[goffice] bar/col: fix log axis handling.

[Morten Welinder <mortenw src gnome org>]

commit 2f46c05e0123251967ef578df23832bdd00fcab9
Author: Morten Welinder <terra gnome org>
Date:   Tue Mar 24 20:22:28 2015 -0400

    bar/col: fix log axis handling.

 ChangeLog                      |   11 ++++++++++-
 NEWS                           |    1 +
 goffice/graph/gog-axis.c       |   21 ++++++++++++++++++++-
 goffice/graph/gog-axis.h       |    2 ++
 plugins/plot_barcol/gog-1.5d.c |   32 ++++++++++++++++++--------------
 5 files changed, 51 insertions(+), 16 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 485fa09..e50898b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2015-03-24  Morten Welinder  <terra gnome org>
+
+       * plugins/plot_barcol/gog-1.5d.c (gog_plot1_5d_axis_get_bounds):
+       Use gog_axis_is_zero_important.  Avoid underflow.
+       (gog_plot1_5d_update): Use gog_axis_data_get_bounds.
+
+       * goffice/graph/gog-axis.c (gog_axis_is_zero_important): New
+       function.
+
 2015-03-20  Morten Welinder  <terra gnome org>
 
        * goffice/math/go-math.c (_go_math_init): generate positive nan.
@@ -5,7 +14,7 @@
 2015-03-19  Jean Brefort  <jean brefort normalesup org>
 
        * goffice/graph/gog-axis-line.c (axis_line_point): fix selection of
-       axes using only part fo the plot area. [#746456]
+       axes using only part of the plot area. [#746456]
 
 2015-03-19  Morten Welinder  <terra gnome org>
 
diff --git a/NEWS b/NEWS
index c0aa49c..d85cc6b 100644
--- a/NEWS
+++ b/NEWS
@@ -9,6 +9,7 @@ Johannes Deutsch:
 Morten:
        * Improve log axis bounds.
        * Fix format used for stacked percentage graphs.
+       * Don't force bar/col axis to include 0 for log axis.
 
 --------------------------------------------------------------------------
 goffice 0.10.21:
diff --git a/goffice/graph/gog-axis.c b/goffice/graph/gog-axis.c
index c24e3dc..f49e55a 100644
--- a/goffice/graph/gog-axis.c
+++ b/goffice/graph/gog-axis.c
@@ -873,7 +873,6 @@ map_linear_calc_ticks (GogAxis *axis)
        }
        range = maximum - minimum;
 
-
        maj_step = gog_axis_get_entry (axis, GOG_AXIS_ELEM_MAJOR_TICK, NULL);
        if (maj_step <= 0.) maj_step = range;
        while (1) {
@@ -3883,6 +3882,26 @@ gog_axis_data_get_bounds (GogAxis *axis, GOData *data,
                go_data_get_bounds (data, minimum, maximum);
 }
 
+/*
+ * gog_axis_is_zero_important:
+ * @axis: the axis to check
+ *
+ * Returns %TRUE if the axis is of a type in which zero is important and
+ * preferentially should be included in the range.
+ *
+ * This generally means a linear axis, i.e., not a log axis and not a
+ * date formatted axis.
+ */
+gboolean
+gog_axis_is_zero_important (GogAxis *axis)
+{
+       GogAxisMapDesc const *desc = axis->actual_map_desc;
+
+       return !axis->is_discrete &&
+               desc->map_finite (0.0) &&
+               desc->auto_bound != map_date_auto_bound;
+}
+
 /**
  * gog_axis_get_grid_line:
  * @axis: #GogAxis
diff --git a/goffice/graph/gog-axis.h b/goffice/graph/gog-axis.h
index 20752e2..b34fdaa 100644
--- a/goffice/graph/gog-axis.h
+++ b/goffice/graph/gog-axis.h
@@ -108,6 +108,8 @@ void              gog_axis_bound_changed      (GogAxis *axis, GogObject *contrib);
 
 void          gog_axis_data_get_bounds    (GogAxis *axis, GOData *data, double *minimum, double *maximum);
 
