Add support for horizontal scrolling sequences (#15368)

This PR introduces four new escapes sequences: `DECIC` (Insert Column),
`DECDC` (Delete Column), `DECBI` (Back Index), and `DECFI` (Forward
Index), which allow for horizontal scrolling within a margin area.

## References and Relevant Issues

This follows on from the horizontal margins PR #15084 to complete the
requirements for the horizontal scrolling extension.

## Detailed Description of the Pull Request / Additional comments

The implementation is fairly straightforward, since they're all built on
top of the existing `_ScrollRectHorizontally` method.

## Validation Steps Performed

Thanks to @al20878, these operations have been extensively tested on a
number of DEC terminals and I've manually confirmed our implementation
matches their behavior.

I've also added a unit tests that covers the basic execution of each of
the operations.

Closes #15109

Author: j4james

.github/actions/spelling/expect/expect.txt

@@ -410,6 +410,7 @@ DECANM
 DECARM
 DECAUPSS
 DECAWM
+DECBI
 DECBKM
 DECCARA
 DECCIR
@@ -418,13 +419,16 @@ DECCKSR
 DECCOLM
 DECCRA
 DECCTR
+DECDC
 DECDHL
 decdld
 DECDMAC
 DECDWL
 DECEKBD
 DECERA
+DECFI
 DECFRA
+DECIC
 DECID
 DECINVM
 DECKPAM
@@ -571,6 +575,7 @@ EDITTEXT
 EDITUPDATE
 edputil
 Efast
+efghijklmn
 EHsc
 EINS
 EJO
@@ -971,6 +976,8 @@ KLF
 KLMNO
 KLMNOPQRST
 KLMNOPQRSTQQQQQ
+KLMNOPQRSTUVWXY
+KLMNOPQRSTY
 KOK
 KPRIORITY
 KVM
@@ -1134,6 +1141,7 @@ mmsystem
 MNC
 MNOPQ
 MNOPQR
+MNOPQRSTUVWXY
 MODALFRAME
 MODERNCORE
 MONITORINFO
@@ -2044,6 +2052,7 @@ USRDLL
 utr
 UVWX
 UVWXY
+UVWXYZ
 uwa
 uwp
 uxtheme
@@ -2304,7 +2313,9 @@ YOffset
 YSubstantial
 YVIRTUALSCREEN
 YWalk
+Zab
 zabcd
+Zabcdefghijklmn
 Zabcdefghijklmnopqrstuvwxyz
 ZCmd
 ZCtrl

src/host/ut_host/ScreenBufferTests.cpp

@@ -186,6 +186,7 @@ class ScreenBufferTests
     TEST_METHOD(InsertReplaceMode);
     TEST_METHOD(InsertChars);
     TEST_METHOD(DeleteChars);
+    TEST_METHOD(HorizontalScrollOperations);
     TEST_METHOD(ScrollingWideCharsHorizontally);
 
     TEST_METHOD(EraseScrollbackTests);
@@ -4346,6 +4347,117 @@ void ScreenBufferTests::DeleteChars()
     }
 }
 
