/
request.py
751 lines (637 loc) · 26.2 KB
/
request.py
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# -*- coding: utf-8 -*-
# imageio is distributed under the terms of the (new) BSD License.
"""
Definition of the Request object, which acts as a kind of bridge between
what the user wants and what the plugins can.
"""
import os
from io import BytesIO
import zipfile
import tempfile
import shutil
import enum
import warnings
from ..core import urlopen, get_remote_file
from pathlib import Path
from urllib.parse import urlparse
from typing import Optional
# URI types
URI_BYTES = 1
URI_FILE = 2
URI_FILENAME = 3
URI_ZIPPED = 4
URI_HTTP = 5
URI_FTP = 6
class IOMode(str, enum.Enum):
"""Available Image modes
This is a helper enum for ``Request.Mode`` which is a composite of a
``Request.ImageMode`` and ``Request.IOMode``. The IOMode that tells the
plugin if the resource should be read from or written to. Available values are
- read ("r"): Read from the specified resource
- write ("w"): Write to the specified resource
"""
read = "r"
write = "w"
class ImageMode(str, enum.Enum):
"""Available Image modes
This is a helper enum for ``Request.Mode`` which is a composite of a
``Request.ImageMode`` and ``Request.IOMode``. The image mode that tells the
plugin the desired (and expected) image shape. Available values are
- single_image ("i"): Return a single image extending in two spacial
dimensions
- multi_image ("I"): Return a list of images extending in two spacial
dimensions
- single_volume ("v"): Return an image extending into multiple dimensions.
E.g. three spacial dimensions for image stacks, or two spatial and one
time dimension for videos
- multi_volume ("V"): Return a list of images extending into multiple
dimensions.
- any_mode ("?"): Return an image in any format (the plugin decides the
appropriate action).
"""
single_image = "i"
multi_image = "I"
single_volume = "v"
multi_volume = "V"
any_mode = "?"
@enum.unique
class Mode(str, enum.Enum):
"""The mode to use when interacting with the resource
``Request.Mode`` is a composite of ``Request.ImageMode`` and
``Request.IOMode``. The image mode that tells the plugin the desired (and
expected) image shape and the ``Request.IOMode`` tells the plugin the way
the resource should be interacted with. For a detailed description of the
available modes, see the documentation for ``Request.ImageMode`` and
``Request.IOMode`` respectively.
Available modes are all combinations of ``Request.IOMode`` and ``Request.ImageMode``:
- read_single_image ("ri")
- read_multi_image ("rI")
- read_single_volume ("rv")
- read_multi_volume ("rV")
- read_any ("r?")
- write_single_image ("wi")
- write_multi_image ("wI")
- write_single_volume ("wv")
- write_multi_volume ("wV")
- write_any ("w?")
Examples
--------
>>> Request.Mode("rI") # a list of simple images should be read from the resource
>>> Request.Mode("wv") # a single volume should be written to the resource
"""
read_single_image = "ri"
read_multi_image = "rI"
read_single_volume = "rv"
read_multi_volume = "rV"
read_any = "r?"
write_single_image = "wi"
write_multi_image = "wI"
write_single_volume = "wv"
write_multi_volume = "wV"
write_any = "w?"
@classmethod
def _missing_(cls, value):
"""Enable Mode("r") and Mode("w")
The sunder method ``_missing_`` is called whenever the constructor fails
to directly look up the corresponding enum value from the given input.
In our case, we use it to convert the modes "r" and "w" (from the v3
API) into their legacy versions "r?" and "w?".
More info on _missing_:
https://docs.python.org/3/library/enum.html#supported-sunder-names
"""
if value == "r":
return cls("r?")
elif value == "w":
return cls("w?")
else:
raise ValueError(f"{value} is no valid Mode.")
