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708 lines
28 KiB
Python
708 lines
28 KiB
Python
"""
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weasyprint.images
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-----------------
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Fetch and decode images in various formats.
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"""
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import math
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from io import BytesIO
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from itertools import cycle
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import pydyf
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from PIL import Image
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from .layout.percentages import percentage
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from .logger import LOGGER
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from .svg import SVG
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from .urls import URLFetchingError, fetch
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class ImageLoadingError(ValueError):
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"""An error occured when loading an image.
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The image data is probably corrupted or in an invalid format.
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"""
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@classmethod
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def from_exception(cls, exception):
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name = type(exception).__name__
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value = str(exception)
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return cls(f'{name}: {value}' if value else name)
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class RasterImage:
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def __init__(self, pillow_image, optimize_size):
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self.pillow_image = pillow_image
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self.optimize_size = optimize_size
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self._intrinsic_width = pillow_image.width
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self._intrinsic_height = pillow_image.height
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self.intrinsic_ratio = (
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self._intrinsic_width / self._intrinsic_height
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if self._intrinsic_height != 0 else float('inf'))
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def get_intrinsic_size(self, image_resolution, _font_size):
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# Raster images are affected by the 'image-resolution' property.
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return (self._intrinsic_width / image_resolution,
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self._intrinsic_height / image_resolution)
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def draw(self, context, concrete_width, concrete_height, image_rendering):
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has_size = (
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concrete_width > 0
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and concrete_height > 0
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and self._intrinsic_width > 0
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and self._intrinsic_height > 0
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)
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if not has_size:
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return
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image_name = context.add_image(
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self.pillow_image, image_rendering, self.optimize_size)
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# Use the real intrinsic size here,
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# not affected by 'image-resolution'.
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context.push_state()
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context.transform(
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concrete_width, 0, 0, -concrete_height, 0, concrete_height)
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context.draw_x_object(image_name)
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context.pop_state()
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class SVGImage:
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def __init__(self, string, base_url, url_fetcher, context):
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self._svg = SVG(string, base_url)
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self._base_url = base_url
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self._url_fetcher = url_fetcher
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self._context = context
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def get_intrinsic_size(self, _image_resolution, font_size):
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self._intrinsic_width, self._intrinsic_height = (
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self._svg.get_intrinsic_size(font_size))
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viewbox = self._svg.get_viewbox()
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if self._intrinsic_width and self._intrinsic_height:
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self.intrinsic_ratio = (
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self._intrinsic_width / self._intrinsic_height)
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elif viewbox and viewbox[2] and viewbox[3]:
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self.intrinsic_ratio = viewbox[2] / viewbox[3]
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if self._intrinsic_width:
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self._intrinsic_height = (
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self._intrinsic_width / self.intrinsic_ratio)
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elif self._intrinsic_height:
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self._intrinsic_width = (
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self._intrinsic_height * self.intrinsic_ratio)
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else:
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self.intrinsic_ratio = None
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return self._intrinsic_width, self._intrinsic_height
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def draw(self, context, concrete_width, concrete_height, image_rendering):
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if not concrete_width or not concrete_height:
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return
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# Use the real intrinsic size here, not affected by 'image-resolution'.
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context.push_state()
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self._svg.draw(
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context, concrete_width, concrete_height, self._base_url,
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self._url_fetcher, self._context)
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context.pop_state()
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def get_image_from_uri(cache, url_fetcher, optimize_size, url,
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forced_mime_type=None, context=None):
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"""Get an Image instance from an image URI."""
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missing = object()
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image = cache.get(url, missing)
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if image is not missing:
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return image
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try:
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with fetch(url_fetcher, url) as result:
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if 'string' in result:
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string = result['string']
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else:
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string = result['file_obj'].read()
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mime_type = forced_mime_type or result['mime_type']
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image = None
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svg_exceptions = []
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# Try to rely on given mimetype for SVG
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if mime_type == 'image/svg+xml':
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try:
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image = SVGImage(string, url, url_fetcher, context)
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except Exception as svg_exception:
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svg_exceptions.append(svg_exception)
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# Try pillow for raster images, or for failing SVG
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if image is None:
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try:
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pillow_image = Image.open(BytesIO(string))
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except Exception as raster_exception:
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if mime_type == 'image/svg+xml':
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# Tried SVGImage then Pillow for a SVG, abort
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raise ImageLoadingError.from_exception(
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svg_exceptions[0])
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try:
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# Last chance, try SVG
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image = SVGImage(string, url, url_fetcher, context)
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except Exception:
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# Tried Pillow then SVGImage for a raster, abort
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raise ImageLoadingError.from_exception(
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raster_exception)
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else:
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image = RasterImage(pillow_image, optimize_size)
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except (URLFetchingError, ImageLoadingError) as exception:
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LOGGER.error('Failed to load image at %r: %s', url, exception)
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image = None
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cache[url] = image
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return image
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def process_color_stops(vector_length, positions):
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"""Give color stops positions on the gradient vector.
