matplotlib.backends.backend_agg

An agg http://antigrain.com/ backend

Features that are implemented

• capstyles and join styles
• dashes
• linewidth
• lines, rectangles, ellipses
• clipping to a rectangle
• output to RGBA and PNG, optionally JPEG and TIFF
• alpha blending
• DPI scaling properly - everything scales properly (dashes, linewidths, etc)
• draw polygon
• freetype2 w/ ft2font

TODO:

• integrate screen dpi w/ ppi and text

matplotlib.backends.backend_agg.FigureCanvas

alias of FigureCanvasAgg

class matplotlib.backends.backend_agg.FigureCanvasAgg(figure)

Bases: matplotlib.backend_bases.FigureCanvasBase

The canvas the figure renders into. Calls the draw and print fig methods, creates the renderers, etc…

Attributes

figure

(matplotlib.figure.Figure) A high-level Figure instance

buffer_rgba()

Get the image as an RGBA byte string

draw must be called at least once before this function will work and to update the renderer for any subsequent changes to the Figure.

Returns:bytes

copy_from_bbox(bbox)

draw()

Draw the figure using the renderer

get_renderer(cleared=False)

print_jpeg(filename_or_obj, *args, **kwargs)

Other Parameters:  

quality : int

The image quality, on a scale from 1 (worst) to 95 (best). The default is 95, if not given in the matplotlibrc file in the savefig.jpeg_quality parameter. Values above 95 should be avoided; 100 completely disables the JPEG quantization stage.

optimize : bool

If present, indicates that the encoder should make an extra pass over the image in order to select optimal encoder settings.

progressive : bool

If present, indicates that this image should be stored as a progressive JPEG file.

print_jpg(filename_or_obj, *args, **kwargs)

Other Parameters:  

quality : int

The image quality, on a scale from 1 (worst) to 95 (best). The default is 95, if not given in the matplotlibrc file in the savefig.jpeg_quality parameter. Values above 95 should be avoided; 100 completely disables the JPEG quantization stage.

optimize : bool

If present, indicates that the encoder should make an extra pass over the image in order to select optimal encoder settings.

progressive : bool

If present, indicates that this image should be stored as a progressive JPEG file.

print_png(filename_or_obj, *args, **kwargs)

print_raw(filename_or_obj, *args, **kwargs)

print_rgba(filename_or_obj, *args, **kwargs)

print_tif(filename_or_obj, *args, **kwargs)

print_tiff(filename_or_obj, *args, **kwargs)

print_to_buffer()

restore_region(region, bbox=None, xy=None)

tostring_argb()

Get the image as an ARGB byte string

draw must be called at least once before this function will work and to update the renderer for any subsequent changes to the Figure.

Returns:bytes

tostring_rgb()

Get the image as an RGB byte string

draw must be called at least once before this function will work and to update the renderer for any subsequent changes to the Figure.

Returns:bytes

class matplotlib.backends.backend_agg.RendererAgg(width, height, dpi)

Bases: matplotlib.backend_bases.RendererBase

The renderer handles all the drawing primitives using a graphics context instance that controls the colors/styles

buffer_rgba()

clear()

debug

Deprecated since version 2.2: The debug function was deprecated in version 2.2.

draw_markers(*kl, **kw)

draw_mathtext(gc, x, y, s, prop, angle)

Draw the math text using matplotlib.mathtext

draw_path(gc, path, transform, rgbFace=None)

Draw the path

draw_path_collection(*kl, **kw)

draw_tex(gc, x, y, s, prop, angle, ismath='TeX!', mtext=None)

draw_text(gc, x, y, s, prop, angle, ismath=False, mtext=None)

Render the text

get_canvas_width_height()

return the canvas width and height in display coords

get_text_width_height_descent(s, prop, ismath)

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

lock = <unlocked _thread.RLock object owner=0 count=0>

option_image_nocomposite()

option_scale_image()

agg backend doesn’t support arbitrary scaling of image.

points_to_pixels(points)

convert point measures to pixes using dpi and the pixels per inch of the display

restore_region(region, bbox=None, xy=None)

Restore the saved region. If bbox (instance of BboxBase, or its extents) is given, only the region specified by the bbox will be restored. xy (a tuple of two floasts) optionally specifies the new position (the LLC of the original region, not the LLC of the bbox) where the region will be restored.

>>> region = renderer.copy_from_bbox()
>>> x1, y1, x2, y2 = region.get_extents()
>>> renderer.restore_region(region, bbox=(x1+dx, y1, x2, y2),
...                         xy=(x1-dx, y1))

start_filter()

Start filtering. It simply create a new canvas (the old one is saved).

stop_filter(post_processing)

Save the plot in the current canvas as a image and apply the post_processing function.

def post_processing(image, dpi):

# ny, nx, depth = image.shape # image (numpy array) has RGBA channels and has a depth of 4. … # create a new_image (numpy array of 4 channels, size can be # different). The resulting image may have offsets from # lower-left corner of the original image return new_image, offset_x, offset_y

The saved renderer is restored and the returned image from post_processing is plotted (using draw_image) on it.

tostring_argb()

tostring_rgb()

tostring_rgba_minimized()

matplotlib.backends.backend_agg.get_hinting_flag()