[gnumeric] Fix auto transparency in xlsx charts.

[Jean Bréfort <jbrefort src gnome org>]

commit 02ec6e40a21ef2d2083dbbba745429923689f66f
Author: Jean Brefort <jean brefort normalesup org>
Date:   Tue Feb 28 17:56:55 2017 +0100

    Fix auto transparency in xlsx charts.

 plugins/excel/ChangeLog            |    5 +++++
 plugins/excel/xlsx-write-drawing.c |    3 ++-
 2 files changed, 7 insertions(+), 1 deletions(-)
---
diff --git a/plugins/excel/ChangeLog b/plugins/excel/ChangeLog
index 9b4a5c5..ba9f319 100644
--- a/plugins/excel/ChangeLog
+++ b/plugins/excel/ChangeLog
@@ -1,3 +1,8 @@
+2017-02-28  Jean Brefort  <jean brefort normalesup org>
+
+       * xlsx-write-drawing.c (xlsx_write_go_style_full): do not export
+       transparent fill style if auto.
+
 2017-02-26  Jean Brefort  <jean brefort normalesup org>
 
        * xlsx-write-drawing.c (xlsx_write_go_style_full): always export a
diff --git a/plugins/excel/xlsx-write-drawing.c b/plugins/excel/xlsx-write-drawing.c
index 0a743a4..24bda5f 100644
--- a/plugins/excel/xlsx-write-drawing.c
+++ b/plugins/excel/xlsx-write-drawing.c
@@ -360,7 +360,8 @@ xlsx_write_go_style_full (GsfXMLOut *xml, GOStyle *style, const XLSXStyleContext
                case GO_STYLE_FILL_IMAGE:
                        /* FIXME: export image */
                case GO_STYLE_FILL_NONE:
-                       gsf_xml_out_simple_element (xml, "a:noFill", NULL);
+                       if (!style->fill.auto_type)
+                               gsf_xml_out_simple_element (xml, "a:noFill", NULL);
                        break;
                case GO_STYLE_FILL_PATTERN: {
                        const char *pattname = NULL;