[goffice] Fix crash in countour plots when no color is used. [#705913]

[Jean Bréfort <jbrefort src gnome org>]

commit 4f7db3d44d75158a8f711745b76be706a4790a92
Author: Jean Brefort <jean brefort normalesup org>
Date:   Wed Aug 14 15:57:51 2013 +0200

    Fix crash in countour plots when no color is used. [#705913]

 ChangeLog                          |    8 +++++++-
 NEWS                               |    1 +
 plugins/plot_surface/gog-contour.c |    2 ++
 3 files changed, 10 insertions(+), 1 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 2c706c3..f3490ed 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2013-08-14  Jean Brefort  <jean brefort normalesup org>
+
+       * plugins/plot_surface/gog-contour.c (gog_contour_view_render): don't crash
+       if there is no color is used. [#705913]
+
 2013-08-11  Morten Welinder  <terra gnome org>
 
        * goffice/utils/formats.c (_go_format_builtins)
@@ -10,7 +15,8 @@
        * goffice/graph/gog-renderer.h: ditto.
        * goffice/utils/go-editor.c (go_editor_add_page): ditto.
        * goffice/utils/go-image.c (go_image_draw_fb),
-       (go_image_get_pixbuf_fb), (go_image_new_from_data): ditto and .
+       (go_image_get_pixbuf_fb), (go_image_new_from_data): ditto and fix crash
++      when drawing a fallback image without gtk (from ssconvert). [#705677]
 
 2013-08-05  Jean Brefort  <jean brefort normalesup org>
 
diff --git a/NEWS b/NEWS
index 80a388b..4c9683e 100644
--- a/NEWS
+++ b/NEWS
@@ -11,6 +11,7 @@ Jean:
        * Implement get_data_at_point for area and line plots. [#627277][#689661]
        * Fix rendring of stacked area plots. [#705034]
        * Fix crash when drawing a fallback image without gtk. [#705677]
+       * Fix crash in countour plots when no color is used. [#705913]
 
 Morten:
        * Add prescaling to go_linear_regression_leverage.  [#703381]
diff --git a/plugins/plot_surface/gog-contour.c b/plugins/plot_surface/gog-contour.c
index 3566eb9..e5fa7b9 100644
--- a/plugins/plot_surface/gog-contour.c
+++ b/plugins/plot_surface/gog-contour.c
@@ -285,6 +285,8 @@ gog_contour_view_render (GogView *view, GogViewAllocation const *bbox)
                return;
        series = GOG_SERIES (plot->base.series->data);
        max = GOG_CONTOUR_PLOT (plot)->max_colors;
+       if (max < 1)
+               return;
        if (plot->transposed) {
                imax = plot->columns;
                jmax = plot->rows;