+void ScreenBufferTests::HorizontalScrollOperations()
+{
+    BEGIN_TEST_METHOD_PROPERTIES()
+        TEST_METHOD_PROPERTY(L"Data:op", L"{0, 1, 2, 3}")
+    END_TEST_METHOD_PROPERTIES();
+
+    enum Op : int
+    {
+        DECIC,
+        DECDC,
+        DECFI,
+        DECBI
+    } op;
+    VERIFY_SUCCEEDED(TestData::TryGetValue(L"op", (int&)op));
+
+    auto& gci = ServiceLocator::LocateGlobals().getConsoleInformation();
+    auto& si = gci.GetActiveOutputBuffer().GetActiveBuffer();
+    auto& stateMachine = si.GetStateMachine();
+    WI_SetFlag(si.OutputMode, ENABLE_VIRTUAL_TERMINAL_PROCESSING);
+
+    // Set the buffer width to 40, with a centered viewport of 20.
+    const auto bufferWidth = 40;
+    const auto bufferHeight = si.GetBufferSize().Height();
+    const auto viewportStart = 10;
+    const auto viewportEnd = viewportStart + 20;
+    VERIFY_SUCCEEDED(si.ResizeScreenBuffer({ bufferWidth, bufferHeight }, false));
+    si.SetViewport(Viewport::FromExclusive({ viewportStart, 0, viewportEnd, 25 }), true);
+
+    // Set the margin area to columns 10 to 29 and rows 14 to 19 (zero based).
+    stateMachine.ProcessString(L"\x1b[?69h");
+    stateMachine.ProcessString(L"\x1b[11;30s");
+    stateMachine.ProcessString(L"\x1b[15;20r");
+    // Make sure we clear the margins on exit so they can't break other tests.
+    auto clearMargins = wil::scope_exit([&] {
+        stateMachine.ProcessString(L"\x1b[r");
+        stateMachine.ProcessString(L"\x1b[s");
+        stateMachine.ProcessString(L"\x1b[?69l");
+    });
+
+    // Fill the buffer with text. Red on Blue.
+    const auto bufferChars = L"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmn";
+    const auto bufferAttr = TextAttribute{ FOREGROUND_RED | BACKGROUND_BLUE };
+    _FillLines(0, 25, bufferChars, bufferAttr);
+
+    // Set the attributes that will be used to fill the revealed area.
+    auto fillAttr = TextAttribute{ RGB(12, 34, 56), RGB(78, 90, 12) };
+    fillAttr.SetCrossedOut(true);
+    fillAttr.SetReverseVideo(true);
+    fillAttr.SetUnderlined(true);
+    si.SetAttributes(fillAttr);
+    // But note that the meta attributes are expected to be cleared.
+    auto expectedFillAttr = fillAttr;
+    expectedFillAttr.SetStandardErase();
+
+    auto& cursor = si.GetTextBuffer().GetCursor();
+    switch (op)
+    {
+    case DECIC:
+        Log::Comment(L"Insert 4 columns in the middle of the margin area.");
+        cursor.SetPosition({ 20, 17 });
+        stateMachine.ProcessString(L"\x1b[4'}");
+        VERIFY_ARE_EQUAL(til::point(20, 17), cursor.GetPosition(), L"The cursor should not move.");
+        VERIFY_IS_TRUE(_ValidateLinesContain(10, 14, 20, L"KLMNOPQRST", bufferAttr),
+                       L"The margin area left of the cursor position should remain unchanged.");
+        VERIFY_IS_TRUE(_ValidateLinesContain(20, 14, 20, L"    ", expectedFillAttr),
+                       L"4 blank columns should be inserted at the cursor position.");
+        VERIFY_IS_TRUE(_ValidateLinesContain(24, 14, 20, L"UVWXYZ", bufferAttr),
+                       L"The area right of that should be scrolled right by 4 columns.");
+        break;
+    case DECDC:
+        Log::Comment(L"Delete 4 columns in the middle of the margin area.");
+        cursor.SetPosition({ 20, 17 });
+        stateMachine.ProcessString(L"\x1b[4'~");
+        VERIFY_ARE_EQUAL(til::point(20, 17), cursor.GetPosition(), L"The cursor should not move.");
+        VERIFY_IS_TRUE(_ValidateLinesContain(10, 14, 20, L"KLMNOPQRSTYZabcd", bufferAttr),
+                       L"The area right of the cursor position should be scrolled left by 4 columns.");
+        VERIFY_IS_TRUE(_ValidateLinesContain(26, 14, 20, L"    ", expectedFillAttr),
+                       L"4 blank columns should be inserted at the right of the margin area.");
+        break;
+    case DECFI:
+        Log::Comment(L"Forward index 4 times, 2 columns before the right margin.");
+        cursor.SetPosition({ 27, 17 });
+        stateMachine.ProcessString(L"\x1b\x39\x1b\x39\x1b\x39\x1b\x39");
+        VERIFY_ARE_EQUAL(til::point(29, 17), cursor.GetPosition(), L"The cursor should not pass the right margin.");
+        VERIFY_IS_TRUE(_ValidateLinesContain(10, 14, 20, L"MNOPQRSTUVWXYZabcd", bufferAttr),
+                       L"The margin area should scroll left by 2 columns.");
+        VERIFY_IS_TRUE(_ValidateLinesContain(28, 14, 20, L"  ", expectedFillAttr),
+                       L"2 blank columns should be inserted at the right of the margin area.");
+        break;
+    case DECBI:
+        Log::Comment(L"Back index 4 times, 2 columns before the left margin.");
+        cursor.SetPosition({ 12, 17 });
+        stateMachine.ProcessString(L"\x1b\x36\x1b\x36\x1b\x36\x1b\x36");
+        VERIFY_ARE_EQUAL(til::point(10, 17), cursor.GetPosition(), L"The cursor should not pass the left margin.");
+        VERIFY_IS_TRUE(_ValidateLinesContain(10, 14, 20, L"  ", expectedFillAttr),
+                       L"2 blank columns should be inserted at the left of the margin area.");
+        VERIFY_IS_TRUE(_ValidateLinesContain(12, 14, 20, L"KLMNOPQRSTUVWXYZab", bufferAttr),
+                       L"The rest of the margin area should scroll right by 2 columns.");
+        break;
+    }
+
+    VERIFY_IS_TRUE(_ValidateLinesContain(0, 14, bufferChars, bufferAttr),
+                   L"Content above the top margin should remain unchanged.");
+    VERIFY_IS_TRUE(_ValidateLinesContain(20, 25, bufferChars, bufferAttr),
+                   L"Content below the bottom margin should remain unchanged.");
+    VERIFY_IS_TRUE(_ValidateLinesContain(0, 14, 20, L"ABCDEFGHIJ", bufferAttr),
+                   L"Content before the left margin should remain unchanged.");
+    VERIFY_IS_TRUE(_ValidateLinesContain(30, 14, 20, L"efghijklmn", bufferAttr),
+                   L"Content beyond the right margin should remain unchanged.");
+}
+
 void ScreenBufferTests::ScrollingWideCharsHorizontally()
 {
     // The point of this test is to make sure wide characters can be

