Terminal uses system default for number of rows scrolled at a time. Can be overridden in settings file.

doc/cascadia/SettingsSchema.md

@@ -10,6 +10,7 @@ Properties listed below affect the entire window, regardless of the profile sett
 | `defaultProfile` | _Required_ | String | PowerShell guid | Sets the default profile. Opens by typing <kbd>Ctrl</kbd> + <kbd>T</kbd> or by clicking the '+' icon. The guid of the desired default profile is used as the value. |
 | `initialCols` | _Required_ | Integer | `120` | The number of columns displayed in the window upon first load. |
 | `initialRows` | _Required_ | Integer | `30` | The number of rows displayed in the window upon first load. |
+| `rowsToScroll` | Optional | Integer | `system` | The number of rows to scroll at a time with the mouse wheel. This will override the system setting if the value is not zero or "system". |
 | `requestedTheme` | _Required_ | String | `system` | Sets the theme of the application. Possible values: `"light"`, `"dark"`, `"system"` |
 | `showTerminalTitleInTitlebar` | _Required_ | Boolean | `true` | When set to `true`, titlebar displays the title of the selected tab. When set to `false`, titlebar displays "Windows Terminal". |
 | `showTabsInTitlebar` | Optional | Boolean | `true` | When set to `true`, the tabs are moved into the titlebar and the titlebar disappears. When set to `false`, the titlebar sits above the tabs. |

doc/cascadia/profiles.schema.json

@@ -284,6 +284,13 @@
           "minimum": 1,
           "type": "integer"
         },
+        "rowsToScroll": {
+          "default": "system",
+          "description": "The number of rows to scroll at a time with the mouse wheel. This will override the system setting if the value is not zero or 'system'.",
+          "maximum": 999,
+          "minimum": 0,
+          "type": "integer"
+        },
         "keybindings": {
           "description": "Properties are specific to each custom key binding.",
           "items": {

src/cascadia/LocalTests_TerminalApp/SettingsTests.cpp

@@ -433,15 +433,17 @@ namespace TerminalAppLocalTests
             "globals": {
                 "alwaysShowTabs": true,
                 "initialCols" : 120,
-                "initialRows" : 30
+                "initialRows" : 30,
+                "rowsToScroll" :  4,
             }
         })" };
         const std::string settings1String{ R"(
         {
             "globals": {
                 "showTabsInTitlebar": false,
                 "initialCols" : 240,
-                "initialRows" : 60
+                "initialRows" : 60,
+                "rowsToScroll" : 8 
             }
         })" };
         const auto settings0Json = VerifyParseSucceeded(settings0String);
@@ -453,12 +455,14 @@ namespace TerminalAppLocalTests
         VERIFY_ARE_EQUAL(true, settings._globals._alwaysShowTabs);
         VERIFY_ARE_EQUAL(120, settings._globals._initialCols);
         VERIFY_ARE_EQUAL(30, settings._globals._initialRows);
+        VERIFY_ARE_EQUAL(4, settings._globals._rowsToScroll);
         VERIFY_ARE_EQUAL(true, settings._globals._showTabsInTitlebar);
 
         settings.LayerJson(settings1Json);
         VERIFY_ARE_EQUAL(true, settings._globals._alwaysShowTabs);
         VERIFY_ARE_EQUAL(240, settings._globals._initialCols);
         VERIFY_ARE_EQUAL(60, settings._globals._initialRows);
+        VERIFY_ARE_EQUAL(8, settings._globals._rowsToScroll);
         VERIFY_ARE_EQUAL(false, settings._globals._showTabsInTitlebar);
     }
 

src/cascadia/TerminalApp/GlobalAppSettings.cpp

@@ -21,6 +21,7 @@ static constexpr std::string_view DefaultProfileKey{ "defaultProfile" };
 static constexpr std::string_view AlwaysShowTabsKey{ "alwaysShowTabs" };
 static constexpr std::string_view InitialRowsKey{ "initialRows" };
 static constexpr std::string_view InitialColsKey{ "initialCols" };
+static constexpr std::string_view RowsToScrollKey{ "rowsToScroll" };
 static constexpr std::string_view InitialPositionKey{ "initialPosition" };
 static constexpr std::string_view ShowTitleInTitlebarKey{ "showTerminalTitleInTitlebar" };
 static constexpr std::string_view RequestedThemeKey{ "requestedTheme" };
@@ -41,6 +42,7 @@ GlobalAppSettings::GlobalAppSettings() :
     _alwaysShowTabs{ true },
     _initialRows{ DEFAULT_ROWS },
     _initialCols{ DEFAULT_COLS },
+    _rowsToScroll{ DEFAULT_ROWSTOSCROLL },
     _initialX{},
     _initialY{},
     _showTitleInTitlebar{ true },
@@ -175,6 +177,7 @@ void GlobalAppSettings::ApplyToSettings(TerminalSettings& settings) const noexce
     settings.KeyBindings(GetKeybindings());
     settings.InitialRows(_initialRows);
     settings.InitialCols(_initialCols);
+    settings.RowsToScroll(_rowsToScroll);
 
