233 lines
9.5 KiB
Python
233 lines
9.5 KiB
Python
"""
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Text drawers.
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"""
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from math import cos, radians, sin
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from .bounding_box import (
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EMPTY_BOUNDING_BOX, extend_bounding_box, is_valid_bounding_box)
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from .helpers import distance, normalize, point_angle, size, zip_letters
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from .surface import cairo
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from .url import parse_url
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def path_length(path):
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"""Get the length of ``path``."""
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total_length = 0
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for item in path:
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if item[0] == cairo.PATH_MOVE_TO:
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old_point = item[1]
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elif item[0] == cairo.PATH_LINE_TO:
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new_point = item[1]
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length = distance(
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old_point[0], old_point[1], new_point[0], new_point[1])
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total_length += length
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old_point = new_point
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return total_length
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def point_following_path(path, width):
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"""Get the point at ``width`` distance on ``path``."""
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total_length = 0
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for item in path:
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if item[0] == cairo.PATH_MOVE_TO:
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old_point = item[1]
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elif item[0] == cairo.PATH_LINE_TO:
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new_point = item[1]
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length = distance(
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old_point[0], old_point[1], new_point[0], new_point[1])
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total_length += length
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if total_length < width:
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old_point = new_point
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else:
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length -= total_length - width
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angle = point_angle(
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old_point[0], old_point[1], new_point[0], new_point[1])
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x = cos(angle) * length + old_point[0]
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y = sin(angle) * length + old_point[1]
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return x, y
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def text(surface, node, draw_as_text=False):
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"""Draw a text ``node``."""
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font_family = (
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(node.get('font-family') or 'sans-serif').split(',')[0].strip('"\' '))
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font_style = getattr(
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cairo, f'font_slant_{node.get("font-style")}'.upper(),
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cairo.FONT_SLANT_NORMAL)
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node_font_weight = node.get('font-weight')
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if (node_font_weight and node_font_weight.isdigit()
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and int(node_font_weight) >= 550):
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node_font_weight = 'bold'
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font_weight = getattr(
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cairo, (f'font_weight_{node_font_weight}'.upper()),
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cairo.FONT_WEIGHT_NORMAL)
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surface.context.select_font_face(font_family, font_style, font_weight)
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surface.context.set_font_size(surface.font_size)
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ascent, descent, _, max_x_advance, max_y_advance = (
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surface.context.font_extents())
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text_path_href = parse_url(node.get_href() or node.parent.get_href() or '')
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if text_path_href.fragment:
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text_path = surface.paths.get(text_path_href.fragment)
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else:
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text_path = None
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letter_spacing = size(surface, node.get('letter-spacing'))
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x_bearing, y_bearing, width, height = (
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surface.context.text_extents(node.text)[:4])
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x, y, dx, dy, rotate = [], [], [], [], [0]
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if 'x' in node:
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x = [size(surface, i, 'x')
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for i in normalize(node['x']).strip().split(' ')]
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if 'y' in node:
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y = [size(surface, i, 'y')
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for i in normalize(node['y']).strip().split(' ')]
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if 'dx' in node:
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dx = [size(surface, i, 'x')
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for i in normalize(node['dx']).strip().split(' ')]
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if 'dy' in node:
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dy = [size(surface, i, 'y')
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for i in normalize(node['dy']).strip().split(' ')]
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if 'rotate' in node:
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rotate = [radians(float(i)) if i else 0
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for i in normalize(node['rotate']).strip().split(' ')]
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last_r = rotate[-1]
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letters_positions = zip_letters(x, y, dx, dy, rotate, node.text)
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x_align = 0
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y_align = 0
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text_anchor = node.get('text-anchor')
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if text_anchor == 'middle':
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x_align = - (width / 2 + x_bearing)
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if letter_spacing and node.text:
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x_align -= (len(node.text) - 1) * letter_spacing / 2
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elif text_anchor == 'end':
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x_align = - (width + x_bearing)
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if letter_spacing and node.text:
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x_align -= (len(node.text) - 1) * letter_spacing
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# TODO: This is a hack. The rest of the baseline alignment tags of the SVG
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# 1.1 spec (section 10.9.2) are not supported. We only try to align things
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# that look like Western horizontal fonts.
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# Finally, we add a "display-anchor" attribute for aligning the specific
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# text rather than the font baseline.
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# Nonetheless, there are times when one needs to align text vertically, and
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# this will at least make that possible.