src/terminal/adapter/ITermDispatch.hpp

@@ -51,6 +51,8 @@ class Microsoft::Console::VirtualTerminal::ITermDispatch
     virtual bool ScrollDown(const VTInt distance) = 0; // SD
     virtual bool InsertLine(const VTInt distance) = 0; // IL
     virtual bool DeleteLine(const VTInt distance) = 0; // DL
+    virtual bool InsertColumn(const VTInt distance) = 0; // DECIC
+    virtual bool DeleteColumn(const VTInt distance) = 0; // DECDC
     virtual bool SetKeypadMode(const bool applicationMode) = 0; // DECKPAM, DECKPNM
     virtual bool SetAnsiMode(const bool ansiMode) = 0; // DECANM
     virtual bool SetTopBottomScrollingMargins(const VTInt topMargin, const VTInt bottomMargin) = 0; // DECSTBM
@@ -59,6 +61,8 @@ class Microsoft::Console::VirtualTerminal::ITermDispatch
     virtual bool CarriageReturn() = 0; // CR
     virtual bool LineFeed(const DispatchTypes::LineFeedType lineFeedType) = 0; // IND, NEL, LF, FF, VT
     virtual bool ReverseLineFeed() = 0; // RI
+    virtual bool BackIndex() = 0; // DECBI
+    virtual bool ForwardIndex() = 0; // DECFI
     virtual bool SetWindowTitle(std::wstring_view title) = 0; // OscWindowTitle
     virtual bool HorizontalTabSet() = 0; // HTS
     virtual bool ForwardTab(const VTInt numTabs) = 0; // CHT, HT