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"""
A Cairo backend for matplotlib
Author: Steve Chaplin
Cairo is a vector graphics library with cross-device output support.
Features of Cairo:
* anti-aliasing
* alpha channel
* saves image files as PNG, PostScript, PDF
http://cairographics.org
Requires (in order, all available from Cairo website):
cairo, pycairo
Naming Conventions
* classes MixedUpperCase
* varables lowerUpper
* functions underscore_separated
"""
from __future__ import division
import os, sys, warnings, gzip
import numpy as np
def _fn_name(): return sys._getframe(1).f_code.co_name
try:
import cairo
except ImportError:
raise ImportError("Cairo backend requires that pycairo is installed.")
_version_required = (1,2,0)
if cairo.version_info < _version_required:
raise ImportError ("Pycairo %d.%d.%d is installed\n"
"Pycairo %d.%d.%d or later is required"
% (cairo.version_info + _version_required))
backend_version = cairo.version
del _version_required
from matplotlib.backend_bases import RendererBase, GraphicsContextBase,\
FigureManagerBase, FigureCanvasBase
from matplotlib.cbook import is_string_like
from matplotlib.figure import Figure
from matplotlib.mathtext import MathTextParser
from matplotlib.path import Path
from matplotlib.transforms import Bbox, Affine2D
from matplotlib.font_manager import ttfFontProperty
from matplotlib import rcParams
_debug = False
#_debug = True
# Image::color_conv(format) for draw_image()
if sys.byteorder == 'little':
BYTE_FORMAT = 0 # BGRA
else:
BYTE_FORMAT = 1 # ARGB
class RendererCairo(RendererBase):
fontweights = {
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,
'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,
}
fontangles = {
'italic' : cairo.FONT_SLANT_ITALIC,
'normal' : cairo.FONT_SLANT_NORMAL,
'oblique' : cairo.FONT_SLANT_OBLIQUE,
}
def __init__(self, dpi):
"""
"""
if _debug: print '%s.%s()' % (self.__class__.__name__, _fn_name())
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)
def set_ctx_from_surface (self, surface):
self.gc.ctx = cairo.Context (surface)
def set_width_height(self, width, height):
self.width = width
self.height = height
self.matrix_flipy = cairo.Matrix (yy=-1, y0=self.height)
# use matrix_flipy for ALL rendering?
# - problem with text? - will need to switch matrix_flipy off, or do a
# font transform?
def _fill_and_stroke (self, ctx, fill_c, alpha):
if fill_c is not None:
ctx.save()
if len(fill_c) == 3:
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], alpha*fill_c[3])
ctx.fill_preserve()
ctx.restore()
ctx.stroke()
@staticmethod
def convert_path(ctx, path, transform):
for points, code in path.iter_segments(transform):
if code == Path.MOVETO:
ctx.move_to(*points)
elif code == Path.LINETO:
ctx.line_to(*points)
elif code == Path.CURVE3:
ctx.curve_to(points[0], points[1],
points[0], points[1],
points[2], points[3])
elif code == Path.CURVE4:
ctx.curve_to(*points)
elif code == Path.CLOSEPOLY:
ctx.close_path()
def draw_path(self, gc, path, transform, rgbFace=None):
if len(path.vertices) > 18980:
raise ValueError("The Cairo backend can not draw paths longer than 18980 points.")