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``vector_length`` is the distance between the starting point and ending
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point of the vector gradient.
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``positions`` is a list of ``None``, or ``Dimension`` in px or %. 0 is the
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starting point, 1 the ending point.
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See http://dev.w3.org/csswg/css-images-3/#color-stop-syntax.
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Return processed color stops, as a list of floats in px.
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"""
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# Resolve percentages
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positions = [percentage(position, vector_length) for position in positions]
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# First and last default to 100%
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if positions[0] is None:
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positions[0] = 0
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if positions[-1] is None:
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positions[-1] = vector_length
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# Make sure positions are increasing
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previous_pos = positions[0]
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for i, position in enumerate(positions):
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if position is not None:
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if position < previous_pos:
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positions[i] = previous_pos
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else:
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previous_pos = position
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# Assign missing values
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previous_i = -1
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for i, position in enumerate(positions):
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if position is not None:
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base = positions[previous_i]
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increment = (position - base) / (i - previous_i)
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for j in range(previous_i + 1, i):
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positions[j] = base + j * increment
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previous_i = i
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return positions
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def normalize_stop_positions(positions):
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"""Normalize stop positions between 0 and 1.
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Return ``(first, last, positions)``.
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first: original position of the first position.
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last: original position of the last position.
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positions: list of positions between 0 and 1.
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"""
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first, last = positions[0], positions[-1]
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total_length = last - first
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if total_length == 0:
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positions = [0] * len(positions)
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else:
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positions = [(pos - first) / total_length for pos in positions]
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return first, last, positions
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def gradient_average_color(colors, positions):
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"""
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http://dev.w3.org/csswg/css-images-3/#gradient-average-color
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"""
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nb_stops = len(positions)
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assert nb_stops > 1
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assert nb_stops == len(colors)
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total_length = positions[-1] - positions[0]
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if total_length == 0:
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positions = list(range(nb_stops))
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total_length = nb_stops - 1
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premul_r = [r * a for r, g, b, a in colors]
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premul_g = [g * a for r, g, b, a in colors]
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premul_b = [b * a for r, g, b, a in colors]
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alpha = [a for r, g, b, a in colors]
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result_r = result_g = result_b = result_a = 0
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total_weight = 2 * total_length
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for i, position in enumerate(positions[1:], 1):
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weight = (position - positions[i - 1]) / total_weight
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for j in (i - 1, i):
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result_r += premul_r[j] * weight
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result_g += premul_g[j] * weight
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result_b += premul_b[j] * weight
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result_a += alpha[j] * weight
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# Un-premultiply:
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return (result_r / result_a, result_g / result_a,
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result_b / result_a, result_a) if result_a != 0 else (0, 0, 0, 0)
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class Gradient:
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def __init__(self, color_stops, repeating):
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assert color_stops
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# List of (r, g, b, a)
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self.colors = tuple(color for color, _ in color_stops)
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# List of Dimensions
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self.stop_positions = tuple(position for _, position in color_stops)
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# Boolean
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self.repeating = repeating
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def get_intrinsic_size(self, _image_resolution, _font_size):
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# Gradients are not affected by image resolution, parent or font size.
