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Version:
5.3.0 ▾
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enable
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svg.py
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# (C) Copyright 2005-2022 Enthought, Inc., Austin, TX
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD
# license included in LICENSE.txt and may be redistributed only under
# the conditions described in the aforementioned license. The license
# is also available online at http://www.enthought.com/licenses/BSD.txt
#
# Thanks for using Enthought open source!
""" Chaco's SVG backend
:Copyright: ActiveState
:License: BSD Style
:Author: David Ascher (davida@activestate.com)
:Version: $Revision: 1.5 $
"""
####
#
# Known limitations
#
# * BUG: Weird behavior with compound plots
# * Limitation: text widths are lousy if reportlab is not installed
# * Missing feature: rotated text
"""
Miscellaneous notes:
* the way to do links:
<a xlink:href="http://www.w3.org">
<ellipse cx="2.5" cy="1.5" rx="2" ry="1" fill="red" />
</a>
"""
from base64 import b64encode
from io import BytesIO, StringIO
import os
import warnings
from numpy import arange, ndarray, ravel
# Local, relative Kiva imports
from . import affine
from . import basecore2d
from . import constants
from .constants import FILL, FILL_STROKE, EOF_FILL_STROKE, EOF_FILL, STROKE
def _strpoints(points):
c = StringIO()
for x, y in points:
c.write("%3.2f,%3.2f " % (x, y))
return c.getvalue()
def _mkstyle(kw):
return "; ".join([str(k) + ":" + str(v) for k, v in kw.items()])
def default_filter(kw1):
kw = {}
for (k, v) in kw1.items():
if isinstance(v, tuple):
if v[0] != v[1]:
kw[k] = v[0]
else:
kw[k] = v
return kw
line_cap_map = {
constants.CAP_ROUND: "round",
constants.CAP_SQUARE: "square",
constants.CAP_BUTT: "butt",
}
line_join_map = {
constants.JOIN_ROUND: "round",
constants.JOIN_BEVEL: "bevel",
constants.JOIN_MITER: "miter",
}
xmltemplate = """<?xml version="1.0"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.0//EN"
"http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd">
<svg xmlns="http://www.w3.org/2000/svg"
xmlns:text="http://xmlns.graougraou.com/svg/text/"
xmlns:a3="http://ns.adobe.com/AdobeSVGViewerExtensions/3.0/"
xmlns:xlink="http://www.w3.org/1999/xlink"
a3:scriptImplementation="Adobe"
width="%(width)f"
height="%(height)f"
viewBox="0 0 %(width)f %(height)f"
>
<g transform="translate(0,%(height)f)">
<g transform="scale(1,-1)">
%(contents)s
</g>
</g>
</svg>
"""
htmltemplate = """<html xmlns:svg="http://www.w3.org/2000/svg"
xmlns:xlink="http://www.w3.org/1999/xlink">
<object id="AdobeSVG" CLASSID="clsid:78156a80-c6a1-4bbf-8e6a-3cd390eeb4e2">
</object>
<?import namespace="svg" implementation="#AdobeSVG"?>
<body>
<svg:svg width="100%%" height="100%%" viewBox="0 0 %(width)f %(height)f">
%(contents)s
</svg:svg>
</body>
</html>
"""
try:
# expensive way of computing string widths
import reportlab.pdfbase.pdfmetrics as pdfmetrics
import reportlab.pdfbase._fontdata as _fontdata
_reportlab_loaded = 1
except ImportError:
from . import pdfmetrics
from . import _fontdata
_reportlab_loaded = 0
# This backend has no compiled path object, yet.
class CompiledPath(object):
pass
_clip_counter = 0
class GraphicsContext(basecore2d.GraphicsContextBase):
def __init__(self, size, *args, **kwargs):
super().__init__(self, size, *args, **kwargs)
self.size = size
self._height = size[1]
self.contents = StringIO()
self._clipmap = {}
def render(self, format):
assert format == "svg"
height, width = self.size
contents = (
self.contents.getvalue()
.replace("<svg:", "<")
.replace("</svg:", "</")
)
return xmltemplate % locals()
def clear(self):
self.contents = StringIO()
def width(self):
return self.size[0]
def height(self):
return self.size[1]
def save(self, filename, file_format=None, pil_options=None):
with open(filename, "w", encoding="utf-8") as f:
ext = os.path.splitext(filename)[1]
if ext == ".svg":
template = xmltemplate
width, height = self.size
contents = (
self.contents.getvalue()
.replace("<svg:", "<")
.replace("</svg:", "</")
)
elif ext == ".html":
width, height = self.size[0] * 3, self.size[1] * 3
contents = self.contents.getvalue()
template = htmltemplate
else:
raise ValueError("don't know how to write a %s file" % ext)
f.write(template % locals())
# Text handling code
def set_font(self, font):
self.face_name = font.face_name
self.font_size = font.size
# actual implementation =)
def device_show_text(self, text):
ttm = self.get_text_matrix()
ctm = self.get_ctm() # not device_ctm!!
