Implement ConEmu's OSC 9;4 to set the taskbar progress indicator (#8055)

This commit implements the OSC 9;4 sequence per the [ConEmu style].

| sequence                   | description                                       |
| ------------               | ------------                                      |
| `ESC ] 9 ; 4 ; st ; pr ST` | Set progress state on taskbar and tab.            |
|                            | When `st` is:                                     |
|                            |                                                   |
|                            | `0`: remove progress.                             |
|                            | `1`: set progress value to `pr` (number, 0-100).  |
|                            | `2`: set the taskbar to the "Error" state         |
|                            | `3`: set the taskbar to the "Indeterminate" state |
|                            | `4`: set the taskbar to the "Warning" state       |

We've also extended this with:
* st 3: set indeterminate state
* st 4: set paused state

We handle multiple tabs sending the sequence by using the the last focused
control's taskbar state/progress.

Upon receiving the sequence in `TerminalApi`, we send an event that gets caught
by `TerminalPage`. `TerminalPage` then fires another event that gets caught by
`AppHost` and that's where we set the taskbar progress. 

Closes #3004 

[ConEmu style]: https://conemu.github.io/en/AnsiEscapeCodes.html#ConEmu_specific_OSC

.github/actions/spell-check/dictionary/apis.txt

@@ -32,6 +32,8 @@ IInheritable
 IMap
 IObject
 IStorage
+ITaskbar
+llabs
 LCID
 llabs
 localtime
@@ -42,6 +44,7 @@ NCHITTEST
 NCLBUTTONDBLCLK
 NCRBUTTONDBLCLK
 NOAGGREGATION
+NOPROGRESS
 NOREDIRECTIONBITMAP
 oaidl
 ocidl
@@ -63,6 +66,7 @@ sregex
 STDCPP
 strchr
 syscall
+TBPF
 THEMECHANGED
 tmp
 tx

src/cascadia/TerminalApp/AppLogic.cpp

@@ -1051,6 +1051,32 @@ namespace winrt::TerminalApp::implementation
         }
     }
 
+    // Method Description:
+    // - Gets the taskbar state value from the last active control
+    // Return Value:
+    // - The taskbar state of the last active control
+    size_t AppLogic::GetLastActiveControlTaskbarState()
+    {
+        if (_root)
+        {
+            return _root->GetLastActiveControlTaskbarState();
+        }
+        return {};
+    }
+
+    // Method Description:
+    // - Gets the taskbar progress value from the last active control
+    // Return Value:
+    // - The taskbar progress of the last active control
+    size_t AppLogic::GetLastActiveControlTaskbarProgress()
+    {
+        if (_root)
+        {
+            return _root->GetLastActiveControlTaskbarProgress();
+        }
+        return {};
+    }
+
     // Method Description:
     // - Sets the initial commandline to process on startup, and attempts to
     //   parse it. Commands will be parsed into a list of ShortcutActions that

src/cascadia/TerminalApp/AppLogic.h

@@ -50,6 +50,9 @@ namespace winrt::TerminalApp::implementation
 
         void WindowCloseButtonClicked();
 
+        size_t GetLastActiveControlTaskbarState();
+        size_t GetLastActiveControlTaskbarProgress();
+
         winrt::Windows::Foundation::IAsyncOperation<winrt::Windows::UI::Xaml::Controls::ContentDialogResult> ShowDialog(winrt::Windows::UI::Xaml::Controls::ContentDialog dialog);
 
         // -------------------------------- WinRT Events ---------------------------------
@@ -110,6 +113,7 @@ namespace winrt::TerminalApp::implementation
         FORWARDED_TYPED_EVENT(FocusModeChanged, winrt::Windows::Foundation::IInspectable, winrt::Windows::Foundation::IInspectable, _root, FocusModeChanged);
         FORWARDED_TYPED_EVENT(FullscreenChanged, winrt::Windows::Foundation::IInspectable, winrt::Windows::Foundation::IInspectable, _root, FullscreenChanged);
         FORWARDED_TYPED_EVENT(AlwaysOnTopChanged, winrt::Windows::Foundation::IInspectable, winrt::Windows::Foundation::IInspectable, _root, AlwaysOnTopChanged);
+        FORWARDED_TYPED_EVENT(SetTaskbarProgress, winrt::Windows::Foundation::IInspectable, winrt::Windows::Foundation::IInspectable, _root, SetTaskbarProgress);
     };
 }
 

src/cascadia/TerminalApp/AppLogic.idl

@@ -52,6 +52,9 @@ namespace TerminalApp
         void TitlebarClicked();
         void WindowCloseButtonClicked();
 
+        UInt64 GetLastActiveControlTaskbarState();
+        UInt64 GetLastActiveControlTaskbarProgress();
+
         // See IDialogPresenter and TerminalPage's DialogPresenter for more
         // information.
         Windows.Foundation.IAsyncOperation<Windows.UI.Xaml.Controls.ContentDialogResult> ShowDialog(Windows.UI.Xaml.Controls.ContentDialog dialog);
@@ -63,5 +66,6 @@ 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, Object> SetTaskbarProgress;
     }
 }

src/cascadia/TerminalApp/TerminalPage.cpp

@@ -1132,6 +1132,9 @@ namespace winrt::TerminalApp::implementation
 
         term.OpenHyperlink({ this, &TerminalPage::_OpenHyperlinkHandler });
 
