Implement Keyboard Selection (#10824)

Implements the following keyboard selection non-configurable key bindings:
- shift+arrow --> move endpoint by character
- ctrl+shift+left/right --> move endpoint by word
- shift+home/end --> move to beginning/end of line
- ctrl+shift+home/end --> move to beginning/end of buffer

This was purposefully done in the ControlCore layer to make keyboard selection an innate part of how the terminal functions (aka a shared component across terminal consumers).

## References
#715 - Keyboard Selection
#2840 - Spec

## Detailed Description of the Pull Request / Additional comment
The most relevant section is `TerminalSelection.cpp`, where we define how each movement operates. It's basically a giant embedded switch-case statement. We leverage a lot of the work done in a11y to perform the movements.

## Validation Steps Performed
- General cases:
   - test all of the key bindings added
- Corner cases:
   - `char`: wide glyph support
   - `word`: move towards, away, and across the selection pivot
   - automatically scroll viewport
   - ESC (and other key combos) are still clearing the selection properly

doc/cascadia/profiles.schema.json

@@ -847,7 +847,7 @@
         }
       ],
       "required": [ "actions" ]
-    }, 
+    },
     "CommandPaletteAction": {
       "description": "Arguments for a commandPalette action",
       "allOf": [

src/buffer/out/textBuffer.cpp

@@ -1430,12 +1430,13 @@ const til::point TextBuffer::GetGlyphStart(const til::point pos, std::optional<t
 }
 
 // Method Description:
-// - Update pos to be the end of the current glyph/character. This is used for accessibility
+// - Update pos to be the end of the current glyph/character.
 // Arguments:
 // - pos - a COORD on the word you are currently on
+// - accessibilityMode - this is being used for accessibility; make the end exclusive.
 // Return Value:
 // - pos - The COORD for the last cell of the current glyph (exclusive)
-const til::point TextBuffer::GetGlyphEnd(const til::point pos, std::optional<til::point> limitOptional) const
+const til::point TextBuffer::GetGlyphEnd(const til::point pos, bool accessibilityMode, std::optional<til::point> limitOptional) const
 {
     COORD resultPos = pos;
     const auto bufferSize = GetSize();
@@ -1453,7 +1454,10 @@ const til::point TextBuffer::GetGlyphEnd(const til::point pos, std::optional<til
     }
 
     // increment one more time to become exclusive
-    bufferSize.IncrementInBounds(resultPos, true);
+    if (accessibilityMode)
+    {
+        bufferSize.IncrementInBounds(resultPos, true);
+    }
     return resultPos;
 }
 

src/buffer/out/textBuffer.hpp

@@ -147,7 +147,7 @@ class TextBuffer final
     bool MoveToPreviousWord(COORD& pos, const std::wstring_view wordDelimiters) const;
 
     const til::point GetGlyphStart(const til::point pos, std::optional<til::point> limitOptional = std::nullopt) const;
-    const til::point GetGlyphEnd(const til::point pos, std::optional<til::point> limitOptional = std::nullopt) const;
+    const til::point GetGlyphEnd(const til::point pos, bool accessibilityMode = false, std::optional<til::point> limitOptional = std::nullopt) const;
     bool MoveToNextGlyph(til::point& pos, bool allowBottomExclusive = false, std::optional<til::point> limitOptional = std::nullopt) const;
     bool MoveToPreviousGlyph(til::point& pos, std::optional<til::point> limitOptional = std::nullopt) const;
 

src/cascadia/PublicTerminalCore/HwndTerminal.cpp

@@ -549,11 +549,11 @@ try
 
     if (multiClickMapper == 3)
     {
-        _terminal->MultiClickSelection(cursorPosition / fontSize, ::Terminal::SelectionExpansionMode::Line);
+        _terminal->MultiClickSelection(cursorPosition / fontSize, ::Terminal::SelectionExpansion::Line);
     }
     else if (multiClickMapper == 2)
     {
-        _terminal->MultiClickSelection(cursorPosition / fontSize, ::Terminal::SelectionExpansionMode::Word);
+        _terminal->MultiClickSelection(cursorPosition / fontSize, ::Terminal::SelectionExpansion::Word);
     }
     else
     {

src/cascadia/TerminalControl/ControlCore.cpp

@@ -359,28 +359,38 @@ namespace winrt::Microsoft::Terminal::Control::implementation
                                       const ControlKeyStates modifiers,
                                       const bool keyDown)
     {
-        // When there is a selection active, escape should clear it and NOT flow through
-        // to the terminal. With any other keypress, it should clear the selection AND
-        // flow through to the terminal.
+        // Update the selection, if it's present
         // GH#6423 - don't dismiss selection if the key that was pressed was a
         // modifier key. We'll wait for a real keystroke to dismiss the
         // GH #7395 - don't dismiss selection when taking PrintScreen
         // selection.
-        // GH#8522, GH#3758 - Only dismiss the selection on key _down_. If we
-        // dismiss on key up, then there's chance that we'll immediately dismiss
+        // GH#8522, GH#3758 - Only modify the selection on key _down_. If we
+        // modify on key up, then there's chance that we'll immediately dismiss
         // a selection created by an action bound to a keydown.
         if (HasSelection() &&
             !KeyEvent::IsModifierKey(vkey) &&
             vkey != VK_SNAPSHOT &&
             keyDown)
         {
+            // try to update the selection
+            if (const auto updateSlnParams{ ::Terminal::ConvertKeyEventToUpdateSelectionParams(modifiers, vkey) })
+            {
+                auto lock = _terminal->LockForWriting();
+                _terminal->UpdateSelection(updateSlnParams->first, updateSlnParams->second);
+                _renderer->TriggerSelection();
+                return true;
+            }
+
             // GH#8791 - don't dismiss selection if Windows key was also pressed as a key-combination.
             if (!modifiers.IsWinPressed())
             {
                 _terminal->ClearSelection();
                 _renderer->TriggerSelection();
             }
 