     settings.WordDelimiters(_wordDelimiters);
     settings.CopyOnSelect(_copyOnSelect);
@@ -193,6 +196,7 @@ Json::Value GlobalAppSettings::ToJson() const
     jsonObject[JsonKey(DefaultProfileKey)] = winrt::to_string(Utils::GuidToString(_defaultProfile));
     jsonObject[JsonKey(InitialRowsKey)] = _initialRows;
     jsonObject[JsonKey(InitialColsKey)] = _initialCols;
+    jsonObject[JsonKey(RowsToScrollKey)] = _rowsToScroll;
     jsonObject[JsonKey(InitialPositionKey)] = _SerializeInitialPosition(_initialX, _initialY);
     jsonObject[JsonKey(AlwaysShowTabsKey)] = _alwaysShowTabs;
     jsonObject[JsonKey(ShowTitleInTitlebarKey)] = _showTitleInTitlebar;
@@ -239,6 +243,18 @@ void GlobalAppSettings::LayerJson(const Json::Value& json)
     {
         _initialCols = initialCols.asInt();
     }
+    if (auto rowsToScroll{ json[JsonKey(RowsToScrollKey)] })
+    {
+        //if it's not an int we fall back to setting it to 0, which implies using the system setting. This will be the case if it's set to "system"
+        if (rowsToScroll.isInt())
+        {
+            _rowsToScroll = rowsToScroll.asInt();
+        }
+        else
+        {
+            _rowsToScroll = 0;
+        }
+    }
     if (auto initialPosition{ json[JsonKey(InitialPositionKey)] })
     {
         _ParseInitialPosition(GetWstringFromJson(initialPosition), _initialX, _initialY);

src/cascadia/TerminalApp/GlobalAppSettings.h

@@ -85,6 +85,8 @@ class TerminalApp::GlobalAppSettings final
     int32_t _initialRows;
     int32_t _initialCols;
 
+    int32_t _rowsToScroll;
+
     std::optional<int32_t> _initialX;
     std::optional<int32_t> _initialY;
 

src/cascadia/TerminalControl/TermControl.cpp

@@ -351,6 +351,9 @@ namespace winrt::Microsoft::Terminal::TerminalControl::implementation
         foregroundBrush.Color(ColorRefToColor(_settings.DefaultForeground()));
         _tsfInputControl.Foreground(foregroundBrush);
         _tsfInputControl.Margin(newMargin);
+
+        // set number of rows to scroll at a time
+        _rowsToScroll = _settings.RowsToScroll();
     }
 
     // Method Description:
@@ -1151,13 +1154,10 @@ namespace winrt::Microsoft::Terminal::TerminalControl::implementation
         // However, for us, the signs are flipped.
         const auto rowDelta = mouseDelta < 0 ? 1.0 : -1.0;
 
-        // TODO: Should we be getting some setting from the system
-        //      for number of lines scrolled?
         // With one of the precision mouses, one click is always a multiple of 120,
         // but the "smooth scrolling" mode results in non-int values
 
-        // Conhost seems to use four lines at a time, so we'll emulate that for now.
-        double newValue = (4 * rowDelta) + (currentOffset);
+        double newValue = (_rowsToScroll * rowDelta) + (currentOffset);
 
         // Clear our expected scroll offset. The viewport will now move in
         //      response to our user input.
@@ -1321,6 +1321,7 @@ namespace winrt::Microsoft::Terminal::TerminalControl::implementation
     // - Event handler for the GotFocus event. This is used to...
     //   - enable accessibility notifications for this TermControl
     //   - start blinking the cursor when the window is focused
+    //   - update the number of lines to scroll to the value set in the system
     void TermControl::_GotFocusHandler(Windows::Foundation::IInspectable const& /* sender */,
                                        RoutedEventArgs const& /* args */)
     {
@@ -1346,6 +1347,7 @@ namespace winrt::Microsoft::Terminal::TerminalControl::implementation
             _terminal->SetCursorVisible(true);
             _cursorTimer.value().Start();
         }
+        _rowsToScroll = _settings.RowsToScroll();
     }
 
