+/* Increment the size of every unit by INC.
+ Note that INC is signed. So if INC is negative,
+ then size will end up smaller.
+*/
+static void
+axis_increment (PsppireAxis *axis, gint inc)
+{
+ struct tower_node *n = tower_first (&axis->pixel_tower);
+
+ while (n)
+ {
+ struct axis_node *an = tower_data (n, struct axis_node, pixel_node);
+ struct tower_node *pn = &an->pixel_node;
+ const gint existing_size = tower_node_get_size (pn);
+
+ tower_resize (&axis->pixel_tower, pn, existing_size + inc *
+ tower_node_get_size (&an->unit_node));
+
+ n = tower_next (&axis->pixel_tower, n);
+ }
+}
+
+