Revert the revert of "Hide the window until we're finished with initialization" (#13811)

This is a revert of the revert of #12979. We mainly reverted that PR
because of an issue where restored windows would grow/shrink slightly on
external displays. It was too close to the ship date for that release,
so we backed it out wholesale (in #13098). I think I've found the real
root of the problem, and fixed it here.

The money diff here from the original PR:
4c08b9a1bc2e90b8284e4d8117d0de400784520f...c34495dcfc19ea67a9f4f9673d422760200683ab.
Basically, I had put the part where we actually handle the creation of
the window into `_AppInitializedHandler`, when we should have left the
window to be created in `_HandleCreateWindow` We create it there,
_hidden_, and then should only _show_ it in `_AppInitializedHandler`.

I'm _NOT_ incorporating the change for #9053. I reverted that bit in
1fac40355. I am too worried about that messing with the phwnd that I
wanted to get that reviewed and committed atomically, separately.

* fixes  #11561
* tested manually
* I work here

src/cascadia/TerminalApp/TerminalPage.cpp

@@ -623,7 +623,7 @@ namespace winrt::TerminalApp::implementation
     // - <none>
     // Return Value:
     // - <none>
-    void TerminalPage::_CompleteInitialization()
+    winrt::fire_and_forget TerminalPage::_CompleteInitialization()
     {
         _startupState = StartupState::Initialized;
 
@@ -643,10 +643,39 @@ namespace winrt::TerminalApp::implementation
         if (_tabs.Size() == 0 && !(_shouldStartInboundListener || _isEmbeddingInboundListener))
         {
             _LastTabClosedHandlers(*this, winrt::make<LastTabClosedEventArgs>(false));
+            co_return;
         }
         else
         {
-            _InitializedHandlers(*this, nullptr);
+            // GH#11561: When we start up, our window is initially just a frame
+            // with a transparent content area. We're gonna do all this startup
+            // init on the UI thread, so the UI won't actually paint till it's
+            // all done. This results in a few frames where the frame is
+            // visible, before the page paints for the first time, before any
+            // tabs appears, etc.
+            //
+            // To mitigate this, we're gonna wait for the UI thread to finish
+            // everything it's gotta do for the initial init, and _then_ fire
+            // our Initialized event. By waiting for everything else to finish
+            // (CoreDispatcherPriority::Low), we let all the tabs and panes
+            // actually get created. In the window layer, we're gonna cloak the
+            // window till this event is fired, so we don't actually see this
+            // frame until we're actually all ready to go.
+            //
+            // This will result in the window seemingly not loading as fast, but
+            // it will actually take exactly the same amount of time before it's
+            // usable.
+            //
+            // We also experimented with drawing a solid BG color before the
+            // initialization is finished. However, there are still a few frames
+            // after the frame is displayed before the XAML content first draws,
+            // so that didn't actually resolve any issues.
+            Dispatcher().RunAsync(CoreDispatcherPriority::Low, [weak = get_weak()]() {
+                if (auto self{ weak.get() })
+                {
+                    self->_InitializedHandlers(*self, nullptr);
+                }
+            });
         }
     }
 

src/cascadia/TerminalApp/TerminalPage.h

@@ -180,7 +180,7 @@ namespace winrt::TerminalApp::implementation
         TYPED_EVENT(AlwaysOnTopChanged, IInspectable, IInspectable);
         TYPED_EVENT(RaiseVisualBell, IInspectable, IInspectable);
         TYPED_EVENT(SetTaskbarProgress, IInspectable, IInspectable);
-        TYPED_EVENT(Initialized, IInspectable, winrt::Windows::UI::Xaml::RoutedEventArgs);
+        TYPED_EVENT(Initialized, IInspectable, IInspectable);
         TYPED_EVENT(IdentifyWindowsRequested, IInspectable, IInspectable);
         TYPED_EVENT(RenameWindowRequested, Windows::Foundation::IInspectable, winrt::TerminalApp::RenameWindowRequestedArgs);
         TYPED_EVENT(SummonWindowRequested, IInspectable, IInspectable);
@@ -447,7 +447,7 @@ namespace winrt::TerminalApp::implementation
 
         void _StartInboundListener();
 