+gboolean      gog_axis_is_zero_important  (GogAxis *axis);
+
 GogGridLine  *gog_axis_get_grid_line     (GogAxis *axis, gboolean major);
 
 void                   gog_axis_set_polar_unit         (GogAxis *axis, GogAxisPolarUnit unit);
diff --git a/plugins/plot_barcol/gog-1.5d.c b/plugins/plot_barcol/gog-1.5d.c
index 2f0b716..b886eba 100644
--- a/plugins/plot_barcol/gog-1.5d.c
+++ b/plugins/plot_barcol/gog-1.5d.c
@@ -162,8 +162,9 @@ gog_plot1_5d_update (GogObject *obj)
        GSList *ptr;
        GOData *index_dim = NULL;
        GogPlot *plot_that_labeled_axis;
-       GogAxis *axis;
        gboolean index_changed = FALSE;
+       GogAxis *iaxis = gog_plot1_5d_get_index_axis (model);
+       GogAxis *vaxis = gog_plot1_5d_get_value_axis (model);
 
        old_minima =  model->minima;
        old_maxima =  model->maxima;
@@ -191,7 +192,7 @@ gog_plot1_5d_update (GogObject *obj)
                        if (gog_error_bar_is_visible (series->errors))
                                gog_error_bar_get_minmax (series->errors, &minima, &maxima);
                        else
-                               go_data_get_bounds (series->base.values[1].data, &minima, &maxima);
+                               gog_axis_data_get_bounds (vaxis, series->base.values[1].data, &minima, 
&maxima);
                        if (series->base.plot->desc.series.num_dim == 3) {
                                double tmp_min, tmp_max;
                                go_data_get_bounds (series->base.values[2].data, &tmp_min, &tmp_max);
@@ -210,17 +211,17 @@ gog_plot1_5d_update (GogObject *obj)
                model->date_conv = go_data_date_conv (series->base.values[1].data);
                index_dim = series->base.values[0].data;
        }
-       axis = gog_plot1_5d_get_index_axis (model);
+
        if (model->num_elements != num_elements ||
            model->implicit_index ^ (index_dim == NULL) ||
-           (index_dim != gog_axis_get_labels (axis, &plot_that_labeled_axis) &&
+           (index_dim != gog_axis_get_labels (iaxis, &plot_that_labeled_axis) &&
             GOG_PLOT (model) == plot_that_labeled_axis)) {
                model->num_elements = num_elements;
                model->implicit_index = (index_dim == NULL);
-               gog_axis_bound_changed (axis, GOG_OBJECT (model));
+               gog_axis_bound_changed (iaxis, GOG_OBJECT (model));
        } else {
                if (index_changed)
-                       gog_axis_bound_changed (axis, GOG_OBJECT (model));
+                       gog_axis_bound_changed (iaxis, GOG_OBJECT (model));
        }
 
        model->num_series = num_series;
@@ -257,8 +258,7 @@ gog_plot1_5d_update (GogObject *obj)
        }
 
        if (old_minima != model->minima || old_maxima != model->maxima)
-               gog_axis_bound_changed (
-                       gog_plot1_5d_get_value_axis (model), GOG_OBJECT (model));
+               gog_axis_bound_changed (vaxis, GOG_OBJECT (model));
 
        gog_object_emit_changed (GOG_OBJECT (obj), FALSE);
        if (plot1_5d_parent_klass->update)
@@ -266,11 +266,14 @@ gog_plot1_5d_update (GogObject *obj)
 }
 
 static GOData *
-gog_plot1_5d_axis_get_bounds (GogPlot *plot, GogAxisType axis,
+gog_plot1_5d_axis_get_bounds (GogPlot *plot, GogAxisType atype,
                              GogPlotBoundInfo *bounds)
 {
        GogPlot1_5d *model = GOG_PLOT1_5D (plot);
-       if (axis == gog_axis_get_atype (gog_plot1_5d_get_value_axis (model))) {
+       GogAxis *iaxis = gog_plot1_5d_get_index_axis (model);
+       GogAxis *vaxis = gog_plot1_5d_get_value_axis (model);
+
+       if (atype == gog_axis_get_atype (vaxis)) {
                bounds->val.minima = model->minima;
                bounds->val.maxima = model->maxima;
                if (model->type == GOG_1_5D_AS_PERCENTAGE) {
@@ -292,14 +295,15 @@ gog_plot1_5d_axis_get_bounds (GogPlot *plot, GogAxisType axis,
                 * value. See https://bugzilla.gnome.org/show_bug.cgi?id=663717.
                 * The check for num_dim is there because the requirement is less
                 * obvious for dropbars. */
-               if (plot->desc.series.num_dim == 4 && bounds->val.minima * bounds->val.maxima > 0) {
-                       if (bounds->val.minima > 0)
+               if (gog_axis_is_zero_important (vaxis) &&
+                   plot->desc.series.num_dim == 4) {
+                       if (bounds->val.minima > 0 && bounds->val.maxima > 0)
                                bounds->val.minima = 0;
-                       else
+                       else if (bounds->val.minima < 0 && bounds->val.maxima < 0)
                                bounds->val.maxima = 0.;
                }
                return NULL;
-       } else if (axis == gog_axis_get_atype (gog_plot1_5d_get_index_axis (model))) {
+       } else if (atype == gog_axis_get_atype (iaxis)) {
                GSList *ptr;
 
                bounds->val.minima = 1.;