+            // When there is a selection active, escape should clear it and NOT flow through
+            // to the terminal. With any other keypress, it should clear the selection AND
+            // flow through to the terminal.
             if (vkey == VK_ESCAPE)
             {
                 return true;
@@ -1399,18 +1409,18 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         // handle ALT key
         _terminal->SetBlockSelection(altEnabled);
 
-        ::Terminal::SelectionExpansionMode mode = ::Terminal::SelectionExpansionMode::Cell;
+        ::Terminal::SelectionExpansion mode = ::Terminal::SelectionExpansion::Char;
         if (numberOfClicks == 1)
         {
-            mode = ::Terminal::SelectionExpansionMode::Cell;
+            mode = ::Terminal::SelectionExpansion::Char;
         }
         else if (numberOfClicks == 2)
         {
-            mode = ::Terminal::SelectionExpansionMode::Word;
+            mode = ::Terminal::SelectionExpansion::Word;
         }
         else if (numberOfClicks == 3)
         {
-            mode = ::Terminal::SelectionExpansionMode::Line;
+            mode = ::Terminal::SelectionExpansion::Line;
         }
 
         // Update the selection appropriately
@@ -1435,7 +1445,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
             _terminal->SetSelectionEnd(terminalPosition, mode);
             selectionNeedsToBeCopied = true;
         }
-        else if (mode != ::Terminal::SelectionExpansionMode::Cell || shiftEnabled)
+        else if (mode != ::Terminal::SelectionExpansion::Char || shiftEnabled)
         {
             // If we are handling a double / triple-click or shift+single click
             // we establish selection using the selected mode
@@ -1534,5 +1544,4 @@ namespace winrt::Microsoft::Terminal::Control::implementation
 
         return hstring(ss.str());
     }
-
 }

src/cascadia/TerminalCore/Terminal.hpp

@@ -227,16 +227,30 @@ class Microsoft::Terminal::Core::Terminal final :
 
 #pragma region TextSelection
     // These methods are defined in TerminalSelection.cpp
-    enum class SelectionExpansionMode
+    enum class SelectionDirection
     {
-        Cell,
+        Left,
+        Right,
+        Up,
+        Down
+    };
+
+    enum class SelectionExpansion
+    {
+        Char,
         Word,
-        Line
+        Line, // Mouse selection only!
+        Viewport,
+        Buffer
     };
-    void MultiClickSelection(const COORD viewportPos, SelectionExpansionMode expansionMode);
+    void MultiClickSelection(const COORD viewportPos, SelectionExpansion expansionMode);
     void SetSelectionAnchor(const COORD position);
-    void SetSelectionEnd(const COORD position, std::optional<SelectionExpansionMode> newExpansionMode = std::nullopt);
+    void SetSelectionEnd(const COORD position, std::optional<SelectionExpansion> newExpansionMode = std::nullopt);
     void SetBlockSelection(const bool isEnabled) noexcept;
+    void UpdateSelection(SelectionDirection direction, SelectionExpansion mode);
+
+    using UpdateSelectionParams = std::optional<std::pair<SelectionDirection, SelectionExpansion>>;
+    static UpdateSelectionParams ConvertKeyEventToUpdateSelectionParams(const ControlKeyStates mods, const WORD vkey);
 
     const TextBuffer::TextAndColor RetrieveSelectedTextFromBuffer(bool trimTrailingWhitespace);
 #pragma endregion
@@ -308,7 +322,7 @@ class Microsoft::Terminal::Core::Terminal final :
     std::optional<SelectionAnchors> _selection;
     bool _blockSelection;
     std::wstring _wordDelimiters;
-    SelectionExpansionMode _multiClickSelectionMode;
+    SelectionExpansion _multiClickSelectionMode;
 #pragma endregion
 
     // TODO: These members are not shared by an alt-buffer. They should be
@@ -375,6 +389,10 @@ class Microsoft::Terminal::Core::Terminal final :
     std::pair<COORD, COORD> _PivotSelection(const COORD targetPos, bool& targetStart) const;
     std::pair<COORD, COORD> _ExpandSelectionAnchors(std::pair<COORD, COORD> anchors) const;
     COORD _ConvertToBufferCell(const COORD viewportPos) const;
+    void _MoveByChar(SelectionDirection direction, COORD& pos);
+    void _MoveByWord(SelectionDirection direction, COORD& pos);
+    void _MoveByViewport(SelectionDirection direction, COORD& pos);
+    void _MoveByBuffer(SelectionDirection direction, COORD& pos);
 #pragma endregion
 
     Microsoft::Console::VirtualTerminal::SgrStack _sgrStack;