mirror of
https://github.com/Kozea/WeasyPrint.git
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266 lines
9.6 KiB
Python
266 lines
9.6 KiB
Python
# coding: utf8
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"""
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weasyprint.text
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---------------
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Interface with Pango to decide where to do line breaks and to draw text.
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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 os
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from io import BytesIO
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from cgi import escape
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import cairo
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from .compat import xrange, basestring
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from .logger import LOGGER
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USING_INTROSPECTION = bool(os.environ.get('WEASYPRINT_USE_INTROSPECTION'))
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if not USING_INTROSPECTION:
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try:
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import pygtk
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pygtk.require('2.0')
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import pango as Pango
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except ImportError:
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USING_INTROSPECTION = True
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if USING_INTROSPECTION:
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from gi.repository import Pango, PangoCairo
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from gi.repository.PangoCairo import create_layout as create_pango_layout
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if Pango.version() < 12903:
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LOGGER.warn('Using Pango-introspection %s. Versions before '
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'1.29.3 are known to be buggy.', Pango.version_string())
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PANGO_VARIANT = {
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'normal': Pango.Variant.NORMAL,
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'small-caps': Pango.Variant.SMALL_CAPS,
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}
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PANGO_STYLE = {
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'normal': Pango.Style.NORMAL,
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'italic': Pango.Style.ITALIC,
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'oblique': Pango.Style.OBLIQUE,
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}
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PANGO_STRETCH = {
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'ultra-condensed': Pango.Stretch.ULTRA_CONDENSED,
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'extra-condensed': Pango.Stretch.EXTRA_CONDENSED,
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'condensed': Pango.Stretch.CONDENSED,
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'semi-condensed': Pango.Stretch.SEMI_CONDENSED,
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'normal': Pango.Stretch.NORMAL,
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'semi-expanded': Pango.Stretch.SEMI_EXPANDED,
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'expanded': Pango.Stretch.EXPANDED,
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'extra-expanded': Pango.Stretch.EXTRA_EXPANDED,
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'ultra-expanded': Pango.Stretch.ULTRA_EXPANDED,
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}
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PANGO_WRAP_WORD = Pango.WrapMode.WORD
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def set_text(layout, text):
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layout.set_text(text, -1)
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def parse_markup(markup):
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_, attributes_list, _, _ = Pango.parse_markup(markup, -1, '\x00')
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return attributes_list
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def get_size(line):
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_ink_extents, logical_extents = line.get_extents()
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return (units_to_double(logical_extents.width),
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units_to_double(logical_extents.height))
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def show_first_line(cairo_context, pango_layout, hinting):
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"""Draw the given ``line`` to the Cairo ``context``."""
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if hinting:
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PangoCairo.update_layout(cairo_context, pango_layout)
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lines = pango_layout.get_lines_readonly()
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PangoCairo.show_layout_line(cairo_context, lines[0])
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else:
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import pango as Pango
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import pangocairo
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PANGO_VARIANT = {
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'normal': Pango.VARIANT_NORMAL,
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'small-caps': Pango.VARIANT_SMALL_CAPS,
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}
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PANGO_STYLE = {
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'normal': Pango.STYLE_NORMAL,
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'italic': Pango.STYLE_ITALIC,
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'oblique': Pango.STYLE_OBLIQUE,
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}
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PANGO_STRETCH = {
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'ultra-condensed': Pango.STRETCH_ULTRA_CONDENSED,
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'extra-condensed': Pango.STRETCH_EXTRA_CONDENSED,
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'condensed': Pango.STRETCH_CONDENSED,
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'semi-condensed': Pango.STRETCH_SEMI_CONDENSED,
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'normal': Pango.STRETCH_NORMAL,
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'semi-expanded': Pango.STRETCH_SEMI_EXPANDED,
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'expanded': Pango.STRETCH_EXPANDED,
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'extra-expanded': Pango.STRETCH_EXTRA_EXPANDED,
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'ultra-expanded': Pango.STRETCH_ULTRA_EXPANDED,
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}
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PANGO_WRAP_WORD = Pango.WRAP_WORD
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set_text = Pango.Layout.set_text
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def create_pango_layout(context):
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return pangocairo.CairoContext(context).create_layout()
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def parse_markup(markup):
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attributes_list, _, _ = Pango.parse_markup(markup, '\x00')
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return attributes_list
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def get_size(line):
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_ink_extents, logical_extents = line.get_extents()
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_x, _y, width, height = logical_extents
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return units_to_double(width), units_to_double(height)
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def show_first_line(cairo_context, pango_layout, hinting):
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"""Draw the given ``line`` to the Cairo ``context``."""
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context = pangocairo.CairoContext(cairo_context)
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if hinting:
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context.update_layout(pango_layout)
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context.show_layout_line(pango_layout.get_line(0))
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def units_from_double(value):
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return int(value * Pango.SCALE)
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def units_to_double(value):
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# True division, with the __future__ import
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return value / Pango.SCALE
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def create_layout(text, style, hinting, max_width):
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"""Return an opaque Pango layout with default Pango line-breaks.
