add experimental ctypes Python binding

start hacking on a new Python interface

.gitignore

@@ -7,6 +7,7 @@ TAGS
 *.lo
 *.la
 *.pc
+*.pyc
 .deps
 .libs
 aclocal.m4

TODO

@@ -69,10 +69,6 @@
 
 	- some way for nip2 to get the vips bin area
 
-	- some way for nip2 to get EXEEXT
-
-	- wrap a basic set of Magick filters
-
 
 
 - need vips_image_invalidate_area()

python/README

@@ -0,0 +1,11 @@
+Experimental Python binding using ctypes
+
+The current Python binding uses swig to wrap the C++ interface. This causes
+problems on Windows, since compiling all of the DLLs correctly to work with
+the various python binaries is painful, and makes the bainding very large.
+
+The idea here is to use ctypes to make a binding that's just Python and which
+directly wraps the C API. The new vips8 C API is much more wrapper-friendly,
+plus we can reuse parts of the gobject binding, so this should be possible. 
+
+

python/finalize.py

@@ -0,0 +1,41 @@
+#!/usr/bin/python
+
+# Finalization with weakrefs
+# This is designed for avoiding __del__.
+
+
+import sys
+import traceback
+import logging
+import weakref
+
+__author__ = "Benjamin Peterson <benjamin@python.org>"
+
+class OwnerRef(weakref.ref):
+    """A simple weakref.ref subclass, so attributes can be added."""
+    pass
+
+def _run_finalizer(ref):
+    """Internal weakref callback to run finalizers"""
+    del _finalize_refs[id(ref)]
+    finalizer = ref.finalizer
+    item = ref.item
+    try:
+        finalizer(item)
+    except Exception as e:
+        logging.debug("Exception %s running %s", repr(e), format(finalizer))
+        traceback.print_exc()
+
+_finalize_refs = {}
+
+def track(owner, item, finalizer):
+    """Register an object for finalization.
+
+    ``owner`` is the the object which is responsible for ``item``.
+    ``finalizer`` will be called with ``item`` as its only argument when
+    ``owner`` is destroyed by the garbage collector.
+    """
+    ref = OwnerRef(owner, _run_finalizer)
+    ref.item = item
+    ref.finalizer = finalizer
+    _finalize_refs[id(ref)] = ref

python/test.py

@@ -0,0 +1,14 @@
+#!/usr/bin/python
+
+import logging
+
+import vipsimage
+
+logging.basicConfig(level = logging.DEBUG)
+
+# should work
+a = vipsimage.VipsImage('/home/john/pics/healthygirl.jpg')
+a.write('x.png')
+
+# should raise an error
+a = vipsimage.VipsImage('banana')

python/vipsimage.py

@@ -0,0 +1,50 @@
+#!/usr/bin/python
+
+"""This module wraps up libvips in a less awful interface.
+
+Author: J.Cupitt
+GNU LESSER GENERAL PUBLIC LICENSE
+"""
+
+import logging
+import ctypes
+
+import vipsobject
+
+libvips = vipsobject.libvips
+
+vips_image_new = libvips.vips_image_new
+vips_image_new.restype = vipsobject.check_pointer_return
+
+vips_image_new_from_file = libvips.vips_image_new_from_file
+vips_image_new_from_file.restype = vipsobject.check_pointer_return
+vips_image_new_from_file.argtypes = [ctypes.c_char_p]
+
+vips_image_new_mode = libvips.vips_image_new_mode
+vips_image_new_mode.restype = vipsobject.check_pointer_return
+vips_image_new_mode.argtypes = [ctypes.c_char_p, ctypes.c_char_p]
+
+vips_image_write = libvips.vips_image_write
+vips_image_write.restype = vipsobject.check_int_return
+vips_image_write.argtypes = [ctypes.c_void_p, ctypes.c_char_p]
+
+class VipsImage(vipsobject.VipsObject):
+    """Manipulate a libvips image."""
+
+    def __init__(self, filename = None, mode = None):
+        logging.debug('vipsimage: init')
+
+        vipsobject.VipsObject.__init__(self)
+
+        if filename == None and mode == None:
+            self.vipsobject = vips_image_new()
+        elif filename != None and mode == None:
+            self.vipsobject = vips_image_new_from_file(filename)
+        else:
+            self.vipsobject = vips_image_new_mode(filename, mode)
+
+    def write(self, filename):
+        vips_image_write(self.vipsobject, filename)
+
+
+

python/vipsobject.py

@@ -0,0 +1,66 @@
+#!/usr/bin/python
+
+"""This module wraps up libvips in a less awful interface.
+
+Wrap VipsObject.
+
+Author: J.Cupitt
+GNU LESSER GENERAL PUBLIC LICENSE
+"""
+
+import logging
+import sys
+import ctypes
+
+import finalize
+
+# .15 is 7.25+ with the new vips8 API
+libvips = ctypes.CDLL('libvips.so.15')
+libvips.vips_init(sys.argv[0])
+
+class Error(Exception):
+
+    """An error from libvips.
+
+    message -- a high-level description of the error
+    detail -- a string with some detailed diagnostics
+    """
+
+    def __init__(self, message):
+        self.message = message
+        self.detail = vips_error_buffer()
+        libvips.vips_error_clear()
+
+        logging.debug('vipsobject: Error %s %s', self.message, self.detail)
+
+    def __str__(self):
+        return '%s - %s' %(self.message, self.detail)
+
+def check_int_return(value):
+    if value != 0:
+        raise Error('Error calling vips function.')
+    return value
+
+def check_pointer_return(value):
+    if value == None:
+        raise Error('Error calling vips function.')
+    return value
+
+vips_error_buffer = libvips.vips_error_buffer
+vips_error_buffer.restype = ctypes.c_char_p
+
+class VipsObject:
+    """Abstract base class for libvips."""
+
+    def unref_vips(self):
+        if self.vipsobject != None:
+            libvips.g_object_unref(self.vipsobject)
+            self.vipsobject = None
+
+    def __init__(self):
+        logging.debug('vipsobject: init')
+
+        self.vipsobject = None
+        finalize.track(self, self, self.unref_vips)
+
+