document the mapping to CellRenderers

and clarify that g-lo-CellIndex is the index from the external pov

Change-Id: Id747acaeabab50755188732637a72c1fce8a97dc
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/95519
Tested-by: Caolán McNamara <caolanm@redhat.com>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
(cherry picked from commit 36f57d5aebe448701ffe3bbc529f29d2112dec94)

1 files changed, 7 insertions, 1 deletions

diff --git a/vcl/unx/gtk3/gtk3gtkinst.cxx b/vcl/unx/gtk3/gtk3gtkinst.cxx
index b2c2a3b7f17b..e1b65a2e460c 100644
--- a/vcl/unx/gtk3/gtk3gtkinst.cxx
+++ b/vcl/unx/gtk3/gtk3gtkinst.cxx
@@ -8472,6 +8472,11 @@ public:
         , m_nKeyPressSignalId(g_signal_connect(pTreeView, "key-press-event", G_CALLBACK(signalKeyPress), this))
         , m_pChangeEvent(nullptr)
     {
+        /* The outside concept of a column maps to a gtk CellRenderer, rather than
+           a TreeViewColumn. If the first TreeViewColumn has two CellRenderers, and
+           the first CellRenderer is an image, that CellRenderer is considered to
+           be index -1.
+        */
         m_pColumns = gtk_tree_view_get_columns(m_pTreeView);
         int nIndex(0);
         int nViewColumn(0);
@@ -8483,7 +8488,6 @@ public:
             for (GList* pRenderer = g_list_first(pRenderers); pRenderer; pRenderer = g_list_next(pRenderer))
             {
                 GtkCellRenderer* pCellRenderer = GTK_CELL_RENDERER(pRenderer->data);
-                g_object_set_data(G_OBJECT(pCellRenderer), "g-lo-CellIndex", reinterpret_cast<gpointer>(nIndex));
                 if (GTK_IS_CELL_RENDERER_TEXT(pCellRenderer))
                 {
                     if (m_nTextCol == -1)
@@ -8511,6 +8515,8 @@ public:
                     else if (m_nImageCol == -1)
                         m_nImageCol = nIndex;
                 }
+                int nExternalIndex = to_external_model(nIndex);
+                g_object_set_data(G_OBJECT(pCellRenderer), "g-lo-CellIndex", reinterpret_cast<gpointer>(nExternalIndex));
                 ++nIndex;
             }
             g_list_free(pRenderers);