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return None, None
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intrinsic_ratio = None
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def draw(self, context, concrete_width, concrete_height, _image_rendering):
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# TODO: handle color spaces
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scale_y, type_, points, positions, colors = self.layout(
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concrete_width, concrete_height)
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if type_ == 'solid':
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context.rectangle(0, 0, concrete_width, concrete_height)
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red, green, blue, alpha = colors[0]
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context.set_color_rgb(red, green, blue)
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if alpha != 1:
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context.set_alpha(alpha, stroke=False)
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context.fill()
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return
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alphas = [color[3] for color in colors]
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alpha_couples = [
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(alphas[i], alphas[i + 1])
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for i in range(len(alphas) - 1)]
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color_couples = [
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[colors[i][:3], colors[i + 1][:3], 1]
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for i in range(len(colors) - 1)]
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# Premultiply colors
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for i, alpha in enumerate(alphas):
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if alpha == 0:
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if i > 0:
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color_couples[i - 1][1] = color_couples[i - 1][0]
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if i < len(colors) - 1:
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color_couples[i][0] = color_couples[i][1]
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for i, (a0, a1) in enumerate(alpha_couples):
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if 0 not in (a0, a1) and (a0, a1) != (1, 1):
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color_couples[i][2] = a0 / a1
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shading = context.add_shading()
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shading['ShadingType'] = 2 if type_ == 'linear' else 3
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shading['ColorSpace'] = '/DeviceRGB'
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shading['Domain'] = pydyf.Array([positions[0], positions[-1]])
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shading['Coords'] = pydyf.Array(points)
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shading['Function'] = pydyf.Dictionary({
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'FunctionType': 3,
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'Domain': pydyf.Array([positions[0], positions[-1]]),
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'Encode': pydyf.Array((len(colors) - 1) * [0, 1]),
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'Bounds': pydyf.Array(positions[1:-1]),
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'Functions': pydyf.Array([
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pydyf.Dictionary({
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'FunctionType': 2,
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'Domain': pydyf.Array([0, 1]),
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'C0': pydyf.Array(c0),
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'C1': pydyf.Array(c1),
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'N': n,
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}) for c0, c1, n in color_couples
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]),
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})
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if not self.repeating:
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shading['Extend'] = pydyf.Array([b'true', b'true'])
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context.transform(1, 0, 0, scale_y, 0, 0)
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if any(alpha != 1 for alpha in alphas):
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alpha_stream = context.add_transparency_group(
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[0, 0, concrete_width, concrete_height])
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alpha_state = pydyf.Dictionary({
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'Type': '/ExtGState',
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'SMask': pydyf.Dictionary({
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'Type': '/Mask',
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'S': '/Luminosity',
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'G': alpha_stream,
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}),
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'ca': 1,
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'AIS': 'false',
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})
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alpha_state_id = f'as{len(context._alpha_states)}'
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context._alpha_states[alpha_state_id] = alpha_state
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context.set_state(alpha_state_id)
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alpha_shading = alpha_stream.add_shading()
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alpha_shading['ShadingType'] = 2 if type_ == 'linear' else 3
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alpha_shading['ColorSpace'] = '/DeviceGray'
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alpha_shading['Domain'] = pydyf.Array(
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[positions[0], positions[-1]])
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alpha_shading['Coords'] = pydyf.Array(points)
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alpha_shading['Function'] = pydyf.Dictionary({
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'FunctionType': 3,
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'Domain': pydyf.Array([positions[0], positions[-1]]),
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'Encode': pydyf.Array((len(colors) - 1) * [0, 1]),
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'Bounds': pydyf.Array(positions[1:-1]),
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'Functions': pydyf.Array([
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pydyf.Dictionary({
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'FunctionType': 2,
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'Domain': pydyf.Array([0, 1]),
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'C0': pydyf.Array([c0]),
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'C1': pydyf.Array([c1]),
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'N': 1,
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}) for c0, c1 in alpha_couples
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]),
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})
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if not self.repeating:
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alpha_shading['Extend'] = pydyf.Array([b'true', b'true'])
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alpha_stream.transform(1, 0, 0, scale_y, 0, 0)
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alpha_stream.stream = [f'/{alpha_shading.id} sh']
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context.shading(shading.id)
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def layout(self, width, height):
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"""Get layout information about the gradient.
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width, height: Gradient box. Top-left is at coordinates (0, 0).
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Returns (scale_y, type_, points, positions, colors).
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scale_y: vertical scale of the gradient. float, used for ellipses
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radial gradients. 1 otherwise.
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type_: gradient type.
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points: coordinates of useful points, depending on type_:
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'solid': None.
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'linear': (x0, y0, x1, y1)
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coordinates of the starting and ending points.
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'radial': (cx0, cy0, radius0, cx1, cy1, radius1)
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coordinates of the starting end ending circles
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positions: positions of the color stops. list of floats in between 0
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and 1 (0 at the starting point, 1 at the ending point).
