Improve the DECSC/DECRC implementation

src/host/outputStream.cpp

@@ -299,6 +299,31 @@ BOOL ConhostInternalGetSet::PrivateSetExtendedTextAttributes(const ExtendedAttri
     return TRUE;
 }
 
+// Method Description:
+// - Retrieves the current TextAttribute of the active screen buffer.
+// Arguments:
+// - pAttrs: Receives the TextAttribute value.
+// Return Value:
+// - TRUE if successful. FALSE otherwise.
+BOOL ConhostInternalGetSet::PrivateGetTextAttributes(TextAttribute* const pAttrs) const
+{
+    *pAttrs = _io.GetActiveOutputBuffer().GetAttributes();
+    return TRUE;
+}
+
+// Method Description:
+// - Sets the current TextAttribute of the active screen buffer. Text
+//   written to this buffer will be written with these attributes.
+// Arguments:
+// - attrs: The new TextAttribute to use
+// Return Value:
+// - TRUE if successful. FALSE otherwise.
+BOOL ConhostInternalGetSet::PrivateSetTextAttributes(const TextAttribute& attrs)
+{
+    _io.GetActiveOutputBuffer().SetAttributes(attrs);
+    return TRUE;
+}
+
 // Routine Description:
 // - Connects the WriteConsoleInput API call directly into our Driver Message servicing call inside Conhost.exe
 // Arguments:

src/host/outputStream.hpp

@@ -90,6 +90,8 @@ class ConhostInternalGetSet final : public Microsoft::Console::VirtualTerminal::
     BOOL PrivateBoldText(const bool bolded) override;
     BOOL PrivateGetExtendedTextAttributes(ExtendedAttributes* const pAttrs) override;
     BOOL PrivateSetExtendedTextAttributes(const ExtendedAttributes attrs) override;
+    BOOL PrivateGetTextAttributes(TextAttribute* const pAttrs) const override;
+    BOOL PrivateSetTextAttributes(const TextAttribute& attrs) override;
 
     BOOL PrivateWriteConsoleInputW(_Inout_ std::deque<std::unique_ptr<IInputEvent>>& events,
                                    _Out_ size_t& eventsWritten) override;

src/host/ut_host/ScreenBufferTests.cpp

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft Corporation.
+// Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 
 #include "precomp.h"
@@ -193,6 +193,8 @@ class ScreenBufferTests
     TEST_METHOD(CursorUpDownAcrossMargins);
     TEST_METHOD(CursorUpDownOutsideMargins);
     TEST_METHOD(CursorUpDownExactlyAtMargins);
+
+    TEST_METHOD(CursorSaveRestore);
 };
 
 void ScreenBufferTests::SingleAlternateBufferCreationTest()
@@ -5045,3 +5047,121 @@ void ScreenBufferTests::CursorUpDownExactlyAtMargins()
 
