From 52b7267aacb41deb9747e72bb042da47c893965b Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Sun, 23 Feb 2020 14:47:42 +0100
Subject: [PATCH] Add wxGrid::m_dragMoveCol field separate from m_dragRowOrCol

Don't reuse the same m_dragRowOrCol variable for both the index of the
row or column being drag-resized and for the index of the column being
drag-moved. Reusing it was confusing and made it more difficult what the
code was doing and what invariants were preserved in it, and just wasn't
worth saving a few bytes per wxGrid object.

No real changes.
---
 include/wx/generic/grid.h |  4 ++++
 src/generic/grid.cpp      | 17 +++++++++--------
 2 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/include/wx/generic/grid.h b/include/wx/generic/grid.h
index d3b076783e..6175ef2580 100644
--- a/include/wx/generic/grid.h
+++ b/include/wx/generic/grid.h
@@ -2298,6 +2298,10 @@ protected:
     bool    m_canDragGridSize;
     bool    m_canDragCell;
 
+    // Index of the column being drag-moved or -1 if there is no move operation
+    // in progress.
+    int     m_dragMoveCol;
+
     // the last position (horizontal or vertical depending on whether the user
     // is resizing a column or a row) where a row or column separator line was
     // dragged by the user or -1 of there is no drag operation in progress
diff --git a/src/generic/grid.cpp b/src/generic/grid.cpp
index 3199afe5ce..22674b4696 100644
--- a/src/generic/grid.cpp
+++ b/src/generic/grid.cpp
@@ -2673,6 +2673,7 @@ void wxGrid::Init()
     m_canDragColSize = true;
     m_canDragGridSize = true;
     m_canDragCell = false;
+    m_dragMoveCol = -1;
     m_dragLastPos  = -1;
     m_dragRowOrCol = -1;
     m_isDragging = false;
@@ -3837,7 +3838,7 @@ void wxGrid::ProcessColLabelMouseEvent( wxMouseEvent& event, wxGridColLabelWindo
 
                         const wxColour *color;
                         //Moving to the same place? Don't draw a marker
-                        if ( colNew == m_dragRowOrCol )
+                        if ( colNew == m_dragMoveCol )
                             color = wxLIGHT_GREY;
                         else
                             color = wxBLUE;
@@ -3963,7 +3964,7 @@ void wxGrid::ProcessColLabelMouseEvent( wxMouseEvent& event, wxGridColLabelWindo
                 break;
 
             case WXGRID_CURSOR_MOVE_COL:
-                if ( m_dragLastPos == -1 || col == m_dragRowOrCol )
+                if ( m_dragLastPos == -1 || col == m_dragMoveCol )
                 {
                     // the column didn't actually move anywhere
                     if ( col != -1 )
@@ -3989,7 +3990,7 @@ void wxGrid::ProcessColLabelMouseEvent( wxMouseEvent& event, wxGridColLabelWindo
                     const bool onNearPart = (x <= middle);
 
                     // adjust for the column being dragged itself
-                    if ( pos < GetColPos(m_dragRowOrCol) )
+                    if ( pos < GetColPos(m_dragMoveCol) )
                         pos++;
 
                     // and if it's on the near part of the target column,
@@ -4763,18 +4764,18 @@ void wxGrid::DoEndDragResizeCol(const wxMouseEvent& event, wxGridWindow* gridWin
 
 void wxGrid::DoStartMoveCol(int col)
 {
-    m_dragRowOrCol = col;
+    m_dragMoveCol = col;
 }
 
 void wxGrid::DoEndMoveCol(int pos)
 {
-    wxASSERT_MSG( m_dragRowOrCol != -1, "no matching DoStartMoveCol?" );
+    wxASSERT_MSG( m_dragMoveCol != -1, "no matching DoStartMoveCol?" );
 
-    if ( SendEvent(wxEVT_GRID_COL_MOVE, -1, m_dragRowOrCol) != -1 )
-        SetColPos(m_dragRowOrCol, pos);
+    if ( SendEvent(wxEVT_GRID_COL_MOVE, -1, m_dragMoveCol) != -1 )
+        SetColPos(m_dragMoveCol, pos);
     //else: vetoed by user
 
-    m_dragRowOrCol = -1;
+    m_dragMoveCol = -1;
 }
 
 void wxGrid::RefreshAfterColPosChange()