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colors: list of (r, g, b, a).
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"""
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raise NotImplementedError
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class LinearGradient(Gradient):
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def __init__(self, color_stops, direction, repeating):
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Gradient.__init__(self, color_stops, repeating)
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# ('corner', keyword) or ('angle', radians)
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self.direction_type, self.direction = direction
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def layout(self, width, height):
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# Only one color, render the gradient as a solid color
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if len(self.colors) == 1:
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return 1, 'solid', None, [], [self.colors[0]]
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# Define the (dx, dy) unit vector giving the direction of the gradient.
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# Positive dx: right, positive dy: down.
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if self.direction_type == 'corner':
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y, x = self.direction.split('_')
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factor_x = -1 if x == 'left' else 1
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factor_y = -1 if y == 'top' else 1
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diagonal = math.hypot(width, height)
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# Note the direction swap: dx based on height, dy based on width
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# The gradient line is perpendicular to a diagonal.
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dx = factor_x * height / diagonal
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dy = factor_y * width / diagonal
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else:
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assert self.direction_type == 'angle'
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angle = self.direction # 0 upwards, then clockwise
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dx = math.sin(angle)
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dy = -math.cos(angle)
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# Round dx and dy to avoid floating points errors caused by
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# trigonometry and angle units conversions
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dx, dy = round(dx, 9), round(dy, 9)
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# Normalize colors positions
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colors = list(self.colors)
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vector_length = abs(width * dx) + abs(height * dy)
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positions = process_color_stops(vector_length, self.stop_positions)
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if not self.repeating:
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# Add explicit colors at boundaries if needed, because PDF doesn’t
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# extend color stops that are not displayed
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if positions[0] == positions[1]:
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positions.insert(0, positions[0] - 1)
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colors.insert(0, colors[0])
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if positions[-2] == positions[-1]:
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positions.append(positions[-1] + 1)
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colors.append(colors[-1])
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first, last, positions = normalize_stop_positions(positions)
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if self.repeating:
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# Render as a solid color if the first and last positions are equal
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# See https://drafts.csswg.org/css-images-3/#repeating-gradients
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if first == last:
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color = gradient_average_color(colors, positions)
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return 1, 'solid', None, [], [color]
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# Define defined gradient length and steps between positions
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stop_length = last - first
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assert stop_length > 0
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position_steps = [
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positions[i + 1] - positions[i]
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for i in range(len(positions) - 1)]
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# Create cycles used to add colors
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next_steps = cycle([0] + position_steps)