     stateMachine.ProcessString(L"\x1b[r");
 }
+
+void ScreenBufferTests::CursorSaveRestore()
+{
+    auto& gci = ServiceLocator::LocateGlobals().getConsoleInformation();
+    auto& si = gci.GetActiveOutputBuffer();
+    auto& stateMachine = si.GetStateMachine();
+    auto& cursor = si.GetTextBuffer().GetCursor();
+
+    const auto defaultAttrs = TextAttribute{};
+    const auto colorAttrs = TextAttribute{ RGB(12, 34, 56), RGB(78, 90, 12) };
+
+    const auto asciiText = L"lwkmvj";
+    const auto graphicText = L"┌┬┐└┴┘";
+
+    const auto selectAsciiChars = L"\x1b(B";
+    const auto selectGraphicsChars = L"\x1b(0";
+    const auto saveCursor = L"\x1b[s";
+    const auto restoreCursor = L"\x1b[u";
+    const auto setDECOM = L"\x1b[?6h";
+    const auto resetDECOM = L"\x1b[?6l";
+
+    Log::Comment(L"Make sure the viewport is at 0,0");
+    VERIFY_SUCCEEDED(si.SetViewportOrigin(true, COORD({ 0, 0 }), true));
+
+    Log::Comment(L"Restore after save.");
+    // Set the cursor position, attributes, and character set.
+    cursor.SetPosition(COORD{ 20, 10 });
+    si.SetAttributes(colorAttrs);
+    stateMachine.ProcessString(selectGraphicsChars);
+    // Save state.
+    stateMachine.ProcessString(saveCursor);
+    // Reset the cursor position, attributes, and character set.
+    cursor.SetPosition(COORD{ 0, 0 });
+    si.SetAttributes(defaultAttrs);
+    stateMachine.ProcessString(selectAsciiChars);
+    // Restore state.
+    stateMachine.ProcessString(restoreCursor);
+    // Verify initial position, colors, and graphic character set.
+    VERIFY_ARE_EQUAL(COORD({ 20, 10 }), cursor.GetPosition());
+    VERIFY_ARE_EQUAL(colorAttrs, si.GetAttributes());
+    stateMachine.ProcessString(asciiText);
+    VERIFY_IS_TRUE(_ValidateLineContains(COORD({ 20, 10 }), graphicText, colorAttrs));
+
+    Log::Comment(L"Restore again without save.");
+    // Reset the cursor position, attributes, and character set.
+    cursor.SetPosition(COORD{ 0, 0 });
+    si.SetAttributes(defaultAttrs);
+    stateMachine.ProcessString(selectAsciiChars);
+    // Restore state.
+    stateMachine.ProcessString(restoreCursor);
+    // Verify initial saved position, colors, and graphic character set.
+    VERIFY_ARE_EQUAL(COORD({ 20, 10 }), cursor.GetPosition());
+    VERIFY_ARE_EQUAL(colorAttrs, si.GetAttributes());
+    stateMachine.ProcessString(asciiText);
+    VERIFY_IS_TRUE(_ValidateLineContains(COORD({ 20, 10 }), graphicText, colorAttrs));
+
+    Log::Comment(L"Restore after reset.");
+    // Soft reset.
+    stateMachine.ProcessString(L"\x1b[!p");
+    // Set the cursor position, attributes, and character set.
+    cursor.SetPosition(COORD{ 20, 10 });
+    si.SetAttributes(colorAttrs);
+    stateMachine.ProcessString(selectGraphicsChars);
+    // Restore state.
+    stateMachine.ProcessString(restoreCursor);
+    // Verify home position, default attributes, and ascii character set.
+    VERIFY_ARE_EQUAL(COORD({ 0, 0 }), cursor.GetPosition());
+    VERIFY_ARE_EQUAL(defaultAttrs, si.GetAttributes());
+    stateMachine.ProcessString(asciiText);
+    VERIFY_IS_TRUE(_ValidateLineContains(COORD({ 0, 0 }), asciiText, defaultAttrs));
+
+    Log::Comment(L"Restore origin mode.");
+    // Set margins and origin mode to relative.
+    stateMachine.ProcessString(L"\x1b[10;20r");
+    stateMachine.ProcessString(setDECOM);
+    // Verify home position inside margins.
+    VERIFY_ARE_EQUAL(COORD({ 0, 9 }), cursor.GetPosition());
+    // Save state and reset origin mode to absolute.
+    stateMachine.ProcessString(saveCursor);
+    stateMachine.ProcessString(resetDECOM);
+    // Verify home position at origin.
+    VERIFY_ARE_EQUAL(COORD({ 0, 0 }), cursor.GetPosition());
+    // Restore state and move to home position.
+    stateMachine.ProcessString(restoreCursor);
+    stateMachine.ProcessString(L"\x1b[H");
+    // Verify home position inside margins, i.e. relative origin mode restored.
+    VERIFY_ARE_EQUAL(COORD({ 0, 9 }), cursor.GetPosition());
+
+    Log::Comment(L"Clamp inside top margin.");
+    // Reset margins, with absolute origin, and set cursor position.
+    stateMachine.ProcessString(L"\x1b[r");
+    stateMachine.ProcessString(setDECOM);
+    cursor.SetPosition(COORD{ 5, 15 });
+    // Save state.
+    stateMachine.ProcessString(saveCursor);
+    // Set margins and restore state.
+    stateMachine.ProcessString(L"\x1b[20;25r");
+    stateMachine.ProcessString(restoreCursor);
+    // Verfify Y position is clamped inside the top margin
+    VERIFY_ARE_EQUAL(COORD({ 5, 19 }), cursor.GetPosition());
+
+    Log::Comment(L"Clamp inside bottom margin.");
+    // Reset margins, with absolute origin, and set cursor position.
+    stateMachine.ProcessString(L"\x1b[r");
+    stateMachine.ProcessString(setDECOM);
+    cursor.SetPosition(COORD{ 5, 15 });
+    // Save state.
+    stateMachine.ProcessString(saveCursor);
+    // Set margins and restore state.
+    stateMachine.ProcessString(L"\x1b[1;10r");
+    stateMachine.ProcessString(restoreCursor);
+    // Verfify Y position is clamped inside the top margin
+    VERIFY_ARE_EQUAL(COORD({ 5, 9 }), cursor.GetPosition());
+
+    // Reset origin mode and margins.
+    stateMachine.ProcessString(resetDECOM);
+    stateMachine.ProcessString(L"\x1b[r");
+}