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if max_x_advance > 0 and max_y_advance == 0:
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display_anchor = node.get('display-anchor')
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alignment_baseline = (node.get('dominant-baseline') or
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node.get('alignment-baseline'))
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if display_anchor == 'middle':
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y_align = -height / 2 - y_bearing
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elif display_anchor == 'top':
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y_align = -y_bearing
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elif display_anchor == 'bottom':
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y_align = -height - y_bearing
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elif (alignment_baseline == 'central' or
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alignment_baseline == 'middle'):
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# TODO: This is wrong, Cairo gives no reasonable access to x-height
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# information, so we use font top-to-bottom
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y_align = (ascent + descent) / 2 - descent
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elif (alignment_baseline == 'text-before-edge' or
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alignment_baseline == 'before_edge' or
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alignment_baseline == 'top' or
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alignment_baseline == 'hanging' or
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alignment_baseline == 'text-top'):
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y_align = ascent
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elif (alignment_baseline == 'text-after-edge' or
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alignment_baseline == 'after_edge' or
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alignment_baseline == 'bottom' or
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alignment_baseline == 'text-bottom'):
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y_align = -descent
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bounding_box = EMPTY_BOUNDING_BOX
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if text_path:
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surface.context.new_path()
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surface.stroke_and_fill = False
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surface.draw(text_path)
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surface.stroke_and_fill = True
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cairo_path = surface.context.copy_path_flat()
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surface.context.new_path()
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length = path_length(cairo_path) + x_bearing
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start_offset = size(surface, node.get('startOffset', 0), length)
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if node.tag == 'textPath':
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surface.text_path_width += start_offset
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surface.text_path_width += x_align
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bounding_box = extend_bounding_box(bounding_box, ((start_offset, 0),))
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if node.text:
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for i, ((x, y, dx, dy, r), letter) in enumerate(letters_positions):
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if x:
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surface.cursor_d_position[0] = 0
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if y:
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surface.cursor_d_position[1] = 0
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surface.cursor_d_position[0] += dx or 0
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surface.cursor_d_position[1] += dy or 0
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text_extents = surface.context.text_extents(letter)
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extents = text_extents[4]
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if text_path:
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start = surface.text_path_width + surface.cursor_d_position[0]
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start_point = point_following_path(cairo_path, start)
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middle = start + extents / 2
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middle_point = point_following_path(cairo_path, middle)
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end = start + extents
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end_point = point_following_path(cairo_path, end)
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if i:
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extents += letter_spacing
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surface.text_path_width += extents
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if not all((start_point, middle_point, end_point)):
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continue
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if not 0 <= middle <= length:
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continue
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surface.context.save()
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surface.context.translate(*start_point)
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surface.context.rotate(point_angle(*(start_point + end_point)))
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surface.context.translate(0, surface.cursor_d_position[1])
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surface.context.move_to(0, 0)
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bounding_box = extend_bounding_box(
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bounding_box, ((end_point[0], text_extents[3]),))
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else:
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surface.context.save()
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x = surface.cursor_position[0] if x is None else x
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y = surface.cursor_position[1] if y is None else y
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if i:
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x += letter_spacing
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surface.context.move_to(x, y)
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cursor_position = x + extents, y
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surface.context.rel_move_to(*surface.cursor_d_position)
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surface.context.rel_move_to(x_align, y_align)
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surface.context.rotate(last_r if r is None else r)
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points = (
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(cursor_position[0] + x_align +
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surface.cursor_d_position[0],
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cursor_position[1] + y_align +
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surface.cursor_d_position[1]),
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(cursor_position[0] + x_align + text_extents[4] +
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surface.cursor_d_position[0],
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cursor_position[1] + y_align + text_extents[3] +
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surface.cursor_d_position[1]))
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bounding_box = extend_bounding_box(bounding_box, points)
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# Only draw characters with 'content' (workaround for bug in cairo)
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if not letter.isspace():
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if draw_as_text:
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surface.context.show_text(letter)
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else:
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surface.context.text_path(letter)
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surface.context.restore()
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if not text_path:
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surface.cursor_position = cursor_position
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else:
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x = x[0] if x else surface.cursor_position[0]
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y = y[0] if y else surface.cursor_position[1]
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dx = dx[0] if dx else 0
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dy = dy[0] if dy else 0
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surface.cursor_position = (x + dx, y + dy)
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# If a valid bounding box is calculated store it in the node
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if is_valid_bounding_box(bounding_box):
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node['text_bounding_box'] = bounding_box
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