[gimp] app: round mouse-entered GimpSpinScale values to the spinbutton's precision

[Michael Natterer <mitch src gnome org>]

commit be80f49018d46a0a5fb2d7427a99cd54bd131d86
Author: Michael Natterer <mitch gimp org>
Date:   Thu Jun 19 15:49:27 2014 +0200

    app: round mouse-entered GimpSpinScale values to the spinbutton's precision
    
    So the adjustment's value is always what is shown (and can be entered
    manually) in the widget. This way a GimpSpinScale will never change
    its adjustment on focus-out, and not cause whatever unexpected updates
    of its model and whatever is connected to it (like changing the
    properties and thus unvalidating the caches of a Gegl graph).

 app/widgets/gimpspinscale.c |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)
---
diff --git a/app/widgets/gimpspinscale.c b/app/widgets/gimpspinscale.c
index b913821..25d3e5b 100644
--- a/app/widgets/gimpspinscale.c
+++ b/app/widgets/gimpspinscale.c
@@ -587,6 +587,7 @@ gimp_spin_scale_change_value (GtkWidget *widget,
   gdouble               upper;
   gint                  width;
   gdouble               value;
+  gint                  digits;
 
   gimp_spin_scale_get_limits (GIMP_SPIN_SCALE (widget), &lower, &upper);
 
@@ -620,6 +621,16 @@ gimp_spin_scale_change_value (GtkWidget *widget,
       value = fraction * (upper - lower) + lower;
     }
 
+  digits = gtk_spin_button_get_digits (spin_button);
+
+  /*  round the value to the possible precision of the spinbutton, so
+   *  a focus-out will not change the value again, causing inadvertend
+   *  adjustment signals.
+   */
+  value *= powl (10, digits);
+  value = RINT (value);
+  value /= powl (10, digits);
+
   gtk_adjustment_set_value (adjustment, value);
 }