@property
def io_mode(self) -> IOMode:
return IOMode(self.value[0])
@property
def image_mode(self) -> ImageMode:
return ImageMode(self.value[1])
def __getitem__(self, key):
"""For backwards compatibility with the old non-enum modes"""
if key == 0:
return self.io_mode
elif key == 1:
return self.image_mode
else:
raise IndexError(f"Mode has no item {key}")
SPECIAL_READ_URIS = "<video", "<screen>", "<clipboard>"
# The user can use this string in a write call to get the data back as bytes.
RETURN_BYTES = "<bytes>"
# Example images that will be auto-downloaded
EXAMPLE_IMAGES = {
"astronaut.png": "Image of the astronaut Eileen Collins",
"camera.png": "A grayscale image of a photographer",
"checkerboard.png": "Black and white image of a chekerboard",
"wood.jpg": "A (repeatable) texture of wooden planks",
"bricks.jpg": "A (repeatable) texture of stone bricks",
"clock.png": "Photo of a clock with motion blur (Stefan van der Walt)",
"coffee.png": "Image of a cup of coffee (Rachel Michetti)",
"chelsea.png": "Image of Stefan's cat",
"wikkie.png": "Image of Almar's cat",
"coins.png": "Image showing greek coins from Pompeii",
"horse.png": "Image showing the silhouette of a horse (Andreas Preuss)",
"hubble_deep_field.png": "Photograph taken by Hubble telescope (NASA)",
"immunohistochemistry.png": "Immunohistochemical (IHC) staining",
"moon.png": "Image showing a portion of the surface of the moon",
"page.png": "A scanned page of text",
"text.png": "A photograph of handdrawn text",
"chelsea.zip": "The chelsea.png in a zipfile (for testing)",
"chelsea.bsdf": "The chelsea.png in a BSDF file(for testing)",
"newtonscradle.gif": "Animated GIF of a newton's cradle",
"cockatoo.mp4": "Video file of a cockatoo",
"stent.npz": "Volumetric image showing a stented abdominal aorta",
"meadow_cube.jpg": "A cubemap image of a meadow, e.g. to render a skybox.",
}
class Request(object):
"""ImageResource handling utility.
Represents a request for reading or saving an image resource. This
object wraps information to that request and acts as an interface
for the plugins to several resources; it allows the user to read
from filenames, files, http, zipfiles, raw bytes, etc., but offer
a simple interface to the plugins via ``get_file()`` and
``get_local_filename()``.
For each read/write operation a single Request instance is used and passed
to the can_read/can_write method of a format, and subsequently to
the Reader/Writer class. This allows rudimentary passing of
information between different formats and between a format and
associated reader/writer.
Parameters
----------
uri : {str, bytes, file}
The resource to load the image from.
mode : str
The first character is "r" or "w", indicating a read or write
request. The second character is used to indicate the kind of data:
"i" for an image, "I" for multiple images, "v" for a volume,
"V" for multiple volumes, "?" for don't care.
"""
def __init__(self, uri, mode, *, extension=None, format_hint: str = None, **kwargs):
# General
self.raw_uri = uri
self._uri_type = None
self._filename = None
self._extension = None
self._format_hint = None
self._kwargs = kwargs
self._result = None # Some write actions may have a result
# To handle the user-side
self._filename_zip = None # not None if a zipfile is used
self._bytes = None # Incoming bytes
self._zipfile = None # To store a zipfile instance (if used)
# To handle the plugin side
self._file = None # To store the file instance
self._file_is_local = False # whether the data needs to be copied at end
self._filename_local = None # not None if using tempfile on this FS
self._firstbytes = None # For easy header parsing
# To store formats that may be able to fulfil this request
# self._potential_formats = []
# Check mode
try:
self._mode = Mode(mode)
except ValueError:
raise ValueError(f"Invalid Request.Mode: {mode}")
# Parse what was given
self._parse_uri(uri)
# Set extension
if extension is not None:
if extension[0] != ".":
raise ValueError(
"`extension` should be a file extension starting with a `.`,"
f" but is `{extension}`."
)
self._extension = extension
elif self._filename is not None:
if self._uri_type in (URI_FILENAME, URI_ZIPPED):
path = self._filename
else:
path = urlparse(self._filename).path
ext = Path(path).suffix.lower()
self._extension = ext if ext != "" else None
if format_hint is not None:
warnings.warn(
"The usage of `format_hint` is deprecated and will be removed "
"in ImageIO v3. Use `extension` instead.",
DeprecationWarning,
)
if format_hint is not None and format_hint[0] != ".":
raise ValueError(
"`format_hint` should be a file extension starting with a `.`,"
f" but is `{format_hint}`."
