Source code for node_figure_to_image

# This file is part of Sympathy for Data.
# Copyright (c) 2018, Combine Control Systems AB
#
# SYMPATHY FOR DATA COMMERCIAL LICENSE
# You should have received a link to the License with Sympathy for Data.
import numpy as np

from matplotlib.backends.backend_agg import FigureCanvasAgg

from sympathy.api import node
from sympathy.api.nodeconfig import Port, Ports, Tag, Tags

from sylib.imageprocessing.image import ImagePort




class FigureToImage(node.Node):
    author = 'Mathias Broxvall'
    icon = 'image_figure_to_image.svg'
    description = 'Converts a figure object to an image'
    tags = Tags(Tag.ImageProcessing.IO)
    name = 'Figure to image'
    nodeid = 'com.sympathyfordata.imageanalysis.figure_to_image'

    __doc__ = description

    inputs = Ports([
        Port.Custom('figure', 'Input figure', name='figure'),
    ])
    outputs = Ports([
        ImagePort('Result', name='result'),
    ])

    parameters = node.parameters()
    parameters.set_float(
        'width', value=6,
        description='Width of image, measured in inches',
        label='Width (inches)'
    )
    parameters.set_float(
        'height', value=4,
        description='Height of image, measured in inches',
        label='Height (inches)'
    )
    parameters.set_float(
        'dpi', value=120,
        description=(
            'Number of dots (pixels) per inch, also affects relationship '
            'between fontsizes and rendered pixels'),
        label='Dots per inch (dpi)'
    )

    def execute(self, node_context):
        params = node_context.parameters
        dpi = params['dpi'].value
        width = params['width'].value
        height = params['height'].value
        figure_obj = node_context.input['figure']
        fig = figure_obj.get_mpl_figure()
        fig.set_dpi(dpi)
        fig.set_size_inches((width, height))
        fig.canvas = FigureCanvasAgg(fig)
        fig.canvas.draw()
        im = np.array(fig.canvas.renderer._renderer)
        node_context.output['result'].set_image(im)