Source code for panel.pane.image

"""
Contains Image panes including renderers for PNG, SVG, GIF and JPG
file types.
"""
from __future__ import annotations

import asyncio
import base64

from io import BytesIO
from pathlib import PurePath
from typing import (
    Any, ClassVar, List, Mapping,
)

import param

from ..util import isfile, isurl
from .markup import DivPaneBase, escape


[docs]class FileBase(DivPaneBase): embed = param.Boolean(default=True, doc=""" Whether to embed the file as base64.""") _rerender_params: ClassVar[List[str]] = [ 'embed', 'object', 'style', 'width', 'height' ] __abstract = True def __init__(self, object=None, **params): if isinstance(object, PurePath): object = str(object) super().__init__(object=object, **params) def _type_error(self, object): if isinstance(object, str): raise ValueError("%s pane cannot parse string that is not a filename " "or URL." % type(self).__name__) super()._type_error(object)
[docs] @classmethod def applies(cls, obj: Any) -> float | bool | None: filetype = cls.filetype if hasattr(obj, '_repr_{}_'.format(filetype)): return True if isinstance(obj, PurePath): obj = str(obj.absolute()) if isinstance(obj, str): if isfile(obj) and obj.endswith('.'+filetype): return True if isurl(obj, [cls.filetype]): return True elif isurl(obj, None): return 0 elif isinstance(obj, bytes): try: cls._imgshape(obj) return True except Exception: return False if hasattr(obj, 'read'): # Check for file like object return True return False
def _data(self): if hasattr(self.object, '_repr_{}_'.format(self.filetype)): return getattr(self.object, '_repr_' + self.filetype + '_')() if isinstance(self.object, str): if isfile(self.object): with open(self.object, 'rb') as f: return f.read() elif isinstance(self.object, bytes): return self.object if hasattr(self.object, 'read'): if hasattr(self.object, 'seek'): self.object.seek(0) return self.object.read() if isurl(self.object, None): from ..io.state import state if state._is_pyodide: from ..io.pyodide import _IN_WORKER, fetch_binary if _IN_WORKER: return fetch_binary(self.object).read() else: from pyodide.http import pyfetch async def replace_content(): self.object = await (await pyfetch(self.object)).bytes() asyncio.create_task(replace_content()) else: import requests r = requests.request(url=self.object, method='GET') return r.content
[docs]class ImageBase(FileBase): """ Encodes an image as base64 and wraps it in a Bokeh Div model. This is an abstract base class that needs the image type to be specified and specific code for determining the image shape. The filetype determines the filetype, extension, and MIME type for this image. Each image type (png,jpg,gif) has a base class that supports anything with a `_repr_X_` method (where X is `png`, `gif`, etc.), a local file with the given file extension, or a HTTP(S) url with the given extension. Subclasses of each type can provide their own way of obtaining or generating a PNG. """ alt_text = param.String(default=None, doc=""" alt text to add to the image tag. The alt text is shown when a user cannot load or display the image.""") link_url = param.String(default=None, doc=""" A link URL to make the image clickable and link to some other website.""") filetype: ClassVar[str] = 'None' _rerender_params: ClassVar[List[str]] = [ 'alt_text', 'link_url', 'embed', 'object', 'style', 'width', 'height' ] _target_transforms: ClassVar[Mapping[str, str | None]] = { 'object': """'<img src="' + value + '"></img>'""" } __abstract = True def _b64(self): data = self._data() if not isinstance(data, bytes): data = data.encode('utf-8') b64 = base64.b64encode(data).decode("utf-8") return "data:image/"+self.filetype+f";base64,{b64}" def _imgshape(self, data): """Calculate and return image width,height""" raise NotImplementedError def _get_properties(self): p = super()._get_properties() if self.object is None: return dict(p, text='<img></img>') data = self._data() if data is None: return dict(p, text='<img></img>') if not isinstance(data, bytes): data = base64.b64decode(data) width, height = self._imgshape(data) if self.width is not None: if self.height is None: height = int((self.width/width)*height) else: height = self.height width = self.width elif self.height is not None: width = int((self.height/height)*width) height = self.height if not self.embed: src = self.object else: b64 = base64.b64encode(data).decode("utf-8") src = "data:image/"+self.filetype+";base64,{b64}".format(b64=b64) smode = self.sizing_mode if smode in ['fixed', None]: w, h = '%spx' % width, '%spx' % height elif smode == 'stretch_both': w, h = '100%', '100%' elif smode == 'stretch_width': w, h = '%spx' % width, '100%' elif smode == 'stretch_height': w, h = '100%', '%spx' % height elif smode == 'scale_height': w, h = 'auto', '100%' else: w, h = '100%', 'auto' html = '<img src="{src}" width="{width}" height="{height}" alt="{alt}"></img>'.format( src=src, width=w, height=h, alt=self.alt_text or '') if self.link_url: html = '<a href="{url}" target="_blank">{html}</a>'.format( url=self.link_url, html=html) return dict(p, width=width, height=height, text=escape(html))
