"""
A Cairo backend for matplotlib
==============================
:Author: Steve Chaplin and others
This backend depends on cairocffi or pycairo.
"""
import gzip
import math
import numpy as np
try:
import cairo
if cairo.version_info < (1, 11, 0):
# Introduced create_for_data for Py3.
raise ImportError
except ImportError:
try:
import cairocffi as cairo
except ImportError as err:
raise ImportError(
"cairo backend requires that pycairo>=1.11.0 or cairocffi"
"is installed") from err
from .. import cbook, font_manager
from matplotlib.backend_bases import (
_Backend, _check_savefig_extra_args, FigureCanvasBase, FigureManagerBase,
GraphicsContextBase, RendererBase)
from matplotlib.font_manager import ttfFontProperty
from matplotlib.mathtext import MathTextParser
from matplotlib.path import Path
from matplotlib.transforms import Affine2D
backend_version = cairo.version
if cairo.__name__ == "cairocffi":
# Convert a pycairo context to a cairocffi one.
def _to_context(ctx):
if not isinstance(ctx, cairo.Context):
ctx = cairo.Context._from_pointer(
cairo.ffi.cast(
'cairo_t **',
id(ctx) + object.__basicsize__)[0],
incref=True)
return ctx
else:
# Pass-through a pycairo context.
def _to_context(ctx):
return ctx
def _append_path(ctx, path, transform, clip=None):
for points, code in path.iter_segments(
transform, remove_nans=True, clip=clip):
if code == Path.MOVETO:
ctx.move_to(*points)
elif code == Path.CLOSEPOLY:
ctx.close_path()
elif code == Path.LINETO:
ctx.line_to(*points)
elif code == Path.CURVE3:
cur = np.asarray(ctx.get_current_point())
a = points[:2]
b = points[-2:]
ctx.curve_to(*(cur / 3 + a * 2 / 3), *(a * 2 / 3 + b / 3), *b)
elif code == Path.CURVE4:
ctx.curve_to(*points)
def _cairo_font_args_from_font_prop(prop):
"""
Convert a `.FontProperties` or a `.FontEntry` to arguments that can be
passed to `.Context.select_font_face`.
"""
def attr(field):
try:
return getattr(prop, f"get_{field}")()
except AttributeError:
return getattr(prop, field)
name = attr("name")
slant = getattr(cairo, f"FONT_SLANT_{attr('style').upper()}")
weight = attr("weight")
weight = (cairo.FONT_WEIGHT_NORMAL
if font_manager.weight_dict.get(weight, weight) < 550
else cairo.FONT_WEIGHT_BOLD)
return name, slant, weight
[docs]class RendererCairo(RendererBase):
@cbook.deprecated("3.3")
@property
def fontweights(self):
return {
100: cairo.FONT_WEIGHT_NORMAL,
200: cairo.FONT_WEIGHT_NORMAL,
300: cairo.FONT_WEIGHT_NORMAL,
400: cairo.FONT_WEIGHT_NORMAL,
500: cairo.FONT_WEIGHT_NORMAL,
600: cairo.FONT_WEIGHT_BOLD,
700: cairo.FONT_WEIGHT_BOLD,
800: cairo.FONT_WEIGHT_BOLD,
900: cairo.FONT_WEIGHT_BOLD,
'ultralight': cairo.FONT_WEIGHT_NORMAL,
'light': cairo.FONT_WEIGHT_NORMAL,
'normal': cairo.FONT_WEIGHT_NORMAL,
'medium': cairo.FONT_WEIGHT_NORMAL,
'regular': cairo.FONT_WEIGHT_NORMAL,
'semibold': cairo.FONT_WEIGHT_BOLD,
'bold': cairo.FONT_WEIGHT_BOLD,
'heavy': cairo.FONT_WEIGHT_BOLD,
'ultrabold': cairo.FONT_WEIGHT_BOLD,
'black': cairo.FONT_WEIGHT_BOLD,
}
@cbook.deprecated("3.3")
@property
def fontangles(self):
return {
'italic': cairo.FONT_SLANT_ITALIC,
'normal': cairo.FONT_SLANT_NORMAL,
'oblique': cairo.FONT_SLANT_OBLIQUE,
}
def __init__(self, dpi):
self.dpi = dpi
self.gc = GraphicsContextCairo(renderer=self)
self.text_ctx = cairo.Context(
cairo.ImageSurface(cairo.FORMAT_ARGB32, 1, 1))
self.mathtext_parser = MathTextParser('Cairo')
RendererBase.__init__(self)
[docs] def set_ctx_from_surface(self, surface):
self.gc.ctx = cairo.Context(surface)