+        // Add an event handler for when the terminal wants to set a progress indicator on the taskbar
+        term.SetTaskbarProgress({ this, &TerminalPage::_SetTaskbarProgressHandler });
+
         // Bind Tab events to the TermControl and the Tab's Pane
         hostingTab.Initialize(term);
 
@@ -1984,6 +1987,16 @@ namespace winrt::TerminalApp::implementation
         return control.CopySelectionToClipboard(singleLine, formats);
     }
 
+    // Method Description:
+    // - Send an event (which will be caught by AppHost) to set the progress indicator on the taskbar
+    // Arguments:
+    // - sender (not used)
+    // - eventArgs: the arguments specifying how to set the progress indicator
+    void TerminalPage::_SetTaskbarProgressHandler(const IInspectable /*sender*/, const IInspectable /*eventArgs*/)
+    {
+        _setTaskbarProgressHandlers(*this, nullptr);
+    }
+
     // Method Description:
     // - Paste text from the Windows Clipboard to the focused terminal
     void TerminalPage::_PasteText()
@@ -2365,6 +2378,32 @@ namespace winrt::TerminalApp::implementation
         _dialogPresenter = dialogPresenter;
     }
 
+    // Method Description:
+    // - Gets the taskbar state value from the last active control
+    // Return Value:
+    // - The taskbar state of the last active control
+    size_t TerminalPage::GetLastActiveControlTaskbarState()
+    {
+        if (auto control{ _GetActiveControl() })
+        {
+            return gsl::narrow_cast<size_t>(control.TaskbarState());
+        }
+        return {};
+    }
+
+    // Method Description:
+    // - Gets the taskbar progress value from the last active control
+    // Return Value:
+    // - The taskbar progress of the last active control
+    size_t TerminalPage::GetLastActiveControlTaskbarProgress()
+    {
+        if (auto control{ _GetActiveControl() })
+        {
+            return gsl::narrow_cast<size_t>(control.TaskbarProgress());
+        }
+        return {};
+    }
+
     // Method Description:
     // - This is the method that App will call when the titlebar
     //   has been clicked. It dismisses any open flyouts.
@@ -2890,4 +2929,5 @@ namespace winrt::TerminalApp::implementation
     DEFINE_EVENT_WITH_TYPED_EVENT_HANDLER(TerminalPage, FocusModeChanged, _focusModeChangedHandlers, winrt::Windows::Foundation::IInspectable, winrt::Windows::Foundation::IInspectable);
     DEFINE_EVENT_WITH_TYPED_EVENT_HANDLER(TerminalPage, FullscreenChanged, _fullscreenChangedHandlers, winrt::Windows::Foundation::IInspectable, winrt::Windows::Foundation::IInspectable);
     DEFINE_EVENT_WITH_TYPED_EVENT_HANDLER(TerminalPage, AlwaysOnTopChanged, _alwaysOnTopChangedHandlers, winrt::Windows::Foundation::IInspectable, winrt::Windows::Foundation::IInspectable);
+    DEFINE_EVENT_WITH_TYPED_EVENT_HANDLER(TerminalPage, SetTaskbarProgress, _setTaskbarProgressHandlers, winrt::Windows::Foundation::IInspectable, winrt::Windows::Foundation::IInspectable);
 }

src/cascadia/TerminalApp/TerminalPage.h

@@ -71,6 +71,9 @@ namespace winrt::TerminalApp::implementation
         winrt::TerminalApp::IDialogPresenter DialogPresenter() const;
         void DialogPresenter(winrt::TerminalApp::IDialogPresenter dialogPresenter);
 
+        size_t GetLastActiveControlTaskbarState();
+        size_t GetLastActiveControlTaskbarProgress();
+
         void ShowKeyboardServiceWarning();
         winrt::hstring KeyboardServiceDisabledText();
 
@@ -81,6 +84,7 @@ namespace winrt::TerminalApp::implementation
         DECLARE_EVENT_WITH_TYPED_EVENT_HANDLER(FocusModeChanged, _focusModeChangedHandlers, winrt::Windows::Foundation::IInspectable, winrt::Windows::Foundation::IInspectable);
         DECLARE_EVENT_WITH_TYPED_EVENT_HANDLER(FullscreenChanged, _fullscreenChangedHandlers, winrt::Windows::Foundation::IInspectable, winrt::Windows::Foundation::IInspectable);
         DECLARE_EVENT_WITH_TYPED_EVENT_HANDLER(AlwaysOnTopChanged, _alwaysOnTopChangedHandlers, winrt::Windows::Foundation::IInspectable, winrt::Windows::Foundation::IInspectable);
+        DECLARE_EVENT_WITH_TYPED_EVENT_HANDLER(SetTaskbarProgress, _setTaskbarProgressHandlers, winrt::Windows::Foundation::IInspectable, winrt::Windows::Foundation::IInspectable);
         TYPED_EVENT(Initialized, winrt::Windows::Foundation::IInspectable, winrt::Windows::UI::Xaml::RoutedEventArgs);
 
     private:
@@ -195,6 +199,8 @@ namespace winrt::TerminalApp::implementation
         void _ShowCouldNotOpenDialog(winrt::hstring reason, winrt::hstring uri);
         bool _CopyText(const bool singleLine, const Windows::Foundation::IReference<Microsoft::Terminal::TerminalControl::CopyFormat>& formats);
 
