[goffice] GOFormat: improve "General".

[Morten Welinder <mortenw src gnome org>]

commit 41272052a4c48f7beda034216a9f38e08569d9ad
Author: Morten Welinder <terra gnome org>
Date:   Mon Dec 30 22:13:49 2013 -0500

    GOFormat: improve "General".
    
    When we're not width-limited, make sure the value we render will
    round-trip.

 ChangeLog                 |    6 +++++
 NEWS                      |    1 +
 goffice/utils/go-format.c |   51 ++++++++++++++++++++++++++++++++------------
 3 files changed, 44 insertions(+), 14 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 55c4292..115551c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2013-12-30  Morten Welinder  <terra gnome org>
+
+       * goffice/utils/go-format.c (go_render_general): If we're not
+       width-limited, add an extra digit if we don't round-trip properly.
+       Fix dropping of ".00000".
+
 2013-12-23  Morten Welinder  <terra gnome org>
 
        * goffice/math/go-quad.c (go_quad_atan2_special): Do quarters too.
diff --git a/NEWS b/NEWS
index afd4ae2..6b3caee 100644
--- a/NEWS
+++ b/NEWS
@@ -11,6 +11,7 @@ Morten:
        * Add quad precision atan2, sin, sinpi, asin, cos, cospi, acos
          functions.
        * Add go_sinpi, go_cospi, go_tanpi, go_atan2pi.
+       * Improve "General" format.
 
 --------------------------------------------------------------------------
 goffice 0.10.9:
diff --git a/goffice/utils/go-format.c b/goffice/utils/go-format.c
index a116da4..cba3b7a 100644
--- a/goffice/utils/go-format.c
+++ b/goffice/utils/go-format.c
@@ -4676,6 +4676,23 @@ go_format_measure_strlen (const GString *str,
        }                                                               \
        } while (0)
 
+#ifdef DEFINE_COMMON
+static void
+drop_zeroes (GString *str, int *prec)
+{
+       while (str->str[str->len - 1] == '0') {
+               g_string_truncate (str, str->len - 1);
+               (*prec)--;
+       }
+       if (*prec == 0) {
+               /* We got "xxxxxx.000" and dropped the zeroes.  */
+               const char *dot = g_utf8_prev_char (str->str + str->len);
+               g_string_truncate (str, dot - str->str);
+       }
+}
+#endif
+
+
 /**
  * go_render_general:
  * @layout: Optional PangoLayout, probably preseeded with font attribute.
@@ -4721,11 +4738,12 @@ SUFFIX(go_render_general) (PangoLayout *layout, GString *str,
                           guint shape_flags)
 {
        DOUBLE aval, l10;
-       int prec, safety, digs, maxdigits;
+       int prec, safety, digs, maxdigits = PREFIX(DIG);
        size_t epos;
        gboolean rounds_to_0;
        int sign_width;
        int min_digit_width = metrics->min_digit_width;
+       gboolean check_val = TRUE;
 
        if (num_shape > 0) {
                /* FIXME: We should adjust min_digit_width if num_shape != 0 */
@@ -4733,11 +4751,15 @@ SUFFIX(go_render_general) (PangoLayout *layout, GString *str,
 
        if (col_width == -1) {
                measure = go_format_measure_zero;
-               maxdigits = PREFIX(DIG);
                col_width = INT_MAX;
                sign_width = 0;
        } else {
-               maxdigits = MIN (PREFIX(DIG), col_width / min_digit_width);
+               int w = col_width / min_digit_width;
+               if (w <= maxdigits) {
+                       /* We're limited by width.  */
+                       maxdigits = w;
+                       check_val = FALSE;
+               }
                sign_width = unicode_minus
                        ? metrics->minus_width
                        : metrics->hyphen_width;
@@ -4798,19 +4820,19 @@ SUFFIX(go_render_general) (PangoLayout *layout, GString *str,
 
        prec = maxdigits - digs;
        g_string_printf (str, "%.*" FORMAT_f, prec, val);
+       if (check_val) {
+               /*
+                * We're not width-limited; we may have to increase maxdigits
+                * by one.  This is a terribly wasteful way of doing this.
+                */
+               if (val != STRTO(str->str, NULL)) {
+                       maxdigits++, prec++;
+                       g_string_printf (str, "%.*" FORMAT_f, prec, val);
+               }
+       }
        HANDLE_NUMERAL_SHAPE;
        HANDLE_SIGN (0);
-       while (str->str[str->len - 1] == '0') {
-               g_string_truncate (str, str->len - 1);
-               prec--;
-       }
-       if (prec == 0) {
-               /* We got "xxxxxx.000" and dropped the zeroes.  */
-               const char *dot = g_utf8_prev_char (str->str + str->len);
-               g_string_truncate (str, dot - str->str);
-               SETUP_LAYOUT;
-               return;
-       }
+       drop_zeroes (str, &prec);
 
        while (prec > 0) {
                int w;
@@ -4822,6 +4844,7 @@ SUFFIX(go_render_general) (PangoLayout *layout, GString *str,
 
                prec--;
                g_string_printf (str, "%.*" FORMAT_f, prec, val);
+               drop_zeroes (str, &prec);
                HANDLE_NUMERAL_SHAPE;
                HANDLE_SIGN (0);
        }