# 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