Change plugin handling to be more agnostic (#39)

Author: scaramallion

docs/release_notes/v1.1.0.rst

@@ -2,3 +2,8 @@
 
 1.1.0
 =====
+
+* Simplified the plugin interface
+* Removed the ``plugins`` and ``_config`` modules
+* Added ``utils.get_decoders()`` function
+* Added ``pydicom.utils.get_pixel_data_decoders()`` function

pylibjpeg/__init__.py

@@ -5,9 +5,7 @@
 
 
 from ._version import __version__
-from ._config import PLUGINS
-from .plugins import load_plugins
-from .utils import decode
+from .utils import decode, add_handler
 
 
 # Setup default logging
@@ -27,11 +25,11 @@ def debug_logger():
     logger.addHandler(handler)
 
 
-load_plugins(PLUGINS)
+#load_plugins()
 
 
 # Must be after loading the plugins
-from .utils import add_handler
+
 
 try:
     import pydicom

pylibjpeg/_config.py

@@ -39,63 +39,28 @@
 import logging
 
 import numpy as np
+
 from pydicom.encaps import generate_pixel_data_frame
 from pydicom.pixel_data_handlers.util import pixel_dtype, get_expected_length
 
-from pylibjpeg.pydicom.utils import get_uid_decoder_dict
+from .utils import get_pixel_data_decoders
 
 
 LOGGER = logging.getLogger(__name__)
 
 
-try:
-    import pylibjpeg.plugins.libjpeg
-    HAVE_LIBJPEG = True
-    LOGGER.debug("libjpeg available to the pixel data handler")
-except ImportError:
-    HAVE_LIBJPEG = False
-    LOGGER.debug("libjpeg unavailable to the pixel data handler")
-
-try:
-    import pylibjpeg.plugins.openjpeg
-    HAVE_OPENJPEG = True
-    LOGGER.debug("openjpeg available to the pixel data handler")
-except ImportError:
-    HAVE_OPENJPEG = False
-    LOGGER.debug("openjpeg unavailable to the pixel data handler")
-
-
 HANDLER_NAME = 'pylibjpeg'
 DEPENDENCIES = {
     'numpy': ('http://www.numpy.org/', 'NumPy'),
-    'libjpeg': (
-        'http://github.com/pydicom/pylibjpeg-libjpeg/', 'libjpeg plugin'
-    ),
-    'openjpeg': (
-        'http://github.com/pydicom/pylibjpeg-openjpeg/', 'openjpeg plugin'
-    ),
 }
 
-
-_DECODERS = get_uid_decoder_dict()
-_LIBJPEG_SYNTAXES = [
-    '1.2.840.10008.1.2.4.50',
-    '1.2.840.10008.1.2.4.51',
-    '1.2.840.10008.1.2.4.57',
-    '1.2.840.10008.1.2.4.70',
-    '1.2.840.10008.1.2.4.80',
-    '1.2.840.10008.1.2.4.81'
-]
-_OPENJPEG_SYNTAXES = [
-    '1.2.840.10008.1.2.4.90',
-    '1.2.840.10008.1.2.4.91'
-]
-SUPPORTED_TRANSFER_SYNTAXES = _LIBJPEG_SYNTAXES + _OPENJPEG_SYNTAXES
+_DECODERS = get_pixel_data_decoders()
+SUPPORTED_TRANSFER_SYNTAXES = list(_DECODERS.keys())
 
 
 def is_available():
     """Return ``True`` if the handler has its dependencies met."""
-    return HAVE_LIBJPEG or HAVE_OPENJPEG
+    return True
 
 
 def supports_transfer_syntax(tsyntax):
@@ -134,13 +99,8 @@ def get_pixeldata(ds):
     Parameters
     ----------
     ds : pydicom.dataset.Dataset
-        The :class:`Dataset` containing an Image Pixel, Floating Point Image
-        Pixel or Double Floating Point Image Pixel module and the
-        *Pixel Data*, *Float Pixel Data* or *Double Float Pixel Data* to be
-        converted. If (0028,0004) *Photometric Interpretation* is
-        `'YBR_FULL_422'` then the pixel data will be
-        resampled to 3 channel data as per Part 3, :dcm:`Annex C.7.6.3.1.2
-        <part03/sect_C.7.6.3.html#sect_C.7.6.3.1.2>` of the DICOM Standard.
+        The :class:`Dataset` containing an Image Pixel module and the
+        *Pixel Data* to be converted.
 