ctx = gc.ctx
transform = transform + \
Affine2D().scale(1.0, -1.0).translate(0, self.height)
ctx.new_path()
self.convert_path(ctx, path, transform)
self._fill_and_stroke(ctx, rgbFace, gc.get_alpha())
def draw_image(self, gc, x, y, im):
# bbox - not currently used
if _debug: print '%s.%s()' % (self.__class__.__name__, _fn_name())
clippath, clippath_trans = gc.get_clip_path()
im.flipud_out()
rows, cols, buf = im.color_conv (BYTE_FORMAT)
surface = cairo.ImageSurface.create_for_data (
buf, cairo.FORMAT_ARGB32, cols, rows, cols*4)
# function does not pass a 'gc' so use renderer.ctx
ctx = self.gc.ctx
ctx.save()
if clippath is not None:
ctx.new_path()
RendererCairo.convert_path(ctx, clippath, clippath_trans)
ctx.clip()
y = self.height - y - rows
ctx.set_source_surface (surface, x, y)
ctx.paint()
ctx.restore()
im.flipud_out()
def draw_text(self, gc, x, y, s, prop, angle, ismath=False):
# Note: x,y are device/display coords, not user-coords, unlike other
# draw_* methods
if _debug: print '%s.%s()' % (self.__class__.__name__, _fn_name())
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 (prop.get_name(),
self.fontangles [prop.get_style()],
self.fontweights[prop.get_weight()])
size = prop.get_size_in_points() * self.dpi / 72.0
ctx.save()
if angle:
ctx.rotate (-angle * np.pi / 180)
ctx.set_font_size (size)
ctx.show_text (s.encode("utf-8"))
ctx.restore()
def _draw_mathtext(self, gc, x, y, s, prop, angle):
if _debug: print '%s.%s()' % (self.__class__.__name__, _fn_name())
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 (-angle * np.pi / 180)
for font, fontsize, s, ox, oy in glyphs:
ctx.new_path()
ctx.move_to(ox, oy)
fontProp = ttfFontProperty(font)
ctx.save()
ctx.select_font_face (fontProp.name,
self.fontangles [fontProp.style],
self.fontweights[fontProp.weight])
size = fontsize * self.dpi / 72.0
ctx.set_font_size(size)
ctx.show_text(s.encode("utf-8"))
ctx.restore()
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()
def flipy(self):
if _debug: print '%s.%s()' % (self.__class__.__name__, _fn_name())
return True
#return False # tried - all draw objects ok except text (and images?)
# which comes out mirrored!
def get_canvas_width_height(self):
if _debug: print '%s.%s()' % (self.__class__.__name__, _fn_name())
return self.width, self.height
def get_text_width_height_descent(self, s, prop, ismath):
if _debug: print '%s.%s()' % (self.__class__.__name__, _fn_name())
if ismath:
width, height, descent, fonts, used_characters = self.mathtext_parser.parse(
s, self.dpi, prop)
return width, height, descent
ctx = self.text_ctx
ctx.save()
ctx.select_font_face (prop.get_name(),
self.fontangles [prop.get_style()],
self.fontweights[prop.get_weight()])
# 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
size = prop.get_size_in_points() * self.dpi / 72.0
# problem - scale remembers last setting and font can become
# enormous causing program to crash
# save/restore prevents the problem
ctx.set_font_size (size)
y_bearing, w, h = ctx.text_extents (s)[1:4]
ctx.restore()
return w, h, h + y_bearing
def new_gc(self):
if _debug: print '%s.%s()' % (self.__class__.__name__, _fn_name())
self.gc.ctx.save()
return self.gc
def points_to_pixels(self, points):
if _debug: print '%s.%s()' % (self.__class__.__name__, _fn_name())
return points/72.0 * self.dpi
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
def restore(self):
self.ctx.restore()
def set_alpha(self, alpha):
GraphicsContextBase.set_alpha(self, alpha)
_alpha = self.get_alpha()
rgb = self._rgb
self.ctx.set_source_rgba (rgb[0], rgb[1], rgb[2], _alpha)
#def set_antialiased(self, b):
# enable/disable anti-aliasing is not (yet) supported by Cairo
def set_capstyle(self, cs):
if cs in ('butt', 'round', 'projecting'):
self._capstyle = cs
self.ctx.set_line_cap (self._capd[cs])
else:
raise ValueError('Unrecognized cap style. Found %s' % cs)
def set_clip_rectangle(self, rectangle):
if not rectangle: return
x,y,w,h = rectangle.bounds
# pixel-aligned clip-regions are faster
x,y,w,h = round(x), round(y), round(w), round(h)
ctx = self.ctx
ctx.new_path()
ctx.rectangle (x, self.renderer.height - h - y, w, h)
ctx.clip ()
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(1.0, -1.0).translate(0.0, self.renderer.height)
