mirror of
https://github.com/Kozea/WeasyPrint.git
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673 lines
26 KiB
Python
673 lines
26 KiB
Python
# coding: utf8
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"""
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weasyprint.draw
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---------------
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Take an "after layout" box tree and draw it onto a cairo context.
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:copyright: Copyright 2011-2012 Simon Sapin and contributors, see AUTHORS.
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:license: BSD, see LICENSE for details.
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"""
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from __future__ import division, unicode_literals
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import contextlib
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import math
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import operator
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import cairocffi as cairo
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from .formatting_structure import boxes
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from .layout.backgrounds import box_rectangle
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from .stacking import StackingContext
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from .text import show_first_line
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from .compat import xrange
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# Map values of the image-rendering property to cairo FILTER values:
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# Values are normalized to lower case.
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IMAGE_RENDERING_TO_FILTER = dict(
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optimizespeed=cairo.FILTER_FAST,
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auto=cairo.FILTER_GOOD,
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optimizequality=cairo.FILTER_BEST,
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)
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@contextlib.contextmanager
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def stacked(context):
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"""Save and restore the context when used with the ``with`` keyword."""
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context.save()
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try:
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yield
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finally:
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context.restore()
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def lighten(color, offset):
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"""Return a lighter color (or darker, for negative offsets)."""
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return (
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color.red + offset,
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color.green + offset,
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color.blue + offset,
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color.alpha)
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def draw_page(page, context, enable_hinting):
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"""Draw the given PageBox."""
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stacking_context = StackingContext.from_page(page)
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draw_background(context, stacking_context.box.background, enable_hinting)
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draw_background(context, page.canvas_background, enable_hinting)
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draw_border(context, page, enable_hinting)
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draw_stacking_context(context, stacking_context, enable_hinting)
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def draw_box_background_and_border(context, page, box, enable_hinting):
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draw_background(context, box.background, enable_hinting)
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if not isinstance(box, boxes.TableBox):
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draw_border(context, box, enable_hinting)
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else:
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for column_group in box.column_groups:
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draw_background(context, column_group.background, enable_hinting)
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for column in column_group.children:
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draw_background(context, column.background, enable_hinting)
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for row_group in box.children:
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draw_background(context, row_group.background, enable_hinting)
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for row in row_group.children:
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draw_background(context, row.background, enable_hinting)
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for cell in row.children:
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draw_background(context, cell.background, enable_hinting)
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if box.style.border_collapse == 'separate':
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draw_border(context, box, enable_hinting)
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for row_group in box.children:
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for row in row_group.children:
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for cell in row.children:
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draw_border(context, cell, enable_hinting)
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else:
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draw_collapsed_borders(context, box, enable_hinting)
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def draw_stacking_context(context, stacking_context, enable_hinting):
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"""Draw a ``stacking_context`` on ``context``."""
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# See http://www.w3.org/TR/CSS2/zindex.html
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with stacked(context):
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box = stacking_context.box
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if box.is_absolutely_positioned() and box.style.clip:
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top, right, bottom, left = box.style.clip
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if top == 'auto':
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top = 0
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if right == 'auto':
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right = 0
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if bottom == 'auto':
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bottom = box.border_height()
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if left == 'auto':
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left = box.border_width()
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context.rectangle(
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box.border_box_x() + right,
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box.border_box_y() + top,
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left - right,
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bottom - top)
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context.clip()
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if box.style.overflow != 'visible':
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context.rectangle(*box_rectangle(box, 'padding-box'))
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context.clip()
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if box.style.opacity < 1:
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context.push_group()
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if box.transformation_matrix:
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context.transform(box.transformation_matrix)
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# Point 1 is done in draw_page
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# Point 2
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if isinstance(box, (boxes.BlockBox, boxes.MarginBox,
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boxes.InlineBlockBox)):
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# The canvas background was removed by set_canvas_background
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draw_box_background_and_border(
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context, stacking_context.page, box, enable_hinting)
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# Point 3
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for child_context in stacking_context.negative_z_contexts:
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draw_stacking_context(context, child_context, enable_hinting)
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# Point 4
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for block in stacking_context.block_level_boxes:
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draw_box_background_and_border(
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context, stacking_context.page, block, enable_hinting)
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# Point 5
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for child_context in stacking_context.float_contexts:
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draw_stacking_context(context, child_context, enable_hinting)
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# Point 6
