Viewport selection is now an option

TODO: connect to setting

src/cascadia/TerminalCore/Terminal.cpp

@@ -133,6 +133,9 @@ void Terminal::UpdateSettings(winrt::Microsoft::Terminal::Settings::ICoreSetting
 
     _snapOnInput = settings.SnapOnInput();
 
+    // TODO: import tripleClickSelection setting from Settings
+    _tripleClickMode = TripleClickSelectionMode::Line;
+
     // TODO:MSFT:21327402 - if HistorySize has changed, resize the buffer so we
     // have a smaller scrollback. We should do this carefully - if the new buffer
     // size is smaller than where the mutable viewport currently is, we'll want
@@ -645,15 +648,44 @@ void Terminal::DoubleClickSelection(const COORD position)
 }
 
 // Method Description:
-// - Select the entire row of the position clicked
+// - Performs a triple click selection based on the setting
 // Arguments:
 // - position: the (x,y) coordinate on the visible viewport
 void Terminal::TripleClickSelection(const COORD position)
+{
+    switch (_tripleClickMode)
+    {
+    case TripleClickSelectionMode::VisibleViewport:
+        _SelectViewport();
+        break;
+    case TripleClickSelectionMode::Line:
+        _SelectRow(position);
+        break;
+    case TripleClickSelectionMode::Disabled:
+    default:
+        SetSelectionAnchor(position);
+        break;
+    }
+}
+
+// Method Description:
+// - Create a selection of the entire row of the position clicked
+// Arguments:
+// - position: the (x,y) coordinate on the visible viewport
+void Terminal::_SelectRow(const COORD position)
 {
     SetSelectionAnchor({ 0, position.Y });
     SetEndSelectionPosition({ _buffer->GetSize().RightInclusive(), position.Y });
 }
 
+// Method Description:
+// - Create a selection of the entire visible viewport present
+void Terminal::_SelectViewport()
+{
+    SetSelectionAnchor({ 0, 0 });
+    SetEndSelectionPosition(_mutableViewport.Dimensions());
+}
+
 // Method Description:
 // - expand the double click selection to the left (stopped by delimiter)
 // Arguments:

src/cascadia/TerminalCore/Terminal.hpp

@@ -147,15 +147,24 @@ class Microsoft::Terminal::Core::Terminal final :
     bool _snapOnInput;
 
     // Text Selection
+    enum TripleClickSelectionMode
+    {
+        Disabled = 0,
+        Line,
+        VisibleViewport
+    };
     COORD _selectionAnchor;
     COORD _endSelectionPosition;
     bool _boxSelection;
     bool _selectionActive;
     SHORT _selectionAnchor_YOffset;
     SHORT _endSelectionPosition_YOffset;
+    TripleClickSelectionMode _tripleClickMode;
     void _ExpandDoubleClickSelectionLeft(const COORD position);
     void _ExpandDoubleClickSelectionRight(const COORD position);
     const bool _DoubleClickDelimiterCheck(std::wstring_view cellChar) const;
+    void _SelectRow(const COORD position);
+    void _SelectViewport();
     const COORD _ConvertToBufferCell(const COORD viewportPos) const;
 
     std::shared_mutex _readWriteLock;