[docs]class PNG(ImageBase): """ The `PNG` pane embeds a .png image file in a panel if provided a local path, or will link to a remote image if provided a URL. Reference: https://panel.holoviz.org/reference/panes/PNG.html :Example: >>> PNG( ... 'https://panel.holoviz.org/_static/logo_horizontal.png', ... alt_text='The Panel Logo', ... link_url='https://panel.holoviz.org/index.html', ... width=500 ... ) """ filetype: ClassVar[str] = 'png' @classmethod def _imgshape(cls, data): import struct w, h = struct.unpack('>LL', data[16:24]) return int(w), int(h)
[docs]class GIF(ImageBase): """ The `GIF` pane embeds a .gif image file in a panel if provided a local path, or will link to a remote image if provided a URL. Reference: https://panel.holoviz.org/reference/panes/GIF.html :Example: >>> GIF( ... 'https://upload.wikimedia.org/wikipedia/commons/b/b1/Loading_icon.gif', ... alt_text='A loading spinner', ... link_url='https://commons.wikimedia.org/wiki/File:Loading_icon.gif', ... width=500 ... ) """ filetype: ClassVar[str] = 'gif' @classmethod def _imgshape(cls, data): import struct w, h = struct.unpack("<HH", data[6:10]) return int(w), int(h)
[docs]class ICO(ImageBase): """ The `ICO` pane embeds an .ico image file in a panel if provided a local path, or will link to a remote image if provided a URL. Reference: https://panel.holoviz.org/reference/panes/ICO.html :Example: >>> ICO( ... some_url, ... alt_text='An .ico file', ... link_url='https://en.wikipedia.org/wiki/ICO_(file_format)', ... width=50 ... """ filetype: ClassVar[str] = 'ico' @classmethod def _imgshape(cls, data): import struct w, h = struct.unpack("<BB" , data[6:8]) return int(w or 256), int(h or 256)
[docs]class JPG(ImageBase): """ The `JPG` pane embeds a .jpg or .jpeg image file in a panel if provided a local path, or will link to a remote image if provided a URL. Reference: https://panel.holoviz.org/reference/panes/JPG.html :Example: >>> JPG( ... 'https://www.gstatic.com/webp/gallery/4.sm.jpg', ... alt_text='A nice tree', ... link_url='https://en.wikipedia.org/wiki/JPEG', ... width=500 ... ) """ filetype: ClassVar[str] = 'jpg' @classmethod def _imgshape(cls, data): import struct b = BytesIO(data) b.read(2) c = b.read(1) while (c and ord(c) != 0xDA): while (ord(c) != 0xFF): c = b.read(1) while (ord(c) == 0xFF): c = b.read(1) if (ord(c) >= 0xC0 and ord(c) <= 0xC3): b.read(3) h, w = struct.unpack(">HH", b.read(4)) break else: b.read(int(struct.unpack(">H", b.read(2))[0])-2) c = b.read(1) return int(w), int(h)
[docs]class SVG(ImageBase): """ The `SVG` pane embeds a .svg image file in a panel if provided a local path, or will link to a remote image if provided a URL. Reference: https://panel.holoviz.org/reference/panes/SVG.html :Example: >>> SVG( ... 'https://upload.wikimedia.org/wikipedia/commons/6/6b/Bitmap_VS_SVG.svg', ... alt_text='A gif vs svg comparison', ... link_url='https://en.wikipedia.org/wiki/SVG', ... width=300, height=400 ... ) """ encode = param.Boolean(default=False, doc=""" Whether to enable base64 encoding of the SVG, base64 encoded SVGs do not support links.""") filetype: ClassVar[str] = 'svg' _rerender_params: ClassVar[List[str]] = ImageBase._rerender_params + ['encode']
[docs] @classmethod def applies(cls, obj: Any) -> float | bool | None: return (super().applies(obj) or (isinstance(obj, str) and obj.lstrip().startswith('<svg')))
def _type_error(self, object): if isinstance(object, str): raise ValueError("%s pane cannot parse string that is not a filename, " "URL or a SVG XML contents." % type(self).__name__) super()._type_error(object) def _data(self): if (isinstance(self.object, str) and self.object.lstrip().startswith('<svg')): return self.object return super()._data() def _b64(self): data = self._data() if not isinstance(data, bytes): data = data.encode('utf-8') b64 = base64.b64encode(data).decode("utf-8") return f"data:image/svg+xml;base64,{b64}" def _imgshape(self, data): return (self.width, self.height) def _get_properties(self): p = super(ImageBase, self)._get_properties() if self.object is None: return dict(p, text='<img></img>') data = self._data() width, height = self._imgshape(data) if not isinstance(data, bytes): data = data.encode('utf-8') if self.encode: b64 = base64.b64encode(data).decode("utf-8") src = "data:image/svg+xml;base64,{b64}".format(b64=b64) html = "<img src='{src}' width={width} height={height}></img>".format( src=src, width=width, height=height ) else: html = data.decode("utf-8") return dict(p, width=width, height=height, text=escape(html))
[docs]class PDF(FileBase): """ The `PDF` pane embeds a .pdf image file in a panel if provided a local path, or will link to a remote image if provided a URL. Reference: https://panel.holoviz.org/reference/panes/PDF.html :Example: >>> PDF( ... 'https://www.w3.org/WAI/ER/tests/xhtml/testfiles/resources/pdf/dummy.pdf', ... width=300, height=410 ... ) """ filetype: ClassVar[str] = 'pdf' def _get_properties(self): p = super()._get_properties() if self.object is None: return dict(p, text='<embed></embed>') if self.embed: data = self._data() if not isinstance(data, bytes): data = data.encode('utf-8') base64_pdf = base64.b64encode(data).decode("utf-8") src = f"data:application/pdf;base64,{base64_pdf}" else: src = self.object w, h = self.width or '100%', self.height or '100%' html = f'<embed src="{src}" width={w!r} height={h!r} type="application/pdf">' return dict(p, text=escape(html))