-        void _CompleteInitialization();
+        winrt::fire_and_forget _CompleteInitialization();
 
         void _FocusActiveControl(IInspectable sender, IInspectable eventArgs);
 

src/cascadia/TerminalApp/TerminalPage.idl

@@ -89,7 +89,7 @@ namespace TerminalApp
         event Windows.Foundation.TypedEventHandler<Object, Object> FocusModeChanged;
         event Windows.Foundation.TypedEventHandler<Object, Object> FullscreenChanged;
         event Windows.Foundation.TypedEventHandler<Object, Object> AlwaysOnTopChanged;
-        event Windows.Foundation.TypedEventHandler<Object, Windows.UI.Xaml.RoutedEventArgs> Initialized;
+        event Windows.Foundation.TypedEventHandler<Object, Object> Initialized;
         event Windows.Foundation.TypedEventHandler<Object, Object> SetTaskbarProgress;
         event Windows.Foundation.TypedEventHandler<Object, Object> IdentifyWindowsRequested;
         event Windows.Foundation.TypedEventHandler<Object, RenameWindowRequestedArgs> RenameWindowRequested;

src/cascadia/TerminalApp/TerminalWindow.h

@@ -203,6 +203,8 @@ namespace winrt::TerminalApp::implementation
         // These are events that are handled by the TerminalPage, but are
         // exposed through the AppLogic. This macro is used to forward the event
         // directly to them.
+        FORWARDED_TYPED_EVENT(Initialized, winrt::Windows::Foundation::IInspectable, winrt::Windows::Foundation::IInspectable, _root, Initialized);
+
         FORWARDED_TYPED_EVENT(SetTitleBarContent, winrt::Windows::Foundation::IInspectable, winrt::Windows::UI::Xaml::UIElement, _root, SetTitleBarContent);
         FORWARDED_TYPED_EVENT(TitleChanged, winrt::Windows::Foundation::IInspectable, winrt::hstring, _root, TitleChanged);
         FORWARDED_TYPED_EVENT(LastTabClosed, winrt::Windows::Foundation::IInspectable, winrt::TerminalApp::LastTabClosedEventArgs, _root, LastTabClosed);

src/cascadia/TerminalApp/TerminalWindow.idl

@@ -114,6 +114,8 @@ namespace TerminalApp
         // information.
         void DismissDialog();
 
+        event Windows.Foundation.TypedEventHandler<Object, Object> Initialized;
+
         event Windows.Foundation.TypedEventHandler<Object, Windows.UI.Xaml.UIElement> SetTitleBarContent;
         event Windows.Foundation.TypedEventHandler<Object, String> TitleChanged;
         event Windows.Foundation.TypedEventHandler<Object, LastTabClosedEventArgs> LastTabClosed;

src/cascadia/WindowsTerminal/AppHost.cpp

@@ -60,8 +60,7 @@ AppHost::AppHost(const winrt::TerminalApp::AppLogic& logic,
     auto pfn = std::bind(&AppHost::_HandleCreateWindow,
                          this,
                          std::placeholders::_1,
-                         std::placeholders::_2,
-                         std::placeholders::_3);
+                         std::placeholders::_2);
     _window->SetCreateCallback(pfn);
 
     // Event handlers:
@@ -339,6 +338,7 @@ void AppHost::Initialize()
 
     _window->UpdateSettingsRequested({ this, &AppHost::_requestUpdateSettings });
 
+    _revokers.Initialized = _windowLogic.Initialized(winrt::auto_revoke, { this, &AppHost::_WindowInitializedHandler });
     _revokers.RequestedThemeChanged = _windowLogic.RequestedThemeChanged(winrt::auto_revoke, { this, &AppHost::_UpdateTheme });
     _revokers.FullscreenChanged = _windowLogic.FullscreenChanged(winrt::auto_revoke, { this, &AppHost::_FullscreenChanged });
     _revokers.FocusModeChanged = _windowLogic.FocusModeChanged(winrt::auto_revoke, { this, &AppHost::_FocusModeChanged });
@@ -510,12 +510,31 @@ LaunchPosition AppHost::_GetWindowLaunchPosition()
     return pos;
 }
 
