Add support for DECSCUSR "0" to restore cursor to user default

src/cascadia/TerminalCore/ITerminalApi.hpp

@@ -40,6 +40,7 @@ namespace Microsoft::Terminal::Core
 
         virtual bool SetCursorStyle(const ::Microsoft::Console::VirtualTerminal::DispatchTypes::CursorStyle cursorStyle) noexcept = 0;
         virtual bool SetCursorColor(const DWORD color) noexcept = 0;
+        virtual bool RestoreCursorStyleToUserDefault() noexcept = 0;
 
         virtual bool SetDefaultForeground(const DWORD color) noexcept = 0;
         virtual bool SetDefaultBackground(const DWORD color) noexcept = 0;

src/cascadia/TerminalCore/Terminal.cpp

@@ -134,6 +134,10 @@ void Terminal::UpdateSettings(ICoreSettings settings)
                                       cursorShape);
     }
 
+    _defaultCursorHeight = settings.CursorHeight();
+    _defaultCursorColor = settings.CursorColor();
+    _defaultCursorShape = cursorShape;
+
     for (int i = 0; i < 16; i++)
     {
         _colorTable.at(i) = settings.GetColorTableEntry(i);

src/cascadia/TerminalCore/Terminal.hpp

@@ -94,6 +94,7 @@ class Microsoft::Terminal::Core::Terminal final :
     bool SetColorTableEntry(const size_t tableIndex, const COLORREF color) noexcept override;
     bool SetCursorStyle(const ::Microsoft::Console::VirtualTerminal::DispatchTypes::CursorStyle cursorStyle) noexcept override;
     bool SetCursorColor(const COLORREF color) noexcept override;
+    bool RestoreCursorStyleToUserDefault() noexcept override;
     bool SetDefaultForeground(const COLORREF color) noexcept override;
     bool SetDefaultBackground(const COLORREF color) noexcept override;
 
@@ -214,6 +215,9 @@ class Microsoft::Terminal::Core::Terminal final :
     std::array<COLORREF, XTERM_COLOR_TABLE_SIZE> _colorTable;
     COLORREF _defaultFg;
     COLORREF _defaultBg;
+    ULONG _defaultCursorHeight;
+    COLORREF _defaultCursorColor;
+    CursorType _defaultCursorShape;
     bool _screenReversed;
 
     bool _snapOnInput;

src/cascadia/TerminalCore/TerminalApi.cpp

@@ -426,6 +426,18 @@ bool Terminal::SetCursorStyle(const DispatchTypes::CursorStyle cursorStyle) noex
     return true;
 }
 
+bool Terminal::RestoreCursorStyleToUserDefault() noexcept
+{
+    if (_buffer)
+    {
+        _buffer->GetCursor().SetStyle(_defaultCursorHeight,
+                                      _defaultCursorColor,
+                                      _defaultCursorShape);
+    }
+
+    return true;
+}
+
 // Method Description:
 // - Updates the default foreground color from a COLORREF, format 0x00BBGGRR.
 // Arguments:

src/cascadia/TerminalCore/TerminalDispatch.cpp

@@ -153,6 +153,13 @@ try
 }
 CATCH_LOG_RETURN_FALSE()
 
+bool TerminalDispatch::RestoreCursorStyleToUserDefault() noexcept
+try
+{
+    return _terminalApi.RestoreCursorStyleToUserDefault();
+}
+CATCH_LOG_RETURN_FALSE()
+
 bool TerminalDispatch::SetClipboard(std::wstring_view content) noexcept
 try
 {

src/cascadia/TerminalCore/TerminalDispatch.hpp

@@ -36,6 +36,7 @@ class TerminalDispatch : public Microsoft::Console::VirtualTerminal::TermDispatc
     bool SetColorTableEntry(const size_t tableIndex, const DWORD color) noexcept override;
     bool SetCursorStyle(const ::Microsoft::Console::VirtualTerminal::DispatchTypes::CursorStyle cursorStyle) noexcept override;
     bool SetCursorColor(const DWORD color) noexcept override;
+    bool RestoreCursorStyleToUserDefault() noexcept override;
 
     bool SetClipboard(std::wstring_view content) noexcept override;
 

src/terminal/adapter/DispatchTypes.hpp

@@ -216,7 +216,7 @@ namespace Microsoft::Console::VirtualTerminal::DispatchTypes
 
     enum class CursorStyle : unsigned int
     {
-        BlinkingBlock = 0,
+        BlinkingBlock = 0, // Implemented as "restore cursor to user default".
         BlinkingBlockDefault = 1,
         SteadyBlock = 2,
         BlinkingUnderline = 3,