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next_colors = cycle(colors)
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previous_steps = cycle([0] + position_steps[::-1])
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previous_colors = cycle(colors[::-1])
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# Add colors after last step
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while last < vector_length:
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step = next(next_steps)
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colors.append(next(next_colors))
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positions.append(positions[-1] + step)
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last += step * stop_length
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# Add colors before last step
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while first > 0:
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step = next(previous_steps)
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colors.insert(0, next(previous_colors))
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positions.insert(0, positions[0] - step)
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first -= step * stop_length
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# Define the coordinates of the starting and ending points
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start_x = (width - dx * vector_length) / 2
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start_y = (height - dy * vector_length) / 2
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points = (
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start_x + dx * first, start_y + dy * first,
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start_x + dx * last, start_y + dy * last)
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return 1, 'linear', points, positions, colors
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class RadialGradient(Gradient):
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def __init__(self, color_stops, shape, size, center, repeating):
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Gradient.__init__(self, color_stops, repeating)
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# Center of the ending shape. (origin_x, pos_x, origin_y, pos_y)
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self.center = center
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# Type of ending shape: 'circle' or 'ellipse'
|
||
self.shape = shape
|
||
# size_type: 'keyword'
|
||
# size: 'closest-corner', 'farthest-corner',
|
||
# 'closest-side', or 'farthest-side'
|
||
# size_type: 'explicit'
|
||
# size: (radius_x, radius_y)
|
||
self.size_type, self.size = size
|
||
|
||
def layout(self, width, height):
|
||
# Only one color, render the gradient as a solid color
|
||
if len(self.colors) == 1:
|
||
return 1, 'solid', None, [], [self.colors[0]]
|
||
|
||
# Define the center of the gradient
|
||
origin_x, center_x, origin_y, center_y = self.center
|
||
center_x = percentage(center_x, width)
|
||
center_y = percentage(center_y, height)
|
||
if origin_x == 'right':
|
||
center_x = width - center_x
|
||
if origin_y == 'bottom':
|
||
center_y = height - center_y
|
||
|
||
# Resolve sizes and vertical scale
|
||
size_x, size_y = self._handle_degenerate(
|
||
*self._resolve_size(width, height, center_x, center_y))
|
||
scale_y = size_y / size_x
|
||
|
||
# Normalize colors positions
|
||
colors = list(self.colors)
|
||
positions = process_color_stops(size_x, self.stop_positions)
|
||
if not self.repeating:
|
||
# Add explicit colors at boundaries if needed, because PDF doesn’t
|
||
# extend color stops that are not displayed
|
||
if positions[0] > 0 and positions[0] == positions[1]:
|
||
positions.insert(0, 0)
|
||
colors.insert(0, colors[0])
|
||
if positions[-2] == positions[-1]:
|
||
positions.append(positions[-1] + 1)
|
||
colors.append(colors[-1])
|
||
if positions[0] < 0:
|
||
# PDF doesn’t like negative radiuses, shift into the positive realm
|
||
if self.repeating:
|
||
# Add vector lengths to first position until positive
|
||
vector_length = positions[-1] - positions[0]
|
||
offset = vector_length * (1 + (-positions[0] // vector_length))
|
||
positions = [position + offset for position in positions]
|
||
else:
|
||
# Only keep colors with position >= 0, interpolate if needed
|
||
if positions[-1] <= 0:
|
||
# All stops are negative, fill with the last color
|
||
return 1, 'solid', None, [], [self.colors[-1]]
|
||
for i, position in enumerate(positions):
|
||
if position == 0:
|
||
# Keep colors and positions from this rank
|
||
colors, positions = colors[i:], positions[i:]
|
||
break
|
||
if position > 0:
|
||
# Interpolate with previous rank to get color at 0
|
||
color = colors[i]
|
||
previous_color = colors[i - 1]
|
||
previous_position = positions[i - 1]
|
||
assert previous_position < 0
|
||
intermediate_color = gradient_average_color(
|
||
[previous_color, previous_color, color, color],
|
||
[previous_position, 0, 0, position])
|
||
colors = [intermediate_color] + colors[i:]
|
||
positions = [0] + positions[i:]
|
||
break
|
||
first, last, positions = normalize_stop_positions(positions)
|
||
|
||
# Render as a solid color if the first and last positions are the same
|
||
# See https://drafts.csswg.org/css-images-3/#repeating-gradients
|
||
if first == last and self.repeating:
|
||