+// Method Description:
+// - Callback for when the window is first being created (during WM_CREATE).
+//   Stash the proposed size for later. We'll need that once we're totally
+//   initialized, so that we can show the window in the right position *when we
+//   want to show it*. If we did the _initialResizeAndRepositionWindow work now,
+//   it would have no effect, because the window is not yet visible.
+// Arguments:
+// - hwnd: The HWND of the window we're about to create.
+// - proposedRect: The location and size of the window that we're about to
+//   create. We'll use this rect to determine which monitor the window is about
+//   to appear on.
+void AppHost::_HandleCreateWindow(const HWND /* hwnd */, const til::rect& proposedRect)
+{
+    // GH#11561: Hide the window until we're totally done being initialized.
+    // More commentary in TerminalPage::_CompleteInitialization
+    _initialResizeAndRepositionWindow(_window->GetHandle(), proposedRect, _launchMode);
+}
+
 // Method Description:
 // - Resize the window we're about to create to the appropriate dimensions, as
-//   specified in the settings. This will be called during the handling of
-//   WM_CREATE. We'll load the settings for the app, then get the proposed size
-//   of the terminal from the app. Using that proposed size, we'll resize the
-//   window we're creating, so that it'll match the values in the settings.
+//   specified in the settings. This is called once the app has finished it's
+//   initial setup, once we have created all the tabs, panes, etc. We'll load
+//   the settings for the app, then get the proposed size of the terminal from
+//   the app. Using that proposed size, we'll resize the window we're creating,
+//   so that it'll match the values in the settings.
 // Arguments:
 // - hwnd: The HWND of the window we're about to create.
 // - proposedRect: The location and size of the window that we're about to
@@ -524,7 +543,7 @@ LaunchPosition AppHost::_GetWindowLaunchPosition()
 // - launchMode: A LaunchMode enum reference that indicates the launch mode
 // Return Value:
 // - None
-void AppHost::_HandleCreateWindow(const HWND hwnd, til::rect proposedRect, LaunchMode& launchMode)
+void AppHost::_initialResizeAndRepositionWindow(const HWND hwnd, til::rect proposedRect, LaunchMode& launchMode)
 {
     launchMode = _windowLogic.GetLaunchMode();
 
@@ -1211,6 +1230,42 @@ void AppHost::_PropertyChangedHandler(const winrt::Windows::Foundation::IInspect
     }
 }
 
+winrt::fire_and_forget AppHost::_WindowInitializedHandler(const winrt::Windows::Foundation::IInspectable& /*sender*/,
+                                                          const winrt::Windows::Foundation::IInspectable& /*arg*/)
+{
+    // GH#11561: We're totally done being initialized. Resize the window to
+    // match the initial settings, and then call ShowWindow to finally make us
+    // visible.
+
+    auto nCmdShow = SW_SHOW;
+    if (WI_IsFlagSet(_launchMode, LaunchMode::MaximizedMode))
+    {
+        nCmdShow = SW_MAXIMIZE;
+    }
+
+    // For inexplicable reasons, again, hop to the BG thread, then back to the
+    // UI thread. This is shockingly load bearing - without this, then
+    // sometimes, we'll _still_ show the HWND before the XAML island actually
+    // paints.
+    co_await winrt::resume_background();
+    co_await wil::resume_foreground(_windowLogic.GetRoot().Dispatcher(), winrt::Windows::UI::Core::CoreDispatcherPriority::Low);
+    ShowWindow(_window->GetHandle(), nCmdShow);
+
+    // If we didn't start the window hidden (in one way or another), then try to
+    // pull ourselves to the foreground. Don't necessarily do a whole "summon",
+    // we don't really want to STEAL foreground if someone rightfully took it
+
+    const bool noForeground = nCmdShow == SW_SHOWMINIMIZED ||
+                              nCmdShow == SW_SHOWNOACTIVATE ||
+                              nCmdShow == SW_SHOWMINNOACTIVE ||
+                              nCmdShow == SW_SHOWNA ||
+                              nCmdShow == SW_FORCEMINIMIZE;
+    if (!noForeground)
+    {
+        SetForegroundWindow(_window->GetHandle());
+    }
+}
+
 winrt::TerminalApp::TerminalWindow AppHost::Logic()
 {
     return _windowLogic;