src/terminal/adapter/ITermDispatch.hpp

@@ -111,6 +111,7 @@ class Microsoft::Console::VirtualTerminal::ITermDispatch
 
     virtual bool SetCursorStyle(const DispatchTypes::CursorStyle cursorStyle) = 0; // DECSCUSR
     virtual bool SetCursorColor(const COLORREF color) = 0; // OSCSetCursorColor, OSCResetCursorColor
+    virtual bool RestoreCursorStyleToUserDefault() = 0; // DECSCUSR "0"
 
     virtual bool SetClipboard(std::wstring_view content) = 0; // OSCSetClipboard
 

src/terminal/adapter/adaptDispatch.cpp

@@ -2222,6 +2222,15 @@ bool AdaptDispatch::SetCursorColor(const COLORREF cursorColor)
     return _pConApi->SetCursorColor(cursorColor);
 }
 
+// Method Description:
+// - Restore the cursor style to user's default setting.
+// Return Value:
+// True if handled successfully. False otherwise.
+bool AdaptDispatch::RestoreCursorStyleToUserDefault() noexcept
+{
+    return false;
+}
+
 // Routine Description:
 // - OSC Copy to Clipboard
 // Arguments:

src/terminal/adapter/adaptDispatch.hpp

@@ -107,6 +107,7 @@ namespace Microsoft::Console::VirtualTerminal
         bool EnableAlternateScroll(const bool enabled) override; // ?1007
         bool SetCursorStyle(const DispatchTypes::CursorStyle cursorStyle) override; // DECSCUSR
         bool SetCursorColor(const COLORREF cursorColor) override;
+        bool RestoreCursorStyleToUserDefault() noexcept override; // DECSCUSR "0"
 
         bool SetClipboard(const std::wstring_view content) noexcept override; // OSCSetClipboard
 

src/terminal/adapter/termDispatch.hpp

@@ -105,6 +105,7 @@ class Microsoft::Console::VirtualTerminal::TermDispatch : public Microsoft::Cons
 
     bool SetCursorStyle(const DispatchTypes::CursorStyle /*cursorStyle*/) noexcept override { return false; } // DECSCUSR
     bool SetCursorColor(const COLORREF /*color*/) noexcept override { return false; } // OSCSetCursorColor, OSCResetCursorColor
+    bool RestoreCursorStyleToUserDefault() noexcept override { return false; } // DECSCUSR "0"
 
     bool SetClipboard(std::wstring_view /*content*/) noexcept override { return false; } // OscSetClipboard
 

src/terminal/parser/OutputStateMachineEngine.cpp

@@ -662,7 +662,17 @@ bool OutputStateMachineEngine::ActionCsiDispatch(const VTID id, gsl::span<const
             TermTelemetry::Instance().Log(TermTelemetry::Codes::REP);
             break;
         case CsiActionCodes::DECSCUSR_SetCursorStyle:
-            success = _dispatch->SetCursorStyle(cursorStyle);
+            if (cursorStyle == DispatchTypes::CursorStyle::BlinkingBlock)
+            {
+                // Treat DECSCUSR "0" as "restore cursor to user default".
+                // See:GH:#1604
+                success = _dispatch->RestoreCursorStyleToUserDefault();
+            }
+            else
+            {
+                success = _dispatch->SetCursorStyle(cursorStyle);
+            }
+
             TermTelemetry::Instance().Log(TermTelemetry::Codes::DECSCUSR);
             break;
         case CsiActionCodes::DECSTR_SoftReset:

src/terminal/parser/OutputStateMachineEngine.hpp

@@ -238,7 +238,7 @@ namespace Microsoft::Console::VirtualTerminal
         bool _GetOscSetColor(const std::wstring_view string,
                              DWORD& rgb) const noexcept;
 
-        static constexpr DispatchTypes::CursorStyle DefaultCursorStyle = DispatchTypes::CursorStyle::BlinkingBlockDefault;
+        static constexpr DispatchTypes::CursorStyle DefaultCursorStyle = DispatchTypes::CursorStyle::BlinkingBlock;
         bool _GetCursorStyle(const gsl::span<const size_t> parameters,
                              DispatchTypes::CursorStyle& cursorStyle) const noexcept;