add conversion between coordinates and cursor position

This is the core of the workspace, and will be used in functions such as
going up/down and every mouse event

docs/sphinx/source/api/class-work-space.rst

@@ -5,19 +5,28 @@
 
 .. class:: WorkSpace
 
-   A WorkSpace, to display and edit signed speech.
-		   
-   .. attribute:: sep(Vector2)
+A WorkSpace, to display and edit signed speech.
 
-	  The size of the horizontal and vertical separators between signs.
-	  This attribute is a script variable.
+  .. attribute:: sep(Vector2)
 
-   .. attribute:: text(signs Array)
-				  
-	  The signed speech, stored in one single array (like strings).
+     The size of the horizontal and vertical separators between signs.
+     This attribute is a script variable.
 
-	  .. todo:: Should be accessed through functions.
+  .. attribute:: text(signs Array)
+	       
+     The signed speech, stored in one single array (like strings).
 
-   .. function:: dispose_childs()
+     .. todo:: Should be accessed through functions.
 
-	  Draw all signs in the speech
+  .. method:: dispose_childs()
+
+     Draw all signs in the speech
+
+  .. method:: get_nearest_gap(pos)
+
+     get the gap between two signs which is the nearest from a position (usefull for aligning elements)
+
+     :param Vector2 pos: the position to query
+     :return: the index ``i`` of :attr:`text` such that the first element to the left of the gap is ``text[i]``. If
+	      ``i == len(text)``, the nearest gap is the end of the speech.
+     :rettype: int

editor/WorkSpace.gd

@@ -34,9 +34,45 @@ func dispose_childs():
 			
 		fit_child_in_rect(symb, Rect2(pos, symb_size))
 		pos.x += space.x
+
+
+# return true iff the nearest gap from position pos is before the sign sig
+# to be used in get_nearest_gap dichotomy
+func _is_before(pos, sig):
+	var sig_pos = sig.get_position()
+	var sig_size = sig.get_size()
+
+	# vertical (y) dichotomy
+	if pos.y < sig_pos.y - sep.y/2:
+		return true
+	if pos.y > sig_pos.y + sig_size.y + sep.y/2:
+		return false
+
+	# horizontal (x) dichotomy
+	if pos.x < sig_pos.x + sig_size.x / 2:
+		return true
+	return false
+	
+func get_nearest_gap(pos):
+	# simple dichotomy
+	var beg = -1
+	var end = len(text)
+	var mid = 0
+
+	# invariant: the gap is between text[beg] and text[end]
+	while end - beg > 1:
+		mid = (beg + end) / 2
+
+		if _is_before(pos, text[mid]):
+			end = mid
+		else:
+			beg = mid
+			
+	return end
+			
 		
-		
-func test(n):
+# testing the disposition of childs with a 
+func test_disposition(n):
 	var symb
 	
 	var pos_in_line
@@ -66,14 +102,34 @@ func test(n):
 						  line_number * (symb_size + sep).y)
 		real_pos = text[i].get_position()
 		if real_pos != est_pos:
-			print("Workspace Test Failure, pos should be: ", est_pos,
-				  "it is: ", real_pos)
+			push_error("Workspace Test Failure, pos should be: %s, it is %s"
+					   % [est_pos, real_pos])
+
+	# test nearest gap (random)
+
+	var bound = Rect2(- sep.x - symb_size.x/2, -sep.y/2,
+		   			  sep.x + symb_size.x, sep.y + symb_size.y)
+
+	var twid = Vector2(0,0)
+	var gap = 0
+	var pos = Vector2(0,0)
+	
+	for i in range(len(text)):
+		twid = Vector2(rand_range(bound.position.x, bound.end.x),
+					   rand_range(bound.position.y, bound.end.y))
+		pos = text[i].get_position() + twid
+		gap = get_nearest_gap(pos)
+		if gap != i:
+			push_error("Nearest Gap Error: should be %d, is %d, pos %f"
+					   % [i, gap, pos])
+		else:
+			print(twid)
 
 		   
 # Called when the node enters the scene tree for the first time.
 func _ready():
 	if DEBUG:
-		test(20)
+		test_disposition(20)
 # Called every frame. 'delta' is the elapsed time since the previous frame.
 #func _process(delta):
 #	pass