c++ /WinRT WinUI3:如何在我关闭主窗口之前显示一个内容对话框?

Question

我试图显示一个ContentDialog，以确保用户确认关闭时，他们选择窗口的关闭按钮。但是在WinUI3中，我找不到CloseRequested Event.

我尝试使用AppWindow和Hwnd Interop和AppWindow。快结束了，但没有成功。在我点击关闭按钮后，什么也没发生。

我用的是Mica Window，我相信问题一定在这里。

m_closedRevoker = this->Closed(winrt::auto_revoke, [&](IInspectable const&, WindowEventArgs const& e)
{
if (!_closing)
{
_closing = true;
e.Handled(true);
if (have_saved)
{
DispatcherQueue().TryEnqueue([&](auto&& ...)
{
if (nullptr != m_backdropController)
{
m_backdropController.Close();
m_backdropController = nullptr;
}
if (nullptr != m_dispatcherQueueController)
{
m_dispatcherQueueController.ShutdownQueueAsync();
m_dispatcherQueueController = nullptr;
}
Close();
});
}
else
{
winrt::Microsoft::UI::Xaml::Controls::ContentDialog dialog;
dialog.XamlRoot(Content().XamlRoot());
dialog.Title(winrt::box_value(L"Save ?"));
dialog.PrimaryButtonText(L"Yes");
dialog.SecondaryButtonText(L"No");
dialog.CloseButtonText(L"Cancel");
dialog.DefaultButton(winrt::Microsoft::UI::Xaml::Controls::ContentDialogButton::Primary);
dialog.PrimaryButtonClick([&](auto&& ...)
{
if (save_data(winrt::Lexical_Frequency::implementation::amount))
{
DispatcherQueue().TryEnqueue([&](auto&& ...)
{
if (nullptr != m_backdropController)
{
m_backdropController.Close();
m_backdropController = nullptr;
}
if (nullptr != m_dispatcherQueueController)
{
m_dispatcherQueueController.ShutdownQueueAsync();
m_dispatcherQueueController = nullptr;
}
Close();
});
}
});
dialog.SecondaryButtonClick([&](auto&& ...)
{
DispatcherQueue().TryEnqueue([&](auto&& ...)
{
if (nullptr != m_backdropController)
{
m_backdropController.Close();
m_backdropController = nullptr;
}
if (nullptr != m_dispatcherQueueController)
{                                       m_dispatcherQueueController.ShutdownQueueAsync();
m_dispatcherQueueController = nullptr;
}
Close();
});
});
dialog.ShowAsync().Completed([&](auto&& ...)
{
_closing = false;
});
}
}
});

Answer 1

这是一个基于Window的解决方案。已关闭的事件，它有一个我们可以使用的已处理属性。在MainWindow.cpp:

namespace winrt::WinUIApp1CPP::implementation
{
MainWindow::MainWindow()
{
InitializeComponent();
_closing = false;
Closed([&](IInspectable const&, WindowEventArgs const& e)
{
if (!_closing)
{
_closing = true;
e.Handled(true);
ContentDialog dialog;
dialog.XamlRoot(Content().XamlRoot());
dialog.Title(box_value(L"Do you really want to close the app?"));
dialog.PrimaryButtonText(L"Yes, close");
dialog.CloseButtonText(L"No, cancel");
dialog.DefaultButton(ContentDialogButton::Close);
dialog.PrimaryButtonClick([&](auto&& ...)
{
DispatcherQueue().TryEnqueue([&](auto&& ...)
{
Close();
});
});
dialog.ShowAsync().Completed([&](auto&& ...)
{
_closing = false;
});
}
});
}
}

与MainWindow.h:

namespace winrt::WinUIApp1CPP::implementation
{
struct MainWindow : MainWindowT<MainWindow>
{
MainWindow();
...
bool _closing;
...
};
}

至于它的价值，在c# (MainWindow.xaml.cs)中等效:

public MainWindow()
{
InitializeComponent();
var closing = false;
Closed += async (s, e) =>
{
if (!closing)
{
closing = true;
e.Handled = true;
var dialog = new ContentDialog();
dialog.XamlRoot = Content.XamlRoot;
dialog.Title = "Do you really want to close the app?";
dialog.PrimaryButtonText = "Yes, close";
dialog.CloseButtonText = "No, cancel";
dialog.DefaultButton = ContentDialogButton.Close;
dialog.PrimaryButtonClick += (s, e) => DispatcherQueue.TryEnqueue(Close);
var result = await dialog.ShowAsync();
closing = false;
}
};
}

注意:DispatcherQueue的用法。TryEnqueue不应该是必需的，但是如果没有它，Close()调用目前会导致WinUI3崩溃…