Patch from jdavisp3 to further improve region gain line behaviour, as discussed in...

git-svn-id: svn://localhost/ardour2/trunk@2599 d708f5d6-7413-0410-9779-e7cbd77b26cf

diff --git a/gtk2_ardour/editor_mouse.cc b/gtk2_ardour/editor_mouse.cc
index ad4dfad009ff77197af57ecb04e688c9d53e7d4b..dc961f51ea0f889af7d118095131a0e79207678c 100644 (file)
--- a/gtk2_ardour/editor_mouse.cc
+++ b/gtk2_ardour/editor_mouse.cc
@@ -74,6 +74,8 @@ using namespace sigc;
 using namespace Gtk;
 using namespace Editing;
 
+const static double ZERO_GAIN_FRACTION = gain_to_slider_position(dB_to_coefficient(0.0));
+
 nframes_t
 Editor::event_frame (GdkEvent* event, double* pcx, double* pcy)
 {
@@ -2599,6 +2601,16 @@ Editor::start_control_point_grab (ArdourCanvas::Item* item, GdkEvent* event)
 
        start_grab (event, fader_cursor);
 
+       // start the grab at the center of the control point so
+       // the point doesn't 'jump' to the mouse after the first drag
+       drag_info.grab_x = control_point->get_x();
+       drag_info.grab_y = control_point->get_y();
+       control_point->line().parent_group().i2w(drag_info.grab_x, drag_info.grab_y);
+       track_canvas.w2c(drag_info.grab_x, drag_info.grab_y,
+                                                                        drag_info.grab_x, drag_info.grab_y);
+
+       drag_info.grab_frame = pixel_to_frame(drag_info.grab_x);
+
        control_point->line().start_drag (control_point, drag_info.grab_frame, 0);
 
        double fraction = 1.0 - ((control_point->get_y() - control_point->line().y_position()) / (double)control_point->line().height());
@@ -2624,6 +2636,18 @@ Editor::control_point_drag_motion_callback (ArdourCanvas::Item* item, GdkEvent*
        double cx = drag_info.grab_x + drag_info.cumulative_x_drag + dx;
        double cy = drag_info.grab_y + drag_info.cumulative_y_drag + dy;
 
+       // calculate zero crossing point. back off by .01 to stay on the
+       // positive side of zero
+       double _unused = 0;
+       double zero_gain_y = (1.0 - ZERO_GAIN_FRACTION) * cp->line().height() - .01;
+       cp->line().parent_group().i2w(_unused, zero_gain_y);
+
+       // make sure we hit zero when passing through
+       if ((cy < zero_gain_y and (cy - dy) > zero_gain_y)
+                       or (cy > zero_gain_y and (cy - dy) < zero_gain_y)) {
+               cy = zero_gain_y;
+       }
+
        if (drag_info.x_constrained) {
                cx = drag_info.grab_x;
        }
@@ -2761,6 +2785,18 @@ Editor::line_drag_motion_callback (ArdourCanvas::Item* item, GdkEvent* event)
        double cx = drag_info.current_pointer_x;
        double cy = drag_info.grab_y + drag_info.cumulative_y_drag + dy;
 
+       // calculate zero crossing point. back off by .01 to stay on the
+       // positive side of zero
+       double _unused = 0;
+       double zero_gain_y = (1.0 - ZERO_GAIN_FRACTION) * line->height() - .01;
+       line->parent_group().i2w(_unused, zero_gain_y);
+
+       // make sure we hit zero when passing through
+       if ((cy < zero_gain_y and (cy - dy) > zero_gain_y)
+                       or (cy > zero_gain_y and (cy - dy) < zero_gain_y)) {
+               cy = zero_gain_y;
+       }
+
        drag_info.cumulative_y_drag = cy - drag_info.grab_y;
 
        line->parent_group().w2i (cx, cy);