[goffice] Draw background and outline for data labels. [#592]

[Jean Bréfort <jbrefort src gnome org>]

commit 65b03b6424ee4ffdbfd3dedfeaa04e9c6fae2384
Author: Jean Brefort <jean brefort normalesup org>
Date:   Sat Aug 28 11:30:32 2021 +0200

    Draw background and outline for data labels. [#592]

 ChangeLog                    |  7 +++++++
 NEWS                         |  1 +
 goffice/graph/gog-renderer.c | 49 ++++++++++++++++++++++++++++++++------------
 plugins/plot_xy/gog-xy.c     |  2 +-
 4 files changed, 45 insertions(+), 14 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index a37a4fefb..a44239d87 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2021-08-28  Jean Brefort  <jean brefort normalesup org>
+
+       reviewed by: <delete if not using a buddy>
+
+       * goffice/graph/gog-renderer.c (gog_renderer_draw_data_label):
+       * plugins/plot_xy/gog-xy.c (gog_xy_view_render):
+
 2021-06-11  Jean Brefort  <jean brefort normalesup org>
 
        * plugins/plot_xy/gog-xy.c (gog_xy_view_render): do not clip markers. #584.
diff --git a/NEWS b/NEWS
index eb020a5a1..a5ee0f8a2 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,7 @@ goffice 0.10.51:
 
 Jean:
        * Do not clip markers in scatter plots. [#584]
+       * Draw background and outline for data labels. [#592]
 
 --------------------------------------------------------------------------
 goffice 0.10.50:
diff --git a/goffice/graph/gog-renderer.c b/goffice/graph/gog-renderer.c
index fecc03e81..9237f1eba 100644
--- a/goffice/graph/gog-renderer.c
+++ b/goffice/graph/gog-renderer.c
@@ -1136,7 +1136,9 @@ gog_renderer_draw_data_label (GogRenderer *rend, GogSeriesLabelElt const *elt,
        GOStyle const *style;
        int iw, ih;
        PangoAttrList *attrs;
-       PangoRectangle rect;
+       PangoRectangle rect, ir, lr;
+       GogViewAllocation rectangle;
+       double w;
 
        g_return_if_fail (elt != NULL && elt->str != NULL);
        g_return_if_fail (GOG_IS_RENDERER (rend));
@@ -1157,11 +1159,8 @@ gog_renderer_draw_data_label (GogRenderer *rend, GogSeriesLabelElt const *elt,
        if (attrs)
                pango_layout_set_attributes (layout, attrs);
        pango_cairo_context_set_resolution (context, 72.0);
-       /*now get the real size */
-       pango_layout_get_size (layout, &iw, &ih);
        if (elt->legend_pos >= 0) {
                /* we need to add enough room to draw the legend entry */
-               PangoRectangle rect;
                PangoAttribute *attr;
                rect.x = rect.y = 0;
                pango_layout_get_size (layout, &iw, &ih);
@@ -1172,8 +1171,11 @@ gog_renderer_draw_data_label (GogRenderer *rend, GogSeriesLabelElt const *elt,
                attr->end_index = elt->legend_pos + 1;
                pango_attr_list_insert (attrs, attr);
                pango_layout_set_attributes (layout, attrs);
-               pango_layout_get_size (layout, &iw, &ih);
        }
+       /*now get the real size */
+       pango_layout_get_extents (layout, &ir, &lr);
+       iw = lr.width;
+       ih = lr.height;
        pango_attr_list_unref (attrs);
 
        obr.w = rend->scale * ((double) iw + (double) PANGO_SCALE / 2.0)
@@ -1185,22 +1187,24 @@ gog_renderer_draw_data_label (GogRenderer *rend, GogSeriesLabelElt const *elt,
        obr.y = pos->y;
        go_geometry_OBR_to_AABR (&obr, &aabr);
 
+       w = ((style->interesting_fields | GO_STYLE_LINE) && (style->line.width > 0.))?
+                       gog_renderer_line_size (rend, style->line.width): 1.; 
        switch (anchor) {
                case GO_ANCHOR_NW: case GO_ANCHOR_W: case GO_ANCHOR_SW:
-                       obr.x += aabr.w / 2.0;
+                       obr.x += aabr.w / 2.0 + w;
                        break;
                case GO_ANCHOR_NE : case GO_ANCHOR_SE : case GO_ANCHOR_E :
-                       obr.x -= aabr.w / 2.0;
+                       obr.x -= aabr.w / 2.0 + w;
                        break;
                default : break;
        }
 