src/cascadia/WindowsTerminal/AppHost.h

@@ -39,6 +39,7 @@ private:
     winrt::com_ptr<IVirtualDesktopManager> _desktopManager{ nullptr };
 
     bool _useNonClientArea{ false };
+    winrt::Microsoft::Terminal::Settings::Model::LaunchMode _launchMode{};
 
     std::shared_ptr<ThrottledFuncTrailing<bool>> _showHideWindowThrottler;
 
@@ -47,7 +48,8 @@ private:
     void _HandleCommandlineArgs(const winrt::Microsoft::Terminal::Remoting::WindowRequestedArgs& args);
     winrt::Microsoft::Terminal::Settings::Model::LaunchPosition _GetWindowLaunchPosition();
 
-    void _HandleCreateWindow(const HWND hwnd, til::rect proposedRect, winrt::Microsoft::Terminal::Settings::Model::LaunchMode& launchMode);
+    void _HandleCreateWindow(const HWND hwnd, const til::rect& proposedRect);
+
     void _UpdateTitleBarContent(const winrt::Windows::Foundation::IInspectable& sender,
                                 const winrt::Windows::UI::Xaml::UIElement& arg);
     void _UpdateTheme(const winrt::Windows::Foundation::IInspectable&,
@@ -60,6 +62,9 @@ private:
                                   const winrt::Windows::Foundation::IInspectable& arg);
     void _AlwaysOnTopChanged(const winrt::Windows::Foundation::IInspectable& sender,
                              const winrt::Windows::Foundation::IInspectable& arg);
+    winrt::fire_and_forget _WindowInitializedHandler(const winrt::Windows::Foundation::IInspectable& sender,
+                                                     const winrt::Windows::Foundation::IInspectable& arg);
+
     void _RaiseVisualBell(const winrt::Windows::Foundation::IInspectable& sender,
                           const winrt::Windows::Foundation::IInspectable& arg);
     void _WindowMouseWheeled(const til::point coord, const int32_t delta);
@@ -116,7 +121,7 @@ private:
     void _PropertyChangedHandler(const winrt::Windows::Foundation::IInspectable& sender,
                                  const winrt::Windows::UI::Xaml::Data::PropertyChangedEventArgs& args);
 
-    void _initialResizeAndRepositionWindow(const HWND hwnd, RECT proposedRect, winrt::Microsoft::Terminal::Settings::Model::LaunchMode& launchMode);
+    void _initialResizeAndRepositionWindow(const HWND hwnd, til::rect proposedRect, winrt::Microsoft::Terminal::Settings::Model::LaunchMode& launchMode);
 
     void _handleMoveContent(const winrt::Windows::Foundation::IInspectable& sender,
                             winrt::TerminalApp::RequestMoveContentArgs args);
@@ -146,8 +151,10 @@ private:
         winrt::Microsoft::Terminal::Remoting::Peasant::SummonRequested_revoker peasantSummonRequested;
         winrt::Microsoft::Terminal::Remoting::Peasant::DisplayWindowIdRequested_revoker peasantDisplayWindowIdRequested;
         winrt::Microsoft::Terminal::Remoting::Peasant::QuitRequested_revoker peasantQuitRequested;
+
         winrt::Microsoft::Terminal::Remoting::Peasant::AttachRequested_revoker AttachRequested;
 
