matplotlib.backends.backend_cairo

A Cairo backend for matplotlib

Author:Steve Chaplin and others

This backend depends on cairocffi or pycairo.

matplotlib.backends.backend_cairo.FigureCanvas

alias of matplotlib.backends.backend_cairo.FigureCanvasCairo

class matplotlib.backends.backend_cairo.FigureCanvasCairo(figure)[source]

Bases: matplotlib.backend_bases.FigureCanvasBase

print_pdf(self, fobj, *args, **kwargs)[source]
print_png(self, fobj, *args, **kwargs)[source]
print_ps(self, fobj, *args, **kwargs)[source]
print_raw(self, fobj, *args, **kwargs)
print_rgba(self, fobj, *args, **kwargs)[source]
print_svg(self, fobj, *args, **kwargs)[source]
print_svgz(self, fobj, *args, **kwargs)[source]
class matplotlib.backends.backend_cairo.GraphicsContextCairo(renderer)[source]

Bases: matplotlib.backend_bases.GraphicsContextBase

get_rgb(self)[source]

Return a tuple of three or four floats from 0-1.

restore(self)[source]

Restore the graphics context from the stack - needed only for backends that save graphics contexts on a stack.

set_alpha(self, alpha)[source]

Set the alpha value used for blending - not supported on all backends.

If alpha=None (the default), the alpha components of the foreground and fill colors will be used to set their respective transparencies (where applicable); otherwise, alpha will override them.

set_capstyle(self, cs)[source]

Set the capstyle to be one of ('butt', 'round', 'projecting').

set_clip_path(self, path)[source]

Set the clip path and transformation.

Parameters:
pathTransformedPath or None
set_clip_rectangle(self, rectangle)[source]

Set the clip rectangle with sequence (left, bottom, width, height)

set_dashes(self, offset, dashes)[source]

Set the dash style for the gc.

Parameters:
dash_offsetfloat or None

The offset (usually 0).

dash_listarray-like or None

The on-off sequence as points.

Notes

(None, None) specifies a solid line.

See p. 107 of to PostScript blue book for more info.

set_foreground(self, fg, isRGBA=None)[source]

Set the foreground color.

Parameters:
fgcolor
isRGBAbool

If fg is known to be an (r, g, b, a) tuple, isRGBA can be set to True to improve performance.

set_joinstyle(self, js)[source]

Set the join style to be one of ('miter', 'round', 'bevel').

set_linewidth(self, w)[source]

Set the linewidth in points.

class matplotlib.backends.backend_cairo.RendererCairo(dpi)[source]

Bases: matplotlib.backend_bases.RendererBase

draw_image(self, gc, x, y, im)[source]

Draw an RGBA image.

Parameters:
gcGraphicsContextBase

a graphics context with clipping information.

xscalar

the distance in physical units (i.e., dots or pixels) from the left hand side of the canvas.

yscalar

the distance in physical units (i.e., dots or pixels) from the bottom side of the canvas.

imarray-like, shape=(N, M, 4), dtype=np.uint8

An array of RGBA pixels.

transformmatplotlib.transforms.Affine2DBase

If and only if the concrete backend is written such that option_scale_image() returns True, an affine transformation may be passed to draw_image(). It takes the form of a Affine2DBase instance. The translation vector of the transformation is given in physical units (i.e., dots or pixels). Note that the transformation does not override x and y, and has to be applied before translating the result by x and y (this can be accomplished by adding x and y to the translation vector defined by transform).

draw_markers(self, gc, marker_path, marker_trans, path, transform, rgbFace=None)[source]

Draw a marker at each of the vertices in path.

This includes all vertices, including control points on curves. To avoid that behavior, those vertices should be removed before calling this function.

This provides a fallback implementation of draw_markers that makes multiple calls to draw_path(). Some backends may want to override this method in order to draw the marker only once and reuse it multiple times.

Parameters:
gcGraphicsContextBase

The graphics context.

marker_transmatplotlib.transforms.Transform

An affine transform applied to the marker.

transmatplotlib.transforms.Transform

An affine transform applied to the path.

draw_path(self, gc, path, transform, rgbFace=None)[source]

Draw a Path instance using the given affine transform.

draw_text(self, gc, x, y, s, prop, angle, ismath=False, mtext=None)[source]

Draw the text instance.