RendererCairo.convert_path(ctx, tpath, affine)
ctx.clip()
def set_dashes(self, offset, dashes):
self._dashes = offset, dashes
if dashes == None:
self.ctx.set_dash([], 0) # switch dashes off
else:
self.ctx.set_dash (
self.renderer.points_to_pixels (np.asarray(dashes)), offset)
def set_foreground(self, fg, isRGB=None):
GraphicsContextBase.set_foreground(self, fg, isRGB)
if len(self._rgb) == 3:
self.ctx.set_source_rgb(*self._rgb)
else:
self.ctx.set_source_rgba(*self._rgb)
def set_graylevel(self, frac):
GraphicsContextBase.set_graylevel(self, frac)
if len(self._rgb) == 3:
self.ctx.set_source_rgb(*self._rgb)
else:
self.ctx.set_source_rgba(*self._rgb)
def set_joinstyle(self, js):
if js in ('miter', 'round', 'bevel'):
self._joinstyle = js
self.ctx.set_line_join(self._joind[js])
else:
raise ValueError('Unrecognized join style. Found %s' % js)
def set_linewidth(self, w):
self._linewidth = w
self.ctx.set_line_width (self.renderer.points_to_pixels(w))
def new_figure_manager(num, *args, **kwargs): # called by backends/__init__.py
"""
Create a new figure manager instance
"""
if _debug: print '%s.%s()' % (self.__class__.__name__, _fn_name())
FigureClass = kwargs.pop('FigureClass', Figure)
thisFig = FigureClass(*args, **kwargs)
canvas = FigureCanvasCairo(thisFig)
manager = FigureManagerBase(canvas, num)
return manager
class FigureCanvasCairo (FigureCanvasBase):
def print_png(self, fobj, *args, **kwargs):
width, height = self.get_width_height()
renderer = RendererCairo (self.figure.dpi)
renderer.set_width_height (width, height)
surface = cairo.ImageSurface (cairo.FORMAT_ARGB32, width, height)
renderer.set_ctx_from_surface (surface)
self.figure.draw (renderer)
surface.write_to_png (fobj)
def print_pdf(self, fobj, *args, **kwargs):
return self._save(fobj, 'pdf', *args, **kwargs)
def print_ps(self, fobj, *args, **kwargs):
return self._save(fobj, 'ps', *args, **kwargs)
def print_svg(self, fobj, *args, **kwargs):
return self._save(fobj, 'svg', *args, **kwargs)
def print_svgz(self, fobj, *args, **kwargs):
return self._save(fobj, 'svgz', *args, **kwargs)
def get_default_filetype(self):
return rcParams['cairo.format']
def _save (self, fo, format, **kwargs):
# save PDF/PS/SVG
orientation = kwargs.get('orientation', 'portrait')
dpi = 72
self.figure.dpi = dpi
w_in, h_in = self.figure.get_size_inches()
width_in_points, height_in_points = w_in * dpi, h_in * dpi
if orientation == 'landscape':
width_in_points, height_in_points = (height_in_points,
width_in_points)
if format == 'ps':
if not cairo.HAS_PS_SURFACE:
raise RuntimeError ('cairo has not been compiled with PS '
'support enabled')
surface = cairo.PSSurface (fo, width_in_points, height_in_points)
elif format == 'pdf':
if not cairo.HAS_PDF_SURFACE:
raise RuntimeError ('cairo has not been compiled with PDF '
'support enabled')
surface = cairo.PDFSurface (fo, width_in_points, height_in_points)
elif format in ('svg', 'svgz'):
if not cairo.HAS_SVG_SURFACE:
raise RuntimeError ('cairo has not been compiled with SVG '
'support enabled')
if format == 'svgz':
filename = fo
if is_string_like(fo):
fo = open(fo, 'wb')
fo = gzip.GzipFile(None, 'wb', fileobj=fo)
surface = cairo.SVGSurface (fo, width_in_points, height_in_points)
else:
warnings.warn ("unknown format: %s" % format)
return
# surface.set_dpi() can be used
renderer = RendererCairo (self.figure.dpi)
renderer.set_width_height (width_in_points, height_in_points)
renderer.set_ctx_from_surface (surface)
ctx = renderer.gc.ctx
if orientation == 'landscape':
ctx.rotate (np.pi/2)
ctx.translate (0, -height_in_points)
# cairo/src/cairo_ps_surface.c
# '%%Orientation: Portrait' is always written to the file header
# '%%Orientation: Landscape' would possibly cause problems
# since some printers would rotate again ?
# TODO:
# add portrait/landscape checkbox to FileChooser
self.figure.draw (renderer)
show_fig_border = False # for testing figure orientation and scaling
if show_fig_border:
ctx.new_path()
ctx.rectangle(0, 0, width_in_points, height_in_points)
ctx.set_line_width(4.0)
ctx.set_source_rgb(1,0,0)
ctx.stroke()
ctx.move_to(30,30)
ctx.select_font_face ('sans-serif')
ctx.set_font_size(20)
ctx.show_text('Origin corner')
ctx.show_page()
surface.finish()