)
self.format_hint = format_hint
def _parse_uri(self, uri):
"""Try to figure our what we were given"""
is_read_request = self.mode.io_mode is IOMode.read
is_write_request = self.mode.io_mode is IOMode.write
if isinstance(uri, str):
# Explicit
if uri.startswith("imageio:"):
if is_write_request:
raise RuntimeError("Cannot write to the standard images.")
fn = uri.split(":", 1)[-1].lower()
fn, _, zip_part = fn.partition(".zip/")
if zip_part:
fn += ".zip"
if fn not in EXAMPLE_IMAGES:
raise ValueError("Unknown standard image %r." % fn)
self._uri_type = URI_FILENAME
self._filename = get_remote_file("images/" + fn, auto=True)
if zip_part:
self._filename += "/" + zip_part
elif uri.startswith("http://") or uri.startswith("https://"):
self._uri_type = URI_HTTP
self._filename = uri
elif uri.startswith("ftp://") or uri.startswith("ftps://"):
self._uri_type = URI_FTP
self._filename = uri
elif uri.startswith("file://"):
self._uri_type = URI_FILENAME
self._filename = uri[7:]
elif uri.startswith(SPECIAL_READ_URIS) and is_read_request:
self._uri_type = URI_BYTES
self._filename = uri
elif uri.startswith(RETURN_BYTES) and is_write_request:
self._uri_type = URI_BYTES
self._filename = uri
else:
self._uri_type = URI_FILENAME
self._filename = uri
elif isinstance(uri, memoryview) and is_read_request:
self._uri_type = URI_BYTES
self._filename = "<bytes>"
self._bytes = uri.tobytes()
elif isinstance(uri, bytes) and is_read_request:
self._uri_type = URI_BYTES
self._filename = "<bytes>"
self._bytes = uri
elif isinstance(uri, Path):
self._uri_type = URI_FILENAME
self._filename = str(uri)
# Files
elif is_read_request:
if hasattr(uri, "read") and hasattr(uri, "close"):
self._uri_type = URI_FILE
self._filename = "<file>"
self._file = uri # Data must be read from here
elif is_write_request:
if hasattr(uri, "write") and hasattr(uri, "close"):
self._uri_type = URI_FILE
self._filename = "<file>"
self._file = uri # Data must be written here
# Expand user dir
if self._uri_type == URI_FILENAME and self._filename.startswith("~"):
self._filename = os.path.expanduser(self._filename)
# Check if a zipfile
if self._uri_type == URI_FILENAME:
# Search for zip extension followed by a path separator
for needle in [".zip/", ".zip\\"]:
zip_i = self._filename.lower().find(needle)
if zip_i > 0:
zip_i += 4
zip_path = self._filename[:zip_i]
if os.path.isdir(zip_path):
pass # is an existing dir (see #548)
elif is_write_request or os.path.isfile(zip_path):
self._uri_type = URI_ZIPPED
self._filename_zip = (
zip_path,
self._filename[zip_i:].lstrip("/\\"),
)
break
# Check if we could read it
if self._uri_type is None:
uri_r = repr(uri)
if len(uri_r) > 60:
uri_r = uri_r[:57] + "..."
raise IOError("Cannot understand given URI: %s." % uri_r)
# Check if this is supported
noWriting = [URI_HTTP, URI_FTP]
if is_write_request and self._uri_type in noWriting:
raise IOError("imageio does not support writing to http/ftp.")
# Deprecated way to load standard images, give a sensible error message
if is_read_request and self._uri_type in [URI_FILENAME, URI_ZIPPED]:
fn = self._filename
if self._filename_zip:
fn = self._filename_zip[0]
if (not os.path.exists(fn)) and (fn in EXAMPLE_IMAGES):
raise IOError(
"No such file: %r. This file looks like one of "
"the standard images, but from imageio 2.1, "
"standard images have to be specified using "
'"imageio:%s".' % (fn, fn)
)
# Make filename absolute
if self._uri_type in [URI_FILENAME, URI_ZIPPED]:
if self._filename_zip:
self._filename_zip = (
os.path.abspath(self._filename_zip[0]),
self._filename_zip[1],
)
else:
self._filename = os.path.abspath(self._filename)
# Check whether file name is valid
if self._uri_type in [URI_FILENAME, URI_ZIPPED]:
fn = self._filename
if self._filename_zip:
fn = self._filename_zip[0]
if is_read_request:
# Reading: check that the file exists (but is allowed a dir)
if not os.path.exists(fn):
raise FileNotFoundError("No such file: '%s'" % fn)
else:
# Writing: check that the directory to write to does exist
dn = os.path.dirname(fn)
if not os.path.exists(dn):
raise FileNotFoundError("The directory %r does not exist" % dn)
@property
def filename(self):
"""Name of the ImageResource.