+        void _SetTaskbarProgressHandler(const IInspectable sender, const IInspectable eventArgs);
+
         void _PasteText();
 
         void _ControlNoticeRaisedHandler(const IInspectable sender, const Microsoft::Terminal::TerminalControl::NoticeEventArgs eventArgs);

src/cascadia/TerminalApp/TerminalPage.idl

@@ -29,6 +29,9 @@ namespace TerminalApp
         void ShowKeyboardServiceWarning();
         String KeyboardServiceDisabledText { get; };
 
+        UInt64 GetLastActiveControlTaskbarState();
+        UInt64 GetLastActiveControlTaskbarProgress();
+
         event Windows.Foundation.TypedEventHandler<Object, String> TitleChanged;
         event Windows.Foundation.TypedEventHandler<Object, LastTabClosedEventArgs> LastTabClosed;
         event Windows.Foundation.TypedEventHandler<Object, Windows.UI.Xaml.UIElement> SetTitleBarContent;
@@ -36,5 +39,6 @@ namespace TerminalApp
         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> SetTaskbarProgress;
     }
 }

src/cascadia/TerminalApp/TerminalTab.cpp

@@ -105,6 +105,7 @@ namespace winrt::TerminalApp::implementation
             if (lastFocusedControl)
             {
                 lastFocusedControl.Focus(_focusState);
+                lastFocusedControl.TaskbarProgressChanged();
             }
         }
     }

src/cascadia/TerminalControl/TermControl.cpp

@@ -107,6 +107,8 @@ namespace winrt::Microsoft::Terminal::TerminalControl::implementation
         auto pfnCopyToClipboard = std::bind(&TermControl::_CopyToClipboard, this, std::placeholders::_1);
         _terminal->SetCopyToClipboardCallback(pfnCopyToClipboard);
 
+        _terminal->TaskbarProgressChangedCallback([&]() { TermControl::TaskbarProgressChanged(); });
+
         // This event is explicitly revoked in the destructor: does not need weak_ref
         auto onReceiveOutputFn = [this](const hstring str) {
             _terminal->Write(str);
@@ -3091,6 +3093,33 @@ namespace winrt::Microsoft::Terminal::TerminalControl::implementation
         return coreColor.has_value() ? Windows::Foundation::IReference<winrt::Windows::UI::Color>(coreColor.value()) : nullptr;
     }
 
+    // Method Description:
+    // - Sends an event (which will be caught by TerminalPage and forwarded to AppHost after)
+    //   to set the progress indicator on the taskbar
+    winrt::fire_and_forget TermControl::TaskbarProgressChanged()
+    {
+        co_await resume_foreground(Dispatcher(), CoreDispatcherPriority::High);
+        _setTaskbarProgressHandlers(*this, nullptr);
+    }
+
+    // Method Description:
+    // - Gets the internal taskbar state value
+    // Return Value:
+    // - The taskbar state of this control
+    const size_t TermControl::TaskbarState() const noexcept
+    {
+        return _terminal->GetTaskbarState();
+    }
+
+    // Method Description:
+    // - Gets the internal taskbar progress value
+    // Return Value:
+    // - The taskbar progress of this control
+    const size_t TermControl::TaskbarProgress() const noexcept
+    {
+        return _terminal->GetTaskbarProgress();
+    }
+
     // -------------------------------- WinRT Events ---------------------------------
     // Winrt events need a method for adding a callback to the event and removing the callback.
     // These macros will define them both for you.
@@ -3101,6 +3130,7 @@ namespace winrt::Microsoft::Terminal::TerminalControl::implementation
     DEFINE_EVENT_WITH_TYPED_EVENT_HANDLER(TermControl, PasteFromClipboard, _clipboardPasteHandlers, TerminalControl::TermControl, TerminalControl::PasteFromClipboardEventArgs);
     DEFINE_EVENT_WITH_TYPED_EVENT_HANDLER(TermControl, CopyToClipboard, _clipboardCopyHandlers, TerminalControl::TermControl, TerminalControl::CopyToClipboardEventArgs);
     DEFINE_EVENT_WITH_TYPED_EVENT_HANDLER(TermControl, OpenHyperlink, _openHyperlinkHandlers, TerminalControl::TermControl, TerminalControl::OpenHyperlinkEventArgs);
+    DEFINE_EVENT_WITH_TYPED_EVENT_HANDLER(TermControl, SetTaskbarProgress, _setTaskbarProgressHandlers, TerminalControl::TermControl, IInspectable);
     DEFINE_EVENT_WITH_TYPED_EVENT_HANDLER(TermControl, RaiseNotice, _raiseNoticeHandlers, TerminalControl::TermControl, TerminalControl::NoticeEventArgs);
     // clang-format on
 }

src/cascadia/TerminalControl/TermControl.h

@@ -158,6 +158,10 @@ namespace winrt::Microsoft::Terminal::TerminalControl::implementation
 