# Although it may appear natural to automatically call
# `self.set_width_height(surface.get_width(), surface.get_height())`
# here (instead of having the caller do so separately), this would fail
# for PDF/PS/SVG surfaces, which have no way to report their extents.
[docs] def set_width_height(self, width, height):
self.width = width
self.height = height
def _fill_and_stroke(self, ctx, fill_c, alpha, alpha_overrides):
if fill_c is not None:
ctx.save()
if len(fill_c) == 3 or alpha_overrides:
ctx.set_source_rgba(fill_c[0], fill_c[1], fill_c[2], alpha)
else:
ctx.set_source_rgba(fill_c[0], fill_c[1], fill_c[2], fill_c[3])
ctx.fill_preserve()
ctx.restore()
ctx.stroke()
[docs] def draw_path(self, gc, path, transform, rgbFace=None):
# docstring inherited
ctx = gc.ctx
# Clip the path to the actual rendering extents if it isn't filled.
clip = (ctx.clip_extents()
if rgbFace is None and gc.get_hatch() is None
else None)
transform = (transform
+ Affine2D().scale(1, -1).translate(0, self.height))
ctx.new_path()
_append_path(ctx, path, transform, clip)
self._fill_and_stroke(
ctx, rgbFace, gc.get_alpha(), gc.get_forced_alpha())
[docs] def draw_markers(self, gc, marker_path, marker_trans, path, transform,
rgbFace=None):
# docstring inherited
ctx = gc.ctx
ctx.new_path()
# Create the path for the marker; it needs to be flipped here already!
_append_path(ctx, marker_path, marker_trans + Affine2D().scale(1, -1))
marker_path = ctx.copy_path_flat()
# Figure out whether the path has a fill
x1, y1, x2, y2 = ctx.fill_extents()
if x1 == 0 and y1 == 0 and x2 == 0 and y2 == 0:
filled = False
# No fill, just unset this (so we don't try to fill it later on)
rgbFace = None
else:
filled = True
transform = (transform
+ Affine2D().scale(1, -1).translate(0, self.height))
ctx.new_path()
for i, (vertices, codes) in enumerate(
path.iter_segments(transform, simplify=False)):
if len(vertices):
x, y = vertices[-2:]
ctx.save()
# Translate and apply path
ctx.translate(x, y)
ctx.append_path(marker_path)
ctx.restore()
# Slower code path if there is a fill; we need to draw
# the fill and stroke for each marker at the same time.
# Also flush out the drawing every once in a while to
# prevent the paths from getting way too long.
if filled or i % 1000 == 0:
self._fill_and_stroke(
ctx, rgbFace, gc.get_alpha(), gc.get_forced_alpha())
# Fast path, if there is no fill, draw everything in one step
if not filled:
self._fill_and_stroke(
ctx, rgbFace, gc.get_alpha(), gc.get_forced_alpha())
[docs] def draw_image(self, gc, x, y, im):
im = cbook._unmultiplied_rgba8888_to_premultiplied_argb32(im[::-1])
surface = cairo.ImageSurface.create_for_data(
im.ravel().data, cairo.FORMAT_ARGB32,
im.shape[1], im.shape[0], im.shape[1] * 4)
ctx = gc.ctx
y = self.height - y - im.shape[0]
ctx.save()
ctx.set_source_surface(surface, float(x), float(y))
ctx.paint()
ctx.restore()
[docs] def draw_text(self, gc, x, y, s, prop, angle, ismath=False, mtext=None):
# docstring inherited
# Note: (x, y) are device/display coords, not user-coords, unlike other
# draw_* methods
if ismath:
self._draw_mathtext(gc, x, y, s, prop, angle)
else:
ctx = gc.ctx
ctx.new_path()
ctx.move_to(x, y)
ctx.select_font_face(*_cairo_font_args_from_font_prop(prop))
ctx.save()
ctx.set_font_size(prop.get_size_in_points() * self.dpi / 72)
if angle:
ctx.rotate(np.deg2rad(-angle))
ctx.show_text(s)
ctx.restore()
def _draw_mathtext(self, gc, x, y, s, prop, angle):
ctx = gc.ctx
width, height, descent, glyphs, rects = self.mathtext_parser.parse(
s, self.dpi, prop)
ctx.save()
ctx.translate(x, y)
if angle:
ctx.rotate(np.deg2rad(-angle))
for font, fontsize, s, ox, oy in glyphs:
ctx.new_path()
ctx.move_to(ox, oy)
ctx.select_font_face(