The uri for which reading/saving was requested. This
can be a filename, an http address, or other resource
identifier. Do not rely on the filename to obtain the data,
but use ``get_file()`` or ``get_local_filename()`` instead.
"""
return self._filename
@property
def extension(self) -> str:
"""The (lowercase) extension of the requested filename.
Suffixes in url's are stripped. Can be None if the request is
not based on a filename.
"""
return self._extension
@property
def format_hint(self) -> Optional[str]:
return self._format_hint
@format_hint.setter
def format_hint(self, format: str) -> None:
self._format_hint = format
if self._extension is None:
self._extension = format
@property
def mode(self):
"""The mode of the request. The first character is "r" or "w",
indicating a read or write request. The second character is
used to indicate the kind of data:
"i" for an image, "I" for multiple images, "v" for a volume,
"V" for multiple volumes, "?" for don't care.
"""
return self._mode
@property
def kwargs(self):
"""The dict of keyword arguments supplied by the user."""
return self._kwargs
# For obtaining data
def get_file(self):
"""get_file()
Get a file object for the resource associated with this request.
If this is a reading request, the file is in read mode,
otherwise in write mode. This method is not thread safe. Plugins
should not close the file when done.
This is the preferred way to read/write the data. But if a
format cannot handle file-like objects, they should use
``get_local_filename()``.
"""
want_to_write = self.mode.io_mode is IOMode.write
# Is there already a file?
# Either _uri_type == URI_FILE, or we already opened the file,
# e.g. by using firstbytes
if self._file is not None:
return self._file
if self._uri_type == URI_BYTES:
if want_to_write:
# Create new file object, we catch the bytes in finish()
self._file = BytesIO()
self._file_is_local = True
else:
self._file = BytesIO(self._bytes)
elif self._uri_type == URI_FILENAME:
if want_to_write:
self._file = open(self.filename, "wb")
else:
self._file = open(self.filename, "rb")
elif self._uri_type == URI_ZIPPED:
# Get the correct filename
filename, name = self._filename_zip
if want_to_write:
# Create new file object, we catch the bytes in finish()
self._file = BytesIO()
self._file_is_local = True
else:
# Open zipfile and open new file object for specific file
self._zipfile = zipfile.ZipFile(filename, "r")
self._file = self._zipfile.open(name, "r")
self._file = SeekableFileObject(self._file)
elif self._uri_type in [URI_HTTP or URI_FTP]:
assert not want_to_write # This should have been tested in init
timeout = os.getenv("IMAGEIO_REQUEST_TIMEOUT")
if timeout is None or not timeout.isdigit():
timeout = 5
self._file = urlopen(self.filename, timeout=float(timeout))
self._file = SeekableFileObject(self._file)
return self._file
def get_local_filename(self):
"""get_local_filename()
If the filename is an existing file on this filesystem, return
that. Otherwise a temporary file is created on the local file
system which can be used by the format to read from or write to.
"""
if self._uri_type == URI_FILENAME:
return self._filename
else:
# Get filename
if self.extension is not None:
ext = self.extension
else:
ext = os.path.splitext(self._filename)[1]
fd, self._filename_local = tempfile.mkstemp(ext, "imageio_")
os.close(fd)
# Write stuff to it?
if self.mode.io_mode == IOMode.read:
with open(self._filename_local, "wb") as file:
shutil.copyfileobj(self.get_file(), file)
return self._filename_local
def finish(self) -> None:
"""Wrap up this request.
Finishes any pending reads or writes, closes any open files and frees
any resources allocated by this request.