         Windows::Foundation::IReference<winrt::Windows::UI::Color> TabColor() noexcept;
 
+        winrt::fire_and_forget TaskbarProgressChanged();
+        const size_t TaskbarState() const noexcept;
+        const size_t TaskbarProgress() const noexcept;
+
         // clang-format off
         // -------------------------------- WinRT Events ---------------------------------
         DECLARE_EVENT(TitleChanged,             _titleChangedHandlers,              TerminalControl::TitleChangedEventArgs);
@@ -167,6 +171,7 @@ namespace winrt::Microsoft::Terminal::TerminalControl::implementation
         DECLARE_EVENT_WITH_TYPED_EVENT_HANDLER(PasteFromClipboard,  _clipboardPasteHandlers,    TerminalControl::TermControl, TerminalControl::PasteFromClipboardEventArgs);
         DECLARE_EVENT_WITH_TYPED_EVENT_HANDLER(CopyToClipboard,     _clipboardCopyHandlers,     TerminalControl::TermControl, TerminalControl::CopyToClipboardEventArgs);
         DECLARE_EVENT_WITH_TYPED_EVENT_HANDLER(OpenHyperlink, _openHyperlinkHandlers, TerminalControl::TermControl, TerminalControl::OpenHyperlinkEventArgs);
+        DECLARE_EVENT_WITH_TYPED_EVENT_HANDLER(SetTaskbarProgress, _setTaskbarProgressHandlers, TerminalControl::TermControl, IInspectable);
         DECLARE_EVENT_WITH_TYPED_EVENT_HANDLER(RaiseNotice, _raiseNoticeHandlers, TerminalControl::TermControl, TerminalControl::NoticeEventArgs);
 
         TYPED_EVENT(WarningBell, IInspectable, IInspectable);

src/cascadia/TerminalControl/TermControl.idl

@@ -74,6 +74,7 @@ namespace Microsoft.Terminal.TerminalControl
         event Windows.Foundation.TypedEventHandler<TermControl, CopyToClipboardEventArgs> CopyToClipboard;
         event Windows.Foundation.TypedEventHandler<TermControl, PasteFromClipboardEventArgs> PasteFromClipboard;
         event Windows.Foundation.TypedEventHandler<TermControl, OpenHyperlinkEventArgs> OpenHyperlink;
+        event Windows.Foundation.TypedEventHandler<TermControl, Object> SetTaskbarProgress;
         event Windows.Foundation.TypedEventHandler<TermControl, NoticeEventArgs> RaiseNotice;
         event Windows.Foundation.TypedEventHandler<Object, Object> WarningBell;
 
@@ -105,6 +106,10 @@ namespace Microsoft.Terminal.TerminalControl
         void SendInput(String input);
         void ToggleRetroEffect();
 
+        void TaskbarProgressChanged();
+        UInt64 TaskbarState { get; };
+        UInt64 TaskbarProgress { get; };
+
         Windows.Foundation.IReference<Windows.UI.Color> TabColor { get; };
         event Windows.Foundation.TypedEventHandler<Object, Object> TabColorChanged;
     }

src/cascadia/TerminalCore/ITerminalApi.hpp

@@ -63,6 +63,8 @@ namespace Microsoft::Terminal::Core
         virtual bool AddHyperlink(std::wstring_view uri, std::wstring_view params) noexcept = 0;
         virtual bool EndHyperlink() noexcept = 0;
 
+        virtual bool SetTaskbarProgress(const size_t state, const size_t progress) noexcept = 0;
+
     protected:
         ITerminalApi() = default;
     };

src/cascadia/TerminalCore/Terminal.cpp

@@ -50,7 +50,9 @@ Terminal::Terminal() :
     _snapOnInput{ true },
     _altGrAliasing{ true },
     _blockSelection{ false },
-    _selection{ std::nullopt }
+    _selection{ std::nullopt },
+    _taskbarState{ 0 },
+    _taskbarProgress{ 0 }
 {
     auto dispatch = std::make_unique<TerminalDispatch>(*this);
     auto engine = std::make_unique<OutputStateMachineEngine>(std::move(dispatch));
@@ -1102,6 +1104,16 @@ void Terminal::SetBackgroundCallback(std::function<void(const COLORREF)> pfn) no
     _pfnBackgroundColorChanged.swap(pfn);
 }
 
