多视图的UWP问题 [英] UWP problems with multiple views
问题描述
我正在编写一个应用程序，该应用程序应能够运行多个视图以在各自的窗口中编辑不同的文档.我已经写了一些有效的代码，但是我遇到了一些问题.我编写的代码基于Microsoft提供的多视图"示例(https://github.com/Microsoft/Windows-universal-samples/tree/master/Samples/MultipleViews ).
I am writing an app which should be able to run multiple views to edit different documents each in their own window. I've wrote some code which works, but I'm having some problems with it. The code I wrote is based upon the Multiple Views sample provided by Microsoft (https://github.com/Microsoft/Windows-universal-samples/tree/master/Samples/MultipleViews).
我主要有两个问题.第一个是如果我关闭主视图，即启动应用程序时打开的第一个窗口，那么我无法通过单击应用程序磁贴或打开关联的文件类型来打开任何新的视图/窗口，直到我关闭所有视图/窗口，然后重新启动该应用程序.第二个是，当我尝试从MainPage.xaml.cs打开一个新的视图/窗口时，该应用程序崩溃了.
I have mainly two problems. The first one is if I close the main view, that is the first window that was open when the application was launched, then I cannot open any new views/windows by clicking in the app tile or opening an associated file type, until I close all views/windows and relaunch the app. The second one, is that when I try to open a new view/window from MainPage.xaml.cs, the app just crashes.
我用来管理App.xaml.cs中的视图的代码如下:
The code that I use to manage the views in App.xaml.cs is the following:
sealed partial class App : Application
{
//I use this boolean to determine if the application has already been launched once
private bool alreadyLaunched = false;
public ObservableCollection<ViewLifetimeControl> SecondaryViews = new ObservableCollection<ViewLifetimeControl>();
private CoreDispatcher mainDispatcher;
public CoreDispatcher MainDispatcher
{
get
{
return mainDispatcher;
}
}
private int mainViewId;
public int MainViewId
{
get
{
return mainViewId;
}
}
public App()
{
this.InitializeComponent();
this.Suspending += OnSuspending;
}
protected override async void OnLaunched(LaunchActivatedEventArgs e)
{
Frame rootFrame = Window.Current.Content as Frame;
if (rootFrame == null)
{
rootFrame = new Frame();
rootFrame.NavigationFailed += OnNavigationFailed;
if (e.PreviousExecutionState == ApplicationExecutionState.Terminated)
{
//TODO: Load state from previously suspended application
}
// Place the frame in the current Window
Window.Current.Content = rootFrame;
}
if (rootFrame.Content == null)
{
alreadyLaunched = true;
rootFrame.Navigate(typeof(MainPage), e.Arguments);
}
else if(alreadyLaunched)
{
var selectedView = await createMainPageAsync();
if (null != selectedView)
{
selectedView.StartViewInUse();
var viewShown = await ApplicationViewSwitcher.TryShowAsStandaloneAsync(
selectedView.Id,
ViewSizePreference.Default,
ApplicationView.GetForCurrentView().Id,
ViewSizePreference.Default
);
await selectedView.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
var currentPage = (MainPage)((Frame)Window.Current.Content).Content;
Window.Current.Activate();
});
selectedView.StopViewInUse();
}
}
// Ensure the current window is active
Window.Current.Activate();
}
protected override async void OnFileActivated(FileActivatedEventArgs args)
{
base.OnFileActivated(args);
if (alreadyLaunched)
{
//Frame rootFrame = Window.Current.Content as Frame;
//((MainPage)rootFrame.Content).OpenFileActivated(args);
var selectedView = await createMainPageAsync();
if (null != selectedView)
{
selectedView.StartViewInUse();
var viewShown = await ApplicationViewSwitcher.TryShowAsStandaloneAsync(
selectedView.Id,
ViewSizePreference.Default,
ApplicationView.GetForCurrentView().Id,
ViewSizePreference.Default
);
await selectedView.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
var currentPage = (MainPage)((Frame)Window.Current.Content).Content;
Window.Current.Activate();
currentPage.OpenFileActivated(args);
});
selectedView.StopViewInUse();
}
}
else
{
Frame rootFrame = new Frame();
rootFrame.Navigate(typeof(MainPage), args);
Window.Current.Content = rootFrame;
Window.Current.Activate();
alreadyLaunched = true;
}
}
partial void Construct();
partial void OverrideOnLaunched(LaunchActivatedEventArgs args, ref bool handled);
partial void InitializeRootFrame(Frame frame);
partial void OverrideOnLaunched(LaunchActivatedEventArgs args, ref bool handled)
{
// Check if a secondary view is supposed to be shown
ViewLifetimeControl ViewLifetimeControl;
handled = TryFindViewLifetimeControlForViewId(args.CurrentlyShownApplicationViewId, out ViewLifetimeControl);
if (handled)
{
var task = ViewLifetimeControl.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
Window.Current.Activate();
});
}
}
partial void InitializeRootFrame(Frame frame)
{
mainDispatcher = Window.Current.Dispatcher;
mainViewId = ApplicationView.GetForCurrentView().Id;
}
bool TryFindViewLifetimeControlForViewId(int viewId, out ViewLifetimeControl foundData)
{
foreach (var ViewLifetimeControl in SecondaryViews)
{
if (ViewLifetimeControl.Id == viewId)
{
foundData = ViewLifetimeControl;
return true;
}
}
foundData = null;
return false;
}
private async Task<ViewLifetimeControl> createMainPageAsync()
{
ViewLifetimeControl viewControl = null;
await CoreApplication.CreateNewView().Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
// This object is used to keep track of the views and important
// details about the contents of those views across threads
// In your app, you would probably want to track information
// like the open document or page inside that window
viewControl = ViewLifetimeControl.CreateForCurrentView();
viewControl.Title = DateTime.Now.ToString();
// Increment the ref count because we just created the view and we have a reference to it
viewControl.StartViewInUse();
var frame = new Frame();
frame.Navigate(typeof(MainPage), viewControl);
Window.Current.Content = frame;
// This is a change from 8.1: In order for the view to be displayed later it needs to be activated.