src/terminal/adapter/ITermDispatch.hpp

@@ -36,8 +36,8 @@ class Microsoft::Console::VirtualTerminal::ITermDispatch
     virtual bool CursorHorizontalPositionAbsolute(const unsigned int uiColumn) = 0; // CHA
     virtual bool VerticalLinePositionAbsolute(const unsigned int uiLine) = 0; // VPA
     virtual bool CursorPosition(const unsigned int uiLine, const unsigned int uiColumn) = 0; // CUP
-    virtual bool CursorSavePosition() = 0; // DECSC
-    virtual bool CursorRestorePosition() = 0; // DECRC
+    virtual bool CursorSaveState() = 0; // DECSC
+    virtual bool CursorRestoreState() = 0; // DECRC
     virtual bool CursorVisibility(const bool fIsVisible) = 0; // DECTCEM
     virtual bool InsertCharacter(const unsigned int uiCount) = 0; // ICH
     virtual bool DeleteCharacter(const unsigned int uiCount) = 0; // DCH

src/terminal/adapter/adaptDispatch.cpp

@@ -27,17 +27,14 @@ AdaptDispatch::AdaptDispatch(ConGetSet* const pConApi,
                              AdaptDefaults* const pDefaults) :
     _conApi{ THROW_IF_NULL_ALLOC(pConApi) },
     _pDefaults{ THROW_IF_NULL_ALLOC(pDefaults) },
+    _usingAltBuffer(false),
     _fIsOriginModeRelative(false), // by default, the DECOM origin mode is absolute.
-    _fIsSavedOriginModeRelative(false), // as is the origin mode of the saved cursor position.
     _fIsDECCOLMAllowed(false), // by default, DECCOLM is not allowed.
     _fChangedBackground(false),
     _fChangedForeground(false),
     _fChangedMetaAttrs(false),
     _TermOutput()
 {
-    // The top-left corner in VT-speak is 1,1. Our internal array uses 0 indexes, but VT uses 1,1 for top left corner.
-    _coordSavedCursor.X = 1;
-    _coordSavedCursor.Y = 1;
     _srScrollMargins = { 0 }; // initially, there are no scroll margins.
 }
 
@@ -420,7 +417,7 @@ bool AdaptDispatch::CursorPosition(_In_ unsigned int const uiLine, _In_ unsigned
 // - <none>
 // Return Value:
 // - True if handled successfully. False otherwise.
-bool AdaptDispatch::CursorSavePosition()
+bool AdaptDispatch::CursorSaveState()
 {
     // First retrieve some information about the buffer
     CONSOLE_SCREEN_BUFFER_INFOEX csbiex = { 0 };
@@ -429,6 +426,9 @@ bool AdaptDispatch::CursorSavePosition()
     //      before the user scrolled the console output
     bool fSuccess = !!(_conApi->MoveToBottom() && _conApi->GetConsoleScreenBufferInfoEx(&csbiex));
 
