[goffice] Add a display factor to scale axis ticks labels. [#748295]

[Jean Bréfort <jbrefort src gnome org>]

commit 0ff99d37d1bce01c0a9caa2d8d59c0304513ce5b
Author: Jean Brefort <jean brefort normalesup org>
Date:   Mon May 4 15:59:35 2015 +0200

    Add a display factor to scale axis ticks labels. [#748295]

 ChangeLog                |    7 +++++++
 goffice/graph/gog-axis.c |   19 +++++++++++++++++--
 2 files changed, 24 insertions(+), 2 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index bf4f9df..6764cf3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2015-05-04  Jean Brefort  <jean brefort normalesup org>
+
+       * goffice/graph/gog-axis.c (axis_format_value),
+       (gog_axis_set_property), (gog_axis_get_property),
+       (gog_axis_class_init), (gog_axis_init): add a display factor to scale
+       axis ticks labels. [#748295]
+
 2015-04-28  Jean Brefort  <jean brefort normalesup org>
 
        * goffice/utils/go-image.c (go_image_type_for_format): disable metafiles
diff --git a/goffice/graph/gog-axis.c b/goffice/graph/gog-axis.c
index 4ad2993..260a7d6 100644
--- a/goffice/graph/gog-axis.c
+++ b/goffice/graph/gog-axis.c
@@ -182,6 +182,7 @@ struct _GogAxis {
        GSList *refering_axes;
        double metrics_ratio;
        GoUnitId unit;
+       double display_factor;
 };
 
 /*****************************************************************************/
@@ -278,7 +279,7 @@ axis_format_value (GogAxis *axis, double val, GOString **str)
                 go_format_measure_strlen,
                 go_font_metrics_unit,
                 fmt,
-                val, 'F', NULL, NULL,
+                val / axis->display_factor, 'F', NULL, NULL,
                 -1, date_conv, TRUE);
        if (err)
                *str = go_string_new ("#####");
@@ -2152,7 +2153,8 @@ enum {
        AXIS_PROP_METRICS,
        AXIS_PROP_REF_AXIS,
        AXIS_PROP_METRICS_RATIO,
-       AXIS_PROP_METRICS_UNIT
+       AXIS_PROP_METRICS_UNIT,
+       AXIS_PROP_DISPLAY_FACTOR
 };
 
 /*****************************************************************************/
@@ -2458,6 +2460,9 @@ gog_axis_set_property (GObject *obj, guint param_id,
        case AXIS_PROP_METRICS_UNIT:
                axis->unit = (strcmp (g_value_get_string (value), "in"))? GO_UNIT_CENTIMETER: GO_UNIT_INCH;
                break;
+       case AXIS_PROP_DISPLAY_FACTOR:
+               axis->display_factor = g_value_get_double (value);
+               break;
 
        default: G_OBJECT_WARN_INVALID_PROPERTY_ID (obj, param_id, pspec);
                 return; /* NOTE : RETURN */
@@ -2525,6 +2530,9 @@ gog_axis_get_property (GObject *obj, guint param_id,
        case AXIS_PROP_METRICS_UNIT:
                g_value_set_string (value, (axis->unit == GO_UNIT_INCH)? "in": "cm");
                break;
+       case AXIS_PROP_DISPLAY_FACTOR:
+               g_value_set_double (value, axis->display_factor);
+               break;
 
        default: G_OBJECT_WARN_INVALID_PROPERTY_ID (obj, param_id, pspec);
                 break;
@@ -3520,6 +3528,12 @@ gog_axis_class_init (GObjectClass *gobject_klass)
                        _("The unit symbol for the absolute distance unit between ticks. Might be \"cm\" or 
\"in\""),
                        "cm",
                        GSF_PARAM_STATIC | G_PARAM_READWRITE | GO_PARAM_PERSISTENT));
+       g_object_class_install_property (gobject_klass, AXIS_PROP_DISPLAY_FACTOR,
+               g_param_spec_double ("display-factor",
+                       _("Display factor"),
+                       _("Real values are the displayed ones multipled by the display factor."),
+                   G_MINDOUBLE, G_MAXDOUBLE, 1.,
+                       GSF_PARAM_STATIC | G_PARAM_READWRITE | GO_PARAM_PERSISTENT));
 
        gog_object_register_roles (gog_klass, roles, G_N_ELEMENTS (roles));
 
@@ -3560,6 +3574,7 @@ gog_axis_init (GogAxis *axis)
        axis->auto_color_map = TRUE;
        axis->metrics_ratio = 1.;
        axis->unit = GO_UNIT_CENTIMETER;
+       axis->display_factor = 1.;
 }
 
 static void