Increase threshold for zoom-by-horizontal movement;

ignore movements to y positions outside the scroomer;
round page size and value to prevent 'quivering' during
drags.  Should fix #4299.

git-svn-id: svn://localhost/ardour2/branches/3.0@10063 d708f5d6-7413-0410-9779-e7cbd77b26cf

diff --git a/libs/gtkmm2ext/scroomer.cc b/libs/gtkmm2ext/scroomer.cc
index 85092379f495b79f728bffb22c98a65f6135fd70..dcef6eae334b229f8e83b8f896293e3dca7d5186 100644 (file)
--- a/libs/gtkmm2ext/scroomer.cc
+++ b/libs/gtkmm2ext/scroomer.cc
@@ -74,6 +74,10 @@ Scroomer::on_motion_notify_event (GdkEventMotion* ev)
                return true;
        }
 
+       if (ev->y < 0 || ev->y > get_height ()) {
+               return true;
+       }
+
        grab_y = ev->y;
 
        if (ev->state & Keyboard::PrimaryModifier) {
@@ -138,10 +142,11 @@ Scroomer::on_motion_notify_event (GdkEventMotion* ev)
 
        /* Then we handle zoom, which is dragging horizontally. We zoom around the area that is
         * the current y pointer value, not from the area that was the start of the drag.
-        * the point of zoom must have the same 
+        * We don't start doing zoom until we are at least one scroomer width outside the scroomer's
+        * area.
         */
        
-       if (ev->x > get_width()) {
+       if (ev->x > (get_width() * 2)) {
                zoom = ev->x - get_width();
                
                double higher = unzoomed_val + unzoomed_page - half_min_page - val_at_pointer;
@@ -194,9 +199,10 @@ Scroomer::on_motion_notify_event (GdkEventMotion* ev)
                val = unzoomed_val;
                page = unzoomed_page;
        }
-       
-       adj.set_page_size(page);
-       adj.set_value(val);
+
+       /* Round these values to stop the scroomer handlers quivering about during drags */
+       adj.set_page_size (rint (page));
+       adj.set_value (rint (val));
        adj.value_changed();
        
        return true;