color = gradient_average_color(colors, positions)
|
||
return 1, 'solid', None, [], [color]
|
||
|
||
# Define the coordinates of the gradient circles
|
||
points = (
|
||
center_x, center_y / scale_y, first,
|
||
center_x, center_y / scale_y, last)
|
||
|
||
if self.repeating:
|
||
points, positions, colors = self._repeat(
|
||
width, height, scale_y, points, positions, colors)
|
||
|
||
return scale_y, 'radial', points, positions, colors
|
||
|
||
def _repeat(self, width, height, scale_y, points, positions, colors):
|
||
# Keep original lists and values, they’re useful
|
||
original_colors = colors.copy()
|
||
original_positions = positions.copy()
|
||
gradient_length = points[5] - points[2]
|
||
|
||
# Get the maximum distance between the center and the corners, to find
|
||
# how many times we have to repeat the colors outside
|
||
max_distance = max(
|
||
math.hypot(width - points[0], height / scale_y - points[1]),
|
||
math.hypot(width - points[0], -points[1] * scale_y),
|
||
math.hypot(-points[0], height / scale_y - points[1]),
|
||
math.hypot(-points[0], -points[1] * scale_y))
|
||
repeat_after = math.ceil((max_distance - points[5]) / gradient_length)
|
||
if repeat_after > 0:
|
||
# Repeat colors and extrapolate positions
|
||
repeat = 1 + repeat_after
|
||
colors *= repeat
|
||
positions = [
|
||
i + position for i in range(repeat) for position in positions]
|
||
points = points[:5] + (points[5] + gradient_length * repeat_after,)
|
||
|
||
if points[2] == 0:
|
||
# Inner circle has 0 radius, no need to repeat inside, return
|
||
return points, positions, colors
|
||
|
||
# Find how many times we have to repeat the colors inside
|
||
repeat_before = points[2] / gradient_length
|
||
|
||
# Set the inner circle size to 0
|
||
points = points[:2] + (0,) + points[3:]
|
||
|
||
# Find how many times the whole gradient can be repeated
|
||
full_repeat = int(repeat_before)
|
||
if full_repeat:
|
||
# Repeat colors and extrapolate positions
|
||
colors += original_colors * full_repeat
|
||
positions = [
|
||
i - full_repeat + position for i in range(full_repeat)
|
||
for position in original_positions] + positions
|
||
|
||
# Find the ratio of gradient that must be added to reach the center
|
||
partial_repeat = repeat_before - full_repeat
|
||
if partial_repeat == 0:
|
||
# No partial repeat, return
|
||
return points, positions, colors
|
||
|
||
# Iterate through positions in reverse order, from the outer
|
||
# circle to the original inner circle, to find positions from
|
||
# the inner circle (including full repeats) to the center
|
||
assert (original_positions[0], original_positions[-1]) == (0, 1)
|
||
assert 0 < partial_repeat < 1
|
||
reverse = original_positions[::-1]
|
||
ratio = 1 - partial_repeat
|
||
for i, position in enumerate(reverse, start=1):
|
||
if position == ratio:
|
||
# The center is a color of the gradient, truncate original
|
||
# colors and positions and prepend them
|
||
colors = original_colors[-i:] + colors
|
||
new_positions = [
|
||
position - full_repeat - 1
|
||
for position in original_positions[-i:]]
|
||
positions = new_positions + positions
|
||
return points, positions, colors
|
||
if position < ratio:
|
||
# The center is between two colors of the gradient,
|
||
# define the center color as the average of these two
|
||
# gradient colors
|
||
color = original_colors[-i]
|
||
next_color = original_colors[-(i - 1)]
|
||
next_position = original_positions[-(i - 1)]
|
||
average_colors = [color, color, next_color, next_color]
|
||
average_positions = [position, ratio, ratio, next_position]
|
||
zero_color = gradient_average_color(
|
||
average_colors, average_positions)
|
||
colors = [zero_color] + original_colors[-(i - 1):] + colors
|
||
new_positions = [
|
||
position - 1 - full_repeat for position
|
||
in original_positions[-(i - 1):]]
|
||
positions = (
|
||
[ratio - 1 - full_repeat] + new_positions + positions)
|
||
return points, positions, colors
|
||
|
||
def _resolve_size(self, width, height, center_x, center_y):
|
||
"""Resolve circle size of the radial gradient."""
|
||
if self.size_type == 'explicit':
|
||
size_x, size_y = self.size
|
||
size_x = percentage(size_x, width)
|
||
size_y = percentage(size_y, height)
|
||
return size_x, size_y
|
||
left = abs(center_x)
|
||
right = abs(width - center_x)
|
||
top = abs(center_y)
|
||
bottom = abs(height - center_y)
|
||
pick = min if self.size.startswith('closest') else max
|
||
if self.size.endswith('side'):
|
||
if self.shape == 'circle':
|
||
size_xy = pick(left, right, top, bottom)
|
||
return size_xy, size_xy
|
||
# else: ellipse
|
||
return pick(left, right), pick(top, bottom)
|
||
# else: corner
|
||
if self.shape == 'circle':
|
||
size_xy = pick(math.hypot(left, top), math.hypot(left, bottom),
|
||
math.hypot(right, top), math.hypot(right, bottom))
|
||
return size_xy, size_xy
|
||
# else: ellipse
|
||
corner_x, corner_y = pick(
|
||
(left, top), (left, bottom), (right, top), (right, bottom),
|
||
key=lambda a: math.hypot(*a))
|
||
return corner_x * math.sqrt(2), corner_y * math.sqrt(2)
|
||
|
||
def _handle_degenerate(self, size_x, size_y):
|
||
"""Handle degenerate radial gradients.
|
||
|
||
See https://drafts.csswg.org/css-images-3/#degenerate-radials
|
||
|
||
"""
|
||
if size_x == size_y == 0:
|
||
size_x = size_y = 1e-7
|
||
elif size_x == 0:
|
||
size_x = 1e-7
|
||
size_y = 1e7
|
||
elif size_y == 0:
|
||
size_x = 1e7
|
||
size_y = 1e-7
|
||
return size_x, size_y
|