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"""
Coordinate systems and related plotting routines
"""
from igraph.compat import property
from igraph.drawing.baseclasses import AbstractCairoDrawer
from igraph.drawing.utils import BoundingBox
__license__ = "GPL"
#####################################################################
# pylint: disable-msg=R0922
# R0922: Abstract class is only referenced 1 times
class CoordinateSystem(AbstractCairoDrawer):
"""Class implementing a coordinate system object.
Coordinate system objects are used when drawing plots which
2D or 3D coordinate system axes. This is an abstract class
which must be extended in order to use it. In general, you'll
only need the documentation of this class if you intend to
implement an own coordinate system not present in igraph yet.
"""
def __init__(self, context, bbox):
"""Initializes the coordinate system.
@param context: the context on which the coordinate system will
be drawn.
@param bbox: the bounding box that will contain the coordinate
system.
"""
AbstractCairoDrawer.__init__(self, context, bbox)
def draw(self):
"""Draws the coordinate system.
This method must be overridden in derived classes.
"""
raise NotImplementedError("abstract class")
def local_to_context(self, x, y):
"""Converts local coordinates to the context coordinate system (given
by the bounding box).
This method must be overridden in derived classes."""
raise NotImplementedError("abstract class")
class DescartesCoordinateSystem(CoordinateSystem):
"""Class implementing a 2D Descartes coordinate system object."""
def __init__(self, context, bbox, bounds):
"""Initializes the coordinate system.
@param context: the context on which the coordinate system will
be drawn.
@param bbox: the bounding box that will contain the coordinate
system.
@param bounds: minimum and maximum X and Y values in a 4-tuple.
"""
self._bounds, self._bbox = None, None
self._sx, self._sy = None, None
self._ox, self._oy, self._ox2, self._oy2 = None, None, None, None
CoordinateSystem.__init__(self, context, bbox)
self.bbox = bbox
self.bounds = bounds
@property
def bbox(self):
"""Returns the bounding box of the coordinate system"""
return BoundingBox(self._bbox.coords)
@bbox.setter
def bbox(self, bbox):
"""Sets the bounding box of the coordinate system"""
self._bbox = bbox
self._recalc_scale_factors()
@property
def bounds(self):
"""Returns the lower and upper bounds of the X and Y values"""
return self._bounds.coords
@bounds.setter
def bounds(self, bounds):
"""Sets the lower and upper bounds of the X and Y values"""
self._bounds = BoundingBox(bounds)
self._recalc_scale_factors()
def _recalc_scale_factors(self):
"""Recalculates some cached scale factors used within the class"""
if self._bounds is None:
return
self._sx = self._bbox.width / self._bounds.width
self._sy = self._bbox.height / self._bounds.height
self._ox = self._bounds.left
self._oy = self._bounds.top
self._ox2 = self._bbox.left
self._oy2 = self._bbox.bottom
def draw(self):
"""Draws the coordinate system."""
# Draw the frame
coords = self.bbox.coords
self.context.set_source_rgb(0., 0., 0.)
self.context.set_line_width(1)
self.context.rectangle(coords[0], coords[1], \
coords[2]-coords[0], coords[3]-coords[1])
self.context.stroke()
def local_to_context(self, x, y):
"""Converts local coordinates to the context coordinate system (given
by the bounding box).
"""
return (x-self._ox)*self._sx+self._ox2, self._oy2-(y-self._oy)*self._sy
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