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if isinstance(box, boxes.InlineBox):
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draw_inline_level(
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context, stacking_context.page, box, enable_hinting)
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# Point 7
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for block in [box] + stacking_context.blocks_and_cells:
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marker_box = getattr(block, 'outside_list_marker', None)
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if marker_box:
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draw_inline_level(
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context, stacking_context.page, marker_box, enable_hinting)
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if isinstance(block, boxes.ReplacedBox):
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draw_replacedbox(context, block)
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else:
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for child in block.children:
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if isinstance(child, boxes.LineBox):
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# TODO: draw inline tables
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draw_inline_level(
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context, stacking_context.page, child,
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enable_hinting)
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# Point 8
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for child_context in stacking_context.zero_z_contexts:
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draw_stacking_context(context, child_context, enable_hinting)
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# Point 9
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for child_context in stacking_context.positive_z_contexts:
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draw_stacking_context(context, child_context, enable_hinting)
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# Point 10
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draw_outlines(context, box, enable_hinting)
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if box.style.opacity < 1:
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context.pop_group_to_source()
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context.paint_with_alpha(box.style.opacity)
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def percentage(value, refer_to):
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"""Return the evaluated percentage value, or the value unchanged."""
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if value.unit == 'px':
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return value.value
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else:
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assert value.unit == '%'
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return refer_to * value.value / 100
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def draw_background(context, bg, enable_hinting):
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"""Draw the background color and image to a ``cairo.Context``."""
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if bg is None:
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return
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with stacked(context):
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if enable_hinting:
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# Prefer crisp edges on background rectangles.
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context.set_antialias(cairo.ANTIALIAS_NONE)
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if bg.painting_area:
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context.rectangle(*bg.painting_area)
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context.clip()
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#else: unrestricted, whole page box
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# Background color
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if bg.color.alpha > 0:
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context.set_source_rgba(*bg.color)
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context.paint()
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# Background image
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if bg.image is None:
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return
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(positioning_x, positioning_y,
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positioning_width, positioning_height) = bg.positioning_area
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context.translate(positioning_x, positioning_y)
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get_pattern, intrinsic_width, intrinsic_height = bg.image
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bg_size = bg.size
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if bg_size in ('cover', 'contain'):
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scale_x = scale_y = {'cover': max, 'contain': min}[bg_size](
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positioning_width / intrinsic_width,
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positioning_height / intrinsic_height)
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image_width = intrinsic_width * scale_x
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image_height = intrinsic_height * scale_y
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elif bg_size == ('auto', 'auto'):
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scale_x = scale_y = 1
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image_width = intrinsic_width
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image_height = intrinsic_height
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elif bg_size[0] == 'auto':
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image_height = percentage(bg_size[1], positioning_height)
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scale_x = scale_y = image_height / intrinsic_height
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image_width = intrinsic_width * scale_x
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elif bg_size[1] == 'auto':
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image_width = percentage(bg_size[0], positioning_width)
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scale_x = scale_y = image_width / intrinsic_width
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image_height = intrinsic_height * scale_y
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else:
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image_width = percentage(bg_size[0], positioning_width)
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image_height = percentage(bg_size[1], positioning_height)
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scale_x = image_width / intrinsic_width
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scale_y = image_height / intrinsic_height
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bg_position_x, bg_position_y = bg.position
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context.translate(
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percentage(bg_position_x, positioning_width - image_width),
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percentage(bg_position_y, positioning_height - image_height),
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)
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if bg.repeat in ('repeat-x', 'repeat-y'):
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# Get the current clip rectangle. This is the same as
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# painting_area, but in new coordinates after translate()
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clip_x1, clip_y1, clip_x2, clip_y2 = context.clip_extents()
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clip_width = clip_x2 - clip_x1
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clip_height = clip_y2 - clip_y1
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if bg.repeat == 'repeat-x':
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# Limit the drawn area vertically
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clip_y1 = 0 # because of the last context.translate()
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clip_height = image_height
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else:
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# repeat-y
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# Limit the drawn area horizontally
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clip_x1 = 0 # because of the last context.translate()
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clip_width = image_width
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# Second clip for the background image
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context.rectangle(clip_x1, clip_y1, clip_width, clip_height)
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context.clip()
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pattern = get_pattern()
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pattern.set_extend(cairo.EXTEND_NONE if bg.repeat == 'no-repeat'
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else cairo.EXTEND_REPEAT)
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pattern.set_filter(IMAGE_RENDERING_TO_FILTER[bg.image_rendering])
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context.scale(scale_x, scale_y)
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context.set_source(pattern)
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context.paint()
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def get_rectangle_edges(x, y, width, height):
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"""Return the 4 edges of a rectangle as a list.
