[gnumeric] xlsx: export trend lines.

[Morten Welinder <mortenw src gnome org>]

commit 15d08925fcc2d9a7313573e457278884f053c9fb
Author: Morten Welinder <terra gnome org>
Date:   Tue Jan 20 15:05:12 2015 -0500

    xlsx: export trend lines.

 NEWS                               |    2 +-
 plugins/excel/ChangeLog            |    3 ++
 plugins/excel/xlsx-write-drawing.c |   68 +++++++++++++++++++++++++++++-------
 3 files changed, 59 insertions(+), 14 deletions(-)
---
diff --git a/NEWS b/NEWS
index 0588942..abd3a52 100644
--- a/NEWS
+++ b/NEWS
@@ -28,7 +28,7 @@ Morten:
        * Improve xlsx graph import: line colour; marker size; marker color;
          no lines; bounding box; trend lines; regression equations.
        * Improve xlsx graph export: line style; bar/col direction; marker shape;
-         marker size; marker color; axis label; chart title.
+         marker size; marker color; axis label; chart title; trend lines.
        * Improve xlsx export: default col widths; schema validity.
        * Improve modifier handling.  [#743130]
 
diff --git a/plugins/excel/ChangeLog b/plugins/excel/ChangeLog
index 6e257ed..c7c2514 100644
--- a/plugins/excel/ChangeLog
+++ b/plugins/excel/ChangeLog
@@ -1,5 +1,8 @@
 2015-01-20  Morten Welinder  <terra gnome org>
 
+       * xlsx-write-drawing.c (xlsx_write_one_plot): Initial export of
+       trend lines.
+
        * xlsx-read-drawing.c (xlsx_ser_trendline_type): Initial import of
        trend lines.
 
diff --git a/plugins/excel/xlsx-write-drawing.c b/plugins/excel/xlsx-write-drawing.c
index 882638b..705dc74 100644
--- a/plugins/excel/xlsx-write-drawing.c
+++ b/plugins/excel/xlsx-write-drawing.c
@@ -524,29 +524,71 @@ xlsx_write_one_plot (XLSXWriteState *state, GsfXMLOut *xml, GogObject const *cha
        for (series = gog_plot_get_series (GOG_PLOT (plot));
             NULL != series;
             series = series->next) {
+               GogSeries *ser = series->data;
+               GSList *l, *children;
+
                gsf_xml_out_start_element (xml, "c:ser");
 
                xlsx_write_chart_int (xml, "c:idx", -1, count);
                xlsx_write_chart_int (xml, "c:order", -1, count);
-               xlsx_write_series_dim (state, xml, series->data,
-                                      "c:tx", GOG_MS_DIM_LABELS);
+               xlsx_write_series_dim (state, xml, ser, "c:tx", GOG_MS_DIM_LABELS);
                if (!vary_by_element) /* FIXME: we might loose some style elements */
-                       xlsx_write_go_style (xml, go_styled_object_get_style (GO_STYLED_OBJECT 
(series->data)));
+                       xlsx_write_go_style (xml, go_styled_object_get_style (GO_STYLED_OBJECT (ser)));
                if (explosion > 0.)
                        xlsx_write_chart_uint (xml, "c:explosion", 0, (unsigned) (explosion * 100));
                if (use_xy) {
-                       xlsx_write_series_dim (state, xml, series->data,
-                                              "c:xVal",  GOG_MS_DIM_CATEGORIES);
-                       xlsx_write_series_dim (state, xml, series->data,
-                                              "c:yVal", GOG_MS_DIM_VALUES);
-                       xlsx_write_series_dim (state, xml, series->data,
-                                              "c:bubbleSize", GOG_MS_DIM_BUBBLES);
+                       xlsx_write_series_dim (state, xml, ser, "c:xVal", GOG_MS_DIM_CATEGORIES);
+                       xlsx_write_series_dim (state, xml, ser, "c:yVal", GOG_MS_DIM_VALUES);
+                       xlsx_write_series_dim (state, xml, ser, "c:bubbleSize", GOG_MS_DIM_BUBBLES);
                } else {
-                       xlsx_write_series_dim (state, xml, series->data,
-                                              "c:cat",  GOG_MS_DIM_CATEGORIES);
-                       xlsx_write_series_dim (state, xml, series->data,
-                                              "c:val", GOG_MS_DIM_VALUES);
+                       xlsx_write_series_dim (state, xml, ser, "c:cat", GOG_MS_DIM_CATEGORIES);
+                       xlsx_write_series_dim (state, xml, ser, "c:val", GOG_MS_DIM_VALUES);
                }
+
+               children = gog_object_get_children (GOG_OBJECT (ser), NULL);
+               for (l = children; l; l = l->next) {
+                       GogObject *trend = l->data;
+                       const char *trend_type_name = G_OBJECT_TYPE_NAME (trend);
+                       const char *trend_type;
+                       GogObject *eq;
+
+                       if (!GOG_IS_TREND_LINE (trend))
+                               continue;
+
+                       if (strcmp (trend_type_name, "GogExpRegCurve") == 0)
+                               trend_type = "exp";
+                       else if (strcmp (trend_type_name, "GogLinRegCurve") == 0)
+                               trend_type = "linear";
+                       else if (strcmp (trend_type_name, "GogLogRegCurve") == 0)
+                               trend_type = "log";
+                       else if (strcmp (trend_type_name, "GogMovingAvg") == 0)
+                               trend_type = "movingAvg";
+                       else if (strcmp (trend_type_name, "GogPolynomRegCurve") == 0)
+                               trend_type = "poly";
+                       else if (strcmp (trend_type_name, "GogPowerRegCurve") == 0)
+                               trend_type = "power";
+                       else {
+                               trend_type = "linear";
+                               g_warning ("Unknown regression mapped to %s\n", trend_type);
+                       }
+
+
+                       gsf_xml_out_start_element (xml, "c:trendline");
+                       xlsx_write_chart_cstr_unchecked (xml, "c:trendlineType", trend_type);
+                       gsf_xml_out_end_element (xml); /* </c:trendline> */
+
+                       eq = gog_object_get_child_by_name (trend, "Equation");
+                       if (eq) {
+                               gboolean has_r2, has_eq;
+                               g_object_get (eq, "show-r2", &has_r2, "show-eq", &has_eq, NULL);
+                               if (has_r2)
+                                       xlsx_write_chart_bool (xml, "c:dispRSqr", TRUE);
+                               if (has_eq)
+                                       xlsx_write_chart_bool (xml, "c:dispEq", TRUE);
+                       }
+               }
+               g_slist_free (children);
+
                gsf_xml_out_end_element (xml); /* </c:ser> */
        }