Preview the input via the TSF input control. This is awesome, and should go into main

src/cascadia/TerminalApp/ActionPreviewHandlers.cpp

@@ -50,6 +50,7 @@ namespace winrt::TerminalApp::implementation
         {
         case ShortcutAction::SetColorScheme:
         case ShortcutAction::AdjustOpacity:
+        case ShortcutAction::SendInput:
         {
             _RunRestorePreviews();
             break;
@@ -140,6 +141,27 @@ namespace winrt::TerminalApp::implementation
         });
     }
 
+    void TerminalPage::_PreviewSendInput(const Settings::Model::SendInputArgs& args)
+    {
+        const auto backup = _restorePreviewFuncs.empty();
+
+        _ApplyToActiveControls([&](const auto& control) {
+            // // Stash a copy of the original opacity.
+            // auto originalOpacity{ control.BackgroundOpacity() };
+
+            // Apply the new opacity
+            control.PreviewInput(args.Input());
+
+            if (backup)
+            {
+                _restorePreviewFuncs.emplace_back([=]() {
+                    // On dismiss:
+                    control.PreviewInput(L"");
+                });
+            }
+        });
+    }
+
     // Method Description:
     // - Handler for the CommandPalette::PreviewAction event. The Command
     //   Palette will raise this even when an action is selected, but _not_
@@ -176,6 +198,11 @@ namespace winrt::TerminalApp::implementation
                 _PreviewAdjustOpacity(args.ActionAndArgs().Args().try_as<AdjustOpacityArgs>());
                 break;
             }
+            case ShortcutAction::SendInput:
+            {
+                _PreviewSendInput(args.ActionAndArgs().Args().try_as<SendInputArgs>());
+                break;
+            }
             }
 
             // GH#9818 Other ideas for actions that could be preview-able:

src/cascadia/TerminalApp/TerminalPage.cpp

@@ -262,6 +262,7 @@ namespace winrt::TerminalApp::implementation
             }
         });
         AutoCompleteMenu().DispatchCommandRequested({ this, &TerminalPage::_OnDispatchCommandRequested });
+        AutoCompleteMenu().PreviewAction({ this, &TerminalPage::_PreviewActionHandler });
 
         // Settings AllowDependentAnimations will affect whether animations are
         // enabled application-wide, so we don't need to check it each time we

src/cascadia/TerminalApp/TerminalPage.h

@@ -406,6 +406,7 @@ namespace winrt::TerminalApp::implementation
         void _RunRestorePreviews();
         void _PreviewColorScheme(const Microsoft::Terminal::Settings::Model::SetColorSchemeArgs& args);
         void _PreviewAdjustOpacity(const Microsoft::Terminal::Settings::Model::AdjustOpacityArgs& args);
+        void _PreviewSendInput(const Microsoft::Terminal::Settings::Model::SendInputArgs& args);
         winrt::Microsoft::Terminal::Settings::Model::Command _lastPreviewedCommand{ nullptr };
         std::vector<std::function<void()>> _restorePreviewFuncs{};
 

src/cascadia/TerminalControl/TSFInputControl.cpp

@@ -470,4 +470,19 @@ namespace winrt::Microsoft::Terminal::Control::implementation
     void TSFInputControl::_formatUpdatingHandler(CoreTextEditContext sender, CoreTextFormatUpdatingEventArgs const& /*args*/)
     {
     }
+
+    void TSFInputControl::ManuallyDisplayText(const winrt::hstring& text)
+    {
+        _focused = !text.empty();
+        Canvas().Visibility(text.empty() ? Visibility::Collapsed : Visibility::Visible);
+
+        _inputBuffer.clear();
+        // _editContext.NotifyFocusLeave();
+        _activeTextStart = 0;
+        _inComposition = false;
+
+        TextBlock().Text(text);
+        TextBlock().UpdateLayout();
+        TryRedrawCanvas();
+    }
 }

src/cascadia/TerminalControl/TSFInputControl.h

@@ -40,6 +40,8 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         void ClearBuffer();
         void TryRedrawCanvas();
 
+        void ManuallyDisplayText(const winrt::hstring& text);
+
         void Close();
 
         // -------------------------------- WinRT Events ---------------------------------

src/cascadia/TerminalControl/TSFInputControl.idl

@@ -31,6 +31,9 @@ namespace Microsoft.Terminal.Control
         void ClearBuffer();
         void TryRedrawCanvas();
 
+        void ManuallyDisplayText(String text);
+
+
         void Close();
     }
 }

src/cascadia/TerminalControl/TermControl.cpp

@@ -322,6 +322,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
     // - <none>
     void TermControl::SendInput(const winrt::hstring& wstr)
     {
+        PreviewInput(L"");
         _core.SendInput(wstr);
     }
     void TermControl::ClearBuffer(Control::ClearBufferType clearType)
@@ -2781,4 +2782,10 @@ namespace winrt::Microsoft::Terminal::Control::implementation
     {
         return _core.MenuEntries();
     }
+
+    void TermControl::PreviewInput(const winrt::hstring& text)
+    {
+        TSFInputControl().ManuallyDisplayText(text);
+    }
+
 }

src/cascadia/TerminalControl/TermControl.h

@@ -41,6 +41,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         Windows::Foundation::Size CharacterDimensions() const;
         Windows::Foundation::Size MinimumSize();
         float SnapDimensionToGrid(const bool widthOrHeight, const float dimension);
+        void PreviewInput(const winrt::hstring& text);
 
 #pragma region ICoreState
         const uint64_t TaskbarState() const noexcept;

src/cascadia/TerminalControl/TermControl.idl

@@ -82,5 +82,7 @@ namespace Microsoft.Terminal.Control
         // opacity set by the settings should call this instead.
         Double BackgroundOpacity { get; };
 
+        void PreviewInput(String text);
+
     }
 }