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Edges are in clock-wise order, starting from the top.
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Each edge is returned as ``(start_point, end_point)`` and each point
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as ``(x, y)`` coordinates.
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"""
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# In clock-wise order, starting on top left
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corners = [
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(x, y),
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(x + width, y),
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(x + width, y + height),
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(x, y + height)]
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# clock-wise order, starting on top right
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shifted_corners = corners[1:] + corners[:1]
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return zip(corners, shifted_corners)
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def xy_offset(x, y, offset_x, offset_y, offset):
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"""Increment X and Y coordinates by the given offsets."""
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return x + offset_x * offset, y + offset_y * offset
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def draw_border(context, box, enable_hinting):
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"""Draw the box border to a ``cairo.Context``."""
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if box.style.visibility == 'hidden':
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return
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if all(getattr(box, 'border_%s_width' % side) == 0
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for side in ['top', 'right', 'bottom', 'left']):
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# No border, return early.
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return
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for side, border_edge, padding_edge in zip(
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['top', 'right', 'bottom', 'left'],
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get_rectangle_edges(
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box.border_box_x(), box.border_box_y(),
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box.border_width(), box.border_height(),
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),
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get_rectangle_edges(
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box.padding_box_x(), box.padding_box_y(),
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box.padding_width(), box.padding_height(),
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),
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):
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width = getattr(box, 'border_%s_width' % side)
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if width == 0:
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continue
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color = box.style.get_color('border_%s_color' % side)
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if color.alpha == 0:
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continue
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style = box.style['border_%s_style' % side]
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draw_border_segment(context, enable_hinting, style, width, color,
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side, border_edge, padding_edge)
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def draw_border_segment(context, enable_hinting, style, width, color, side,
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border_edge, padding_edge):
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with stacked(context):
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context.set_source_rgba(*color)
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x_offset, y_offset = {
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'top': (0, 1), 'bottom': (0, -1), 'left': (1, 0), 'right': (-1, 0),
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}[side]
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if enable_hinting and (
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# Borders smaller than 1 device unit would disappear
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# without anti-aliasing.
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math.hypot(*context.user_to_device(width, 0)) >= 1 and
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math.hypot(*context.user_to_device(0, width)) >= 1):
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# Avoid an artefact in the corner joining two solid borders
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# of the same color.
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context.set_antialias(cairo.ANTIALIAS_NONE)
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if style not in ('dotted', 'dashed'):
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# Clip on the trapezoid shape
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"""
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Clip on the trapezoid formed by the border edge (longer)
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and the padding edge (shorter).