m = affine.concat(ctm, ttm)
# height = self.get_full_text_extent(text)[1]
a, b, c, d, tx, ty = affine.affine_params(m)
transform = (
"matrix(%(a)f,%(b)f,%(c)f,%(d)f,%(tx)f,%(ty)f) scale(1,-1)"
% locals()
)
self._emit(
"text",
contents=text,
kw={
"font-family": self.face_name,
"font-size": str(self.font_size),
"xml:space": "preserve",
"transform": transform,
},
)
def get_full_text_extent(self, text):
ascent, descent = _fontdata.ascent_descent[self.face_name]
descent = (-descent) * self.font_size / 1000.0
ascent = ascent * self.font_size / 1000.0
height = ascent + descent
width = pdfmetrics.stringWidth(text, self.face_name, self.font_size)
return (
width,
height,
descent,
height * 1.2,
) # assume leading of 1.2*height
def device_draw_image(self, img, rect):
"""
draw_image(img_gc, rect=(x,y,w,h))
Draws another gc into this one. If 'rect' is not provided, then
the image gc is drawn into this one, rooted at (0,0) and at full
pixel size. If 'rect' is provided, then the image is resized
into the (w,h) given and drawn into this GC at point (x,y).
img_gc is either a Numeric array (WxHx3 or WxHx4) or a PIL Image.
Requires the Python Imaging Library (PIL).
"""
from PIL import Image
# We turn img into a PIL object, since that is what ReportLab
# requires.
if isinstance(img, ndarray):
# From numpy array
pil_img = Image.fromarray(img)
elif isinstance(img, Image.Image):
pil_img = img
elif hasattr(img, "bmp_array"):
# An offscreen kiva agg context
if hasattr(img, "convert_pixel_format"):
img = img.convert_pixel_format("rgba32", inplace=0)
pil_img = Image.fromarray(img.bmp_array)
else:
warnings.warn(
"Cannot render image of type %r into SVG context." % type(img)
)
return
if rect is None:
rect = (0, 0, pil_img.width, pil_img.height)
left, top, width, height = rect
if width != pil_img.width or height != pil_img.height:
# This is not strictly required.
pil_img = pil_img.resize((int(width), int(height)), Image.NEAREST)
png_buffer = BytesIO()
pil_img.save(png_buffer, "png")
b64_img_data = b64encode(png_buffer.getvalue()).decode('utf8')
png_buffer.close()
# Draw the actual image.
m = self.get_ctm()
# Place the image on the page.
# Using bottom instead of top here to account for the y-flip.
m = affine.translate(m, left, height + top)
transform = (
"matrix(%f,%f,%f,%f,%f,%f) scale(1,-1)" % affine.affine_params(m)
)
# Flip y to reverse the flip at the start of the document.
image_data = "data:image/png;base64," + b64_img_data
self._emit(
"image",
transform=transform,
width=str(width),
height=str(height),
preserveAspectRatio="none",
kw={"xlink:href": image_data},
)
def device_fill_points(self, points, mode):
points = self._fixpoints(points)
if mode in (FILL, FILL_STROKE, EOF_FILL_STROKE):
fill = self._color(self.state.fill_color)
else:
fill = "none"
if mode in (STROKE, FILL_STROKE, EOF_FILL_STROKE):
stroke = self._color(self.state.line_color)
else:
stroke = "none"
if mode in (EOF_FILL_STROKE, EOF_FILL):
rule = "evenodd"
else:
rule = "nonzero"
linecap = line_cap_map[self.state.line_cap]
linejoin = line_join_map[self.state.line_join]
dasharray = self._dasharray()
width = "%3.3f" % self.state.line_width
clip_id = getattr(self.state, "_clip_id", None)
if clip_id:
clip = "url(#" + clip_id + ")"
else:
clip = None
a, b, c, d, tx, ty = affine.affine_params(self.get_ctm())
transform = "matrix(%(a)f,%(b)f,%(c)f,%(d)f,%(tx)f,%(ty)f)" % locals()
if mode == STROKE:
opacity = "%1.3f" % self.state.line_color[-1]
self._emit(
"polyline",
transform=transform,
points=_strpoints(points),
kw=default_filter({"clip-path": (clip, None)}),
style=_mkstyle(
default_filter(
{
"opacity": (opacity, "1.000"),
"stroke": stroke,
"fill": "none",
"stroke-width": (width, "1.000"),
