Resolve potential ambiguity between the constraint modifier and the copy modifier when beginning a drag.

gtk2_ardour/editor_drag.cc

@@ -237,6 +237,7 @@ Drag::Drag (Editor* e, ArdourCanvas::Item* i, bool trackview_only)
 	, _grab_frame (0)
 	, _last_pointer_frame (0)
 	, _snap_delta (0)
+	, _constraint_pressed (false)
 {
 
 }
@@ -261,6 +262,7 @@ Drag::start_grab (GdkEvent* event, Gdk::Cursor *cursor)
 {
 
 	/* we set up x/y dragging constraints on first move */
+	_constraint_pressed = ArdourKeyboard::indicates_constraint (event->button.state);
 
 	_raw_grab_frame = _editor->canvas_event_sample (event, &_grab_x, &_grab_y);
 
@@ -420,14 +422,14 @@ Drag::motion_handler (GdkEvent* event, bool from_autoscroll)
 				if (Config->get_edit_mode() != Lock) {
 					if (event->motion.state & Gdk::BUTTON2_MASK) {
 						// if dragging with button2, the motion is x constrained, with constraint modifier it is y constrained
-						if (Keyboard::modifier_state_equals (event->button.state, ArdourKeyboard::constraint_modifier ())) {
+						if (_constraint_pressed) {
 							_x_constrained = false;
 							_y_constrained = true;
 						} else {
 							_x_constrained = true;
 							_y_constrained = false;
 						}
-					} else if (Keyboard::modifier_state_equals (event->button.state, ArdourKeyboard::constraint_modifier ())) {
+					} else if (_constraint_pressed) {
 						// if dragging normally, the motion is constrained to the first direction of movement.
 						if (_initially_vertical) {
 							_x_constrained = true;
@@ -3343,7 +3345,7 @@ TempoMarkerDrag::motion (GdkEvent* event, bool first_move)
 
 	}
 
-	if (Keyboard::modifier_state_contains (event->button.state, ArdourKeyboard::constraint_modifier ())) {
+	if (ArdourKeyboard::indicates_constraint (event->button.state)) {
 		/* use vertical movement to alter tempo .. should be log */
 		double new_bpm = _real_section->beats_per_minute() + ((last_pointer_y() - current_pointer_y()) / 5.0);
 		stringstream strs;
@@ -3469,7 +3471,7 @@ BBTRulerDrag::motion (GdkEvent* event, bool first_move)
 		pf = adjusted_current_frame (event);
 	}
 
-	if (Keyboard::modifier_state_contains (event->button.state, ArdourKeyboard::constraint_modifier())) {
+	if (ArdourKeyboard::indicates_constraint (event->button.state)) {
 		/* adjust previous tempo to match pointer frame */
 		_editor->session()->tempo_map().gui_dilate_tempo (_tempo, map.frame_at_pulse (_pulse), pf, _pulse);
 	}

gtk2_ardour/editor_drag.h

@@ -282,6 +282,7 @@ private:
 	 */
 	ARDOUR::frameoffset_t _snap_delta;
 	CursorContext::Handle _cursor_ctx; ///< cursor change context
+	bool _constraint_pressed; ///< if the keyboard indicated constraint modifier was pressed on start_grab()
 };
 
 class RegionDrag;

