Move cursor to left margin for IL and DL controls (microsoft#2731)

* Move cursor position to the left margin after execution of the IL and DL escape sequences.
* Update IL and DL screen buffer tests to account for the cursor moving to the left margin.

Author: j4james

src/host/getset.cpp

@@ -2021,6 +2021,7 @@ void DoSrvPrivateSetDefaultTabStops()
 
 // Routine Description:
 // - internal logic for adding or removing lines in the active screen buffer
+//   this also moves the cursor to the left margin, which is expected behaviour for IL and DL
 // Parameters:
 // - count - the number of lines to modify
 // - insert - true if inserting lines, false if deleting lines
@@ -2069,6 +2070,10 @@ void DoSrvPrivateModifyLinesImpl(const unsigned int count, const bool insert)
                          screenInfo.GetAttributes());
         }
         CATCH_LOG();
+
+        // The IL and DL controls are also expected to move the cursor to the left margin.
+        // For now this is just column 0, since we don't yet support DECSLRM.
+        LOG_IF_NTSTATUS_FAILED(screenInfo.SetCursorPosition({ 0, cursorPosition.Y }, false));
     }
 }
 

src/host/ut_host/ScreenBufferTests.cpp

@@ -3230,8 +3230,16 @@ void ScreenBufferTests::ScrollOperations()
     VERIFY_SUCCEEDED(si.SetCursorPosition(cursorPos, true));
     stateMachine.ProcessString(escapeSequence.str());
 
-    Log::Comment(L"Verify cursor didn't move.");
-    VERIFY_ARE_EQUAL(cursorPos, cursor.GetPosition());
+    // The cursor shouldn't move.
+    auto expectedCursorPos = cursorPos;
+    // Unless this is an IL or DL control, which moves the cursor to the left margin.
+    if (scrollType == InsertLine || scrollType == DeleteLine)
+    {
+        expectedCursorPos.X = 0;
+    }
+
+    Log::Comment(L"Verify expected cursor position.");
+    VERIFY_ARE_EQUAL(expectedCursorPos, cursor.GetPosition());
 
     Log::Comment(L"Field of Zs outside viewport should remain unchanged.");
     VERIFY_IS_TRUE(_ValidateLinesContain(0, viewportStart, bufferChar, bufferAttr));
@@ -3749,7 +3757,8 @@ void ScreenBufferTests::InsertLinesInMargins()
     Log::Comment(NoThrowString().Format(
         L"viewport=%s", VerifyOutputTraits<SMALL_RECT>::ToString(si.GetViewport().ToInclusive()).GetBuffer()));
 
-    VERIFY_ARE_EQUAL(4, cursor.GetPosition().X);
+    // Verify cursor moved to left margin.
+    VERIFY_ARE_EQUAL(0, cursor.GetPosition().X);
     VERIFY_ARE_EQUAL(2, cursor.GetPosition().Y);
     {
         auto iter0 = tbi.GetCellDataAt({ 0, 0 });
@@ -3783,7 +3792,8 @@ void ScreenBufferTests::InsertLinesInMargins()
     Log::Comment(NoThrowString().Format(
         L"viewport=%s", VerifyOutputTraits<SMALL_RECT>::ToString(si.GetViewport().ToInclusive()).GetBuffer()));
 
-    VERIFY_ARE_EQUAL(4, cursor.GetPosition().X);
+    // Verify cursor moved to left margin.
+    VERIFY_ARE_EQUAL(0, cursor.GetPosition().X);
     VERIFY_ARE_EQUAL(1, cursor.GetPosition().Y);
     {
         auto iter0 = tbi.GetCellDataAt({ 0, 0 });
@@ -3824,7 +3834,8 @@ void ScreenBufferTests::DeleteLinesInMargins()
     Log::Comment(NoThrowString().Format(
         L"viewport=%s", VerifyOutputTraits<SMALL_RECT>::ToString(si.GetViewport().ToInclusive()).GetBuffer()));
 
-    VERIFY_ARE_EQUAL(4, cursor.GetPosition().X);
+    // Verify cursor moved to left margin.
+    VERIFY_ARE_EQUAL(0, cursor.GetPosition().X);
     VERIFY_ARE_EQUAL(2, cursor.GetPosition().Y);
     {
         auto iter0 = tbi.GetCellDataAt({ 0, 0 });
@@ -3858,7 +3869,8 @@ void ScreenBufferTests::DeleteLinesInMargins()
     Log::Comment(NoThrowString().Format(
         L"viewport=%s", VerifyOutputTraits<SMALL_RECT>::ToString(si.GetViewport().ToInclusive()).GetBuffer()));
 
-    VERIFY_ARE_EQUAL(4, cursor.GetPosition().X);
+    // Verify cursor moved to left margin.
+    VERIFY_ARE_EQUAL(0, cursor.GetPosition().X);
     VERIFY_ARE_EQUAL(1, cursor.GetPosition().Y);
     {
         auto iter0 = tbi.GetCellDataAt({ 0, 0 });