     Returns
     -------
@@ -161,20 +121,9 @@ def get_pixeldata(ds):
     # The check of transfer syntax must be first
     if tsyntax not in SUPPORTED_TRANSFER_SYNTAXES:
         raise NotImplementedError(
-            "Unable to convert the pixel data as the transfer syntax "
-            "is not supported by the pylibjpeg pixel data handler."
-        )
-
-    if tsyntax in _LIBJPEG_SYNTAXES and not HAVE_LIBJPEG:
-        raise RuntimeError(
-            "The libjpeg plugin is required to decode pixel data with a "
-            "transfer syntax of '{}'".format(tsyntax)
-        )
-
-    if tsyntax in _OPENJPEG_SYNTAXES and not HAVE_OPENJPEG:
-        raise RuntimeError(
-            "The openjpeg plugin is required to decode pixel data with a "
-            "transfer syntax of '{}'".format(tsyntax)
+            "Unable to convert the pixel data as there are no pylibjpeg "
+            "plugins available to decode pixel data encoded using '{}'"
+            .format(tsyntax.name)
         )
 
     # Check required elements

pylibjpeg/plugins.py

@@ -1,62 +1,6 @@
 """Utilities for pydicom and DICOM pixel data"""
 
-from pylibjpeg.plugins import *
-
-
-def decoder_from_uid(uid):
-    """Return a JPEG decoder for `uid`.
-
-    Parameters
-    ----------
-    uid : str or pydicom.uid.UID
-        The *Transfer Syntax UID* that the pixel data has been encoded with.
-
-    Returns
-    -------
-    callable
-        A callable function that can be used to decode the JPEG format
-        corresponding to `uid`.
-    """
-    decoders = get_dicom_decoders()
-    for name in decoders:
-        try:
-            return decoders[name][uid]
-        except KeyError:
-            pass
-
-    msg = (
-        "No decoder is available for the Transfer Syntax UID - '{}'"
-        .format(uid)
-    )
-    raise NotImplementedError(msg)
-
-
-def encoder_from_uid(uid):
-    """Return a JPEG encoder for `uid`.
-
-    Parameters
-    ----------
-    uid : str or pydicom.uid.UID
-        The *Transfer Syntax UID* that the pixel data will be encoded with.
-
-    Returns
-    -------
-    callable
-        A callable function that can be used to encode to the JPEG format
-        corresponding to `uid`.
-    """
-    encoders = get_dicom_encoders()
-    for name in encoders:
-        try:
-            return encoders[name][uid]
-        except KeyError:
-            pass
-
-    msg = (
-        "No encoder is available for the Transfer Syntax UID - '{}'"
-        .format(uid)
-    )
-    raise NotImplementedError(msg)
+from pkg_resources import iter_entry_points
 
 
 def generate_frames(ds):
@@ -75,7 +19,7 @@ def generate_frames(ds):
     from pydicom.encaps import generate_pixel_data_frame
     from pydicom.pixel_data_handlers.util import pixel_dtype
 
-    decoders = get_uid_decoder_dict()
+    decoders = get_pixel_data_decoders()
     decode = decoders[ds.file_meta.TransferSyntaxUID]
 
     p_interp = ds.PhotometricInterpretation
@@ -85,73 +29,13 @@ def generate_frames(ds):
         yield reshape_frame(ds, arr)
 
 
-def get_decodable_uids():
-    """Return a list of decodable *Transfer Syntax UIDs*."""
-    uids = []
-    for name, uid_coder in get_dicom_decoders().items():
-        uids += uid_coder.keys()
-
-    return list(set(uids))
-
-
-def get_dicom_decoders():
-    """Return available plugins with DICOM decoders.
-
-    Returns
-    -------
-    dict
-        A ``dict`` containing the available DICOM decoders as
-        ``{plugin name : {UID : callable}}``.
-    """
-    decoders = {
-        k: getattr(globals()[k], 'DICOM_DECODERS', {}) for k in get_plugins()
-    }
-
-    return decoders
-
-
-def get_dicom_encoders():
-    """Return available plugins with DICOM encoders.
-
-    Returns
-    -------
-    dict
-        A ``dict`` containing the available DICOM encoders as
-        ``{plugin name : {UID : callable}}``.
-    """
-    encoders = {
-        k: getattr(globals()[k], 'DICOM_ENCODERS', {}) for k in get_plugins()
+def get_pixel_data_decoders():
+    """Return a :class:`dict` of {UID: callable}."""
+    return {
+        val.name: val.load()
+        for val in iter_entry_points('pylibjpeg.pixel_data_decoders')
     }
 
-    return encoders
-
-
-def get_encodable_uids():
-    """Return a list of encodable *Transfer Syntax UIDs*."""
-    uids = []
-    for name, uid_coder in get_dicom_encoders().items():
-        uids += uid_coder.keys()
-
-    return list(set(uids))
-
-
-def get_uid_decoder_dict():
-    """Return a :class:`dict` of {UID: decoder}."""
-    decoder_dict = {}
-    for _, uid_decoder_dict in get_dicom_decoders().items():
-        decoder_dict.update(uid_decoder_dict)
-
-    return decoder_dict
-
-
-def get_uid_encoder_dict():
-    """Return a :class:`dict` of {UID: encoder}."""
-    encoder_dict = {}
-    for _, uid_encoder_dict in get_dicom_encoders().items():
-        encoder_dict.update(uid_encoder_dict)
-
-    return encoder_dict
-
 
 def reshape_frame(ds, arr):
     """Return a reshaped :class:`numpy.ndarray` `arr`.