--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/engine/extensions/pychan/autoposition.py	Sat Mar 14 12:13:29 2009 +0000
@@ -0,0 +1,121 @@
+# coding: utf-8
+
+"""
+Automatic widget positioning
+============================
+
+You can use the C{position_techinque} attribute
+on top level widgets which can also be set from xml.
+
+For direct use call L{placeWidget}.
+"""
+
+from internal import screen_width, screen_height
+from exceptions import PyChanException
+
+EXPLICIT = "explicit"
+AUTOMATIC = "automatic"
+
+TOP = "top"
+LEFT = "left"
+RIGHT = "right"
+CENTER = "center"
+BOTTOM = "bottom"
+
+
+def _splicePosition(p):
+	if "+" in p:
+		technique,delta = p.split("+")
+	elif "-" in p:
+		technique,delta = p.split("-")
+		delta = '-' + delta
+	else:
+		technique,delta = p,0
+	delta = int(delta)
+	return technique,delta
+
+def _parsePosition(position):
+	try:
+		if position == AUTOMATIC:
+			position = "center+0:center+0"
+
+		x_pos,y_pos = position.split(":")
+		x_pos, x_delta = _splicePosition(x_pos)
+		y_pos, y_delta = _splicePosition(y_pos)
+
+		if x_pos not in [EXPLICIT,LEFT,CENTER,RIGHT]:
+			raise 
+		if y_pos not in [EXPLICIT,TOP,CENTER,BOTTOM]:
+			raise
+	except:
+		raise PyChanException("Malformed position definition: " + repr(position))
+	return x_pos,x_delta,y_pos,y_delta
+
+def placeWidget(widget,position):
+	"""
+	Place a widget according to a string defining relative coordinates to screen borders.
+
+	The position definition has to be of the form: C{"<x_pos><x_delta>:<y_pos><y_delta>"}
+
+	C{<x_pos>} may be one of:
+          - left
+          - right
+          - center
+          - explicit
+
+	C{<y_pos>} may be one of:
+          - top
+          - bottom
+          - center
+          - explicit
+
+        C{explicit} means that the widgets x or y position will not be touched. The rest should be
+        self explanatory.
+
+	C{<x_delta>} and C{<y_delta>} must be of the form: +pixel_number or -pixel_number. Or comletely
+        omitted. Note that the sign has to be there for for positive deltas, too.
+
+	For brevity two shortcuts exist:
+          - "explict" -> "explict:explict"
+          - "automatic" -> "center:center"
+        
+	A few examples::
+          "right-20:top"
+          "center:top+10"
+          "center:center"
+
+	@param widget: The PyChan widget.
+	@param position: A position definition.
+
+	If the position cannot be parsed a L{PyChanException} is thrown.
+
+	"""
+	if position == EXPLICIT:
+		return
+	x_pos,x_delta,y_pos,y_delta = _parsePosition(position)
+
+	x,y = widget.position
+	w,h = widget.size
+
+	if x_pos == CENTER:
+		x = (screen_width()-w)/2 + x_delta
+
+	if y_pos == CENTER:
+		y = (screen_height()-h)/2 + y_delta
+
+	if x_pos == LEFT:
+		x = x_delta
+
+	if y_pos == TOP:
+		y = y_delta
+
+	if x_pos == RIGHT:
+		x = screen_width() - w + x_delta
+
+	if y_pos == BOTTOM:
+		y = screen_height() - h + y_delta
+
+	widget.position = x,y
+
+
+