     // Method Description:

src/cascadia/TerminalControl/TermControl.h

@@ -132,6 +132,8 @@ namespace winrt::Microsoft::Terminal::TerminalControl::implementation
         FontInfoDesired _desiredFont;
         FontInfo _actualFont;
 
+        int _rowsToScroll;
+
         std::optional<int> _lastScrollOffset;
 
         // Auto scroll occurs when user, while selecting, drags cursor outside viewport. View is then scrolled to 'follow' the cursor.

src/cascadia/TerminalSettings/ICoreSettings.idl

@@ -22,6 +22,8 @@ namespace Microsoft.Terminal.Settings
         Int32 HistorySize;
         Int32 InitialRows;
         Int32 InitialCols;
+        Int32 RowsToScroll;
+
         Boolean SnapOnInput;
 
         UInt32 CursorColor;

src/cascadia/TerminalSettings/TerminalSettings.cpp

@@ -21,6 +21,7 @@ namespace winrt::Microsoft::Terminal::Settings::implementation
         _historySize{ DEFAULT_HISTORY_SIZE },
         _initialRows{ 30 },
         _initialCols{ 80 },
+        _rowsToScroll{ 0 },
         _snapOnInput{ true },
         _cursorColor{ DEFAULT_CURSOR_COLOR },
         _cursorShape{ CursorStyle::Vintage },
@@ -114,6 +115,25 @@ namespace winrt::Microsoft::Terminal::Settings::implementation
         _initialCols = value;
     }
 
+    int32_t TerminalSettings::RowsToScroll() noexcept
+    {
+        if (_rowsToScroll != 0)
+        {
+            return _rowsToScroll;
+        }
+        int systemRowsToScroll;
+        if (!SystemParametersInfo(SPI_GETWHEELSCROLLLINES, 0, &systemRowsToScroll, 0))
+        {
+            systemRowsToScroll = 4;
+        }
+        return systemRowsToScroll;
+    }
+
+    void TerminalSettings::RowsToScroll(int32_t value) noexcept
+    {
+        _rowsToScroll = value;
+    }
+
     bool TerminalSettings::SnapOnInput() noexcept
     {
         return _snapOnInput;

src/cascadia/TerminalSettings/terminalsettings.h

@@ -39,6 +39,8 @@ namespace winrt::Microsoft::Terminal::Settings::implementation
         void InitialRows(int32_t value) noexcept;
         int32_t InitialCols() noexcept;
         void InitialCols(int32_t value) noexcept;
+        int32_t RowsToScroll() noexcept;
+        void RowsToScroll(int32_t value) noexcept;
         bool SnapOnInput() noexcept;
         void SnapOnInput(bool value) noexcept;
         uint32_t CursorColor() noexcept;
@@ -108,6 +110,7 @@ namespace winrt::Microsoft::Terminal::Settings::implementation
         int32_t _historySize;
         int32_t _initialRows;
         int32_t _initialCols;
+        int32_t _rowsToScroll;
         bool _snapOnInput;
         uint32_t _cursorColor;
         Settings::CursorStyle _cursorShape;

src/cascadia/UnitTests_TerminalCore/MockTermSettings.h

@@ -25,6 +25,7 @@ namespace TerminalCoreUnitTests
         int32_t HistorySize() { return _historySize; }
         int32_t InitialRows() { return _initialRows; }
         int32_t InitialCols() { return _initialCols; }
+        int32_t RowsToScroll() { return 4; }
         uint32_t DefaultForeground() { return COLOR_WHITE; }
         uint32_t DefaultBackground() { return COLOR_BLACK; }
         bool SnapOnInput() { return false; }
@@ -44,6 +45,7 @@ namespace TerminalCoreUnitTests
         void HistorySize(int32_t) {}
         void InitialRows(int32_t) {}
         void InitialCols(int32_t) {}
+        void RowsToScroll(int32_t) {}
         void DefaultForeground(uint32_t) {}
         void DefaultBackground(uint32_t) {}
         void SnapOnInput(bool) {}

src/inc/DefaultSettings.h

@@ -35,6 +35,7 @@ constexpr int DEFAULT_FONT_SIZE = 12;
 
 constexpr int DEFAULT_ROWS = 30;
 constexpr int DEFAULT_COLS = 120;
+constexpr int DEFAULT_ROWSTOSCROLL = 0;
 
 const std::wstring DEFAULT_PADDING{ L"8, 8, 8, 8" };
 const std::wstring DEFAULT_STARTING_DIRECTORY{ L"%USERPROFILE%" };