[gnumeric] xlsx: improve roundtrip of axes.

[Morten Welinder <mortenw src gnome org>]

commit 4809ad377beef941c7ac87ab5fbe5f1f6f8a916a
Author: Morten Welinder <terra gnome org>
Date:   Mon Jan 19 15:44:39 2015 -0500

    xlsx: improve roundtrip of axes.

 plugins/excel/ChangeLog           |    2 +
 plugins/excel/xlsx-read-drawing.c |   41 +++++++++++++++++++++++++++++++++---
 2 files changed, 39 insertions(+), 4 deletions(-)
---
diff --git a/plugins/excel/ChangeLog b/plugins/excel/ChangeLog
index 0553bb5..98e721d 100644
--- a/plugins/excel/ChangeLog
+++ b/plugins/excel/ChangeLog
@@ -2,6 +2,8 @@
 
        * xlsx-read-drawing.c (xlsx_drawing_twoCellAnchor_end): Fix
        operator precedence.
+       (xlsx_axis_end): Re-use the id of an automatically generated axis
+       if there is one we can delete that happens to have the right role.
 
        * xlsx-write-drawing.c (xlsx_write_one_plot): Use
        xlsx_plottype_from_type_name for readability.
diff --git a/plugins/excel/xlsx-read-drawing.c b/plugins/excel/xlsx-read-drawing.c
index 74ca83a..28b8f2e 100644
--- a/plugins/excel/xlsx-read-drawing.c
+++ b/plugins/excel/xlsx-read-drawing.c
@@ -23,6 +23,8 @@
 
 #include "sheet-object-widget.h"
 
+#undef DEBUG_AXIS
+
 /*****************************************************************************
  * Various functions common to at least charts and user shapes               *
  *****************************************************************************/
@@ -740,10 +742,11 @@ xlsx_axis_end (GsfXMLIn *xin, G_GNUC_UNUSED GsfXMLBlob *blob)
                GogPlot *plot = state->axis.info->plots->data; /* just use the first */
                char const *type = G_OBJECT_TYPE_NAME (plot);
                char const *role = NULL;
-               GSList *ptr;
+               GSList *ptr, *children;
                gboolean inverted = FALSE;
                gboolean cat_or_date = (state->axis.type == XLSX_AXIS_CAT ||
                                        state->axis.type == XLSX_AXIS_DATE);
+               GogAxis *axis = state->axis.obj;
 
                switch (xlsx_plottype_from_type_name (type)) {
                case XLSX_PT_GOGRADARPLOT:
@@ -772,15 +775,45 @@ xlsx_axis_end (GsfXMLIn *xin, G_GNUC_UNUSED GsfXMLBlob *blob)
 
                /* Set the id, and atype.  Ref to balance.  */
                gog_object_add_by_name (GOG_OBJECT (state->chart),
-                                       role, GOG_OBJECT (g_object_ref (state->axis.obj)));
+                                       role, GOG_OBJECT (g_object_ref (axis)));
                for (ptr = state->axis.info->plots; ptr != NULL ; ptr = ptr->next) {
                        GogPlot *plot = ptr->data;
 #ifdef DEBUG_AXIS
-                       g_printerr ("connect plot %p to %p in role %s\n", plot, state->axis.obj, role);
+                       g_printerr ("connect plot %p to %p in role %s\n", plot, axis, role);
 #endif
-                       gog_plot_set_axis (plot, state->axis.obj);
+                       gog_plot_set_axis (plot, axis);
                }
 
+               /*
+                * Go through the existing axes looking for an auto-generated one
+                * whose id we can take over.  This avoids starting with "X-Axis2"
+                * which (1) looks silly and (2) causes roundtrip issues.
+                */
+               children = gog_object_get_children (GOG_OBJECT (state->chart), NULL);
+               for (ptr = children; ptr != NULL; ptr = ptr->next) {
+                       GogObject *this_axis = ptr->data;
+                       guint id;
+
+                       if (!GOG_IS_AXIS (this_axis) ||
+                           g_hash_table_lookup (state->axis.by_obj, this_axis) ||
+                           !gog_object_is_deletable (this_axis) ||
+                           this_axis->role != GOG_OBJECT(axis)->role)
+                               continue;
+
+#ifdef DEBUG_AXIS
+                       g_printerr ("Axis %s is a going to be deleted and its id taken over\n",
+                                   gog_object_get_name (this_axis));
+#endif
+                       id = gog_object_get_id (this_axis);
+                       gog_object_clear_parent (this_axis);
+                       g_object_unref (this_axis);
+
+                       /* Take over the id of the deleted item.  */
+                       g_object_set (axis, "id", id, NULL);
+                       break;
+               }
+               g_slist_free (children);
+
                state->axis.obj  = NULL;
                state->axis.info = NULL;
        }