Implement snap-on-input for conhost

src/host/_stream.cpp

@@ -97,17 +97,6 @@ static void AdjustCursorPosition(SCREEN_INFORMATION& screenInfo, _In_ til::point
         coordCursor.y = bufferSize.height - 1;
     }
 
-    const auto cursorMovedPastViewport = coordCursor.y > screenInfo.GetViewport().BottomInclusive();
-
-    // if at right or bottom edge of window, scroll right or down one char.
-    if (cursorMovedPastViewport)
-    {
-        til::point WindowOrigin;
-        WindowOrigin.x = 0;
-        WindowOrigin.y = coordCursor.y - screenInfo.GetViewport().BottomInclusive();
-        LOG_IF_FAILED(screenInfo.SetViewportOrigin(false, WindowOrigin, true));
-    }
-
     LOG_IF_FAILED(screenInfo.SetCursorPosition(coordCursor, false));
 }
 
@@ -167,6 +156,8 @@ void WriteCharsLegacy(SCREEN_INFORMATION& screenInfo, const std::wstring_view& t
     auto& gci = ServiceLocator::LocateGlobals().getConsoleInformation();
     auto writer = gci.GetVtWriterForBuffer(&screenInfo);
 
+    const auto snap = screenInfo.SnapOnOutput();
+
     // If we enter this if condition, then someone wrote text in VT mode and now switched to non-VT mode.
     // Since the Console APIs don't support delayed EOL wrapping, we need to first put the cursor back
     // to a position that the Console APIs expect (= not delayed).
@@ -340,6 +331,8 @@ void WriteCharsVT(SCREEN_INFORMATION& screenInfo, const std::wstring_view& str)
     // may change, so get the VtIo reference now, just in case.
     auto writer = gci.GetVtWriterForBuffer(&screenInfo);
 
+    const auto snap = screenInfo.SnapOnOutput();
+
     stateMachine.ProcessString(str);
 
     if (writer)

src/host/input.cpp

@@ -108,7 +108,7 @@ bool ShouldTakeOverKeyboardShortcuts()
 void HandleGenericKeyEvent(INPUT_RECORD event, const bool generateBreak)
 {
     auto& keyEvent = event.Event.KeyEvent;
-    const auto& gci = ServiceLocator::LocateGlobals().getConsoleInformation();
+    auto& gci = ServiceLocator::LocateGlobals().getConsoleInformation();
     auto ContinueProcessing = true;
 
     if (WI_IsAnyFlagSet(keyEvent.dwControlKeyState, CTRL_PRESSED) &&
@@ -167,6 +167,11 @@ void HandleGenericKeyEvent(INPUT_RECORD event, const bool generateBreak)
             keyEvent.bKeyDown = false;
             gci.pInputBuffer->Write(event);
         }
+
+        if (gci.HasActiveOutputBuffer())
+        {
+            gci.GetActiveOutputBuffer().SnapOnInput(keyEvent.wVirtualKeyCode);
+        }
     }
 }
 

src/host/screenInfo.cpp

@@ -1668,39 +1668,58 @@ void SCREEN_INFORMATION::SetCursorDBMode(const bool DoubleCursor)
     return STATUS_SUCCESS;
 }
 
-void SCREEN_INFORMATION::MakeCursorVisible(const til::point CursorPosition)
+static constexpr bool IsInputKey(WORD vkey)
 {
-    til::point WindowOrigin;
+    return vkey != VK_CONTROL &&
+           vkey != VK_LCONTROL &&
+           vkey != VK_RCONTROL &&
+           vkey != VK_MENU &&
+           vkey != VK_LMENU &&
+           vkey != VK_RMENU &&
+           vkey != VK_SHIFT &&
+           vkey != VK_LSHIFT &&
+           vkey != VK_RSHIFT &&
+           vkey != VK_LWIN &&
+           vkey != VK_RWIN &&
+           vkey != VK_SNAPSHOT;
+}
 
-    if (CursorPosition.x > _viewport.RightInclusive())
-    {
-        WindowOrigin.x = CursorPosition.x - _viewport.RightInclusive();
-    }
-    else if (CursorPosition.x < _viewport.Left())
-    {
-        WindowOrigin.x = CursorPosition.x - _viewport.Left();
-    }
-    else
-    {
-        WindowOrigin.x = 0;
-    }
+void SCREEN_INFORMATION::MakeCursorVisible(til::point position)
+{
+    const auto viewportOrigin = _viewport.Origin();
+    const auto viewportSize = _viewport.Dimensions();
+    const auto bufferSize = _textBuffer->GetSize().Dimensions();
+    auto origin = viewportOrigin;
 