+        winrt::TerminalApp::TerminalWindow::Initialized_revoker Initialized;
         winrt::TerminalApp::TerminalWindow::CloseRequested_revoker CloseRequested;
         winrt::TerminalApp::TerminalWindow::RequestedThemeChanged_revoker RequestedThemeChanged;
         winrt::TerminalApp::TerminalWindow::FullscreenChanged_revoker FullscreenChanged;

src/cascadia/WindowsTerminal/IslandWindow.cpp

@@ -111,7 +111,7 @@ void IslandWindow::Close()
 //        window.
 // Return Value:
 // - <none>
-void IslandWindow::SetCreateCallback(std::function<void(const HWND, const til::rect&, LaunchMode& launchMode)> pfn) noexcept
+void IslandWindow::SetCreateCallback(std::function<void(const HWND, const til::rect&)> pfn) noexcept
 {
     _pfnCreateCallback = pfn;
 }
@@ -153,19 +153,13 @@ void IslandWindow::_HandleCreateWindow(const WPARAM, const LPARAM lParam) noexce
     rc.right = rc.left + pcs->cx;
     rc.bottom = rc.top + pcs->cy;
 
-    auto launchMode = LaunchMode::DefaultMode;
     if (_pfnCreateCallback)
     {
-        _pfnCreateCallback(_window.get(), rc, launchMode);
+        _pfnCreateCallback(_window.get(), rc);
     }
 
-    auto nCmdShow = SW_SHOW;
-    if (WI_IsFlagSet(launchMode, LaunchMode::MaximizedMode))
-    {
-        nCmdShow = SW_MAXIMIZE;
-    }
-
-    ShowWindow(_window.get(), nCmdShow);
+    // GH#11561: DO NOT call ShowWindow here. The AppHost will call ShowWindow
+    // once the app has completed its initialization.
 
     UpdateWindow(_window.get());
 

src/cascadia/WindowsTerminal/IslandWindow.h

@@ -39,7 +39,8 @@ public:
 
     virtual void Initialize();
 
-    void SetCreateCallback(std::function<void(const HWND, const til::rect&, winrt::Microsoft::Terminal::Settings::Model::LaunchMode& launchMode)> pfn) noexcept;
+    void SetCreateCallback(std::function<void(const HWND, const til::rect&)> pfn) noexcept;
+
     void SetSnapDimensionCallback(std::function<float(bool widthOrHeight, float dimension)> pfn) noexcept;
 
     void FocusModeChanged(const bool focusMode);
@@ -97,7 +98,7 @@ protected:
     winrt::Windows::UI::Xaml::Controls::Grid _rootGrid;
     wil::com_ptr<ITaskbarList3> _taskbar;
 
-    std::function<void(const HWND, const til::rect&, winrt::Microsoft::Terminal::Settings::Model::LaunchMode& launchMode)> _pfnCreateCallback;
+    std::function<void(const HWND, const til::rect&)> _pfnCreateCallback;
     std::function<float(bool, float)> _pfnSnapDimensionCallback;
 
     void _HandleCreateWindow(const WPARAM wParam, const LPARAM lParam) noexcept;

src/cascadia/WindowsTerminal/WindowEmperor.cpp

@@ -169,18 +169,13 @@ void WindowEmperor::_windowStartedHandlerPostXAML(const std::shared_ptr<WindowTh
     sender->Logic().IsQuakeWindowChanged({ this, &WindowEmperor::_windowIsQuakeWindowChanged });
     sender->UpdateSettingsRequested({ this, &WindowEmperor::_windowRequestUpdateSettings });
 
-    // Summon the window to the foreground, since we might not _currently_ be in
+    // DON'T Summon the window to the foreground, since we might not _currently_ be in
     // the foreground, but we should act like the new window is.
     //
-    // TODO: GH#14957 - use AllowSetForeground from the original wt.exe instead
-    Remoting::SummonWindowSelectionArgs args{};
-    args.OnCurrentDesktop(false);
-    args.WindowID(sender->Peasant().GetID());
-    args.SummonBehavior().MoveToCurrentDesktop(false);
-    args.SummonBehavior().ToggleVisibility(false);
-    args.SummonBehavior().DropdownDuration(0);
-    args.SummonBehavior().ToMonitor(Remoting::MonitorBehavior::InPlace);
-    _manager.SummonWindow(args);
+    // If you summon here, the resulting code will call ShowWindow(SW_SHOW) on
+    // the Terminal window, making it visible BEFORE the XAML island is actually
+    // ready to be drawn. We want to wait till the app's Initialized event
+    // before we make the window visible.
 
     // Now that the window is ready to go, we can add it to our list of windows,
     // because we know it will be well behaved.