Improve the algorithm for determining the number of tick marks to put between pairs...

[synfig.git] / synfig-studio / trunk / src / gtkmm / widget_timeslider.cpp

diff --git a/synfig-studio/trunk/src/gtkmm/widget_timeslider.cpp b/synfig-studio/trunk/src/gtkmm/widget_timeslider.cpp
index e15e2e7..f46b0c8 100644 (file)
--- a/synfig-studio/trunk/src/gtkmm/widget_timeslider.cpp
+++ b/synfig-studio/trunk/src/gtkmm/widget_timeslider.cpp
@@ -505,12 +505,29 @@ bool Widget_Timeslider::redraw(bool /*doublebuffer*/)
                iter = next;
 
        scale = *iter;
-       if (iter != ranges.begin()) iter--;
-       if (iter != ranges.begin()) iter--;
-       if (iter != ranges.begin()) iter--;
 
        // subdivide into this many tick marks (8 or less)
-       const int subdiv = round_to_int(scale / *iter);
+       int subdiv = round_to_int(scale * ifps);
+
+       if (subdiv > 8)
+       {
+               const int ideal = subdiv;
+
+               // find a number of tick marks that nicely divides the scale
+               // (5 minutes divided by 6 is 50s, but that's not 'nice' -
+               //  5 ticks of 1m each is much simpler than 6 ticks of 50s)
+               for (subdiv = 8; subdiv > 0; subdiv--)
+                       if ((ideal <= ifps*2       && (ideal % (subdiv           )) == 0) ||
+                               (ideal <= ifps*2*60    && (ideal % (subdiv*ifps      )) == 0) ||
+                               (ideal <= ifps*2*60*60 && (ideal % (subdiv*ifps*60   )) == 0) ||
+                               (true                  && (ideal % (subdiv*ifps*60*60)) == 0))
+                               break;
+
+               // if we didn't find anything, use 4 ticks
+               if (!subdiv)
+                       subdiv = 4;
+       }
+
        time_per_tickmark = scale / subdiv;
 
        //get first valid line and its position in pixel space