Window.Current.Activate();
//ApplicationView.GetForCurrentView().Title = viewControl.Title;
});
((App)App.Current).SecondaryViews.Add(viewControl);
return viewControl;
}
void OnNavigationFailed(object sender, NavigationFailedEventArgs e)
{
throw new Exception("Failed to load Page " + e.SourcePageType.FullName);
}
private void OnSuspending(object sender, SuspendingEventArgs e)
{
var deferral = e.SuspendingOperation.GetDeferral();
//TODO: Save application state and stop any background activity
deferral.Complete();
}
//I call this function from MainPage.xaml.cs to try to open a new window
public async void LoadNewView()
{
var selectedView = await createMainPageAsync();
if (null != selectedView)
{
selectedView.StartViewInUse();
var viewShown = await ApplicationViewSwitcher.TryShowAsStandaloneAsync(
selectedView.Id,
ViewSizePreference.Default,
ApplicationView.GetForCurrentView().Id,
ViewSizePreference.Default
);
await selectedView.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
var currentPage = (MainPage)((Frame)Window.Current.Content).Content;
Window.Current.Activate();
currentPage.LoadNewFile();
});
selectedView.StopViewInUse();
}
}
}
我用来尝试从MainPage.xaml.cs启动新视图/窗口的代码:
The code I use to try to launch a new view/window from MainPage.xaml.cs:
((App)App.Current).LoadNewView();
我一直在阅读Microsoft文档以尝试理解问题所在，但是我仍然不了解多视图的工作原理，例如，每次打开新视图/窗口时实例化App类的情况.
I've been reading the Microsoft documentation to try and understand what is the issue, but I still don't understand how exactly do Multiple Views work, like if the App class instantiated every time I open a new view/window.
我非常感谢您的帮助.
推荐答案
我已经找到解决问题的方法，并且实际上我决定不使用该示例随附的ViewLifeTime控件.
I've found the solution to my problems, and I've actually decided not to use the ViewLifeTime control that comes with the sample.
问题在于，当关闭主视图时，您必须从其他仍然打开的视图之一中使用Dispatcher.RunAsync()方法来运行该线程
The problem is that when the Main view is closed you have to use the Dispatcher.RunAsync() method from one of the other views that are still open to run it that thread
这是我在App.xaml.cs中为感兴趣的任何人更改的代码:
Here's the code that I've changed in my App.xaml.cs for anyone that is interested:
public bool isMainViewClosed = false;
public ObservableCollection<CoreApplicationView> secondaryViews = new ObservableCollection<CoreApplicationView>();
//...
protected override async void OnLaunched(LaunchActivatedEventArgs e)
{
Frame rootFrame = Window.Current.Content as Frame;
if (rootFrame == null)
{
rootFrame = new Frame();
rootFrame.NavigationFailed += OnNavigationFailed;
if (e.PreviousExecutionState == ApplicationExecutionState.Terminated)
{
//TODO: Load state from previously suspended application
}
Window.Current.Content = rootFrame;
}
if (rootFrame.Content == null)
{
alreadyLaunched = true;
rootFrame.Navigate(typeof(MainPage), e.Arguments);
}
else if(alreadyLaunched)
{
//If the main view is closed, use the thread of one of the views that are still open
if(isMainViewClosed)
{
int newViewId = 0;
await secondaryViews[0].Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
var currentPage = (MainPage)((Frame)Window.Current.Content).Content;
Window.Current.Activate();
currentPage.NewWindow();
newViewId = ApplicationView.GetForCurrentView().Id;
});
bool viewShown = await ApplicationViewSwitcher.TryShowAsStandaloneAsync(newViewId);
}
else
{
CoreApplicationView newView = CoreApplication.CreateNewView();
int newViewId = 0;
await newView.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
Frame frame = new Frame();
frame.Navigate(typeof(MainPage), null);
Window.Current.Content = frame;
var currentPage = (MainPage)((Frame)Window.Current.Content).Content;
Window.Current.Activate();
secondaryViews.Add(CoreApplication.GetCurrentView());
newViewId = ApplicationView.GetForCurrentView().Id;
});
bool viewShown = await ApplicationViewSwitcher.TryShowAsStandaloneAsync(newViewId);
}
}
Window.Current.Activate();
}
这篇关于多视图的UWP问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