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This is on the top side:
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+---------------+ <= border edge ^
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\ / |
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\ / | top border width
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\ / |
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+-------+ <= padding edge v
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<--> <--> <= left and right border widths
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"""
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border_start, border_stop = border_edge
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padding_start, padding_stop = padding_edge
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context.move_to(*border_start)
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for point in [border_stop, padding_stop,
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padding_start, border_start]:
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context.line_to(*point)
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context.clip()
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if style == 'solid':
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# Fill the whole trapezoid
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context.paint()
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elif style in ('inset', 'outset'):
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do_lighten = (side in ('top', 'left')) ^ (style == 'inset')
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factor = 1 if do_lighten else -1
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context.set_source_rgba(*lighten(color, 0.5 * factor))
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context.paint()
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elif style in ('groove', 'ridge'):
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# TODO: these would look better with more color stops
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"""
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Divide the width in 2 and stroke lines in different colors
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+-------------+
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1\ /2
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1'\ / 2'
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+-------+
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"""
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do_lighten = (side in ('top', 'left')) ^ (style == 'groove')
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factor = 1 if do_lighten else -1
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context.set_line_width(width / 2)
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(x1, y1), (x2, y2) = border_edge
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# from the border edge to the center of the first line
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x1, y1 = xy_offset(x1, y1, x_offset, y_offset, width / 4)
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x2, y2 = xy_offset(x2, y2, x_offset, y_offset, width / 4)
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context.move_to(x1, y1)
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context.line_to(x2, y2)
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context.set_source_rgba(*lighten(color, 0.5 * factor))
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context.stroke()
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# Between the centers of both lines. 1/4 + 1/4 = 1/2
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x1, y1 = xy_offset(x1, y1, x_offset, y_offset, width / 2)
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x2, y2 = xy_offset(x2, y2, x_offset, y_offset, width / 2)
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context.move_to(x1, y1)
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context.line_to(x2, y2)
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context.set_source_rgba(*lighten(color, -0.5 * factor))
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context.stroke()
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elif style == 'double':
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"""
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Divide the width in 3 and stroke both outer lines
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+---------------+
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1\ /2
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\ /
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1' \ / 2'
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+-------+
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"""
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context.set_line_width(width / 3)
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(x1, y1), (x2, y2) = border_edge
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# from the border edge to the center of the first line
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x1, y1 = xy_offset(x1, y1, x_offset, y_offset, width / 6)
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x2, y2 = xy_offset(x2, y2, x_offset, y_offset, width / 6)
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context.move_to(x1, y1)
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context.line_to(x2, y2)
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context.stroke()
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# Between the centers of both lines. 1/6 + 1/3 + 1/6 = 2/3
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x1, y1 = xy_offset(x1, y1, x_offset, y_offset, 2 * width / 3)
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x2, y2 = xy_offset(x2, y2, x_offset, y_offset, 2 * width / 3)
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context.move_to(x1, y1)
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context.line_to(x2, y2)
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context.stroke()
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else:
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assert style in ('dotted', 'dashed')
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(x1, y1), (x2, y2) = border_edge
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if style == 'dotted':
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# Half-way from the extremities of the border and padding
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# edges.
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(px1, py1), (px2, py2) = padding_edge
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x1 = (x1 + px1) / 2
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x2 = (x2 + px2) / 2
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y1 = (y1 + py1) / 2
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y2 = (y2 + py2) / 2
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"""
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+---------------+
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\ /
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1 2
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\ /
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+-------+
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"""
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else: # dashed
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# From the border edge to the middle:
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x1, y1 = xy_offset(x1, y1, x_offset, y_offset, width / 2)
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x2, y2 = xy_offset(x2, y2, x_offset, y_offset, width / 2)
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"""
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+---------------+
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\ /
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1 \ / 2
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\ /
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+-------+
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"""
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length = ((x2 - x1) ** 2 + (y2 - y1) ** 2) ** 0.5
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dash = 2 * width
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if style == 'dotted':
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if context.user_to_device_distance(width, 0)[0] > 3:
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# Round so that dash is a divisor of length,
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# but not in the dots are too small.
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dash = length / round(length / dash)
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context.set_line_cap(cairo.LINE_CAP_ROUND)
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context.set_dash([0, dash])
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else: # dashed
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# Round so that 2*dash is a divisor of length
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dash = length / (2 * round(length / (2 * dash)))
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context.set_dash([dash])
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# Stroke along the line in === above, as wide as the border
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context.move_to(x1, y1)
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context.line_to(x2, y2)
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context.set_line_width(width)
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context.stroke()
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def draw_outlines(context, box, enable_hinting):
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width = box.style.outline_width
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color = box.style.get_color('outline_color')
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style = box.style.outline_style
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if box.style.visibility != 'hidden' and width != 0 and color.alpha != 0:
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border_box = (box.border_box_x(), box.border_box_y(),
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box.border_width(), box.border_height())
|
||
outline_box = (border_box[0] - width, border_box[1] - width,
|
||
border_box[2] + 2 * width, border_box[3] + 2 * width)
|
||
for side, border_edge, padding_edge in zip(
|
||
['top', 'right', 'bottom', 'left'],
|
||
get_rectangle_edges(*outline_box),
|
||
get_rectangle_edges(*border_box),
|
||
):
|
||
draw_border_segment(context, enable_hinting, style, width, color,
|
||
side, border_edge, padding_edge)
|
||
|
||
if isinstance(box, boxes.ParentBox):
|
||
for child in box.children:
|
||
if isinstance(child, boxes.Box):
|
||
draw_outlines(context, child, enable_hinting)
|
||
|
||
|
||
def draw_collapsed_borders(context, table, enable_hinting):
|
||
row_heights = [row.height for row_group in table.children
|
||
for row in row_group.children]
|
||
column_widths = table.column_widths
|
||
if not (row_heights and column_widths):
|
||
# One of the list is empty: don’t bother with empty tables
|
||
return
|
||
row_positions = [row.position_y for row_group in table.children
|
||
for row in row_group.children]
|
||
column_positions = table.column_positions
|
||
grid_height = len(row_heights)
|
||
grid_width = len(column_widths)
|
||
assert grid_width == len(column_positions)
