From b8c3c6031603dd425022251a3822a460241bb4f0 Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Mon, 13 Apr 2020 01:23:25 +0200
Subject: [PATCH] Allow extending selection using Shift-Page Up/Down keys

Also make Page Up/Down themselves work consistently with the other
cursor movement keys and clear current selection if they move the
cursor.

Even though DoMoveCursorByPage() is simpler than DoMoveCursorByBlock(),
still factor out AdvanceByPage() for consistency with AdvanceByBlock()
and because it still makes the code more clear.
---
 include/wx/generic/grid.h |  5 ++-
 src/generic/grid.cpp      | 64 +++++++++++++++++++++++++++++++--------
 2 files changed, 55 insertions(+), 14 deletions(-)

diff --git a/include/wx/generic/grid.h b/include/wx/generic/grid.h
index e97d5a1f7d..98f494f376 100644
--- a/include/wx/generic/grid.h
+++ b/include/wx/generic/grid.h
@@ -2771,7 +2771,10 @@ private:
                                   const wxGridDirectionOperations& diroper);
     bool DoMoveCursor(const wxKeyboardState& kbdState,
                       const wxGridDirectionOperations& diroper);
-    bool DoMoveCursorByPage(const wxGridDirectionOperations& diroper);
+    bool DoMoveCursorByPage(const wxKeyboardState& kbdState,
+                            const wxGridDirectionOperations& diroper);
+    bool AdvanceByPage(wxGridCellCoords& coords,
+                       const wxGridDirectionOperations& diroper);
     bool DoMoveCursorByBlock(const wxKeyboardState& kbdState,
                              const wxGridDirectionOperations& diroper);
     void AdvanceToNextNonEmpty(wxGridCellCoords& coords,
diff --git a/src/generic/grid.cpp b/src/generic/grid.cpp
index 58e25b56fa..0ad120676e 100644
--- a/src/generic/grid.cpp
+++ b/src/generic/grid.cpp
@@ -5803,11 +5803,19 @@ void wxGrid::OnKeyDown( wxKeyEvent& event )
                 break;
 
             case WXK_PAGEUP:
-                MovePageUp();
+                DoMoveCursorByPage
+                (
+                    event,
+                    wxGridBackwardOperations(this, wxGridRowOperations())
+                );
                 break;
 
             case WXK_PAGEDOWN:
-                MovePageDown();
+                DoMoveCursorByPage
+                (
+                    event,
+                    wxGridForwardOperations(this, wxGridRowOperations())
+                );
                 break;
 
             case WXK_SPACE:
@@ -7995,37 +8003,67 @@ bool wxGrid::MoveCursorRight(bool expandSelection)
                         wxGridForwardOperations(this, wxGridColumnOperations()));
 }
 
-bool wxGrid::DoMoveCursorByPage(const wxGridDirectionOperations& diroper)
+bool
+wxGrid::AdvanceByPage(wxGridCellCoords& coords,
+                      const wxGridDirectionOperations& diroper)
+{
+    if ( diroper.IsAtBoundary(coords) )
+        return false;
+
+    const int oldRow = coords.GetRow();
+    coords.SetRow(diroper.MoveByPixelDistance(oldRow, m_gridWin->GetClientSize().y));
+    if ( coords.GetRow() == oldRow )
+        diroper.Advance(coords);
+
+    return true;
+}
+
+bool
+wxGrid::DoMoveCursorByPage(const wxKeyboardState& kbdState,
+                           const wxGridDirectionOperations& diroper)
 {
     if ( m_currentCellCoords == wxGridNoCellCoords )
         return false;
 
-    if ( diroper.IsAtBoundary(m_currentCellCoords) )
+    // We don't handle Ctrl-PageUp/Down, it's not really clear what are they
+    // supposed to do, so don't do anything for now.
+    if ( kbdState.ControlDown() )
         return false;
 
-    const int oldRow = m_currentCellCoords.GetRow();
-    int newRow = diroper.MoveByPixelDistance(oldRow, m_gridWin->GetClientSize().y);
-    if ( newRow == oldRow )
+    if ( kbdState.ShiftDown() )
+    {
+        if ( !m_selection )
+            return false;
+
+        wxGridCellCoords coords = m_selection->GetExtensionAnchor();
+        if ( !AdvanceByPage(coords, diroper) )
+            return false;
+
+        if ( m_selection->ExtendCurrentBlock(m_currentCellCoords, coords, kbdState) )
+            MakeCellVisible(coords);
+    }
+    else
     {
         wxGridCellCoords coords(m_currentCellCoords);
-        diroper.Advance(coords);
-        newRow = coords.GetRow();
-    }
+        if ( !AdvanceByPage(coords, diroper) )
+            return false;
 
-    GoToCell(newRow, m_currentCellCoords.GetCol());
+        ClearSelection();
+        GoToCell(coords);
+    }
 
     return true;
 }
 
 bool wxGrid::MovePageUp()
 {
-    return DoMoveCursorByPage(
+    return DoMoveCursorByPage(DummyKeyboardState(false),
                 wxGridBackwardOperations(this, wxGridRowOperations()));
 }
 
 bool wxGrid::MovePageDown()
 {
-    return DoMoveCursorByPage(
+    return DoMoveCursorByPage(DummyKeyboardState(false),
                 wxGridForwardOperations(this, wxGridRowOperations()));
 }