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#############################################################
## ##
## Copyright (c) 2003-2011 by The University of Queensland ##
## Earth Systems Science Computational Centre (ESSCC) ##
## http://www.uq.edu.au/esscc ##
## ##
## Primary Business: Brisbane, Queensland, Australia ##
## Licensed under the Open Software License version 3.0 ##
## http://www.opensource.org/licenses/osl-3.0.php ##
## ##
#############################################################
"""
Defines the L{ImageFormat} class and functions for mapping a
file name extension to an associated C{ImageFormat} object.
"""
import string
import os
import os.path
class ImageFormat(object):
"""
Class representing an image format.
"""
def __init__(self, name):
"""
Constructor.
@type name: str
@param name: Name assigned to this image format.
"""
self.name = name
def getName(self):
"""
Returns the name associated with this image format.
@rtype: str
"""
return self.name
def __str__(self):
return self.getName()
PNG = ImageFormat("PNG")
PNM = ImageFormat("PNM")
_nameFormatDict = dict()
_nameFormatDict[string.upper(str(PNG))] = PNG
_nameFormatDict[string.upper(str(PNM))] = PNM
def _getDelimitedFormatNameString():
return ", ".join(map(str,_nameFormatDict.keys()))
def getFormatFromName(formatName, ext=None):
"""
Returns the C{ImageFormat} object which corresponds
to a specified image-format name (string).
@type formatName: str
@param formatName: The name of an image format, one of: %s
@type ext: str
@param ext: File name extension for error message string.
""" % _getDelimitedFormatNameString()
if _nameFormatDict.has_key(string.upper(formatName)):
return _nameFormatDict[string.upper(formatName)]
raise \
ValueError(
(
"No image format found which matched extension '%s'," +
" valid image file formats are: %s"
)
%
(ext, _getDelimitedFormatNameString())
)
def getFormatFromExtension(fileName):
"""
Returns the C{ImageFormat} object which corresponds
to a specified file name. Uses the C{fileName} extension
to try and deduce the corresponding C{ImageFormat} object.
@type fileName: str
@param fileName: A file name.
@rtype: C{ImageFormat}
@return: An C{ImageFormat} object corresponding to the
specified file name (and corresponding file name extension).
"""
(base, ext) = os.path.splitext(fileName)
if (len(ext) > 0):
formatName = string.lstrip(ext, ".")
else:
raise ValueError(
"Could not determine image format from file "
+
"name " + fileName + ", no extension."
)
return getFormatFromName(formatName, ext)
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