"""
if self.mode.io_mode == IOMode.write:
# See if we "own" the data and must put it somewhere
bytes = None
if self._filename_local:
bytes = Path(self._filename_local).read_bytes()
elif self._file_is_local:
self._file_is_local = False
bytes = self._file.getvalue()
# Put the data in the right place
if bytes is not None:
if self._uri_type == URI_BYTES:
self._result = bytes # Picked up by imread function
elif self._uri_type == URI_FILE:
self._file.write(bytes)
elif self._uri_type == URI_ZIPPED:
zf = zipfile.ZipFile(self._filename_zip[0], "a")
zf.writestr(self._filename_zip[1], bytes)
zf.close()
# elif self._uri_type == URI_FILENAME: -> is always direct
# elif self._uri_type == URI_FTP/HTTP: -> write not supported
# Close open files that we know of (and are responsible for)
if self._file and self._uri_type != URI_FILE:
self._file.close()
self._file = None
if self._zipfile:
self._zipfile.close()
self._zipfile = None
# Remove temp file
if self._filename_local:
try:
os.remove(self._filename_local)
except Exception: # pragma: no cover
warnings.warn(
"Failed to delete the temporary file at "
f"`{self._filename_local}`. Please report this issue."
)
self._filename_local = None
# Detach so gc can clean even if a reference of self lingers
self._bytes = None
def get_result(self):
"""For internal use. In some situations a write action can have
a result (bytes data). That is obtained with this function.
"""
# Is there a reason to disallow reading multiple times?
self._result, res = None, self._result
return res
@property
def firstbytes(self):
"""The first 256 bytes of the file. These can be used to
parse the header to determine the file-format.
"""
if self._firstbytes is None:
self._read_first_bytes()
return self._firstbytes
def _read_first_bytes(self, N=256):
if self._bytes is not None:
self._firstbytes = self._bytes[:N]
else:
# Prepare
try:
f = self.get_file()
except IOError:
if os.path.isdir(self.filename): # A directory, e.g. for DICOM
self._firstbytes = bytes()
return
raise
try:
i = f.tell()
except Exception:
i = None
# Read
self._firstbytes = read_n_bytes(f, N)
# Set back
try:
if i is None:
raise Exception("cannot seek with None")
f.seek(i)
except Exception:
# Prevent get_file() from reusing the file
self._file = None
# If the given URI was a file object, we have a problem,
if self._uri_type == URI_FILE:
raise IOError("Cannot seek back after getting firstbytes!")
def read_n_bytes(f, N):
"""read_n_bytes(file, n)
Read n bytes from the given file, or less if the file has less
bytes. Returns zero bytes if the file is closed.
"""
bb = bytes()
while len(bb) < N:
extra_bytes = f.read(N - len(bb))
if not extra_bytes:
break
bb += extra_bytes
return bb
class SeekableFileObject:
"""A readonly wrapper file object that add support for seeking, even if
the wrapped file object does not. The allows us to stream from http and
still use Pillow.
"""
def __init__(self, f):
self.f = f
self._i = 0 # >=0 but can exceed buffer
self._buffer = b""
self._have_all = False
self.closed = False
def read(self, n=None):
# Fix up n
if n is None:
pass
else:
n = int(n)
if n < 0:
n = None
# Can and must we read more?
if not self._have_all:
more = b""
if n is None:
more = self.f.read()
self._have_all = True
else:
want_i = self._i + n
want_more = want_i - len(self._buffer)
if want_more > 0:
more = self.f.read(want_more)
if len(more) < want_more:
self._have_all = True
self._buffer += more
# Read data from buffer and update pointer
if n is None:
res = self._buffer[self._i :]
else:
res = self._buffer[self._i : self._i + n]
self._i += len(res)
return res
def tell(self):
return self._i
def seek(self, i, mode=0):
# Mimic BytesIO behavior
# Get the absolute new position
i = int(i)
if mode == 0:
if i < 0:
raise ValueError("negative seek value " + str(i))
real_i = i
elif mode == 1:
real_i = max(0, self._i + i) # negative ok here
elif mode == 2:
if not self._have_all:
self.read()
real_i = max(0, len(self._buffer) + i)
else:
raise ValueError("invalid whence (%s, should be 0, 1 or 2)" % i)
# Read some?
if real_i <= len(self._buffer):
pass # no need to read
elif not self._have_all:
assert real_i > self._i # if we don't have all, _i cannot be > _buffer
self.read(real_i - self._i) # sets self._i
self._i = real_i
return self._i
def close(self):
self.closed = True
self.f.close()
def isatty(self):
return False
def seekable(self):
return True
class InitializationError(Exception):
"""The plugin could not initialize from the given request.
This is a _internal_ error that is raised by plugins that fail to handle
a given request. We use this to differentiate incompatibility between
a plugin and a request from an actual error/bug inside a plugin.
"""
pass