added VImage::convert2disc

ChangeLog

@@ -1,6 +1,9 @@
 25/1/08 started 7.14.0
 - bump all version numbers for new stable
-- better CMYK JPEG read
+- better CMYK JPEG read (thanks Ole)
+- add __str__ to VError in Python (thanks Ole)
+- revert the dynamic wrapping for Python :-( next version!
+- added VImage::convert2disc (thanks Ole)
 
 12/12/07 started 7.13.3
 - added "include <cstring>" to VImage.cc to help gcc 4.3

doc/src/vimage.tex

@@ -99,6 +99,25 @@ disc with deflate compression.
 See the manual page for \verb+im_open(3)+ for details of all the file formats
 and conversions available.
 
+\subsection{Large files}
+
+Opening large files in formats like JPEG which do not support random access
+can use large amounts of memory, since the file has to be decompressed before
+it can be used.
+
+The \verb+convert2disc()+ member lets you decompress to a disc file rather
+than to memory. For example:
+
+\begin{verbatim}
+VImage fred = VImage::convert2disc( "im_jpeg2vips", 
+  "file.jpg", "temp.v" );
+\end{verbatim}
+
+/noindent
+Will decompress to the file \verb+temp.v+, then open that and return a
+reference to it. You will need to delete the file once you are finished with
+it.
+
 \subsection{Projection functions}
 
 A set of member functions of \verb+VImage+ provide access to the fields in

include/vips/VImage.h

@@ -192,6 +192,15 @@ public:
 	VImage( im__IMAGE *image );
 	VImage() throw( VError );
 
+	// Convert to a disc file, eg:
+	// 	VImage fred = VImage::convert2disc( "im_jpeg2vips", 
+	// 		"file.jpg", "temp.v" );
+	// Runs im_jpeg2vips to the temp file, then opens that and returns
+	// it. Useful for opening very large files without using a lot of RAM.
+	// FIXME ... what a hack, replace this with something better
+	static VImage convert2disc( const char* convert, 
+		const char* in, const char* disc ) throw( VError );
+
 	// Copy constructor 
 	VImage( const VImage &a );
 
@@ -238,13 +247,9 @@ public:
 	void initdesc( int, int, int, TBandFmt, TCoding, TType, 
 		float = 1.0, float = 1.0, int = 0, int = 0 ) throw( VError );
 
-/* Bindings wrap databased operations at runtime using reflection.
- */
-#ifndef SWIG
 	/* Insert automatically generated headers.
 	 */
 #include "vipsc++.h"
-#endif /*SWIG*/
 
 /* No point getting SWIG to wrap these ... we do this by hand later so we can
  * handle things like "a + 12" correctly.

libsrcCC/VImage.cc

@@ -141,7 +141,7 @@ void VImage::refblock::removeref() throw( VError )
 		delete this;
 }
 
-// Init with name ... means open for read.
+// Init with name ... mode defaults to "r"
 VImage::VImage( const char *name, const char *mode ) throw( VError )
 {
 	_ref = new refblock;
@@ -244,6 +244,22 @@ void VImage::debug_print()
 	im_printdesc( image() );
 }
 
+// Like jpeg2vips, but convert to a disc file rather than to memory
+// We can handle huge files without running out of RAM
+VImage VImage::convert2disc( const char* convert, 
+	const char* in, const char* disc ) throw( VError )
+{
+	VImage out( disc, "w" );
+
+	Vargv _vec( convert );
+
+	_vec.data(0) = (im_object) in;
+	_vec.data(1) = out.image();
+	_vec.call();
+
+	return( out );
+}
+
 // Write this to a VImage
 VImage VImage::write( VImage out ) throw( VError )
 {

python/vipsCC/Makefile.am

@@ -1,5 +1,3 @@
-
-
 INCLUDES = -I${top_srcdir}/include @VIPS_CFLAGS@ @VIPS_INCLUDES@ @PYTHON_INCLUDES@
 
 # we install to a directory inside the python area, since we are a module
@@ -10,8 +8,13 @@ vipscc_PYTHON = VImage.py VDisplay.py VError.py VMask.py __init__.py
 # I tried making a suffix rule for this (and defining SUFFIXES) but I couldn;t
 # get it to work, how annoying 
 # FIXME at some point
+#
+# need an expanded VImage.h ... SWIG's preprocessor b0rks on includes inside
+# class definitions
 vimagemodule.cxx: VImage.i
+	cpp -DSWIG -E $(top_srcdir)/include/vips/VImage.h > VImage.h
 	swig -python -c++ -interface $(@:.cxx=) -I$(top_srcdir)/include -o $@ $<
+
 vdisplaymodule.cxx: VDisplay.i
 	swig -python -c++ -interface $(@:.cxx=) -I$(top_srcdir)/include -o $@ $<
 verrormodule.cxx: VError.i
@@ -38,7 +41,7 @@ vmaskmodule_la_LIBADD = ../../libsrcCC/libvipsCC.la $(VIPS_LIBS)
 nodist_vmaskmodule_la_SOURCES = vmaskmodule.cxx 
 
 CLEANFILES = \
-	vimagemodule.cxx \
+	vimagemodule.cxx VImage.h \
 	verrormodule.cxx vdisplaymodule.cxx vmaskmodule.cxx \
 	VImage.py VDisplay.py VError.py VMask.py
 

python/vipsCC/VError.i

@@ -10,3 +10,10 @@
 %include "std_string.i"
 
 %include vips/VError.h
+
+%extend vips::VError {
+        const char *__str__ () {
+                return $self->what ();
+        }
+}
+

python/vipsCC/VImage.i

@@ -13,13 +13,6 @@
  */
 %rename(__assign__) vips::VImage::operator=;
 
-/* We wrap the C++ VImage class as VImage_core, then write the user-visible
- * VImage class ourselves with a %pythoncode (see below). Our hand-made VImage
- * class wraps all the operators from the VIPS image operation database via
- * __getattr__.
- */
-%rename(VImage_core) VImage;
-
 %include "std_list.i"
 %include "std_complex.i"
 %include "std_vector.i"
@@ -35,42 +28,10 @@ namespace std {
   %template(ImageVector) vector<VImage>;
 }
 
-%include vips/VImage.h
+/* Need the expanded VImage.h in this directory, rather than the usual
-
+ * vips/VImage.h. SWIG b0rks on #include inside class definitions.
-/* Search for a VIPS operation that matches a name and a set of args.
  */
-%inline %{
+%include VImage.h
-
-/* We need to wrap by hand, hmm
- */
-
-%}
-
-/* Now wrap SWIG's VImage_core with our own VImage class which does operations
- * from the VIPS operation database.
- */
-%pythoncode %{
-# proxy class to hold a method name during call
-class VImage_method:
-        def __init__ (self,name):
-                self.method = name
-            
-        def __call__ (self, obj_to_call, arguments):  
-                method = obj_to_call.__getattr__ (self.method)
-                print "VImage_method: calling ", self.method
-                print " with args ", arguments
-                method (arguments)
-
-class VImage (VImage_core):
-        def __init (self, *args):
-                VImage_core.__init__ (self, *args)
-        def __getattr__ (self, name):
-                print "VImage getattr: ", name
-                if (is_a_valid_method (name)):
-                        return VImage_method (name)
-                else:
-                        raise AttributeError ("unknown method %s" % name)
-%}
 
 /* Helper code for vips_init().
  */