Source code for kiva.graphics_state
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""" GraphicsState Class
The GraphicsState class is used Kiva backends which need to have their state
tracked by Python, rather than by an internal graphics state (eg. Wx, SVG and
PDF backends, but not Agg or QPainter).
"""
import copy
from numpy import array, float64
from .constants import CAP_ROUND, JOIN_MITER, TEXT_FILL
from .fonttools import Font
from .line_state import LineState
import kiva.affine as affine
[docs]class GraphicsState(LineState):
""" Holds information used by a graphics context when drawing.
I'm not sure if these should be a separate class, a dictionary,
or part of the GraphicsContext object. Making them a dictionary
or object simplifies save_state and restore_state a little bit.
Also, this is a pretty good candidate for using slots. I'm not
going to use them right now, but, if we standardize on 2.2, slots might
speed things up some.
Attributes
----------
ctm
context transform matrix
fill_color
RGBA array(4) of values 0.0 to 1.0
alpha
transparency value of drawn objects
font
either a special device independent font
object (what does anygui use?) or a
device dependent font object.
text_matrix
coordinate transformation matrix for text
clipping_path
defines the path of the clipping region.
For now, this can only be a rectangle.
current_point
location where next object is drawn.
should_antialias
whether anti-aliasing should be used when
drawing lines and fonts
miter_limit
specifies when and when not to miter line joins.
flatness
specifies tolerance for bumpiness of curves
character_spacing
spacing between drawing text characters
text_drawing_mode
style for drawing text: outline, fill, etc.
These are inherited from LineState:
line_color
RGBA array(4) of values 0.0 to 1.0
line_width
width of drawn lines
line_join
style of how lines are joined. The choices
are: JOIN_ROUND, JOIN_BEVEL, JOIN_MITER
line_cap
style of the end cap on lines. The choices
are: CAP_ROUND, CAP_SQUARE, CAP_BUTT
line_dash
(phase,pattern) dash pattern for lines.
phase is a single value specifying how many
units into the pattern to start. dash is
a 1-D array of floats that alternate between
specifying the number of units on and off
in the pattern. When the end of the array
is reached, the pattern repeats.
Not yet supported:
rendering_intent
deals with colors and color correction in
a sophisticated way.
"""
def __init__(self):
# Line state default values.
line_color = array((0.0, 0.0, 0.0, 1.0))
line_width = 1
line_cap = CAP_ROUND
line_join = JOIN_MITER
line_dash = (0, array([0])) # This will draw a solid line
# FIXME: This is a very wierd class. The following code is here to
# make the basecore2d and the PS, SVG context managers happy
super().__init__(
line_color, line_width, line_cap, line_join, line_dash
)
self.line_state = self
# All other default values.
self.ctm = affine.affine_identity()
self.fill_color = array((0.0, 0.0, 0.0, 1.0))
self.alpha = 1.0
self.font = Font()
self.text_matrix = affine.affine_identity()
self.clipping_path = None # Not sure what the default should be?
# Technically uninitialized in the PDF spec, but 0,0 seems fine to me:
self.current_point = array((0, 0), dtype=float64)
self.antialias = True
self.miter_limit = 1.0
self.flatness = 1.0
self.character_spacing = 0.0
self.text_drawing_mode = TEXT_FILL
self.alpha = 1.0