-    if (CursorPosition.y > _viewport.BottomInclusive())
-    {
-        WindowOrigin.y = CursorPosition.y - _viewport.BottomInclusive();
-    }
-    else if (CursorPosition.y < _viewport.Top())
+    // Ensure the given position is in bounds.
+    position.x = std::clamp(position.x, 0, bufferSize.width - 1);
+    position.y = std::clamp(position.y, 0, bufferSize.height - 1);
+
+    origin.y = std::min(origin.y, position.y); // shift up if above
+    origin.y = std::max(origin.y, position.y - (viewportSize.height - 1)); // shift down if below
+
+    origin.x = std::min(origin.x, position.x); // shift left if left
+    origin.x = std::max(origin.x, position.x - (viewportSize.width - 1)); // shift right if right
+
+    if (origin != viewportOrigin)
     {
-        WindowOrigin.y = CursorPosition.y - _viewport.Top();
+        std::ignore = SetViewportOrigin(true, origin, false);
     }
-    else
+}
+
+void SCREEN_INFORMATION::SnapOnInput(const WORD vkey)
+{
+    if (IsInputKey(vkey))
     {
-        WindowOrigin.y = 0;
+        _makeCursorVisible();
     }
+}
 
-    if (WindowOrigin.x != 0 || WindowOrigin.y != 0)
+void SCREEN_INFORMATION::_makeCursorVisible()
+{
+    if (_textBuffer->GetCursor().IsOn())
     {
-        LOG_IF_FAILED(SetViewportOrigin(false, WindowOrigin, false));
+        MakeCursorVisible(_textBuffer->GetCursor().GetPosition());
     }
 }
 

src/host/screenInfo.hpp

@@ -71,6 +71,18 @@ class SCREEN_INFORMATION : public ConsoleObjectHeader, public Microsoft::Console
     void GetRequiredConsoleSizeInPixels(_Out_ til::size* const pRequiredSize) const;
 
     void MakeCurrentCursorVisible();
+    void MakeCursorVisible(til::point position);
+    void SnapOnInput(WORD vkey);
+    auto SnapOnOutput()
+    {
+        const auto inBounds = _viewport.IsInBounds(_textBuffer->GetCursor().GetPosition());
+        return wil::scope_exit([this, inBounds]() {
+            if (inBounds)
+            {
+                _makeCursorVisible();
+            }
+        });
+    }
 
     void ClipToScreenBuffer(_Inout_ til::inclusive_rect* const psrClip) const;
 
@@ -184,8 +196,6 @@ class SCREEN_INFORMATION : public ConsoleObjectHeader, public Microsoft::Console
     void SetCursorDBMode(const bool DoubleCursor);
     [[nodiscard]] NTSTATUS SetCursorPosition(const til::point Position, const bool TurnOn);
 
-    void MakeCursorVisible(const til::point CursorPosition);
-
     [[nodiscard]] NTSTATUS UseAlternateScreenBuffer(const TextAttribute& initAttributes);
     void UseMainScreenBuffer();
 
@@ -232,6 +242,7 @@ class SCREEN_INFORMATION : public ConsoleObjectHeader, public Microsoft::Console
     void _CalculateViewportSize(const til::rect* const prcClientArea, _Out_ til::size* const pcoordSize);
     void _AdjustViewportSize(const til::rect* const prcClientNew, const til::rect* const prcClientOld, const til::size* const pcoordSize);
     void _InternalSetViewportSize(const til::size* pcoordSize, const bool fResizeFromTop, const bool fResizeFromLeft);
+    void _makeCursorVisible();
 
     static void s_CalculateScrollbarVisibility(const til::rect* const prcClientArea,
                                                const til::size* const pcoordBufferSize,

src/interactivity/win32/Clipboard.cpp

@@ -162,6 +162,11 @@ void Clipboard::StringPaste(_In_reads_(cchData) const wchar_t* const pData,
         const auto bracketedPasteMode = gci.GetBracketedPasteMode();
         auto inEvents = TextToKeyEvents(pData, cchData, vtInputMode && bracketedPasteMode);
         gci.pInputBuffer->Write(inEvents);
+
+        if (gci.HasActiveOutputBuffer())
+        {
+            gci.GetActiveOutputBuffer().SnapOnInput(0);
+        }
     }
     catch (...)
     {