Source code for holoviews.plotting.renderer

Public API for all plotting renderers supported by HoloViews,
regardless of plotting package or backend.
from __future__ import unicode_literals

from io import BytesIO
import os, base64
from contextlib import contextmanager

import param
from import Exporter
from ..core.options import Store, StoreOptions, SkipRendering, Compositor
from ..core.util import find_file, unicode, unbound_dimensions, basestring
from .. import Layout, HoloMap, AdjointLayout
from .widgets import NdWidget, ScrubberWidget, SelectionWidget

from . import Plot
from .comms import JupyterComm
from .util import displayable, collate, initialize_dynamic

from param.parameterized import bothmethod

# Tags used when visual output is to be embedded in HTML
IMAGE_TAG = "<img src='{src}' style='max-width:100%; margin: auto; display: block; {css}'/>"
<video controls style='max-width:100%; margin: auto; display: block; {css}'>
<source src='{src}' type='{mime_type}'>
Your browser does not support the video tag.
PDF_TAG = "<iframe src='{src}' style='width:100%; margin: auto; display: block; {css}'></iframe>"
HTML_TAG = "{src}"

    'base64': 'data:{mime_type};base64,{b64}', # Use to embed data
    'svg':  IMAGE_TAG,
    'png':  IMAGE_TAG,
    'gif':  IMAGE_TAG,
    'webm': VIDEO_TAG,
    'mp4':  VIDEO_TAG,
    'pdf':  PDF_TAG,
    'html': HTML_TAG

    'svg':  'image/svg+xml',
    'png':  'image/png',
    'gif':  'image/gif',
    'webm': 'video/webm',
    'mp4':  'video/mp4',
    'pdf':  'application/pdf',
    'html':  'text/html',
    'json':  'text/json',
    'server': None

static_template = """

