def draw_text_on_line(
self,
coords,
text,
color=(0, 0, 0),
font_size=10,
font_family='Tahoma',
font_style=cairo.FONT_SLANT_NORMAL,
font_weight=cairo.FONT_WEIGHT_NORMAL,
text_halo_width=1,
text_halo_color=(1, 1, 1),
text_halo_line_cap=cairo.LINE_CAP_ROUND,
text_halo_line_join=cairo.LINE_JOIN_ROUND,
text_halo_line_dash=None,
text_transform=None,
):
'''
Draws text on a line. Tries to find a position with the least change
in gradient and which is closest to the middle of the line.
:param coords: iterable containing all coordinates as ``(lon, lat)``
:param text: text to be drawn
:param color: ``(r, g, b[, a])``
:param font_size: font-size in unit (pixel/point)
:param font_family: font name
:param font_style: ``cairo.FONT_SLANT_NORMAL``,
``cairo.FONT_SLANT_ITALIC`` or ``cairo.FONT_SLANT_OBLIQUE``
:param font_weight: ``cairo.FONT_WEIGHT_NORMAL`` or
``cairo.FONT_WEIGHT_BOLD``
:param text_halo_width: border-width in unit (pixel/point)
:param text_halo_color: ``(r, g, b[, a])``
:param text_halo_line_cap: one of :const:`cairo.LINE_CAP_*`
:param text_halo_line_join: one of :const:`cairo.LINE_JOIN_*`
:param text_halo_line_dash: list/tuple used by
:meth:`cairo.Context.set_dash`
:param text_transform: one of ``'lowercase'``, ``'uppercase'`` or
``'capitalize'``
'''
text = text.strip()
if not text:
return
coords = map(lambda c: self.transform_coords(*c), coords)
self.context.select_font_face(font_family, font_style, font_weight)
self.context.set_font_size(font_size)
text = utils.text_transform(text, text_transform)
width, height = self.context.text_extents(text)[2:4]
font_ascent, font_descent = self.context.font_extents()[0:2]
self.context.new_path()
#: make sure line does not intersect other conflict objects
line = LineString(coords)
line = self.map_area.intersection(line)
line = line.difference(self.map_area.exterior.buffer(height))
line = line.difference(self.conflict_area)
#: check whether line is empty or is split into several different parts
if line.geom_type == 'GeometryCollection':
return
elif line.geom_type == 'MultiLineString':
longest = None
min_len = width * 1.2
for seg in line.geoms:
seg_len = seg.length
if seg_len > min_len:
longest = seg
min_len = seg_len
if longest is None:
return
line = longest
coords = tuple(line.coords)
seg = utils.linestring_text_optimal_segment(coords, width)
# line has either to much change in gradients or is too short
if seg is None:
return
#: crop optimal segment of linestring
start, end = seg
coords = coords[start:end+1]
#: make sure text is rendered from left to right
if coords[-1][0] < coords[0][0]:
coords = tuple(reversed(coords))
# translate linestring so text is rendered vertically in the middle
line = LineString(tuple(coords))
offset = font_ascent / 2. - font_descent
line = line.parallel_offset(offset, 'left', resolution=3)
# make sure text is rendered centered on line
start_len = (line.length - width) / 2.
char_coords = None
chars = utils.generate_char_geoms(self.context, text)
#: draw all character paths
for char in utils.iter_chars_on_line(chars, line, start_len):
for geom in char.geoms:
char_coords = iter(geom.exterior.coords)
self.context.move_to(*char_coords.next())
for lon, lat in char_coords:
self.context.line_to(lon, lat)
self.context.close_path()
#: only add line to reserved area if text was drawn
if char_coords is not None:
covered = line.buffer(height)
self.conflict_union(covered)
#: draw border around characters
self.context.set_line_cap(cairo.LINE_CAP_ROUND)
self.context.set_source_rgba(*text_halo_color)
self.context.set_line_width(2 * text_halo_width)
self.context.set_line_cap(text_halo_line_cap)
self.context.set_line_join(text_halo_line_join)
self.context.set_dash(text_halo_line_dash or tuple())
self.context.stroke_preserve()
#: fill actual text
self.context.set_source_rgba(*color)
self.context.fill()
def draw_text(
self,
coord,
text,
color=(0, 0, 0),
font_size=11,
font_family='Tahoma',
font_style=cairo.FONT_SLANT_NORMAL,
font_weight=cairo.FONT_WEIGHT_NORMAL,
text_halo_width=3,
text_halo_color=(1, 1, 1),
text_halo_line_cap=cairo.LINE_CAP_ROUND,
text_halo_line_join=cairo.LINE_JOIN_ROUND,
text_halo_line_dash=None,
text_transform=None,
image=None,
image_margin=4
):
'''
Draws text either centered on coordinate or the image centered on
coordinate and text on the right of the image.
