[gnumeric] Edit: improve percentage editing.

[Morten Welinder <mortenw src gnome org>]

commit 7e62980ae0016db9972dba527439cc5ff1a46a8b
Author: Morten Welinder <terra gnome org>
Date:   Thu Oct 31 18:51:27 2019 -0400

    Edit: improve percentage editing.
    
    This improves the previous fix for percentage editing.  We render potentially
    twice, although most sane values will only need one rendering.

 src/cell.c | 30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)
---
diff --git a/src/cell.c b/src/cell.c
index 4dd1e783c..fb24ef24a 100644
--- a/src/cell.c
+++ b/src/cell.c
@@ -804,6 +804,28 @@ guess_time_format (const char *prefix, gnm_float f)
        return fmt;
 }
 
+static void
+render_percentage (GString *str, gnm_float f)
+{
+       gnm_float f100 = 100 * f;
+       gboolean qneg = (f < 0);
+       gnm_float f2;
+
+       // Render slightly narrow
+       gnm_render_general (NULL, str, go_format_measure_strlen,
+                           go_font_metrics_unit, f100,
+                           12 + qneg, FALSE, 0, 0);
+       // Explicit cast to drop excess precision
+       f2 = (gnm_float)(gnm_strto (str->str, NULL) / 100);
+       if (f2 == f)
+               return;
+
+       // No good -- rerender unconstrained.
+       gnm_render_general (NULL, str, go_format_measure_zero,
+                           go_font_metrics_unit, f100,
+                           -1, FALSE, 0, 0);
+}
+
 /**
  * gnm_cell_get_text_for_editing:
  * @cell: the cell from which we want to pull the content from
@@ -845,13 +867,7 @@ gnm_cell_get_text_for_editing (GnmCell const * cell,
 
                case GO_FORMAT_PERCENTAGE: {
                        GString *new_str = g_string_new (NULL);
-                       gnm_float f100 = 100 * f;
-                       gboolean qsimple = (gnm_abs (f) < 100 && close_to_int (f100, 1e-6));
-                       gboolean qneg = (f < 0);
-                       gnm_render_general (NULL, new_str, go_format_measure_strlen,
-                                           go_font_metrics_unit, f100,
-                                           qsimple ? 12 + qneg: -1,
-                                           FALSE, 0, 0);
+                       render_percentage (new_str, f);
                        if (cursor_pos)
                                *cursor_pos = g_utf8_strlen (new_str->str, -1);
                        g_string_append_c (new_str, '%');