[docs]class Renderer(Exporter): """ The job of a Renderer is to turn the plotting state held within Plot classes into concrete, visual output in the form of the PNG, SVG, MP4 or WebM formats (among others). Note that a Renderer is a type of Exporter and must therefore follow the Exporter interface. The Renderer needs to be able to use the .state property of the appropriate Plot classes associated with that renderer in order to generate output. The process of 'drawing' is execute by the Plots and the Renderer turns the final plotting state into output. """ backend = param.String(doc=""" The full, lowercase name of the rendering backend or third part plotting package used e.g 'matplotlib' or 'cairo'.""") dpi=param.Integer(None, doc=""" The render resolution in dpi (dots per inch)""") fig = param.ObjectSelector(default='auto', objects=['auto'], doc=""" Output render format for static figures. If None, no figure rendering will occur. """) fps=param.Number(20, doc=""" Rendered fps (frames per second) for animated formats.""") holomap = param.ObjectSelector(default='auto', objects=['scrubber','widgets', None, 'auto'], doc=""" Output render multi-frame (typically animated) format. If None, no multi-frame rendering will occur.""") mode = param.ObjectSelector(default='default', objects=['default'], doc=""" The available rendering modes. As a minimum, the 'default' mode must be supported.""") size=param.Integer(100, doc=""" The rendered size as a percentage size""") widget_mode = param.ObjectSelector(default='embed', objects=['embed', 'live'], doc=""" The widget mode determining whether frames are embedded or generated 'live' when interacting with the widget.""") css = param.Dict(default={}, doc="Dictionary of CSS attributes and values to apply to HTML output") info_fn = param.Callable(None, allow_None=True, constant=True, doc=""" Renderers do not support the saving of object info metadata""") key_fn = param.Callable(None, allow_None=True, constant=True, doc=""" Renderers do not support the saving of object key metadata""") post_render_hooks = param.Dict(default={'svg':[], 'png':[]}, doc=""" Optional dictionary of hooks that are applied to the rendered data (according to the output format) before it is returned. Each hook is passed the rendered data and the object that is being rendered. These hooks allow post-processing of rendered data before output is saved to file or displayed.""") # Defines the valid output formats for each mode. mode_formats = {'fig': {'default': [None, 'auto']}, 'holomap': {'default': [None, 'auto']}} # Define comms class and message handler for each mode # The Comm opens a communication channel and the message # handler defines how the message is processed on the frontend comms = {'default': (JupyterComm, None)} # Define appropriate widget classes widgets = {'scrubber': ScrubberWidget, 'widgets': SelectionWidget} core_dependencies = {'jQueryUI': {'js': [''], 'css': ['']}} extra_dependencies = {'jQuery': {'js': ['']}, 'underscore': {'js': ['']}, 'require': {'js': ['']}, 'bootstrap': {'css': ['']}} # Any additional JS and CSS dependencies required by a specific backend backend_dependencies = {} # Whether in a notebook context, set when running Renderer.load_nb notebook_context = False def __init__(self, **params): self.last_plot = None super(Renderer, self).__init__(**params)
[docs] @bothmethod def get_plot(self_or_cls, obj, renderer=None): """ Given a HoloViews Viewable return a corresponding plot instance. """ # Initialize DynamicMaps with first data item initialize_dynamic(obj) if not isinstance(obj, Plot): if not displayable(obj): obj = collate(obj) initialize_dynamic(obj) obj =, mode='data', backend=self_or_cls.backend) if not renderer: renderer = self_or_cls.instance() if not isinstance(obj, Plot): obj = Layout.from_values(obj) if isinstance(obj, AdjointLayout) else obj plot_opts = self_or_cls.plot_options(obj, self_or_cls.size) plot = self_or_cls.plotting_class(obj)(obj, renderer=renderer, **plot_opts) plot.update(0) else: plot = obj return plot
def _validate(self, obj, fmt): """ Helper method to be used in the __call__ method to get a suitable plot or widget object and the appropriate format. """ if isinstance(obj, tuple(self.widgets.values())): return obj, 'html' plot = self.get_plot(obj, renderer=self) fig_formats = self.mode_formats['fig'][self.mode] holomap_formats = self.mode_formats['holomap'][self.mode] if fmt in ['auto', None]: if (((len(plot) == 1 and not plot.dynamic) or (len(plot) > 1 and self.holomap is None) or (plot.dynamic and len(plot.keys[0]) == 0)) or not unbound_dimensions(plot.streams, plot.dimensions, no_duplicates=False)): fmt = fig_formats[0] if self.fig=='auto' else self.fig else: fmt = holomap_formats[0] if self.holomap=='auto' else