"stroke-linejoin": (linejoin, "miter"),
"stroke-linecap": (linecap, "butt"),
"stroke-dasharray": (dasharray, "none"),
}
)
),
)
else:
opacity = "%1.3f" % self.state.fill_color[-1]
self._emit(
"polygon",
transform=transform,
points=_strpoints(points),
kw=default_filter({"clip-path": (clip, None)}),
style=_mkstyle(
default_filter(
{
"opacity": (opacity, "1.000"),
"stroke-width": (width, "1.000"),
"fill": fill,
"fill-rule": rule,
"stroke": stroke,
"stroke-linejoin": (linejoin, "miter"),
"stroke-linecap": (linecap, "butt"),
"stroke-dasharray": (dasharray, "none"),
}
)
),
)
def device_stroke_points(self, points, mode):
# handled by device_fill_points
pass
def _build(self, elname, contents=None, **kw):
x = "<" + elname + " "
for k, v in kw.items():
if isinstance(v, float):
v = "%3.3f" % v
elif isinstance(v, int):
v = "%d" % v
else:
v = "%s" % str(v)
x += k + '="' + v + '" '
if contents is None:
x += "/>\n"
else:
x += ">"
if elname != "text":
x += "\n"
x += contents
x += "</" + elname + ">\n"
return x
def _debug_draw_clipping_path(self, x, y, width, height):
a, b, c, d, tx, ty = affine.affine_params(self.get_ctm())
transform = "matrix(%(a)f,%(b)f,%(c)f,%(d)f,%(tx)f,%(ty)f)" % locals()
self._emit(
"rect",
x=x,
y=y,
width=width,
height=height,
transform=transform,
style=_mkstyle(
{"stroke-width": 5, "fill": "none", "stroke": "green"}
),
)
def device_set_clipping_path(self, x, y, width, height):
# self._debug_draw_clipping_path(x, y, width, height)
# return
global _clip_counter
self.state._clip_id = "clip_%d" % _clip_counter
_clip_counter += 1
x, y = self._fixpoints([[x, y]])[0]
a, b, c, d, tx, ty = affine.affine_params(self.get_ctm())
transform = "matrix(%(a)f,%(b)f,%(c)f,%(d)f,%(tx)f,%(ty)f)" % locals()
rect = self._build("rect", x=x, y=y, width=width, height=height)
clippath = self._build(
"clipPath", contents=rect, id=self.state._clip_id
)
self._emit("g", transform=transform, contents=clippath)
def device_destroy_clipping_path(self):
self.state._clip_id = None
# utility routines
def _fixpoints(self, points):
return points
# convert lines from Kiva coordinate space to PIL coordinate space
# XXX I suspect this is the location of the bug w.r.t. compound graphs
# and "global" sizing.
# XXX this should be made more efficient for NumPy arrays
np = []
for (x, y) in points:
np.append((x, self._height - y))
return np
def _emit(self, name, contents=None, kw={}, **otherkw):
self.contents.write("<svg:%(name)s " % locals())
for k, v in kw.items():
self.contents.write('%(k)s="%(v)s" ' % locals())
for k, v in otherkw.items():
self.contents.write('%(k)s="%(v)s" ' % locals())
if contents is None:
self.contents.write("/>\n")
else:
self.contents.write(">")
if name != "text":
self.contents.write("\n")
self.contents.write(contents)
self.contents.write("</svg:" + name + ">\n")
def _color(self, color):
r, g, b, a = color
return "#%02x%02x%02x" % (int(r * 255), int(g * 255), int(b * 255))
def _dasharray(self):
dasharray = ""
for x in self.state.line_dash:
if type(x) == type(arange(3)): # why is this so hard?
x = ravel(x)[0]
dasharray += " " + "%3.2f" % x
if not dasharray or dasharray == " 0.00 0.00":
dasharray = "none"
return dasharray
# noops which seem to be needed
def device_update_line_state(self):
pass
def device_update_fill_state(self):
pass
def _repr_svg_(self):
""" Return a the current contents of the context as SVG text.
This provides Jupyter and IPython compatibility, so that the graphics
context can be displayed in the Jupyter Notebook or the IPython Qt
console.
Returns
-------
svg : str
The contents of the context as an SVG string.
"""
return self.render('svg')
def font_metrics_provider():
return GraphicsContext((1, 1))
SVGGC = GraphicsContext # for b/w compatibility