+    TextAttribute attributes;
+    fSuccess = fSuccess && !!(_conApi->PrivateGetTextAttributes(&attributes));
+
     if (fSuccess)
     {
         // The cursor is given to us by the API as relative to the whole buffer.
@@ -438,9 +438,12 @@ bool AdaptDispatch::CursorSavePosition()
         SMALL_RECT const srViewport = csbiex.srWindow;
 
         // VT is also 1 based, not 0 based, so correct by 1.
-        _coordSavedCursor.X = coordCursor.X - srViewport.Left + 1;
-        _coordSavedCursor.Y = coordCursor.Y - srViewport.Top + 1;
-        _fIsSavedOriginModeRelative = _fIsOriginModeRelative;
+        auto& savedCursorState = _savedCursorState[_usingAltBuffer];
+        savedCursorState.Column = coordCursor.X - srViewport.Left + 1;
+        savedCursorState.Row = coordCursor.Y - srViewport.Top + 1;
+        savedCursorState.IsOriginModeRelative = _fIsOriginModeRelative;
+        savedCursorState.Attributes = attributes;
+        savedCursorState.TermOutput = _TermOutput;
     }
 
     return fSuccess;
@@ -453,17 +456,34 @@ bool AdaptDispatch::CursorSavePosition()
 // - <none>
 // Return Value:
 // - True if handled successfully. False otherwise.
-bool AdaptDispatch::CursorRestorePosition()
+bool AdaptDispatch::CursorRestoreState()
 {
-    unsigned int const uiRow = _coordSavedCursor.Y;
-    unsigned int const uiCol = _coordSavedCursor.X;
+    auto& savedCursorState = _savedCursorState[_usingAltBuffer];
+
+    auto uiRow = savedCursorState.Row;
+    auto uiCol = savedCursorState.Column;
+
+    // If the origin mode is relative, and the scrolling region is set (the bottom is non-zero),
+    // we need to make sure the restored position is clamped within the margins.
+    if (savedCursorState.IsOriginModeRelative && _srScrollMargins.Bottom != 0)
+    {
+        // VT origin is at 1,1 so we need to add 1 to these margins.
+        uiRow = std::clamp(uiRow, _srScrollMargins.Top + 1u, _srScrollMargins.Bottom + 1u);
+    }
 
     // The saved coordinates are always absolute, so we need reset the origin mode temporarily.
     _fIsOriginModeRelative = false;
-    bool const fSuccess = _CursorMovePosition(&uiRow, &uiCol);
+    bool fSuccess = _CursorMovePosition(&uiRow, &uiCol);
 
     // Once the cursor position is restored, we can then restore the actual origin mode.
-    _fIsOriginModeRelative = _fIsSavedOriginModeRelative;
+    _fIsOriginModeRelative = savedCursorState.IsOriginModeRelative;
+
+    // Restore text attributes.
+    fSuccess = !!(_conApi->PrivateSetTextAttributes(savedCursorState.Attributes)) && fSuccess;
+
+    // Restore designated character set.
+    _TermOutput = savedCursorState.TermOutput;
+
     return fSuccess;
 }
 
@@ -1349,7 +1369,16 @@ bool AdaptDispatch::SetWindowTitle(std::wstring_view title)
 // - True if handled successfully. False otherwise.
 bool AdaptDispatch::UseAlternateScreenBuffer()
 {
-    return !!_conApi->PrivateUseAlternateScreenBuffer();
+    bool fSuccess = CursorSaveState();
+    if (fSuccess)
+    {
+        fSuccess = !!_conApi->PrivateUseAlternateScreenBuffer();
+        if (fSuccess)
+        {
+            _usingAltBuffer = true;
+        }
+    }
+    return fSuccess;
 }
 
 // Routine Description:
@@ -1361,7 +1390,16 @@ bool AdaptDispatch::UseAlternateScreenBuffer()
 // - True if handled successfully. False otherwise.
 bool AdaptDispatch::UseMainScreenBuffer()
 {
-    return !!_conApi->PrivateUseMainScreenBuffer();
+    bool fSuccess = !!_conApi->PrivateUseMainScreenBuffer();
+    if (fSuccess)
+    {
+        _usingAltBuffer = false;
+        if (fSuccess)
+        {
+            fSuccess = CursorRestoreState();
+        }
+    }
+    return fSuccess;
 }
 