self.holomap if fmt in self.widgets: plot = self.get_widget(plot, fmt, display_options={'fps': self.fps}) fmt = 'html' all_formats = set(fig_formats + holomap_formats) if fmt not in all_formats: raise Exception("Format %r not supported by mode %r. Allowed formats: %r" % (fmt, self.mode, fig_formats + holomap_formats)) self.last_plot = plot return plot, fmt def __call__(self, obj, fmt=None): """ Render the supplied HoloViews component or plot instance using the appropriate backend. The output is not a file format but a suitable, in-memory byte stream together with any suitable metadata. """ plot, fmt = self._validate(obj, fmt) if plot is None: return # [Backend specific code goes here to generate data] data = None # Example of how post_render_hooks are applied data = self._apply_post_render_hooks(data, obj, fmt) # Example of the return format where the first value is the rendered data. return data, {'file-ext':fmt, 'mime_type':MIME_TYPES[fmt]} def _apply_post_render_hooks(self, data, obj, fmt): """ Apply the post-render hooks to the data. """ hooks = self.post_render_hooks.get(fmt,[]) for hook in hooks: try: data = hook(data, obj) except Exception as e: self.warning("The post_render_hook %r could not be applied:\n\n %s" % (hook, e)) return data
[docs] def html(self, obj, fmt=None, css=None, comm=True, **kwargs): """ Renders plot or data structure and wraps the output in HTML. The comm argument defines whether the HTML output includes code to initialize a Comm, if the plot supplies one. """ plot, fmt = self._validate(obj, fmt) figdata, _ = self(plot, fmt, **kwargs) if css is None: css = self.css if fmt in ['html', 'json']: return figdata else: if fmt == 'svg': figdata = figdata.encode("utf-8") elif fmt == 'pdf' and 'height' not in css: _, h = self.get_size(plot) css['height'] = '%dpx' % (h*self.dpi*1.15) if isinstance(css, dict): css = '; '.join("%s: %s" % (k, v) for k, v in css.items()) else: raise ValueError("CSS must be supplied as Python dictionary") b64 = base64.b64encode(figdata).decode("utf-8") (mime_type, tag) = MIME_TYPES[fmt], HTML_TAGS[fmt] src = HTML_TAGS['base64'].format(mime_type=mime_type, b64=b64) html = tag.format(src=src, mime_type=mime_type, css=css) if comm and plot.comm is not None: comm, msg_handler = self.comms[self.mode] if msg_handler is None: return html msg_handler = msg_handler.format( return comm.template.format(init_frame=html, msg_handler=msg_handler, else: return html
[docs] def static_html(self, obj, fmt=None, template=None): """ Generates a static HTML with the rendered object in the supplied format. Allows supplying a template formatting string with fields to interpolate 'js', 'css' and the main 'html'. """ js_html, css_html = self.html_assets() if template is None: template = static_template html = self.html(obj, fmt) return template.format(js=js_html, css=css_html, html=html)
@bothmethod def get_widget(self_or_cls, plot, widget_type, **kwargs): if not isinstance(plot, Plot): plot = self_or_cls.get_plot(plot) dynamic = plot.dynamic # Whether dimensions define discrete space discrete = all(d.values for d in plot.dimensions) if widget_type == 'auto': isuniform = plot.uniform if not isuniform: widget_type = 'scrubber' else: widget_type = 'widgets' elif dynamic and not discrete: widget_type = 'widgets' if widget_type in [None, 'auto']: holomap_formats = self_or_cls.mode_formats['holomap'][self_or_cls.mode] widget_type = holomap_formats[0] if self_or_cls.holomap=='auto' else self_or_cls.holomap widget_cls = self_or_cls.widgets[widget_type] return widget_cls(plot, renderer=self_or_cls.instance(), embed=self_or_cls.widget_mode == 'embed', **kwargs)
[docs] @bothmethod def export_widgets(self_or_cls, obj, filename, fmt=None, template=None, json=False, json_path='', **kwargs): """ Render and export object as a widget to a static HTML file. Allows supplying a custom template formatting string with fields to interpolate 'js', 'css' and the main 'html' containing the widget. Also provides options to export widget data to a json file in the supplied json_path (defaults to current path). """ if fmt not in list(self_or_cls.widgets.keys())+['auto', None]: raise ValueError("Renderer.export_widget may only export " "registered widget types.") if not isinstance(obj, NdWidget): if not isinstance(filename, BytesIO): filedir = os.path.dirname(filename) current_path = os.getcwd() html_path = os.path.abspath(filedir) rel_path = os.path.relpath(html_path, current_path) save_path = os.path.join(rel_path, json_path) else: save_path = json_path kwargs['json_save_path'] = save_path kwargs['json_load_path'] = json_path widget = self_or_cls.get_widget(obj, fmt, **kwargs) else: widget = obj html = self_or_cls.static_html(widget, fmt, template) encoded = self_or_cls.encode((html, {'mime_type': 'text/html'})) if isinstance(filename, BytesIO): filename.write(encoded) else: with open(filename, 'wb') as f: f.write(encoded)
