mixer left/right: snap to track

diff --git a/gtk2_ardour/mixer_ui.cc b/gtk2_ardour/mixer_ui.cc
index 4c5317a389e3fe833691af1c0b14dd249b9489fd..978e6500e25931ae06afadd66daab06bc0df83b7 100644 (file)
--- a/gtk2_ardour/mixer_ui.cc
+++ b/gtk2_ardour/mixer_ui.cc
@@ -2044,8 +2044,23 @@ Mixer_UI::scroll_left ()
 {
        if (!scroller.get_hscrollbar()) return;
        Adjustment* adj = scroller.get_hscrollbar()->get_adjustment();
-       /* stupid GTK: can't rely on clamping across versions */
-       scroller.get_hscrollbar()->set_value (max (adj->get_lower(), adj->get_value() - adj->get_step_increment()));
+       int sc_w = scroller.get_width();
+       int sp_w = strip_packer.get_width();
+       if (sp_w <= sc_w) {
+               return;
+       }
+       int lp = adj->get_value();
+       int lm = 0;
+       using namespace Gtk::Box_Helpers;
+       const BoxList& strips = strip_packer.children();
+       for (BoxList::const_iterator i = strips.begin(); i != strips.end(); ++i) {
+               lm += i->get_widget()->get_width ();
+               if (lm >= lp) {
+                       lm -= i->get_widget()->get_width ();
+                       break;
+               }
+       }
+       scroller.get_hscrollbar()->set_value (max (adj->get_lower(), min (adj->get_upper(), lm - 1.0)));
 }
 
 void
@@ -2053,8 +2068,22 @@ Mixer_UI::scroll_right ()
 {
        if (!scroller.get_hscrollbar()) return;
        Adjustment* adj = scroller.get_hscrollbar()->get_adjustment();
-       /* stupid GTK: can't rely on clamping across versions */
-       scroller.get_hscrollbar()->set_value (min (adj->get_upper(), adj->get_value() + adj->get_step_increment()));
+       int sc_w = scroller.get_width();
+       int sp_w = strip_packer.get_width();
+       if (sp_w <= sc_w) {
+               return;
+       }
+       int lp = adj->get_value();
+       int lm = 0;
+       using namespace Gtk::Box_Helpers;
+       const BoxList& strips = strip_packer.children();
+       for (BoxList::const_iterator i = strips.begin(); i != strips.end(); ++i) {
+               lm += i->get_widget()->get_width ();
+               if (lm > lp + 1) {
+                       break;
+               }
+       }
+       scroller.get_hscrollbar()->set_value (max (adj->get_lower(), min (adj->get_upper(), lm - 1.0)));
 }
 
 bool