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:param text: Unicode
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:param style: a :class:`StyleDict` of computed values
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:param hinting: whether to enable text hinting or not
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:param max_width:
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The maximum available width in the same unit as ``style.font_size``,
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or ``None`` for unlimited width.
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"""
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if hinting:
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dummy_context = cairo.Context(cairo.ImageSurface(
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cairo.FORMAT_ARGB32, 1, 1))
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else:
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# None as a the target for PDFSurface is new in pycairo 1.8.8.
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# BytesIO() helps with compat with earlier versions:
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dummy_file = BytesIO()
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dummy_context = cairo.Context(cairo.PDFSurface(dummy_file, 1, 1))
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layout = create_pango_layout(dummy_context)
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font = Pango.FontDescription()
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assert not isinstance(style.font_family, basestring), (
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'font_family should be a list')
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font.set_family(','.join(style.font_family))
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font.set_variant(PANGO_VARIANT[style.font_variant])
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font.set_style(PANGO_STYLE[style.font_style])
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font.set_stretch(PANGO_STRETCH[style.font_stretch])
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font.set_absolute_size(units_from_double(style.font_size))
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font.set_weight(style.font_weight)
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layout.set_font_description(font)
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layout.set_wrap(PANGO_WRAP_WORD)
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set_text(layout, text)
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# Make sure that max_width * Pango.SCALE == max_width * 1024 fits in a
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# signed integer. Treat bigger values same as None: unconstrained width.
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if max_width is not None and max_width < 2 ** 21:
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layout.set_width(units_from_double(max_width))
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word_spacing = style.word_spacing
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letter_spacing = style.letter_spacing
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if letter_spacing == 'normal':
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letter_spacing = 0
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if text and (word_spacing != 0 or letter_spacing != 0):
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word_spacing = units_from_double(word_spacing)
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letter_spacing = units_from_double(letter_spacing)
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markup = escape(text).replace(
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' ', '<span letter_spacing="%i"> </span>' % (
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word_spacing + letter_spacing,))
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markup = '<span letter_spacing="%i">%s</span>' % (
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letter_spacing, markup)
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layout.set_attributes(parse_markup(markup))
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return layout
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def split_first_line(text, style, hinting, max_width):
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"""Fit as much as possible in the available width for one line of text.
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Return ``(layout, length, resume_at, width, height, baseline)``.
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``layout``: a pango Layout with the first line
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``length``: length in UTF-8 bytes of the first line
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``resume_at``: The number of UTF-8 bytes to skip for the next line.
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May be ``None`` if the whole text fits in one line.
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This may be greater than ``length`` in case of preserved
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newline characters.
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``width``: width in pixels of the first line
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``height``: height in pixels of the first line
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``baseline``: baseline in pixels of the first line
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"""
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# Step #1: Get a draft layout with the first line
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layout = None
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if max_width:
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expected_length = int(max_width / style.font_size * 2.5)
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if expected_length < len(text):
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# Try to use a small amount of text instead of the whole text
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layout = create_layout(
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text[:expected_length], style, hinting, max_width)
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if layout.get_line_count() <= 1:
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# The small amount of text fits in one line, give up and use
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# the whole text
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layout = None
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layout = layout or create_layout(text, style, hinting, max_width)
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if layout.get_line_count() > 1:
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resume_at = layout.get_line(1).start_index
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else:
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resume_at = None
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# Step #2: Build the final layout
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if max_width and layout.get_line_count() > 1:
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# The first line may have been cut too early by pango
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second_line_index = layout.get_line(1).start_index
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first_part = text.encode('utf-8')[:second_line_index].decode('utf-8')
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second_part = text.encode('utf-8')[second_line_index:].decode('utf-8')
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next_word = second_part.split(' ', 1)[0]
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if next_word:
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new_first_line = first_part + next_word
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set_text(layout, new_first_line)
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if layout.get_line_count() <= 1:
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resume_at = len(new_first_line.encode('utf-8')) + 1
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# Step #3: We have the right layout, find metrics
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first_line = layout.get_line(0)
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length = first_line.length
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first_line_text = text.encode('utf-8')[:length].decode('utf-8')
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if first_line_text.endswith(' ') and resume_at:
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# Remove trailing spaces
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set_text(layout, first_line_text.rstrip(' '))
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first_line = layout.get_line(0)
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length = first_line.length
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width, height = get_size(first_line)
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baseline = units_to_double(layout.get_iter().get_baseline())
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# Step #4: Return the layout and the metrics
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return layout, length, resume_at, width, height, baseline
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def line_widths(box, enable_hinting, width, skip=None):
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"""Return the width for each line."""
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# TODO: without the lstrip, we get an extra empty line at the beginning. Is
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# there a better solution to avoid that?
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layout = create_layout(
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box.text[(skip or 0):].lstrip(), box.style, enable_hinting, width)
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for i in xrange(layout.get_line_count()):
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width, _height = get_size(layout.get_line(i))
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yield width
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