*_cairo_font_args_from_font_prop(ttfFontProperty(font)))
ctx.set_font_size(fontsize * self.dpi / 72)
ctx.show_text(s)
for ox, oy, w, h in rects:
ctx.new_path()
ctx.rectangle(ox, oy, w, h)
ctx.set_source_rgb(0, 0, 0)
ctx.fill_preserve()
ctx.restore()
[docs] def get_canvas_width_height(self):
# docstring inherited
return self.width, self.height
[docs] def get_text_width_height_descent(self, s, prop, ismath):
# docstring inherited
if ismath:
width, height, descent, fonts, used_characters = \
self.mathtext_parser.parse(s, self.dpi, prop)
return width, height, descent
ctx = self.text_ctx
# problem - scale remembers last setting and font can become
# enormous causing program to crash
# save/restore prevents the problem
ctx.save()
ctx.select_font_face(*_cairo_font_args_from_font_prop(prop))
# Cairo (says it) uses 1/96 inch user space units, ref: cairo_gstate.c
# but if /96.0 is used the font is too small
ctx.set_font_size(prop.get_size_in_points() * self.dpi / 72)
y_bearing, w, h = ctx.text_extents(s)[1:4]
ctx.restore()
return w, h, h + y_bearing
[docs] def new_gc(self):
# docstring inherited
self.gc.ctx.save()
self.gc._alpha = 1
self.gc._forced_alpha = False # if True, _alpha overrides A from RGBA
return self.gc
[docs] def points_to_pixels(self, points):
# docstring inherited
return points / 72 * self.dpi
[docs]class GraphicsContextCairo(GraphicsContextBase):
_joind = {
'bevel': cairo.LINE_JOIN_BEVEL,
'miter': cairo.LINE_JOIN_MITER,
'round': cairo.LINE_JOIN_ROUND,
}
_capd = {
'butt': cairo.LINE_CAP_BUTT,
'projecting': cairo.LINE_CAP_SQUARE,
'round': cairo.LINE_CAP_ROUND,
}
def __init__(self, renderer):
GraphicsContextBase.__init__(self)
self.renderer = renderer
[docs] def restore(self):
self.ctx.restore()
[docs] def set_alpha(self, alpha):
GraphicsContextBase.set_alpha(self, alpha)
_alpha = self.get_alpha()
rgb = self._rgb
if self.get_forced_alpha():
self.ctx.set_source_rgba(rgb[0], rgb[1], rgb[2], _alpha)
else:
self.ctx.set_source_rgba(rgb[0], rgb[1], rgb[2], rgb[3])
# def set_antialiased(self, b):
# cairo has many antialiasing modes, we need to pick one for True and
# one for False.
[docs] def set_capstyle(self, cs):
self.ctx.set_line_cap(cbook._check_getitem(self._capd, capstyle=cs))
self._capstyle = cs
[docs] def set_clip_rectangle(self, rectangle):
if not rectangle:
return
x, y, w, h = np.round(rectangle.bounds)
ctx = self.ctx
ctx.new_path()
ctx.rectangle(x, self.renderer.height - h - y, w, h)
ctx.clip()
[docs] def set_clip_path(self, path):
if not path:
return
tpath, affine = path.get_transformed_path_and_affine()
ctx = self.ctx
ctx.new_path()
affine = (affine
+ Affine2D().scale(1, -1).translate(0, self.renderer.height))
_append_path(ctx, tpath, affine)
ctx.clip()
[docs] def set_dashes(self, offset, dashes):
self._dashes = offset, dashes
if dashes is None:
self.ctx.set_dash([], 0) # switch dashes off
else:
self.ctx.set_dash(
list(self.renderer.points_to_pixels(np.asarray(dashes))),
offset)
[docs] def set_foreground(self, fg, isRGBA=None):
GraphicsContextBase.set_foreground(self, fg, isRGBA)
if len(self._rgb) == 3:
self.ctx.set_source_rgb(*self._rgb)
else:
self.ctx.set_source_rgba(*self._rgb)
[docs] def get_rgb(self):
return self.ctx.get_source().get_rgba()[:3]
[docs] def set_joinstyle(self, js):
self.ctx.set_line_join(cbook._check_getitem(self._joind, joinstyle=js))
self._joinstyle = js
[docs] def set_linewidth(self, w):
self._linewidth = float(w)
self.ctx.set_line_width(self.renderer.points_to_pixels(w))
class _CairoRegion:
def __init__(self, slices, data):
self._slices = slices
self._data = data
@_Backend.export
class _BackendCairo(_Backend):
FigureCanvas = FigureCanvasCairo
FigureManager = FigureManagerBase
