Source code for bokeh.command.subcommands.png

#-----------------------------------------------------------------------------
# Copyright (c) 2012 - 2019, Anaconda, Inc., and Bokeh Contributors.
# All rights reserved.
#
# The full license is in the file LICENSE.txt, distributed with this software.
#-----------------------------------------------------------------------------
'''
To generate a standalone PNG file for a Bokeh application from a single
Python script, pass the script name to ``bokeh png`` on the command
line:

.. code-block:: sh

    bokeh png app_script.py

The generated PNG will be saved in the current working directory with
the name ``app_script.png``.

It is also possible to run the same commmand with jupyter notebooks:

.. code-block:: sh

    bokeh png app_notebook.ipynb

This will generate an PNG file named ``app_notebook.png`` just like
with a python script.

Applications can also be created from directories. The directory should
contain a ``main.py`` (and any other helper modules that are required) as
well as any additional assets (e.g., theme files). Pass the directory name
to ``bokeh png`` to generate the PNG:

.. code-block:: sh

    bokeh png app_dir

It is possible to generate PNG files for multiple applications at once:

.. code-block:: sh

    bokeh png app_script.py app_dir

For all cases, it's required to explicitly add a Bokeh layout to
``bokeh.io.curdoc`` for it to appear in the output.

'''
#-----------------------------------------------------------------------------
# Boilerplate
#-----------------------------------------------------------------------------
from __future__ import absolute_import, division, print_function, unicode_literals

import logging
log = logging.getLogger(__name__)

#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------

# Standard library imports
import io
import sys

# External imports

# Bokeh imports
from ...io.export import get_screenshot_as_png, create_webdriver, terminate_webdriver
from ..util import set_single_plot_width_height
from .file_output import FileOutputSubcommand

#-----------------------------------------------------------------------------
# Globals and constants
#-----------------------------------------------------------------------------

__all__ = (
    'PNG',
)

#-----------------------------------------------------------------------------
# General API
#-----------------------------------------------------------------------------

class PNG(FileOutputSubcommand):
    ''' Subcommand to output applications as standalone PNG files.

    '''

    #: name for this subcommand
    name = "png"

    #: file extension for output generated by this :class:`~bokeh.command.subcommands.file_output.FileOutputSubcommand`
    extension = "png"

    help = "Create standalone PNG files for one or more applications"

    args = (

        FileOutputSubcommand.files_arg("PNG"),

        ('--height', dict(
            metavar='HEIGHT',
            type=int,
            help="The desired height of the exported layout obj only if it's a Plot instance",
            default=None,
        )),

        ('--width', dict(
            metavar='WIDTH',
            type=int,
            help="The desired width of the exported layout obj only if it's a Plot instance",
            default=None,
        )),

    ) + FileOutputSubcommand.other_args()

    def invoke(self, args):
        '''

        '''
        self.driver = create_webdriver()
        try:
            super(PNG, self).invoke(args)
        finally:
            terminate_webdriver(self.driver)

    def write_file(self, args, filename, doc):
        '''

        '''
        contents = self.file_contents(args, doc)
        if filename == '-':
            sys.stdout.buffer.write(contents)
        else:
            with io.open(filename, "w+b") as f:
                f.write(contents)
        self.after_write_file(args, filename, doc)

    def file_contents(self, args, doc):
        '''

        '''
        set_single_plot_width_height(doc, width=args.width, height=args.height)

        image = get_screenshot_as_png(doc, driver=self.driver)
        buf = io.BytesIO()
        image.save(buf, "png")
        buf.seek(0)
        return buf.read()

#-----------------------------------------------------------------------------
# Dev API
#-----------------------------------------------------------------------------

#-----------------------------------------------------------------------------
# Private API
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#-----------------------------------------------------------------------------
# Code
#-----------------------------------------------------------------------------