsSource="{Binding logger.ConsoleOutput}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding ConsoleText}" Foreground="{Binding FontColour}" FontSize="14"/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</ScrollViewer>
</DockPanel>
</Grid>
</Window>
Mein CodeBehind beinhaltet lediglich den DataContext:
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
this.DataContext = new MainWindowViewModel();
}
}
我的 ViewMode 有三個資訊：
- 實體化 MyLogicClass，它在另一個專案中結構化并作為參考給出。
- ConsoleOutputList 被實體化，以便稍后在視圖中顯示“ConsoleOutput”。
- 該按鈕未顯示在視圖中，因為它在視圖中不相關，并且可以正常作業。
這里是 ViewModel：
public class MainWindowViewModel : ObservableObject
{
MyLogicClass myLogicClass = new MyLogicClass(null);
ConsoleOutputList logger = new ConsoleOutputList();
public MainWindowViewModel()
{
MyButtonCommand = new RelayCommand(o => Task.Run(() => myLogicClass.Test()));
}
public ICommand MyButtonCommand { get; }
}
ConsoleOutputList contains an ObservableCollection from "ConsoleLine" (also in another project). The "ConsoleLine" may have a string and a SolidColorBrush in the ctor (I think this one is not relevant either).
public class ConsoleOutputList : ObservableObject
{
public ConsoleOutputList()
{
ConsoleOutput = new ObservableCollection<ConsoleLine>();
// For testing purposes I add a random entry to see if the binding in general works - but this doesn`t work neither
ConsoleOutput.Add(new ConsoleLine("Test", Brushes.Green));
}
public ObservableCollection<ConsoleLine> consoleOutput { get; set; }
public ObservableCollection<ConsoleLine> ConsoleOutput
{
get
{
return consoleOutput;
}
set
{
consoleOutput = value;
}
}
//Used to add new lines to the ObservableCollection
public void WriteToConsole(object msg, SolidColorBrush fontColour)
{
ConsoleOutput.Add(new ConsoleLine(msg, fontColour));
}
}
This classe is used for all application logic (also in another project). As a test I have here the method Test() to simply add a text.
public class MyLogicClass
{
ConsoleOutputList Logger = new ConsoleOutputList();
public void Test()
{
Logger.WriteToConsole($"Test", Brushes.Gray);
}
}
Now I have two problems:
- I add a new element in ctor of ConsoleOutputList as a test to see in general if my view works correctly => But does not work
- I have the Test() method to simply test adding new items to the ObservableCollection to see if they show up after being added => But of course also does not work
And yes I know - I create two instances of ConsoleOutputList and this is not correct (this is the reason for the second problem). But I don`t know how to do it better because I need to access the WriteToConsole() from everywhere in the code. (Maybe change to static?) But how do I solve then the first problem and how does it then works with static property and showing them up in the view.
Update: Even if I change everything to static the "Test" line is shown in green but everything which I add afterwards is not shown in the GUI: Visual Studio
uj5u.com熱心網友回復：
在 WPF 中，您不能系結到方法或欄位。您必須系結到公共屬性（請參閱Microsoft Docs：系結源型別以了解有關支持的系結源的更多資訊）。
要解決問題 1)，您必須將該MainWindowViewModel.logger欄位實作為公共財產。如果預計屬性會發生變化，它必須引發INotifyPropertyChanged.PropertyChanged事件。
ConsoleOutputList要修復 2)，您必須在整個應用程式中分發 的共享實體。將其公開為靜態實體是一種解決方案，但通常不推薦。更好的解決方案是將共享實體傳遞給依賴的每個型別的建構式ConsoleOutputList。
固定的解決方案可能如下所示：
MainWindowViewModel.cs
public class MainWindowViewModel : ObservableObject
{
public MainWindowViewModel(ConsoleOutputList logger, MyLogicClass myLogicClass)
{
this.Logger = logger;
this.MyLogicClass = myLogicClass;
this.MyButtonCommand = new RelayCommand(o => Task.Run(() => myLogicClass.Test()));
}
public ConsoleOutputList Logger { get; }
public ICommand MyButtonCommand { get; }
private MyLogicClass MyLogicClass { get; }
}
MyLogicClass.cs
public class MyLogicClass
{
private ConsoleOutputList Logger { get; }
public MyLogicClass(ConsoleOutputList logger) => this.Logger = logger;
public void Test()
{
this.Logger.WriteToConsole($"Test", Brushes.Gray);
}
}
主視窗.xaml.cs
public partial class MainWindow : Window
{
public MainWindow(MainWindowViewModel mainWindowViewModel)
{
InitializeComponent();
this.DataContext = mainWindowViewModel;
}
}
應用程式.xaml
<Application Startup="App_OnStartup">
</Application>
應用程式.xaml.cs
public partial class App : Application
{
private void App_OnStartup(object sender, StartupEventArgs e)
{
/** Initialize the application with the shared instance **/
var sharedLoggerInstance = new ConsoleOutputList();
var classThatNeedsLogger = new MyLogicClass(sharedLoggerInstance);
var mainViewModel = new MainWindowViewModel(sharedLoggerInstance, classThatNeedsLogger);
var mainWindow = new MainWindow(mainViewModel);
mainWindow.Show();
}
}
Also don't wrap the ItemsControl into a ScrollViewer. Use a ListBox instead. ListBox is an enhanced ItemsControl, that has a ScrollViewer and UI virtualization enabled by default. If you expect to generate many log entries you will end up with many items in the list. If you don't use UI virtualization, your ItemsControl will kill the performance/responsiveness of your GUI.
<DockPanel>
<ListBox ItemsSource="{Binding Logger.ConsoleOutput}">
<ListBox.ItemTemplate>
...
</ListBox.ItemTemplate>
</ListBox>
</DockPanel>
To allow updating the collection ConsoleOutput from a background thread or a non UI thread in general, you can either use the Dispatcher to update the collection (not recommended in this case):
Dispatcher.InvokeAsync(() => myCollection.Add(item));
or configure the binding engine to marshal the collection's CollectionChanged event to the dispatcher thread.
Since the critical object is a collection that serves as a binding source, I recommend to configure the binding engine by calling the static BindingOperations.EnableCollectionSynchronization method. It is essential that the method is invoked on the dispatcher thread:
ConsoleOutputList.cs
public class ConsoleOutputList : ObservableObject
{
private object SyncLock { get; }
public ConsoleOutputList()
{
this.SyncLock = new object();
this.ConsoleOutput = new ObservableCollection<ConsoleLine>();
// Configure the binding engine to marshal the CollectionChanged event
// of this collection to the UI thread to prevent cross-thread exceptions
BindingOperations.EnableCollectionSynchronization(this.ConsoleOutput, this.SyncLock);
}
}
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