Parameters:
gcGraphicsContextBase

The graphics context.

xscalar

The x location of the text in display coords.

yscalar

The y location of the text baseline in display coords.

sstr

The text string.

propmatplotlib.font_manager.FontProperties

The font properties.

anglescalar

The rotation angle in degrees.

mtextmatplotlib.text.Text

The original text object to be rendered.

Notes

backend implementers note

When you are trying to determine if you have gotten your bounding box right (which is what enables the text layout/alignment to work properly), it helps to change the line in text.py:

if 0: bbox_artist(self, renderer)

to if 1, and then the actual bounding box will be plotted along with your text.

fontangles = {'italic': <MyCairoCffi name='mock.FONT_SLANT_ITALIC' id='140544012773392'>, 'normal': <MyCairoCffi name='mock.FONT_SLANT_NORMAL' id='140544012790608'>, 'oblique': <MyCairoCffi name='mock.FONT_SLANT_OBLIQUE' id='140544012803728'>}
fontweights = {100: <MyCairoCffi name='mock.FONT_WEIGHT_NORMAL' id='140544012747216'>, 200: <MyCairoCffi name='mock.FONT_WEIGHT_NORMAL' id='140544012747216'>, 300: <MyCairoCffi name='mock.FONT_WEIGHT_NORMAL' id='140544012747216'>, 400: <MyCairoCffi name='mock.FONT_WEIGHT_NORMAL' id='140544012747216'>, 500: <MyCairoCffi name='mock.FONT_WEIGHT_NORMAL' id='140544012747216'>, 600: <MyCairoCffi name='mock.FONT_WEIGHT_BOLD' id='140544012764368'>, 700: <MyCairoCffi name='mock.FONT_WEIGHT_BOLD' id='140544012764368'>, 800: <MyCairoCffi name='mock.FONT_WEIGHT_BOLD' id='140544012764368'>, 900: <MyCairoCffi name='mock.FONT_WEIGHT_BOLD' id='140544012764368'>, 'ultralight': <MyCairoCffi name='mock.FONT_WEIGHT_NORMAL' id='140544012747216'>, 'light': <MyCairoCffi name='mock.FONT_WEIGHT_NORMAL' id='140544012747216'>, 'normal': <MyCairoCffi name='mock.FONT_WEIGHT_NORMAL' id='140544012747216'>, 'medium': <MyCairoCffi name='mock.FONT_WEIGHT_NORMAL' id='140544012747216'>, 'regular': <MyCairoCffi name='mock.FONT_WEIGHT_NORMAL' id='140544012747216'>, 'semibold': <MyCairoCffi name='mock.FONT_WEIGHT_BOLD' id='140544012764368'>, 'bold': <MyCairoCffi name='mock.FONT_WEIGHT_BOLD' id='140544012764368'>, 'heavy': <MyCairoCffi name='mock.FONT_WEIGHT_BOLD' id='140544012764368'>, 'ultrabold': <MyCairoCffi name='mock.FONT_WEIGHT_BOLD' id='140544012764368'>, 'black': <MyCairoCffi name='mock.FONT_WEIGHT_BOLD' id='140544012764368'>}
get_canvas_width_height(self)[source]

Return the canvas width and height in display coords.

get_text_width_height_descent(self, s, prop, ismath)[source]

Get the width, height, and descent (offset from the bottom to the baseline), in display coords, of the string s with FontProperties prop

new_gc(self)[source]

Return an instance of a GraphicsContextBase.

points_to_pixels(self, points)[source]

Convert points to display units.

You need to override this function (unless your backend doesn't have a dpi, e.g., postscript or svg). Some imaging systems assume some value for pixels per inch:

points to pixels = points * pixels_per_inch/72.0 * dpi/72.0
Parameters:
pointsscalar or array-like

a float or a numpy array of float

Returns:
Points converted to pixels
set_ctx_from_surface(self, surface)[source]
set_width_height(self, width, height)[source]