|
||
# Add the end of the last column, but make a copy from the table attr.
|
||
column_positions += [column_positions[-1] + column_widths[-1]]
|
||
# Add the end of the last row. No copy here, we own this list
|
||
row_positions.append(row_positions[-1] + row_heights[-1])
|
||
vertical_borders, horizontal_borders = table.collapsed_border_grid
|
||
skipped_rows = table.skipped_rows
|
||
|
||
segments = []
|
||
|
||
def half_max_width(border_list, yx_pairs, vertical=True):
|
||
result = 0
|
||
for y, x in yx_pairs:
|
||
if (
|
||
(0 <= y < grid_height and 0 <= x <= grid_width)
|
||
if vertical else
|
||
(0 <= y <= grid_height and 0 <= x < grid_width)
|
||
):
|
||
_, (_, width, _) = border_list[skipped_rows + y][x]
|
||
result = max(result, width)
|
||
return result / 2
|
||
|
||
def add_vertical(x, y):
|
||
score, (style, width, color) = vertical_borders[skipped_rows + y][x]
|
||
if width == 0 or color.alpha == 0:
|
||
return
|
||
half_width = width / 2
|
||
pos_x = column_positions[x]
|
||
pos_y_1 = row_positions[y] - half_max_width(horizontal_borders, [
|
||
(y, x - 1), (y, x)], vertical=False)
|
||
pos_y_2 = row_positions[y + 1] + half_max_width(horizontal_borders, [
|
||
(y + 1, x - 1), (y + 1, x)], vertical=False)
|
||
edge_1 = (pos_x - half_width, pos_y_1), (pos_x - half_width, pos_y_2)
|
||
edge_2 = (pos_x + half_width, pos_y_1), (pos_x + half_width, pos_y_2)
|
||
segments.append((score, style, width, color, 'left', edge_1, edge_2))
|
||
|
||
def add_horizontal(x, y):
|
||
score, (style, width, color) = horizontal_borders[skipped_rows + y][x]
|
||
if width == 0 or color.alpha == 0:
|
||
return
|
||
half_width = width / 2
|
||
pos_y = row_positions[y]
|
||
# TODO: change signs for rtl when we support rtl tables?
|
||
pos_x_1 = column_positions[x] - half_max_width(vertical_borders, [
|
||
(y - 1, x), (y, x)])
|
||
pos_x_2 = column_positions[x + 1] + half_max_width(vertical_borders, [
|
||
(y - 1, x + 1), (y, x + 1)])
|
||
edge_1 = (pos_x_1, pos_y - half_width), (pos_x_2, pos_y - half_width)
|
||
edge_2 = (pos_x_1, pos_y + half_width), (pos_x_2, pos_y + half_width)
|
||
segments.append((score, style, width, color, 'top', edge_1, edge_2))
|
||
|
||
for x in xrange(grid_width):
|
||
add_horizontal(x, 0)
|
||
for y in xrange(grid_height):
|
||
add_vertical(0, y)
|
||
for x in xrange(grid_width):
|
||
add_vertical(x + 1, y)
|
||
add_horizontal(x, y + 1)
|
||
|
||
# Sort bigger scores last (painted later, on top)
|
||
# Since the number of different scores is expected to be small compared
|
||
# to the number of segments, there should be little changes and Timsort
|
||
# should be closer to O(n) than O(n * log(n))
|
||
segments.sort(key=operator.itemgetter(0))
|
||
|
||
for segment in segments:
|
||
draw_border_segment(context, enable_hinting, *segment[1:])
|
||
|
||
def draw_replacedbox(context, box):
|
||
"""Draw the given :class:`boxes.ReplacedBox` to a ``cairo.context``."""