+// Method Description:
+// - Allows settings a callback for settings the taskbar progress indicator
+// Arguments:
+// - pfn: a function callback that takes 2 size_t parameters, one indicating the progress state
+//        and the other indicating the progress value
+void Microsoft::Terminal::Core::Terminal::TaskbarProgressChangedCallback(std::function<void()> pfn) noexcept
+{
+    _pfnTaskbarProgressChanged.swap(pfn);
+}
+
 void Terminal::_InitializeColorTable()
 try
 {
@@ -1168,3 +1180,21 @@ BlinkingState& Terminal::GetBlinkingState() const noexcept
 {
     return _blinkingState;
 }
+
+// Method Description:
+// - Gets the internal taskbar state value
+// Return Value:
+// - The taskbar state
+const size_t Microsoft::Terminal::Core::Terminal::GetTaskbarState() const noexcept
+{
+    return _taskbarState;
+}
+
+// Method Description:
+// - Gets the internal taskbar progress value
+// Return Value:
+// - The taskbar progress
+const size_t Microsoft::Terminal::Core::Terminal::GetTaskbarProgress() const noexcept
+{
+    return _taskbarProgress;
+}

src/cascadia/TerminalCore/Terminal.hpp

@@ -115,6 +115,8 @@ public:
 
     bool AddHyperlink(std::wstring_view uri, std::wstring_view params) noexcept override;
     bool EndHyperlink() noexcept override;
+
+    bool SetTaskbarProgress(const size_t state, const size_t progress) noexcept override;
 #pragma endregion
 
 #pragma region ITerminalInput
@@ -185,6 +187,7 @@ public:
     void SetScrollPositionChangedCallback(std::function<void(const int, const int, const int)> pfn) noexcept;
     void SetCursorPositionChangedCallback(std::function<void()> pfn) noexcept;
     void SetBackgroundCallback(std::function<void(const COLORREF)> pfn) noexcept;
+    void TaskbarProgressChangedCallback(std::function<void()> pfn) noexcept;
 
     void SetCursorOn(const bool isOn);
     bool IsCursorBlinkingAllowed() const noexcept;
@@ -196,6 +199,9 @@ public:
 
     Microsoft::Console::Render::BlinkingState& GetBlinkingState() const noexcept;
 
+    const size_t GetTaskbarState() const noexcept;
+    const size_t GetTaskbarProgress() const noexcept;
+
 #pragma region TextSelection
     // These methods are defined in TerminalSelection.cpp
     enum class SelectionExpansionMode
@@ -221,6 +227,7 @@ private:
     std::function<void(const COLORREF)> _pfnBackgroundColorChanged;
     std::function<void()> _pfnCursorPositionChanged;
     std::function<void(const std::optional<til::color>)> _pfnTabColorChanged;
+    std::function<void()> _pfnTaskbarProgressChanged;
 
     std::unique_ptr<::Microsoft::Console::VirtualTerminal::StateMachine> _stateMachine;
     std::unique_ptr<::Microsoft::Console::VirtualTerminal::TerminalInput> _terminalInput;
@@ -240,6 +247,9 @@ private:
     bool _altGrAliasing;
     bool _suppressApplicationTitle;
 
+    size_t _taskbarState;
+    size_t _taskbarProgress;
+
     size_t _hyperlinkPatternId;
 
 #pragma region Text Selection

src/cascadia/TerminalCore/TerminalApi.cpp

@@ -600,3 +600,21 @@ bool Terminal::EndHyperlink() noexcept
     _buffer->SetCurrentAttributes(attr);
     return true;
 }
+
+// Method Description:
+// - Updates the taskbar progress indicator
+// Arguments:
+// - state: indicates the progress state
+// - progress: indicates the progress value
+// Return Value:
+// - true
+bool Terminal::SetTaskbarProgress(const size_t state, const size_t progress) noexcept
+{
+    _taskbarState = state;
+    _taskbarProgress = progress;
+    if (_pfnTaskbarProgressChanged)
+    {
+        _pfnTaskbarProgressChanged();
+    }
+    return true;
+}

src/cascadia/TerminalCore/TerminalDispatch.cpp

@@ -3,6 +3,9 @@
 
 #include "pch.h"
 #include "TerminalDispatch.hpp"
+#include "../../types/inc/utils.hpp"
+
+using namespace Microsoft::Console;
 using namespace ::Microsoft::Terminal::Core;
 using namespace ::Microsoft::Console::VirtualTerminal;
 
@@ -399,6 +402,60 @@ bool TerminalDispatch::EndHyperlink() noexcept
     return _terminalApi.EndHyperlink();
 }
 