gtk2_ardour/editor_mouse.cc

@@ -684,7 +684,7 @@ Editor::button_press_handler_1 (ArdourCanvas::Item* item, GdkEvent* event, ItemT
 			new TempoMarkerDrag (
 				this,
 				item,
-				Keyboard::modifier_state_equals (event->button.state, Keyboard::CopyModifier)
+				ArdourKeyboard::indicates_copy (event->button.state)
 				),
 			event
 			);
@@ -697,7 +697,7 @@ Editor::button_press_handler_1 (ArdourCanvas::Item* item, GdkEvent* event, ItemT
 			new MeterMarkerDrag (
 				this,
 				item,
-				Keyboard::modifier_state_equals (event->button.state, Keyboard::CopyModifier)
+				ArdourKeyboard::indicates_copy (event->button.state)
 				),
 			event
 			);
@@ -718,9 +718,9 @@ Editor::button_press_handler_1 (ArdourCanvas::Item* item, GdkEvent* event, ItemT
 	case MinsecRulerItem:
 	case BBTRulerItem:
 		if (!Keyboard::modifier_state_equals (event->button.state, Keyboard::PrimaryModifier)
-			&& !Keyboard::modifier_state_contains (event->button.state, ArdourKeyboard::constraint_modifier())) {
+			&& !ArdourKeyboard::indicates_constraint (event->button.state)) {
 			_drags->set (new CursorDrag (this, *playhead_cursor, false), event);
-		} else if (Keyboard::modifier_state_contains (event->button.state, ArdourKeyboard::constraint_modifier())) {
+		} else if (ArdourKeyboard::indicates_constraint (event->button.state)) {
 			_drags->set (new BBTRulerDrag (this, item), event);
 		}
 		return true;
@@ -963,7 +963,7 @@ Editor::button_press_handler_1 (ArdourCanvas::Item* item, GdkEvent* event, ItemT
 				}
 
 				/* click on a normal region view */
-				if (Keyboard::modifier_state_contains (event->button.state, Keyboard::CopyModifier)) {
+				if (ArdourKeyboard::indicates_copy (event->button.state)) {
 					add_region_copy_drag (item, event, clicked_regionview);
 				} else if (Keyboard::the_keyboard().key_is_down (GDK_b)) {
 					add_region_brush_drag (item, event, clicked_regionview);
@@ -1164,7 +1164,7 @@ Editor::button_press_handler_2 (ArdourCanvas::Item* item, GdkEvent* event, ItemT
 	case MouseObject:
 		switch (item_type) {
 		case RegionItem:
-			if (Keyboard::modifier_state_contains (event->button.state, Keyboard::CopyModifier)) {
+			if (ArdourKeyboard::indicates_copy (event->button.state)) {
 				add_region_copy_drag (item, event, clicked_regionview);
 			} else {
 				add_region_drag (item, event, clicked_regionview);

gtk2_ardour/keyboard.cc

@@ -300,6 +300,25 @@ ArdourKeyboard::indicates_snap_delta (guint state)
 	return (contains_d && ((contains_s && d_contains_s) || !contains_s));
 }
 
+/* Constraint and copy modifiers are both in effect at the beginning of some drags, and may be set ambiguously */
+bool
+ArdourKeyboard::indicates_copy (guint state)
+{
+	const bool contains_c = Keyboard::modifier_state_contains (state, Keyboard::CopyModifier);
+	const bool equals_cs = Keyboard::modifier_state_equals (state, constraint_modifier ());
+
+	return  contains_c && !equals_cs;
+}
+
+bool
+ArdourKeyboard::indicates_constraint (guint state)
+{
+	const bool contains_cs = Keyboard::modifier_state_contains (state, constraint_modifier ());
+	const bool equals_c = Keyboard::modifier_state_equals (state, Keyboard::CopyModifier);
+
+	return contains_cs && !equals_c;
+}
+
 void
 ArdourKeyboard::set_constraint_modifier (guint mod)
 {

gtk2_ardour/keyboard.h

@@ -56,6 +56,16 @@ class ArdourKeyboard : public Gtkmm2ext::Keyboard
 	 */
 	static bool indicates_snap_delta (guint state);
 
+	/** @param state The button state from a GdkEvent.
+	 *  @return true if the modifier state indicates copy modifier
+	 */
+	static bool indicates_copy (guint state);
+
+	/** @param state The button state from a GdkEvent.
+	 *  @return true if the modifier state indicates constraint modifier
+	 */
+	static bool indicates_constraint (guint state);
+
 	static void set_constraint_modifier (guint);
 	/** @return Modifier mask to constrain drags in a particular direction;
 	 */