|
||
if box.style.visibility == 'hidden':
|
||
return
|
||
|
||
x, y = box.content_box_x(), box.content_box_y()
|
||
width, height = box.width, box.height
|
||
get_pattern, intrinsic_width, intrinsic_height = box.replacement
|
||
scale_width = width / intrinsic_width
|
||
scale_height = height / intrinsic_height
|
||
# Draw nothing for width:0 or height:0
|
||
if scale_width != 0 and scale_height != 0:
|
||
with stacked(context):
|
||
context.translate(x, y)
|
||
context.rectangle(0, 0, width, height)
|
||
context.clip()
|
||
context.scale(scale_width, scale_height)
|
||
pattern = get_pattern()
|
||
# We might get a shared Pattern that was previously used
|
||
# in a repeating background.
|
||
pattern.set_extend(cairo.EXTEND_NONE)
|
||
pattern.set_filter(IMAGE_RENDERING_TO_FILTER[
|
||
box.style.image_rendering])
|
||
context.set_source(pattern)
|
||
context.paint()
|
||
|
||
|
||
def draw_inline_level(context, page, box, enable_hinting):
|
||
if isinstance(box, StackingContext):
|
||
stacking_context = box
|
||
assert isinstance(stacking_context.box, boxes.InlineBlockBox)
|
||
draw_stacking_context(context, stacking_context, enable_hinting)
|
||
else:
|
||
draw_background(context, box.background, enable_hinting)
|
||
draw_border(context, box, enable_hinting)
|
||
if isinstance(box, (boxes.InlineBox, boxes.LineBox)):
|
||
for child in box.children:
|
||
if isinstance(child, boxes.TextBox):
|
||
draw_text(context, child, enable_hinting)
|
||
else:
|
||
draw_inline_level(context, page, child, enable_hinting)
|
||
elif isinstance(box, boxes.InlineReplacedBox):
|
||
draw_replacedbox(context, box)
|
||
else:
|
||
assert isinstance(box, boxes.TextBox)
|
||
# Should only happen for list markers
|
||
draw_text(context, box, enable_hinting)
|
||
|
||
|
||
def draw_text(context, textbox, enable_hinting):
|
||
"""Draw ``textbox`` to a ``cairo.Context`` from ``PangoCairo.Context``."""
|
||
# Pango crashes with font-size: 0
|
||
assert textbox.style.font_size
|
||
|
||
if textbox.style.visibility == 'hidden':
|
||
return
|
||
|
||
context.move_to(textbox.position_x, textbox.position_y + textbox.baseline)
|
||
context.set_source_rgba(*textbox.style.color)
|
||
show_first_line(context, textbox.pango_layout, enable_hinting)
|
||
values = textbox.style.text_decoration
|
||
if 'overline' in values:
|
||
draw_text_decoration(context, textbox,
|
||
textbox.baseline - 0.15 * textbox.style.font_size,
|
||
enable_hinting)
|
||
elif 'underline' in values:
|
||
draw_text_decoration(context, textbox,
|
||
textbox.baseline + 0.15 * textbox.style.font_size,
|
||
enable_hinting)
|
||
elif 'line-through' in values:
|
||
draw_text_decoration(context, textbox, textbox.height * 0.5,
|
||
enable_hinting)
|
||
|
||
|
||
def draw_text_decoration(context, textbox, offset_y, enable_hinting):
|
||
"""Draw text-decoration of ``textbox`` to a ``cairo.Context``."""
|
||
with stacked(context):
|
||
if enable_hinting:
|
||
context.set_antialias(cairo.ANTIALIAS_NONE)
|
||
context.set_source_rgba(*textbox.style.color)
|
||
context.set_line_width(1) # TODO: make this proportional to font_size?
|
||
context.move_to(textbox.position_x, textbox.position_y + offset_y)
|
||
context.rel_line_to(textbox.width, 0)
|
||
context.stroke()
|