+// Method Description:
+// - Performs a ConEmu action
+// - Currently, the only action we support is setting the taskbar state/progress
+// Arguments:
+// - string: contains the parameters that define which action we do
+// Return Value:
+// - true
+bool TerminalDispatch::DoConEmuAction(const std::wstring_view string) noexcept
+{
+    unsigned int state = 0;
+    unsigned int progress = 0;
+
+    const auto parts = Utils::SplitString(string, L';');
+    unsigned int subParam = 0;
+
+    // For now, the only ConEmu action we support is setting the taskbar state/progress,
+    // which has a sub param value of 4
+    if (parts.size() < 1 || !Utils::StringToUint(til::at(parts, 0), subParam) || subParam != 4)
+    {
+        return false;
+    }
+
+    if (parts.size() >= 2)
+    {
+        // A state parameter is defined, parse it out
+        const auto stateSuccess = Utils::StringToUint(til::at(parts, 1), state);
+        if (!stateSuccess)
+        {
+            return false;
+        }
+        if (parts.size() >= 3)
+        {
+            // A progress parameter is also defined, parse it out
+            const auto progressSuccess = Utils::StringToUint(til::at(parts, 2), progress);
+            if (!progressSuccess)
+            {
+                return false;
+            }
+        }
+    }
+
+    if (state > TaskbarMaxState)
+    {
+        // state is out of bounds, return false
+        return false;
+    }
+    if (progress > TaskbarMaxProgress)
+    {
+        // progress is greater than the maximum allowed value, clamp it to the max
+        progress = TaskbarMaxProgress;
+    }
+    return _terminalApi.SetTaskbarProgress(state, progress);
+}
+
 // Routine Description:
 // - Support routine for routing private mode parameters to be set/reset as flags
 // Arguments:

src/cascadia/TerminalCore/TerminalDispatch.hpp

@@ -4,6 +4,9 @@
 #include "../../terminal/adapter/termDispatch.hpp"
 #include "ITerminalApi.hpp"
 
+static constexpr size_t TaskbarMaxState{ 4 };
+static constexpr size_t TaskbarMaxProgress{ 100 };
+
 class TerminalDispatch : public Microsoft::Console::VirtualTerminal::TermDispatch
 {
 public:
@@ -67,6 +70,8 @@ public:
     bool AddHyperlink(const std::wstring_view uri, const std::wstring_view params) noexcept override;
     bool EndHyperlink() noexcept override;
 
+    bool DoConEmuAction(const std::wstring_view string) noexcept override;
+
 private:
     ::Microsoft::Terminal::Core::ITerminalApi& _terminalApi;
 

src/cascadia/UnitTests_TerminalCore/TerminalApiTest.cpp

@@ -38,6 +38,8 @@ namespace TerminalCoreUnitTests
         TEST_METHOD(AddHyperlink);
         TEST_METHOD(AddHyperlinkCustomId);
         TEST_METHOD(AddHyperlinkCustomIdDifferentUri);
+
+        TEST_METHOD(SetTaskbarProgress);
     };
 };
 
@@ -339,3 +341,50 @@ void TerminalCoreUnitTests::TerminalApiTest::AddHyperlinkCustomIdDifferentUri()
     VERIFY_ARE_EQUAL(tbi.GetHyperlinkUriFromId(oldAttributes.GetHyperlinkId()), L"test.url");
     VERIFY_ARE_NOT_EQUAL(oldAttributes.GetHyperlinkId(), tbi.GetCurrentAttributes().GetHyperlinkId());
 }
+
+void TerminalCoreUnitTests::TerminalApiTest::SetTaskbarProgress()
+{
+    Terminal term;
+    DummyRenderTarget emptyRT;
+    term.Create({ 100, 100 }, 0, emptyRT);
+
+    auto& stateMachine = *(term._stateMachine);
+
+    // Initial values for taskbar state and progress should be 0
+    VERIFY_ARE_EQUAL(term.GetTaskbarState(), gsl::narrow<size_t>(0));
+    VERIFY_ARE_EQUAL(term.GetTaskbarProgress(), gsl::narrow<size_t>(0));
+
+    // Set some values for taskbar state and progress through state machine
+    stateMachine.ProcessString(L"\x1b]9;4;1;50\x9c");
+    VERIFY_ARE_EQUAL(term.GetTaskbarState(), gsl::narrow<size_t>(1));
+    VERIFY_ARE_EQUAL(term.GetTaskbarProgress(), gsl::narrow<size_t>(50));
+
+    // Reset to 0
+    stateMachine.ProcessString(L"\x1b]9;4;0;0\x9c");
+    VERIFY_ARE_EQUAL(term.GetTaskbarState(), gsl::narrow<size_t>(0));
+    VERIFY_ARE_EQUAL(term.GetTaskbarProgress(), gsl::narrow<size_t>(0));
+
+    // Set an out of bounds value for state
+    stateMachine.ProcessString(L"\x1b]9;4;5;50\x9c");
+    // Nothing should have changed (dispatch should have returned false)
+    VERIFY_ARE_EQUAL(term.GetTaskbarState(), gsl::narrow<size_t>(0));
+    VERIFY_ARE_EQUAL(term.GetTaskbarProgress(), gsl::narrow<size_t>(0));
+
+    // Set an out of bounds value for progress
+    stateMachine.ProcessString(L"\x1b]9;4;1;999\x9c");
+    // Progress should have been clamped to 100
+    VERIFY_ARE_EQUAL(term.GetTaskbarState(), gsl::narrow<size_t>(1));
+    VERIFY_ARE_EQUAL(term.GetTaskbarProgress(), gsl::narrow<size_t>(100));
+
+    // Don't specify any params
+    stateMachine.ProcessString(L"\x1b]9;4\x9c");
+    // State and progress should both be reset to 0
+    VERIFY_ARE_EQUAL(term.GetTaskbarState(), gsl::narrow<size_t>(0));
+    VERIFY_ARE_EQUAL(term.GetTaskbarProgress(), gsl::narrow<size_t>(0));
+
+    // Specify additional params
+    stateMachine.ProcessString(L"\x1b]9;4;1;80;123\x9c");
+    // Additional params should be ignored, state and progress still set normally
+    VERIFY_ARE_EQUAL(term.GetTaskbarState(), gsl::narrow<size_t>(1));
+    VERIFY_ARE_EQUAL(term.GetTaskbarProgress(), gsl::narrow<size_t>(80));
+}

