Patch from jdavisp3 to fix bug #1841.

git-svn-id: svn://localhost/ardour2/trunk@2590 d708f5d6-7413-0410-9779-e7cbd77b26cf

1 files changed, 32 insertions, 6 deletions

diff --git a/gtk2_ardour/editor_mouse.cc b/gtk2_ardour/editor_mouse.cc
index 0827fc5321..ad4dfad009 100644
--- a/gtk2_ardour/editor_mouse.cc
+++ b/gtk2_ardour/editor_mouse.cc
@@ -1500,6 +1500,8 @@ Editor::motion_handler (ArdourCanvas::Item* item, GdkEvent* event, ItemType item
 	}
 
 	drag_info.item_type = item_type;
+	drag_info.last_pointer_x = drag_info.current_pointer_x;
+	drag_info.last_pointer_y = drag_info.current_pointer_y;
 	drag_info.current_pointer_frame = event_frame (event, &drag_info.current_pointer_x,
 						       &drag_info.current_pointer_y);
 
@@ -1685,6 +1687,8 @@ Editor::start_grab (GdkEvent* event, Gdk::Cursor *cursor)
 	drag_info.current_pointer_frame = drag_info.grab_frame;
 	drag_info.current_pointer_x = drag_info.grab_x;
 	drag_info.current_pointer_y = drag_info.grab_y;
+	drag_info.last_pointer_x = drag_info.current_pointer_x;
+	drag_info.last_pointer_y = drag_info.current_pointer_y;
 	drag_info.cumulative_x_drag = 0;
 	drag_info.cumulative_y_drag = 0;
 	drag_info.first_move = true;
@@ -1743,6 +1747,8 @@ Editor::end_grab (ArdourCanvas::Item* item, GdkEvent* event)
 	drag_info.item->ungrab (event->button.time);
 
 	if (drag_info.finished_callback) {
+		drag_info.last_pointer_x = drag_info.current_pointer_x;
+		drag_info.last_pointer_y = drag_info.current_pointer_y;
 		(this->*(drag_info.finished_callback)) (item, event);
 	}
 
@@ -2607,11 +2613,16 @@ Editor::control_point_drag_motion_callback (ArdourCanvas::Item* item, GdkEvent*
 {
 	ControlPoint* cp = reinterpret_cast<ControlPoint *> (drag_info.data);
 
-	double cx = drag_info.current_pointer_x;
-	double cy = drag_info.current_pointer_y;
+	double dx = drag_info.current_pointer_x - drag_info.last_pointer_x;
+	double dy = drag_info.current_pointer_y - drag_info.last_pointer_y;
+
+	if (event->button.state & Keyboard::Alt) {
+		dx *= 0.1;
+		dy *= 0.1;
+	}
 
-	drag_info.cumulative_x_drag = cx - drag_info.grab_x ;
-	drag_info.cumulative_y_drag = cy - drag_info.grab_y ;
+	double cx = drag_info.grab_x + drag_info.cumulative_x_drag + dx;
+	double cy = drag_info.grab_y + drag_info.cumulative_y_drag + dy;
 
 	if (drag_info.x_constrained) {
 		cx = drag_info.grab_x;
@@ -2620,6 +2631,9 @@ Editor::control_point_drag_motion_callback (ArdourCanvas::Item* item, GdkEvent*
 		cy = drag_info.grab_y;
 	}
 
+	drag_info.cumulative_x_drag = cx - drag_info.grab_x;
+	drag_info.cumulative_y_drag = cy - drag_info.grab_y;
+
 	cp->line().parent_group().w2i (cx, cy);
 
 	cx = max (0.0, cx);
@@ -2737,11 +2751,23 @@ void
 Editor::line_drag_motion_callback (ArdourCanvas::Item* item, GdkEvent* event)
 {
 	AutomationLine* line = reinterpret_cast<AutomationLine *> (drag_info.data);
+
+	double dy = drag_info.current_pointer_y - drag_info.last_pointer_y;
+
+	if (event->button.state & Keyboard::Alt) {
+		dy *= 0.1;
+	}
+
 	double cx = drag_info.current_pointer_x;
-	double cy = drag_info.current_pointer_y;
+	double cy = drag_info.grab_y + drag_info.cumulative_y_drag + dy;
+
+	drag_info.cumulative_y_drag = cy - drag_info.grab_y;
 
 	line->parent_group().w2i (cx, cy);
-	
+
+	cy = max (0.0, cy);
+	cy = min ((double) line->height(), cy);
+
 	const double fraction = 1.0 - ((cy - line->y_position()) / (double)line->height());
 
 	bool push;