(1.9 port) Fix a number of shutdown crashes in TermControl (#10117)

1. The TSFInputControl may get a layout event after it has been removed
   from service (and no longer has a XAML tree)
   * Two fixes:
      * first, guard the layour updater from accessing detached xaml
	objects
      * second, shut down all pending throttled functions during close
	(not destruction!¹)
2. The TermControlAutomationPeer may be destructed before its events
   fire.
3. The TermControlAutomationPeer may receive a notification after it has
   been detached from XAML (and therefore has no dispatcher).

¹ Close happens before the control is removed from the XAML tree;
destruction happens some time later. We must detach all UI-bound events
in Close so that they don't fire between when we detach and when we
destruct.

Fixes MSFT-32496693
Fixes MSFT-32496158
Fixes MSFT-32509759
Fixes MSFT-32871913

(cherry picked from commit 661fde5937)

src/cascadia/TerminalControl/TSFInputControl.cpp

@@ -134,8 +134,9 @@ namespace winrt::Microsoft::Terminal::Control::implementation
     // Return Value:
     // - <none>
     void TSFInputControl::TryRedrawCanvas()
+    try
     {
-        if (!_focused)
+        if (!_focused || !Canvas())
         {
             return;
         }
@@ -164,6 +165,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
 
         _RedrawCanvas();
     }
+    CATCH_LOG()
 
     // Method Description:
     // - Redraw the Canvas and update the current Text Bounds and Control Bounds for

src/cascadia/TerminalControl/TermControl.cpp

@@ -535,7 +535,8 @@ namespace winrt::Microsoft::Terminal::Control::implementation
 
             _uiaEngine = std::make_unique<::Microsoft::Console::Render::UiaEngine>(autoPeer.get());
             _core->AttachUiaEngine(_uiaEngine.get());
-            return *autoPeer;
+            _automationPeer = *autoPeer;
+            return _automationPeer;
         }
         return nullptr;
     }
@@ -1719,6 +1720,15 @@ namespace winrt::Microsoft::Terminal::Control::implementation
 
             _RestorePointerCursorHandlers(*this, nullptr);
 
+            // These four throttled functions are triggered by terminal output and interact with the UI.
+            // Since Close() is the point after which we are removed from the UI, but before the destructor
+            // has run, we should disconnect them *right now*. If we don't, they may fire between the
+            // throttle delay (from the final output) and the dtor.
+            _tsfTryRedrawCanvas.reset();
+            _updatePatternLocations.reset();
+            _updateScrollBar.reset();
+            _playWarningBell.reset();
+
             // Disconnect the TSF input control so it doesn't receive EditContext events.
             TSFInputControl().Close();
             _autoScrollTimer.Stop();

src/cascadia/TerminalControl/TermControl.h

@@ -138,6 +138,8 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         // in order to safely resolve this unsafe pointer dependency. Otherwise a deallocated
         // IRenderEngine is accessed when ControlCore calls Renderer::TriggerTeardown.
         // (C++ class members are destroyed in reverse order.)
+        // Further, the TermControlAutomationPeer must be destructed after _uiaEngine!
+        winrt::Windows::UI::Xaml::Automation::Peers::AutomationPeer _automationPeer{ nullptr };
         std::unique_ptr<::Microsoft::Console::Render::UiaEngine> _uiaEngine;
 
         winrt::com_ptr<ControlCore> _core;

src/cascadia/TerminalControl/TermControlAutomationPeer.cpp

@@ -46,9 +46,17 @@ namespace winrt::Microsoft::Terminal::Control::implementation
     void TermControlAutomationPeer::SignalSelectionChanged()
     {
         UiaTracing::Signal::SelectionChanged();
-        Dispatcher().RunAsync(Windows::UI::Core::CoreDispatcherPriority::Normal, [&]() {
-            // The event that is raised when the text selection is modified.
-            RaiseAutomationEvent(AutomationEvents::TextPatternOnTextSelectionChanged);
+        auto dispatcher{ Dispatcher() };
+        if (!dispatcher)
+        {
+            return;
+        }
+        dispatcher.RunAsync(Windows::UI::Core::CoreDispatcherPriority::Normal, [weakThis{ get_weak() }]() {
+            if (auto strongThis{ weakThis.get() })
+            {
+                // The event that is raised when the text selection is modified.
+                strongThis->RaiseAutomationEvent(AutomationEvents::TextPatternOnTextSelectionChanged);
+            }
         });
     }
 
@@ -61,9 +69,17 @@ namespace winrt::Microsoft::Terminal::Control::implementation
     void TermControlAutomationPeer::SignalTextChanged()
     {
         UiaTracing::Signal::TextChanged();
-        Dispatcher().RunAsync(Windows::UI::Core::CoreDispatcherPriority::Normal, [&]() {
-            // The event that is raised when textual content is modified.
-            RaiseAutomationEvent(AutomationEvents::TextPatternOnTextChanged);
+        auto dispatcher{ Dispatcher() };
+        if (!dispatcher)
+        {
+            return;
+        }
+        dispatcher.RunAsync(Windows::UI::Core::CoreDispatcherPriority::Normal, [weakThis{ get_weak() }]() {
+            if (auto strongThis{ weakThis.get() })
+            {
+                // The event that is raised when textual content is modified.
+                strongThis->RaiseAutomationEvent(AutomationEvents::TextPatternOnTextChanged);
+            }
         });
     }
 
@@ -76,14 +92,22 @@ namespace winrt::Microsoft::Terminal::Control::implementation
     void TermControlAutomationPeer::SignalCursorChanged()
     {
         UiaTracing::Signal::CursorChanged();
-        Dispatcher().RunAsync(Windows::UI::Core::CoreDispatcherPriority::Normal, [&]() {
-            // The event that is raised when the text was changed in an edit control.
-            // Do NOT fire a TextEditTextChanged. Generally, an app on the other side
-            //    will expect more information. Though you can dispatch that event
-            //    on its own, it may result in a nullptr exception on the other side
-            //    because no additional information was provided. Crashing the screen
-            //    reader.
-            RaiseAutomationEvent(AutomationEvents::TextPatternOnTextSelectionChanged);
+        auto dispatcher{ Dispatcher() };
+        if (!dispatcher)
+        {
+            return;
+        }
+        dispatcher.RunAsync(Windows::UI::Core::CoreDispatcherPriority::Normal, [weakThis{ get_weak() }]() {
+            if (auto strongThis{ weakThis.get() })
+            {
+                // The event that is raised when the text was changed in an edit control.
+                // Do NOT fire a TextEditTextChanged. Generally, an app on the other side
+                //    will expect more information. Though you can dispatch that event
+                //    on its own, it may result in a nullptr exception on the other side
+                //    because no additional information was provided. Crashing the screen
+                //    reader.
+                strongThis->RaiseAutomationEvent(AutomationEvents::TextPatternOnTextSelectionChanged);
+            }
         });
     }