[gnumeric] Improve export of line markers to ODF for interoperability

[Andreas J. Guelzow <guelzow src gnome org>]

commit 71c3d08762b22a5eda61270a123c89987e2dae97
Author: Andreas J. Guelzow <aguelzow pyrshep ca>
Date:   Sun May 10 14:28:25 2020 -0600

    Improve export of line markers to ODF for interoperability
    
    2020-05-10  Andreas J. Guelzow <aguelzow pyrshep ca>
    
            * openoffice-write.c (odf_write_sheet_object_line_style): write marker widths
            (odf_write_arrow_marker_info): write the correct svg:d

 NEWS                                  |  1 +
 plugins/openoffice/ChangeLog          |  7 ++++-
 plugins/openoffice/openoffice-write.c | 50 +++++++++++++++++++++++++++++++----
 3 files changed, 52 insertions(+), 6 deletions(-)
---
diff --git a/NEWS b/NEWS
index e543f093e..7d51d004a 100644
--- a/NEWS
+++ b/NEWS
@@ -3,6 +3,7 @@ Gnumeric 1.12.48
 Andreas:
        * Add axis title to chart in histogram tool. [#408]
        * Fix line end marker roundtrip through strict ODF
+       * Improve export of line markers to ODF for interoperability
 
 --------------------------------------------------------------------------
 Gnumeric 1.12.47
diff --git a/plugins/openoffice/ChangeLog b/plugins/openoffice/ChangeLog
index 4bf3a9659..a493b3b94 100644
--- a/plugins/openoffice/ChangeLog
+++ b/plugins/openoffice/ChangeLog
@@ -1,6 +1,11 @@
 2020-05-10  Andreas J. Guelzow <aguelzow pyrshep ca>
 
-       * openoffice-read.c (oo_marker): for strict ODF use teh info encoded in the
+       * openoffice-write.c (odf_write_sheet_object_line_style): write marker widths
+       (odf_write_arrow_marker_info): write the correct svg:d
+
+2020-05-10  Andreas J. Guelzow <aguelzow pyrshep ca>
+
+       * openoffice-read.c (oo_marker): for strict ODF use the info encoded in the
        marker name
 
 2020-05-09  Morten Welinder <terra gnome org>
diff --git a/plugins/openoffice/openoffice-write.c b/plugins/openoffice/openoffice-write.c
index 906ccd17d..1f6c49d54 100644
--- a/plugins/openoffice/openoffice-write.c
+++ b/plugins/openoffice/openoffice-write.c
@@ -909,10 +909,18 @@ odf_write_sheet_object_line_style (GnmOOExport *state, SheetObject *so)
        gsf_xml_out_start_element (state->xml, STYLE "graphic-properties");
        odf_add_bool (state->xml, STYLE "print-content",
                      sheet_object_get_print_flag (so));
-       if (start_arrow_name != NULL)
+       if (start_arrow_name != NULL) {
                gsf_xml_out_add_cstr (state->xml, DRAW "marker-start", start_arrow_name);
-       if (end_arrow_name != NULL)
+               odf_add_bool (state->xml, DRAW "marker-start-center", TRUE);
+               odf_add_pt (state->xml, DRAW "marker-start-width",
+                           start->typ == GO_ARROW_KITE ? 2 * start->c : 2 * start->a);
+       }
+       if (end_arrow_name != NULL) {
                gsf_xml_out_add_cstr (state->xml, DRAW "marker-end", end_arrow_name);
+               odf_add_bool (state->xml, DRAW "marker-end-center", TRUE);
+               odf_add_pt (state->xml, DRAW "marker-end-width",
+                           end->typ == GO_ARROW_KITE ? 2 * end->c : 2 * end->a);
+       }
        odf_write_gog_style_graphic (state, style, FALSE);
        gsf_xml_out_end_element (state->xml); /* </style:graphic-properties> */
        gsf_xml_out_end_element (state->xml); /* </style:style> */
@@ -5866,6 +5874,12 @@ odf_write_fill_images_info (GOImage *image, char const *name, GnmOOExport *state
 static void
 odf_write_arrow_marker_info (GOArrow const *arrow, char const *name, GnmOOExport *state)
 {
+       char *d_string = NULL;
+       char *box_string = NULL;
+       int a = (int) (arrow->a + 0.5);
+       int b = (int) (arrow->b + 0.5);
+       int c = (int) (arrow->c + 0.5);
+
        gsf_xml_out_start_element (state->xml, DRAW "marker");
        gsf_xml_out_add_cstr_unchecked (state->xml, DRAW "name", name);
 
@@ -5876,9 +5890,35 @@ odf_write_arrow_marker_info (GOArrow const *arrow, char const *name, GnmOOExport
                go_xml_out_add_double (state->xml, GNMSTYLE "arrow-c", arrow->c);
        }
 
-       gsf_xml_out_add_cstr (state->xml, SVG "viewBox", "0 0 20 30");
-       /* FIXME: We should be writing the correct arow head shape rather than a standard fixed one */
-       gsf_xml_out_add_cstr (state->xml, SVG "d", "m10 0-10 30h20z");
+       switch (arrow->typ) {
+       case GO_ARROW_NONE:
+               box_string = g_strdup ("-1 -1 1 1");
+               d_string = g_strdup ("M 0,0");
+               break;
+       case GO_ARROW_KITE:
+               box_string = g_strdup_printf
+                       ("%i 0 %i %i", -c, c, a < b ? b : a);
+               d_string = g_strdup_printf
+                       ("M 0,0 %i,%i 0,%i %i,%i z", -c, b, a, c, b);
+               break;
+       case GO_ARROW_OVAL:
+               box_string = g_strdup_printf ("%d %d %d %d", -a, -a, a, a);
+               d_string = g_strdup_printf
+                       ("M 0,0 m %d,0 a %d,%d 0 1,0 %d,0 a %d,%d 0 1,0 %d,0",
+                        -a, a, b, 2*a, a, b, -2 * a);
+               break;
+       default:
+               box_string = g_strdup ("-100 -100 100 100");
+               d_string = g_strdup ("M 0,-100 -100,-50 0,100 100,-50 z");
+               break;
+       }
+
+       if (box_string)
+               gsf_xml_out_add_cstr (state->xml, SVG "viewBox", box_string);
+       if (d_string)
+               gsf_xml_out_add_cstr (state->xml, SVG "d", d_string);
+       g_free (box_string);
+       g_free (d_string);
 
        gsf_xml_out_end_element (state->xml); /* </draw:marker> */
 }