[goffice] Fix data update in matrix plots, see Debian #988397.

[Jean Bréfort <jbrefort src gnome org>]

commit 58c0d487ecdcd488b3e49f2f5e8b2feffea337a1
Author: Jean Brefort <jean brefort normalesup org>
Date:   Wed May 12 08:38:04 2021 +0200

    Fix data update in matrix plots, see Debian #988397.

 ChangeLog                         | 5 +++++
 NEWS                              | 3 +++
 plugins/plot_surface/gog-matrix.c | 2 +-
 3 files changed, 9 insertions(+), 1 deletion(-)
---
diff --git a/ChangeLog b/ChangeLog
index 4654b7b8b..abf12aac4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2021-05-12  Jean Brefort  <jean brefort normalesup org>
+
+       * plugins/plot_surface/gog-matrix.c (gog_matrix_view_render): call the
+       build_matrix method for the real plot type. Fixes Debian #988397.
+
 2021-04-26  Morten Welinder  <terra gnome org>
 
        * goffice/gtk/go-format-sel.c (set_format_category): This takes a
diff --git a/NEWS b/NEWS
index 8918c4f10..017c81d9c 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,8 @@
 goffice 0.10.50:
 
+Jean:
+       * Fix data update in matrix plots, see Debian #988397.
+
 Morten:
        * Simplify regression equation code.
        * Use only 3 decimals for R^2 for regression lines.
diff --git a/plugins/plot_surface/gog-matrix.c b/plugins/plot_surface/gog-matrix.c
index cb6dfc3fd..da033baee 100644
--- a/plugins/plot_surface/gog-matrix.c
+++ b/plugins/plot_surface/gog-matrix.c
@@ -141,7 +141,7 @@ gog_matrix_view_render (GogView *view, GogViewAllocation const *bbox)
        if (plot->plotted_data)
                data = plot->plotted_data;
        else
-               data = GOG_XYZ_PLOT (plot)->plotted_data = gog_matrix_plot_build_matrix (GOG_XYZ_PLOT (plot), 
NULL);
+               data = GOG_XYZ_PLOT (plot)->plotted_data = GOG_XYZ_PLOT_GET_CLASS (plot)->build_matrix 
(GOG_XYZ_PLOT (plot), NULL);
 
        x_map = gog_axis_map_new (plot->base.axis[0],
                                  view->residual.x , view->residual.w);