[docs] @classmethod def plotting_class(cls, obj): """ Given an object or Element class, return the suitable plotting class needed to render it with the current renderer. """ if isinstance(obj, AdjointLayout) or obj is AdjointLayout: obj = Layout if isinstance(obj, type): element_type = obj else: element_type = obj.type if isinstance(obj, HoloMap) else type(obj) try: plotclass = Store.registry[cls.backend][element_type] except KeyError: raise SkipRendering("No plotting class for {0} " "found".format(element_type.__name__)) return plotclass
[docs] @classmethod def html_assets(cls, core=True, extras=True, backends=None): """ Returns JS and CSS and for embedding of widgets. """ if backends is None: backends = [cls.backend] if cls.backend else [] # Get all the widgets and find the set of required js widget files widgets = [wdgt for r in [Renderer]+Renderer.__subclasses__() for wdgt in r.widgets.values()] css = list({wdgt.css for wdgt in widgets}) basejs = list({wdgt.basejs for wdgt in widgets}) extensionjs = list({wdgt.extensionjs for wdgt in widgets}) # Join all the js widget code into one string path = os.path.dirname(os.path.abspath(__file__)) def open_and_read(path, f): with open(find_file(path, f), 'r') as f: txt = return txt widgetjs = '\n'.join(open_and_read(path, f) for f in basejs + extensionjs if f is not None) widgetcss = '\n'.join(open_and_read(path, f) for f in css if f is not None) dependencies = {} if core: dependencies.update(cls.core_dependencies) if extras: dependencies.update(cls.extra_dependencies) for backend in backends: dependencies['backend'] = Store.renderers[backend].backend_dependencies js_html, css_html = '', '' for _, dep in sorted(dependencies.items(), key=lambda x: x[0]): js_data = dep.get('js', []) if isinstance(js_data, tuple): for js in js_data: js_html += '\n<script type="text/javascript">%s</script>' % js else: for js in js_data: js_html += '\n<script src="%s" type="text/javascript"></script>' % js css_data = dep.get('css', []) if isinstance(js_data, tuple): for css in css_data: css_html += '\n<style>%s</style>' % css else: for css in css_data: css_html += '\n<link rel="stylesheet" href="%s">' % css js_html += '\n<script type="text/javascript">%s</script>' % widgetjs css_html += '\n<style>%s</style>' % widgetcss return unicode(js_html), unicode(css_html)
[docs] @classmethod def plot_options(cls, obj, percent_size): """ Given an object and a percentage size (as supplied by the %output magic) return all the appropriate plot options that would be used to instantiate a plot class for that element. Default plot sizes at the plotting class level should be taken into account. """ raise NotImplementedError
[docs] @bothmethod def save(self_or_cls, obj, basename, fmt='auto', key={}, info={}, options=None, **kwargs): """ Save a HoloViews object to file, either using an explicitly supplied format or to the appropriate default. """ if info or key: raise Exception('Renderer does not support saving metadata to file.') with StoreOptions.options(obj, options, **kwargs): plot = self_or_cls.get_plot(obj) if (fmt in list(self_or_cls.widgets.keys())+['auto']) and len(plot) > 1: with StoreOptions.options(obj, options, **kwargs): if isinstance(basename, basestring): basename = basename+'.html' self_or_cls.export_widgets(plot, basename, fmt) return with StoreOptions.options(obj, options, **kwargs): rendered = self_or_cls(plot, fmt) if rendered is None: return (data, info) = rendered encoded = self_or_cls.encode(rendered) prefix = self_or_cls._save_prefix(info['file-ext']) if prefix: encoded = prefix + encoded if isinstance(basename, BytesIO): basename.write(encoded) else: filename ='%s.%s' % (basename, info['file-ext']) with open(filename, 'wb') as f: f.write(encoded)
@bothmethod def _save_prefix(self_or_cls, ext): "Hook to prefix content for instance JS when saving HTML" return
[docs] @bothmethod def get_size(self_or_cls, plot): """ Return the display size associated with a plot before rendering to any particular format. Used to generate appropriate HTML display. Returns a tuple of (width, height) in pixels. """ raise NotImplementedError
[docs] @classmethod @contextmanager def state(cls): """ Context manager to handle global state for a backend, allowing Plot classes to temporarily override that state. """ yield
[docs] @classmethod def validate(cls, options): """ Validate an options dictionary for the renderer. """ return options
[docs] @classmethod def load_nb(cls, inline=True): """ Loads any resources required for display of plots in the Jupyter notebook """ with param.logging_level('ERROR'): cls.notebook_context = True