[goffice] Ensure that ticks on limits are not hidden because of rounding errors.

[Jean Bréfort <jbrefort src gnome org>]

commit 9a58fd9eb1e92778300de13a72475e29626f4bd6
Author: Jean Brefort <jean brefort normalesup org>
Date:   Tue Mar 10 14:16:51 2015 +0100

    Ensure that ticks on limits are not hidden because of rounding errors.

 ChangeLog                     |    6 ++++++
 goffice/graph/gog-axis-line.c |   12 ++++++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 8a9e779..fc682d7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2015-03-10  Jean Brefort  <jean brefort normalesup org>
+
+       * goffice/graph/gog-axis-line.c (axis_line_get_bbox),
+       (axis_line_render): ensure that ticks on limits are not hidden because of
+       rounding errors.
+
 2015-03-04  Morten Welinder <terra gnome org>
 
        * configure.ac: Post-release bump.
diff --git a/goffice/graph/gog-axis-line.c b/goffice/graph/gog-axis-line.c
index 405d996..970f253 100644
--- a/goffice/graph/gog-axis-line.c
+++ b/goffice/graph/gog-axis-line.c
@@ -1011,6 +1011,7 @@ axis_line_point (GogAxisBase *axis_base, GogRenderer *renderer,
        return go_geometry_point_to_segment (x, y, xa, ya, wa, ha) <= POINT_MIN_DISTANCE;
 }
 
+#define GO_EPSILON 1e-10
 static GogViewAllocation
 axis_line_get_bbox (GogAxisBase *axis_base, GogRenderer *renderer,
                    double x, double y, double w, double h,
@@ -1031,7 +1032,7 @@ axis_line_get_bbox (GogAxisBase *axis_base, GogRenderer *renderer,
        double minor_tick_len, major_tick_len, tick_len;
        double padding = gog_axis_base_get_padding (axis_base);
        double label_size_max = 0;
-       double min, max;
+       double min, max, epsilon;
        unsigned i, tick_nbr;
        gboolean is_line_visible;
 
@@ -1089,6 +1090,9 @@ axis_line_get_bbox (GogAxisBase *axis_base, GogRenderer *renderer,
        map = gog_axis_map_new (axis_base->axis, 0., axis_length);
        gog_axis_map_get_real_bounds (map, &min, &max);
 
+       epsilon = (max - min) * GO_EPSILON;
+       min -= epsilon;
+       max += epsilon;
        obrs = g_new0 (GOGeometryOBR, tick_nbr);
        for (i = 0; i < tick_nbr; i++) {
                if (ticks[i].position < min || ticks[i].position > max)
@@ -1153,7 +1157,7 @@ axis_line_render (GogAxisBase *axis_base,
        double padding = gog_axis_base_get_padding (axis_base);
        double label_size_max = 0;
        double s, e;
-       double min, max;
+       double min, max, epsilon;
        unsigned i, tick_nbr, nobr = 0, *indexmap = NULL;
        gboolean draw_major, draw_minor;
        gboolean is_line_visible;
@@ -1205,6 +1209,10 @@ axis_line_render (GogAxisBase *axis_base,
        gog_renderer_get_text_OBR (renderer, "0", TRUE, &zero_obr, -1.);
        label_padding = zero_obr.h * .15;
 
+       /* add some epsilon toerance to avoid roundin errors */
+       epsilon = (max - min) * GO_EPSILON;
+       min -= epsilon;
+       max += epsilon;
        tick_nbr = gog_axis_base_get_ticks (axis_base, &ticks);
        if (draw_labels) {
                obrs = g_new0 (GOGeometryOBR, tick_nbr);