src/cascadia/WindowsTerminal/AppHost.cpp

@@ -79,6 +79,23 @@ bool AppHost::OnDirectKeyEvent(const uint32_t vkey, const uint8_t scanCode, cons
     return false;
 }
 
+// Method Description:
+// - Event handler to update the taskbar progress indicator
+// - Upon receiving the event, we ask the underlying logic for the taskbar state/progress values
+//   of the last active control
+// Arguments:
+// - sender: not used
+// - args: not used
+void AppHost::SetTaskbarProgress(const winrt::Windows::Foundation::IInspectable& /*sender*/, const winrt::Windows::Foundation::IInspectable& /*args*/)
+{
+    if (_logic)
+    {
+        const auto state = gsl::narrow_cast<size_t>(_logic.GetLastActiveControlTaskbarState());
+        const auto progress = gsl::narrow_cast<size_t>(_logic.GetLastActiveControlTaskbarProgress());
+        _window->SetTaskbarProgress(state, progress);
+    }
+}
+
 // Method Description:
 // - Retrieve any commandline args passed on the commandline, and pass them to
 //   the app logic for processing.
@@ -171,6 +188,7 @@ void AppHost::Initialize()
 
     _logic.TitleChanged({ this, &AppHost::AppTitleChanged });
     _logic.LastTabClosed({ this, &AppHost::LastTabClosed });
+    _logic.SetTaskbarProgress({ this, &AppHost::SetTaskbarProgress });
 
     _window->UpdateTitle(_logic.Title());
 

src/cascadia/WindowsTerminal/AppHost.h

@@ -18,6 +18,7 @@ public:
     void LastTabClosed(const winrt::Windows::Foundation::IInspectable& sender, const winrt::TerminalApp::LastTabClosedEventArgs& args);
     void Initialize();
     bool OnDirectKeyEvent(const uint32_t vkey, const uint8_t scanCode, const bool down);
+    void SetTaskbarProgress(const winrt::Windows::Foundation::IInspectable& sender, const winrt::Windows::Foundation::IInspectable& args);
 
 private:
     bool _useNonClientArea;

src/cascadia/WindowsTerminal/IslandWindow.cpp

@@ -261,6 +261,15 @@ void IslandWindow::Initialize()
 
     _rootGrid = winrt::Windows::UI::Xaml::Controls::Grid();
     _source.Content(_rootGrid);
+
+    // initialize the taskbar object
+    if (auto taskbar = wil::CoCreateInstanceNoThrow<ITaskbarList3>(CLSID_TaskbarList))
+    {
+        if (SUCCEEDED(taskbar->HrInit()))
+        {
+            _taskbar = std::move(taskbar);
+        }
+    }
 }
 
 void IslandWindow::OnSize(const UINT width, const UINT height)
@@ -576,6 +585,48 @@ void IslandWindow::SetAlwaysOnTop(const bool alwaysOnTop)
     }
 }
 
+// Method Description:
+// - Sets the taskbar progress indicator
+// - We follow the ConEmu style for the state and progress values,
+//   more details at https://conemu.github.io/en/AnsiEscapeCodes.html#ConEmu_specific_OSC
+// Arguments:
+// - state: indicates the progress state
+// - progress: indicates the progress value
+void IslandWindow::SetTaskbarProgress(const size_t state, const size_t progress)
+{
+    if (_taskbar)
+    {
+        switch (state)
+        {
+        case 0:
+            // removes the taskbar progress indicator
+            _taskbar->SetProgressState(_window.get(), TBPF_NOPROGRESS);
+            break;
+        case 1:
+            // sets the progress value to value given by the 'progress' parameter
+            _taskbar->SetProgressState(_window.get(), TBPF_NORMAL);
+            _taskbar->SetProgressValue(_window.get(), progress, 100);
+            break;
+        case 2:
+            // sets the progress indicator to an error state
+            _taskbar->SetProgressState(_window.get(), TBPF_ERROR);
+            _taskbar->SetProgressValue(_window.get(), progress, 100);
+            break;
+        case 3:
+            // sets the progress indicator to an indeterminate state
+            _taskbar->SetProgressState(_window.get(), TBPF_INDETERMINATE);
+            break;
+        case 4:
+            // sets the progress indicator to a pause state
+            _taskbar->SetProgressState(_window.get(), TBPF_PAUSED);
+            _taskbar->SetProgressValue(_window.get(), progress, 100);
+            break;
+        default:
+            break;
+        }
+    }
+}
+
 // From GdiEngine::s_SetWindowLongWHelper
 void _SetWindowLongWHelper(const HWND hWnd, const int nIndex, const LONG dwNewLong) noexcept
 {

src/cascadia/WindowsTerminal/IslandWindow.h

@@ -35,6 +35,8 @@ public:
     void FullscreenChanged(const bool fullscreen);
     void SetAlwaysOnTop(const bool alwaysOnTop);
 
+    void SetTaskbarProgress(const size_t state, const size_t progress);
+
 #pragma endregion
 
     DECLARE_EVENT(DragRegionClicked, _DragRegionClickedHandlers, winrt::delegate<>);
@@ -74,6 +76,8 @@ protected:
 
     LONG _getDesiredWindowStyle() const;
 
+    wil::com_ptr<ITaskbarList3> _taskbar;
+
     void _OnGetMinMaxInfo(const WPARAM wParam, const LPARAM lParam);
     long _calculateTotalSize(const bool isWidth, const long clientSize, const long nonClientSize);
 

src/cascadia/WindowsTerminal/pch.h

@@ -29,6 +29,7 @@ Abstract:
 #include <cstring>
 #include <shellscalingapi.h>
 #include <windowsx.h>
+#include <ShObjIdl.h>
 
 // Manually include til after we include Windows.Foundation to give it winrt superpowers
 #define BLOCK_TIL

src/terminal/adapter/ITermDispatch.hpp

@@ -122,6 +122,8 @@ public:
 
     virtual bool AddHyperlink(const std::wstring_view uri, const std::wstring_view params) = 0;
     virtual bool EndHyperlink() = 0;
+
+    virtual bool DoConEmuAction(const std::wstring_view string) = 0;
 };
 inline Microsoft::Console::VirtualTerminal::ITermDispatch::~ITermDispatch() {}
 #pragma warning(pop)

src/terminal/adapter/adaptDispatch.cpp

@@ -2383,6 +2383,16 @@ bool AdaptDispatch::EndHyperlink()
     return _pConApi->PrivateEndHyperlink();
 }
 
+// Method Description:
+// - Ascribes to the ITermDispatch interface
+// - Not actually used in conhost
+// Return Value:
+// - false (so that the command gets flushed to terminal)
+bool AdaptDispatch::DoConEmuAction(const std::wstring_view /*string*/) noexcept
+{
+    return false;
+}
+
 // Routine Description:
 // - Determines whether we should pass any sequence that manipulates
 //   TerminalInput's input generator through the PTY. It encapsulates

src/terminal/adapter/adaptDispatch.hpp

@@ -123,6 +123,8 @@ namespace Microsoft::Console::VirtualTerminal
         bool AddHyperlink(const std::wstring_view uri, const std::wstring_view params) override;
         bool EndHyperlink() override;
 
+        bool DoConEmuAction(const std::wstring_view string) noexcept override;
+
     private:
         enum class ScrollDirection
         {

src/terminal/adapter/termDispatch.hpp

@@ -116,4 +116,6 @@ public:
 
     bool AddHyperlink(const std::wstring_view /*uri*/, const std::wstring_view /*params*/) noexcept override { return false; }
     bool EndHyperlink() noexcept override { return false; }
+
+    bool DoConEmuAction(const std::wstring_view /*string*/) noexcept override { return false; }
 };

src/terminal/parser/OutputStateMachineEngine.cpp

@@ -733,6 +733,11 @@ bool OutputStateMachineEngine::ActionOscDispatch(const wchar_t /*wch*/,
         }
         break;
     }
+    case OscActionCodes::ConEmuAction:
+    {
+        success = _dispatch->DoConEmuAction(string);
+        break;
+    }
     default:
         // If no functions to call, overall dispatch was a failure.
         success = false;

src/terminal/parser/OutputStateMachineEngine.hpp

@@ -160,6 +160,7 @@ namespace Microsoft::Console::VirtualTerminal
             SetWindowProperty = 3, // Not implemented
             SetColor = 4,
             Hyperlink = 8,
+            ConEmuAction = 9,
             SetForegroundColor = 10,
             SetBackgroundColor = 11,
             SetCursorColor = 12,

src/terminal/parser/ut_parser/OutputEngineTest.cpp

@@ -1456,6 +1456,11 @@ public:
         return true;
     }
 
+    bool DoConEmuAction(const std::wstring_view /*string*/) noexcept override
+    {
+        return true;
+    }
+
     size_t _cursorDistance;
     size_t _line;
     size_t _column;