# -*- 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. """ from __future__ import absolute_import, print_function, division import sys import os from io import BytesIO import zipfile import tempfile import shutil from ..core import string_types, binary_type, urlopen, get_remote_file if sys.version_info < (3,): FileNotFoundError = OSError try: from pathlib import Path except ImportError: Path = None # URI types URI_BYTES = 1 URI_FILE = 2 URI_FILENAME = 3 URI_ZIPPED = 4 URI_HTTP = 5 URI_FTP = 6 SPECIAL_READ_URIS = "", "" # The user can use this string in a write call to get the data back as bytes. RETURN_BYTES = "" # Example images that will be auto-downloaded EXAMPLE_IMAGES = { "astronaut.png": "Image of the astronaut Eileen Collins", "camera.png": "Classic grayscale image of a photographer", "checkerboard.png": "Black and white image of a chekerboard", "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", } class Request(object): """ Request(uri, mode, **kwargs) 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, **kwargs): # General self._uri_type = None self._filename = None self._extension = 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._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 self._mode = mode if not isinstance(mode, string_types): raise ValueError("Request requires mode must be a string") if not len(mode) == 2: raise ValueError("Request requires mode to have two chars") if mode[0] not in "rw": raise ValueError('Request requires mode[0] to be "r" or "w"') if mode[1] not in "iIvV?": raise ValueError('Request requires mode[1] to be in "iIvV?"') # Parse what was given self._parse_uri(uri) # Set extension if self._filename is not None: ext = self._filename if self._filename.startswith(("http://", "https://", "ftp://", "ftps://")): ext = ext.split("?")[0] self._extension = "." + ext.split(".")[-1].lower() def _parse_uri(self, uri): """ Try to figure our what we were given """ py3k = sys.version_info[0] == 3 is_read_request = self.mode[0] == "r" is_write_request = self.mode[0] == "w" if isinstance(uri, string_types): # 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 # Less explicit (particularly on py 2.x) elif py3k: self._uri_type = URI_FILENAME self._filename = uri else: # pragma: no cover - our ref for coverage is py3k try: isfile = os.path.isfile(uri) except Exception: isfile = False # If checking does not even work ... if isfile: self._uri_type = URI_FILENAME self._filename = uri elif len(uri) < 256: # Can go wrong with veeery tiny images self._uri_type = URI_FILENAME self._filename = uri elif isinstance(uri, binary_type) and is_read_request: self._uri_type = URI_BYTES self._filename = "" self._bytes = uri else: self._uri_type = URI_FILENAME self._filename = uri elif py3k and isinstance(uri, binary_type) and is_read_request: self._uri_type = URI_BYTES self._filename = "" self._bytes = uri elif Path is not None and 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 = "" self._file = uri elif is_write_request: if hasattr(uri, "write") and hasattr(uri, "close"): self._uri_type = URI_FILE self._filename = "" self._file = uri # 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 separater for needle in [".zip/", ".zip\\"]: zip_i = self._filename.lower().find(needle) if zip_i > 0: zip_i += 4 self._uri_type = URI_ZIPPED self._filename_zip = ( self._filename[:zip_i], 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): """ 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): """ 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 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 do not need to 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[0] == "w" # 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: self._file = BytesIO() 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() else: # Open zipfile and open new file object for specific file self._zipfile = zipfile.ZipFile(filename, "r") self._file = self._zipfile.open(name, "r") make_file_object_support_noop_seeks(self._file) elif self._uri_type in [URI_HTTP or URI_FTP]: assert not want_to_write # This should have been tested in init self._file = urlopen(self.filename, timeout=5) make_file_object_support_noop_seeks(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._uri_type in (URI_HTTP, URI_FTP): ext = os.path.splitext(self._filename.split("?")[0])[1] else: ext = os.path.splitext(self._filename)[1] self._filename_local = tempfile.mktemp(ext, "imageio_") # Write stuff to it? if self.mode[0] == "r": with open(self._filename_local, "wb") as file: shutil.copyfileobj(self.get_file(), file) return self._filename_local def finish(self): """ finish() For internal use (called when the context of the reader/writer exits). Finishes this request. Close open files and process results. """ # Init bytes = None # Collect bytes from temp file if self.mode[0] == "w" and self._filename_local: with open(self._filename_local, "rb") as file: bytes = file.read() # Collect bytes from BytesIO file object. written = (self.mode[0] == "w") and self._file if written and self._uri_type in [URI_BYTES, URI_ZIPPED]: bytes = self._file.getvalue() # 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 pass self._filename_local = None # Handle bytes that we collected if bytes is not None: if self._uri_type == URI_BYTES: self._result = bytes # Picked up by imread function elif self._uri_type == URI_ZIPPED: zf = zipfile.ZipFile(self._filename_zip[0], "a") zf.writestr(self._filename_zip[1], bytes) zf.close() # 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. """ 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 = binary_type() 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 = binary_type() while len(bb) < N: extra_bytes = f.read(N - len(bb)) if not extra_bytes: break bb += extra_bytes return bb def make_file_object_support_noop_seeks(f): """This fixes up an HTTPResponse object so that it can tell(), and also seek() will work if its effectively a no-op. This allows tools like Pillow to use the file object. """ count = [0] def read(n=None): res = ori_read(n) count[0] += len(res) return res def tell(): return count[0] def seek(i, mode=0): if not (mode == 0 and i == count[0]): ori_seek(i, mode) def fail_seek(i, mode=0): raise RuntimeError("No seeking allowed!") # Note, there is currently no protection from wrapping an object more than # once, it will (probably) work though, because closures. ori_read = f.read ori_seek = f.seek if hasattr(f, "seek") else fail_seek f.read = read f.tell = tell f.seek = seek