:param coord: ``(lon, lat)``
:param text: text to be drawn
:param color: ``(r, g, b[, a])``
:param font_size: font-size in unit (pixel/point)
:param font_family: font name
:param font_style: ``cairo.FONT_SLANT_NORMAL``,
``cairo.FONT_SLANT_ITALIC`` or ``cairo.FONT_SLANT_OBLIQUE``
:param font_weight: ``cairo.FONT_WEIGHT_NORMAL`` or
``cairo.FONT_WEIGHT_BOLD``
:param text_halo_width: border-width in unit (pixel/point)
:param text_halo_color: ``(r, g, b[, a])``
:param text_halo_line_cap: one of :const:`cairo.LINE_CAP_*`
:param text_halo_line_join: one of :const:`cairo.LINE_JOIN_*`
:param text_halo_line_dash: list/tuple used by
:meth:`cairo.Context.set_dash`
:param text_transform: one of ``'lowercase'``, ``'uppercase'`` or
``'capitalize'``
:param image: file object or path to image file
:param image_margin: space between text and image in int or float
'''
x, y = self.transform_coords(*coord)
# abort if there are already too many text_paths in this area
if self.conflict_density(x, y) > 0.07:
self.context.new_path()
return
text = utils.text_transform(text, text_transform)
#: draw spot name
self.context.select_font_face(font_family, font_style, font_weight)
self.context.set_font_size(font_size)
width, height = self.context.text_extents(text)[2:4]
if image is not None:
image = cairo.ImageSurface.create_from_png(image)
image_width, image_height = image.get_width(), image.get_height()
text_area = box(
x - image_width / 2.0,
y - max(height, image_height) / 2.0,
x + image_width + width + image_margin,
y + max(height, image_height) / 2.0
)
else:
# place text directly on coord
x -= width / 2.0
text_area = box(x, y - height / 2., x + width, y + height / 2.)
try:
newx, newy = self.find_free_position(text_area)
except TypeError: # no free position found
self.context.new_path()
return
if image is not None:
y = newy + (max(height, image_height) - image_height) / 2.0
self.context.set_source_surface(image, newx, y)
self.context.paint()
image_area = box(x, y, x + image_width, y + image_height)
newx += image_width + image_margin
newy += (image_height + height) / 2.0
else:
# find_free_position uses minx and miny as position but
# cairo uses bottom left corner
newx, newy = newx, newy + height
# abort if new position is too far away from original position
if Point(newx, newy).distance(Point(x, y)) > 0.1 * self.max_size:
self.context.new_path()
return
# round positions for clear text rendering
self.context.move_to(int(newx), int(newy))
self.context.text_path(text)
#: draw text halo
self.context.set_line_cap(cairo.LINE_CAP_ROUND)
self.context.set_source_rgba(*text_halo_color)
self.context.set_line_width(2 * text_halo_width)
self.context.set_line_cap(text_halo_line_cap)
self.context.set_line_join(text_halo_line_join)
self.context.set_dash(text_halo_line_dash or tuple())
self.context.stroke_preserve()
#: determine covered area by text
area = box(*self.context.path_extents())
if image is not None:
area = area.union(image_area)
self.conflict_union(area)
#: fill characters with color
self.context.set_source_rgba(*color)
self.context.fill()
