@@ -56,10 +56,6 @@ class Shape:

 		"""Draw this shape with the given cairo context"""

 		raise NotImplementedError

-	def boundingbox(self):

-		"""Get the bounding box of this shape."""

-		raise NotImplementedError

-

 class TextShape(Shape):

@@ -222,31 +218,63 @@ class Element(CompoundShape):

 	def get_url(self, x, y):

 		return None

+	def get_jump(self, x, y):

+		return None

+

 class Node(Element):

 	def __init__(self, x, y, w, h, shapes, url):

 		Element.__init__(self, shapes)

-		self.x1 = x - w/2

-		self.y1 = y - h/2

-		self.x2 = x + w/2

-		self.y2 = y + h/2

+		self.x = x

+		self.y = y

+

+		self.x1 = x - 0.5*w

+		self.y1 = y - 0.5*h

+		self.x2 = x + 0.5*w

+		self.y2 = y + 0.5*h

 		self.url = url

+	def is_inside(self, x, y):

+		return self.x1 <= x and x <= self.x2 and self.y1 <= y and y <= self.y2

+

 	def get_url(self, x, y):

 		if self.url is None:

 			return None

 		#print (x, y), (self.x1, self.y1), "-", (self.x2, self.y2)

-		if self.x1 <= x and x <= self.x2 and self.y1 <= y and y <= self.y2:

+		if self.is_inside(x, y):

 			return self.url

 		return None

+	def get_jump(self, x, y):

+		if self.is_inside(x, y):

+			return self.x, self.y

+		return None

+

+

+def square_distance(x1, y1, x2, y2):

+	deltax = x2 - x1

+	deltay = y2 - y1

+	return deltax*deltax + deltay*deltay

+

 class Edge(Element):

-	pass

+	def __init__(self, points, shapes):

+		Element.__init__(self, shapes)

+

+		self.points = points

+

+	RADIUS = 10

+

+	def get_jump(self, x, y):

+		if square_distance(x, y, *self.points[0]) <= self.RADIUS*self.RADIUS:

+			return self.points[-1]

+		if square_distance(x, y, *self.points[-1]) <= self.RADIUS*self.RADIUS:

+			return self.points[0]

+		return None

 class Graph(Shape):

@@ -280,6 +308,17 @@ class Graph(Shape):

 				return url

 		return None

+	def get_jump(self, x, y):

+		for edge in self.edges:

+			jump = edge.get_jump(x, y)

+			if jump is not None:

+				return jump

+		for node in self.nodes:

+			jump = node.get_jump(x, y)

+			if jump is not None:

+				return jump

+		return None

+

 class XDotAttrParser:

 	"""Parser for xdot drawing attributes.

@@ -441,7 +480,7 @@ class XDotParser:

 		for node in graph.get_node_list():

 			if node.pos is None:

 				continue

-			x, y = map(float, node.pos.split(","))

+			x, y = self.parse_node_pos(node.pos)

 			w = float(node.width)*72

 			h = float(node.height)*72

 			shapes = []

@@ -454,16 +493,36 @@ class XDotParser:

 				nodes.append(Node(x, y, w, h, shapes, url))

 		for edge in graph.get_edge_list():

+			if edge.pos is None:

+				continue

+			points = self.parse_edge_pos(edge.pos)	

 			shapes = []

 			for attr in ("_draw_", "_ldraw_", "_hdraw_", "_tdraw_", "_hldraw_", "_tldraw_"):

 				if hasattr(edge, attr):

 					parser = XDotAttrParser(self, getattr(edge, attr))

 					shapes.extend(parser.parse())

 			if shapes:

-				edges.append(Edge(shapes))

+				edges.append(Edge(points, shapes))

 		return Graph(width, height, nodes, edges)

+	def parse_node_pos(self, pos):

+		x, y = pos.split(",")

+		return self.transform(float(x), float(y))

+

+	def parse_edge_pos(self, pos):

+		points = []

+		for entry in pos.split(' '):

+			fields = entry.split(',')

+			try:

+				x, y = fields

+			except ValueError:

+				# TODO: handle start/end points

+				continue

+			else:

+				points.append(self.transform(float(x), float(y)))

+		return points

+

 	def transform(self, x, y):

 		# XXX: this is not the right place for this code

 		x = (x + self.xoffset)*self.xscale

@@ -472,6 +531,7 @@ class XDotParser:

 class DotWidget(gtk.DrawingArea):

+	"""PyGTK widget that draws dot graphs."""

 	__gsignals__ = {

 		'expose-event': 'override',

@@ -613,6 +673,13 @@ class DotWidget(gtk.DrawingArea):

 			self.emit('clicked', unicode(url), event)

 			return True

+		jump = self.get_jump(x, y)

+		x, y = self.window2graph(x, y)

+		if jump is not None:

+			jumpx, jumpy = jump

+			self.x += jumpx - x

+			self.y += jumpy - y

+			self.queue_draw()

 		return False

 	def on_area_button_release(self, area, event):

@@ -652,7 +719,7 @@ class DotWidget(gtk.DrawingArea):

 		return True

-	def get_url(self, x, y):

+	def window2graph(self, x, y):

 		rect = self.get_allocation()

 		x -= 0.5*rect.width

 		y -= 0.5*rect.height

@@ -660,9 +727,16 @@ class DotWidget(gtk.DrawingArea):

 		y /= self.zoom_ratio

 		x += self.x

 		y += self.y

-		y = self.graph.height - y

+		return x, y

+

+	def get_url(self, x, y):

+		x, y = self.window2graph(x, y)

 		return self.graph.get_url(x, y)

+	def get_jump(self, x, y):

+		x, y = self.window2graph(x, y)

+		return self.graph.get_jump(x, y)

+

 class DotWindow(gtk.Window):