 //Routine Description:
@@ -1501,9 +1539,11 @@ bool AdaptDispatch::SoftReset()
     }
     if (fSuccess)
     {
-        // Save cursor state: Home position; Absolute addressing.
-        _coordSavedCursor = { 1, 1 };
-        _fIsSavedOriginModeRelative = false;
+        // Reset the saved cursor state.
+        // Note that XTerm only resets the main buffer state, but that
+        // seems likely to be a bug. Most other terminals reset both.
+        _savedCursorState[0] = {}; // Main buffer
+        _savedCursorState[1] = {}; // Alt buffer
     }
 
     return fSuccess;

src/terminal/adapter/adaptDispatch.hpp

@@ -48,8 +48,8 @@ namespace Microsoft::Console::VirtualTerminal
         bool CursorHorizontalPositionAbsolute(_In_ unsigned int const uiColumn) override; // CHA
         bool VerticalLinePositionAbsolute(_In_ unsigned int const uiLine) override; // VPA
         bool CursorPosition(_In_ unsigned int const uiLine, _In_ unsigned int const uiColumn) override; // CUP
-        bool CursorSavePosition() override; // DECSC
-        bool CursorRestorePosition() override; // DECRC
+        bool CursorSaveState() override; // DECSC
+        bool CursorRestoreState() override; // DECRC
         bool CursorVisibility(const bool fIsVisible) override; // DECTCEM
         bool EraseInDisplay(const DispatchTypes::EraseType eraseType) override; // ED
         bool EraseInLine(const DispatchTypes::EraseType eraseType) override; // EL
@@ -120,6 +120,14 @@ namespace Microsoft::Console::VirtualTerminal
             Up,
             Down
         };
+        struct CursorState
+        {
+            unsigned int Row = 1;
+            unsigned int Column = 1;
+            bool IsOriginModeRelative = false;
+            TextAttribute Attributes = {};
+            TerminalOutput TermOutput = {};
+        };
 
         bool _CursorMovement(const CursorDirection dir, _In_ unsigned int const uiDistance) const;
         bool _CursorMovePosition(_In_opt_ const unsigned int* const puiRow, _In_opt_ const unsigned int* const puiCol) const;
@@ -148,11 +156,12 @@ namespace Microsoft::Console::VirtualTerminal
         std::unique_ptr<AdaptDefaults> _pDefaults;
         TerminalOutput _TermOutput;
 
-        COORD _coordSavedCursor;
+        CursorState _savedCursorState[2];
+        bool _usingAltBuffer;
+
         SMALL_RECT _srScrollMargins;
 
         bool _fIsOriginModeRelative;
-        bool _fIsSavedOriginModeRelative;
 
         bool _fIsSetColumnsEnabled;
 

src/terminal/adapter/conGetSet.hpp

@@ -16,6 +16,7 @@ Author(s):
 #pragma once
 
 #include "..\..\types\inc\IInputEvent.hpp"
+#include "..\..\buffer\out\TextAttribute.hpp"
 #include "..\..\inc\conattrs.hpp"
 
 #include <deque>
@@ -54,6 +55,8 @@ namespace Microsoft::Console::VirtualTerminal
         virtual BOOL PrivateBoldText(const bool bolded) = 0;
         virtual BOOL PrivateGetExtendedTextAttributes(ExtendedAttributes* const pAttrs) = 0;
         virtual BOOL PrivateSetExtendedTextAttributes(const ExtendedAttributes attrs) = 0;
+        virtual BOOL PrivateGetTextAttributes(TextAttribute* const pAttrs) const = 0;
+        virtual BOOL PrivateSetTextAttributes(const TextAttribute& attrs) = 0;
 
         virtual BOOL PrivateWriteConsoleInputW(_Inout_ std::deque<std::unique_ptr<IInputEvent>>& events,
                                                _Out_ size_t& eventsWritten) = 0;