        switch (anchor) {
                case GO_ANCHOR_NW: case GO_ANCHOR_N: case GO_ANCHOR_NE:
-                       obr.y += aabr.h / 2.0;
+                       obr.y += aabr.h / 2.0 + w;
                        break;
                case GO_ANCHOR_SE : case GO_ANCHOR_S : case GO_ANCHOR_SW :
-                       obr.y -= aabr.h / 2.0;
+                       obr.y -= aabr.h / 2.0 + w;
                        break;
                default : break;
        }
@@ -1212,10 +1216,27 @@ gog_renderer_draw_data_label (GogRenderer *rend, GogSeriesLabelElt const *elt,
                       obr.y - (obr.w / 2.0) * sin (obr.alpha) -
                       (obr.h / 2.0) * cos (obr.alpha));
        cairo_rotate (cairo, obr.alpha);
-       /* now draw the legen entry if needed */
+
+       /* draw outline and background if needed */
+       gog_renderer_push_style (rend, style);
+       if (style->interesting_fields & (GO_STYLE_FILL | GO_STYLE_LINE)) {
+               GOPath *path = go_path_new ();
+               double  dx = ((double) ir.width / PANGO_SCALE + 2.) * rend->scale,
+                               dy = ((double) ir.height / PANGO_SCALE + 2.) * rend->scale,
+                               x0 = (double) ir.x / PANGO_SCALE - 1.,
+                               y0 = (double) ir.y / PANGO_SCALE - 1.;
+               go_path_move_to (path, x0 - w / 2., y0 - w / 2.);
+               go_path_line_to (path, x0 + dx + w / 2., y0 - w / 2.);
+               go_path_line_to (path, x0 + dx + w / 2., y0 + dy + w / 2.);
+               go_path_line_to (path, x0 - w / 2., y0 + dy + w / 2.);
+               go_path_close (path);
+               cairo_set_line_join (cairo, CAIRO_LINE_JOIN_MITER); /* probably not the right place */
+               gog_renderer_draw_shape (rend, path);
+               go_path_free (path);
+       }
+       /* now draw the legend entry if needed */
        if (elt->legend_pos >= 0 && legend_style != NULL) {
                GOStyle *style = go_style_dup (legend_style);
-               GogViewAllocation rectangle;
                double x, y,w, h;
                pango_layout_index_to_pos (layout, elt->legend_pos, &rect);
                x = (double) rect.x / PANGO_SCALE * rend->scale;
@@ -1251,7 +1272,6 @@ gog_renderer_draw_data_label (GogRenderer *rend, GogSeriesLabelElt const *elt,
                        rectangle.y = y;
                        rectangle.w = w;
                        rectangle.h = h;
-
                        gog_renderer_push_style (rend, style);
                        gog_renderer_draw_rectangle (rend, &rectangle);
                } else if (style->interesting_fields & GO_STYLE_MARKER) {                                     
  /* markers only */
@@ -1259,13 +1279,16 @@ gog_renderer_draw_data_label (GogRenderer *rend, GogSeriesLabelElt const *elt,
                                go_marker_set_size (style->marker.mark, h);
                        gog_renderer_push_style (rend, style);
                        gog_renderer_draw_marker (rend, x + w / 2., y + h / 2.);
-               }
+               } else
+                       gog_renderer_push_style (rend, style); // just to be sure
                gog_renderer_pop_style (rend);
                g_object_unref (style);
        }
        cairo_scale (cairo, rend->scale, rend->scale);
+       cairo_set_source_rgba (cairo, GO_COLOR_TO_CAIRO (style->font.color));
        pango_cairo_show_layout (cairo, layout);
        cairo_restore (cairo);
+       gog_renderer_pop_style (rend);
        g_object_unref (layout);
 }
 
diff --git a/plugins/plot_xy/gog-xy.c b/plugins/plot_xy/gog-xy.c
index 581c7768c..e74f12def 100644
--- a/plugins/plot_xy/gog-xy.c
+++ b/plugins/plot_xy/gog-xy.c
@@ -1594,7 +1594,7 @@ gog_xy_view_render (GogView *view, GogViewAllocation const *bbox)
                                        anchor = GO_ANCHOR_CENTER;
                                        break;
                                case GOG_SERIES_LABELS_TOP:
-                                       alloc.y -= cur_offset * gog_renderer_get_scale (view->renderer);;
+                                       alloc.y -= cur_offset * gog_renderer_get_scale (view->renderer);
                                        anchor = GO_ANCHOR_SOUTH;
                                        break;
                                case GOG_SERIES_LABELS_BOTTOM: