85 lines
2.1 KiB
Python
85 lines
2.1 KiB
Python
#!/usr/bin/python
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"""This module wraps up libvips in a less awful interface.
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Wrap VipsObject.
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Author: J.Cupitt
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GNU LESSER GENERAL PUBLIC LICENSE
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"""
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import logging
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import sys
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import ctypes
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import finalizable
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# .15 is 7.25+ with the new vips8 API
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libvips = ctypes.CDLL('libvips.so.15')
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libvips.vips_init(sys.argv[0])
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# given a class and value, search for a class member with that value
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# handy for enum classes, use to turn numbers to strings
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def class_value(classobject, value):
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for name in dir(classobject):
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if getattr(classobject, name) == value:
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return classobject.__name__ + '.' + name
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return 'unknown'
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class Error(Exception):
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"""An error from libvips.
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message -- a high-level description of the error
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detail -- a string with some detailed diagnostics
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"""
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def __init__(self, message):
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self.message = message
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self.detail = vips_error_buffer()
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libvips.vips_error_clear()
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logging.debug('vipsobject: Error: %s %s', self.message, self.detail)
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def __str__(self):
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return '%s %s' %(self.message, self.detail)
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# handy checkers, assign to errcheck
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def check_int_return(result, func, args):
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if result != 0:
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raise Error('Error calling vips function %s.' % func.__name__)
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return result
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def check_pointer_return(result, func, args):
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if result == None:
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raise Error('Error calling vips function %s.' % func.__name__)
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return result
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vips_error_buffer = libvips.vips_error_buffer
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vips_error_buffer.restype = ctypes.c_char_p
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class VipsObject(finalizable.Finalizable):
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"""Abstract base class for libvips."""
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# attributes we finalize
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ghost_attributes = ('vipsobject', )
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def __finalize__(self):
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logging.debug('vipsobject: __finalize__')
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if self.vipsobject != None:
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logging.debug('vipsobject: unref %s' % hex(self.vipsobject))
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libvips.g_object_unref(self.vipsobject)
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self.vipsobject = None
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def enable_finalize(self):
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self.bind_finalizer(*self.ghost_attributes)
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def __init__(self):
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logging.debug('vipsobject: init')
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self.vipsobject = None
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