import io
from typing import Any, Callable, IO, Iterable, Mapping, Optional, Tuple
from xml.etree import ElementTree as ET
from madam.core import Asset, MetadataProcessor, Processor, UnsupportedFormatError, operator
_INCH_TO_MM = 1 / 25.4
_PX_PER_INCH = 90
_PT_PER_INCH = 1 / 72
_FONT_SIZE_PT = 12
_X_HEIGHT = 0.7
def svg_length_to_px(length: str) -> float:
if length is None:
raise ValueError()
unit_len = 2
if length.endswith('%'):
unit_len = 1
try:
value = float(length)
unit = 'px'
except ValueError:
value = float(length[:-unit_len])
unit = length[-unit_len:]
if unit == 'em':
return value * _PX_PER_INCH * _FONT_SIZE_PT * _PT_PER_INCH
elif unit == 'ex':
return value * _PX_PER_INCH * _X_HEIGHT * _FONT_SIZE_PT * _PT_PER_INCH
elif unit == 'px':
return value
elif unit == 'in':
return value * _PX_PER_INCH
elif unit == 'cm':
return value * _PX_PER_INCH * _INCH_TO_MM * 10
elif unit == 'mm':
return value * _PX_PER_INCH * _INCH_TO_MM
elif unit == 'pt':
return value * _PX_PER_INCH * _PT_PER_INCH
elif unit == 'pc':
return value * _PX_PER_INCH * _PT_PER_INCH * 12
elif unit == '%':
return value
XML_NS = dict(
dc='http://purl.org/dc/elements/1.1/',
rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#',
svg='http://www.w3.org/2000/svg',
xlink='http://www.w3.org/1999/xlink',
)
def _register_xml_namespaces() -> None:
for prefix, uri in XML_NS.items():
if prefix == 'svg':
prefix = ''
ET.register_namespace(prefix, uri)
def _parse_svg(file: IO) -> Tuple[ET.ElementTree, ET.Element]:
_register_xml_namespaces()
try:
tree = ET.parse(file)
except ET.ParseError as e:
raise UnsupportedFormatError('Error while parsing XML in line %d, column %d' % e.position)
root = tree.getroot()
if root.tag not in ('{%s}svg' % XML_NS['svg'], 'svg'):
raise UnsupportedFormatError('XML file is not an SVG file.')
return tree, root
def _write_svg(tree: ET.ElementTree) -> IO:
file = io.BytesIO()
tree.write(file, xml_declaration=False, encoding='utf-8')
file.seek(0)
return file
[docs]class SVGProcessor(Processor):
"""
Represents a processor that handles *Scalable Vector Graphics* (SVG) data.
"""
[docs] def __init__(self, config: Optional[Mapping[str, Any]] = None) -> None:
"""
Initializes a new `SVGProcessor`.
:param config: Mapping with settings.
"""
super().__init__(config)
[docs] def can_read(self, file: IO) -> bool:
try:
_parse_svg(file)
return True
except UnsupportedFormatError:
return False
[docs] def read(self, file: IO) -> Asset:
_, root = _parse_svg(file)
metadata = dict(mime_type='image/svg+xml')
if 'width' in root.keys():
metadata['width'] = svg_length_to_px(root.get('width'))
if 'height' in root.keys():
metadata['height'] = svg_length_to_px(root.get('height'))
file.seek(0)
return Asset(essence=file, **metadata)
@staticmethod
def __remove_xml_whitespace(elem: ET.Element) -> None:
if elem.text:
elem.text = elem.text.strip()
if elem.tail:
elem.tail = elem.tail.strip()
for child in elem:
SVGProcessor.__remove_xml_whitespace(child)
@staticmethod
def __remove_elements(root: ET.Element, qname: str, keep_func: Callable[[ET.Element], bool]) -> None:
parents = root.findall('.//%s/..' % qname, XML_NS)
for parent in parents:
for elem in parent.findall('./%s' % qname, XML_NS):
if not keep_func(elem):
parent.remove(elem)
[docs] @operator
def shrink(self, asset: Asset) -> Asset:
"""
Shrinks the size of an SVG asset.
:param asset: Media asset to be shrunk
:type asset: Asset
:return: Shrunk vector asset
:rtype: Asset
"""
tree, root = _parse_svg(asset.essence)
# Minify XML
SVGProcessor.__remove_xml_whitespace(root)
# Remove empty texts
SVGProcessor.__remove_elements(root, 'svg:text',
lambda e: e.text and
e.text.strip() or
list(e))
# Remove all empty circles with radius 0
SVGProcessor.__remove_elements(root, 'svg:circle',
lambda e: list(e) or
e.get('r') != '0')
# Remove all empty ellipses with x-axis or y-axis radius 0
SVGProcessor.__remove_elements(root, 'svg:ellipse',
lambda e: list(e) or
e.get('rx') != '0' and
e.get('ry') != '0')
# Remove all empty rectangles with width or height 0
SVGProcessor.__remove_elements(root, 'svg:rect',
lambda e: list(e) or
e.get('width') != '0' and
e.get('height') != '0')
# Remove all patterns with width or height 0
SVGProcessor.__remove_elements(root, 'svg:pattern',
lambda e: e.get('width') != '0' and
e.get('height') != '0')
# Remove all images with width or height 0
SVGProcessor.__remove_elements(root, 'svg:image',
lambda e: e.get('width') != '0' and
e.get('height') != '0')
# Remove all paths without coordinates
SVGProcessor.__remove_elements(root, 'svg:path',
lambda e: e.get('d', '').strip())
# Remove all polygons without points
SVGProcessor.__remove_elements(root, 'svg:polygon',
lambda e: e.get('points', '').strip())
# Remove all polylines without points
SVGProcessor.__remove_elements(root, 'svg:polyline',
lambda e: e.get('points', '').strip())
# Remove all invisible or hidden elements
SVGProcessor.__remove_elements(root, '*',
lambda e: e.get('display') != 'none' and
e.get('visibility') != 'hidden' and
e.get('opacity') != '0')
# Remove empty groups
SVGProcessor.__remove_elements(root, 'svg:g',
lambda e: bool(list(e)))
# Remove all invisible or hidden elements
SVGProcessor.__remove_elements(root, 'svg:defs',
lambda e: bool(list(e)))
essence = _write_svg(tree)
metadata = dict(mime_type='image/svg+xml')
for metadata_key in ('width', 'height'):
if metadata_key in asset.metadata:
metadata[metadata_key] = asset.metadata[metadata_key]
return Asset(essence=essence, **metadata)