start adding png stream save

doesn't pass the test suite yet

libvips/foreign/pforeign.h

@@ -190,14 +190,10 @@ int vips__png_read_stream( VipsStreamInput *input, VipsImage *out,
 gboolean vips__png_isinterlaced_stream( VipsStreamInput *input );
 extern const char *vips__png_suffs[];
 
-int vips__png_write( VipsImage *in, const char *filename, 
+int vips__png_write_stream( VipsImage *in, VipsStreamOutput *output,
 	int compress, int interlace, const char *profile,
 	VipsForeignPngFilter filter, gboolean strip,
 	gboolean palette, int colours, int Q, double dither );
-int vips__png_write_buf( VipsImage *in, 
-	void **obuf, size_t *olen, int compression, int interlace, 
-	const char *profile, VipsForeignPngFilter filter, gboolean strip,
-	gboolean palette, int colours, int Q, double dither );
 
 /* Map WEBP metadata names to vips names.
  */

libvips/foreign/pngsave.c

@@ -179,6 +179,63 @@ vips_foreign_save_png_init( VipsForeignSavePng *png )
 	png->dither = 1.0;
 }
 
+typedef struct _VipsForeignSavePngStream {
+	VipsForeignSavePng parent_object;
+
+	VipsStreamOutput *output;
+} VipsForeignSavePngStream;
+
+typedef VipsForeignSavePngClass VipsForeignSavePngStreamClass;
+
+G_DEFINE_TYPE( VipsForeignSavePngStream, vips_foreign_save_png_stream, 
+	vips_foreign_save_png_get_type() );
+
+static int
+vips_foreign_save_png_stream_build( VipsObject *object )
+{
+	VipsForeignSave *save = (VipsForeignSave *) object;
+	VipsForeignSavePng *png = (VipsForeignSavePng *) object;
+	VipsForeignSavePngStream *stream = (VipsForeignSavePngStream *) object;
+
+	if( VIPS_OBJECT_CLASS( vips_foreign_save_png_stream_parent_class )->
+		build( object ) )
+		return( -1 );
+
+	if( vips__png_write_stream( save->ready, stream->output,
+		png->compression, png->interlace, png->profile, png->filter,
+		save->strip, png->palette, png->colours, png->Q, png->dither ) )
+		return( -1 );
+
+	return( 0 );
+}
+
+static void
+vips_foreign_save_png_stream_class_init( VipsForeignSavePngStreamClass *class )
+{
+	GObjectClass *gobject_class = G_OBJECT_CLASS( class );
+	VipsObjectClass *object_class = (VipsObjectClass *) class;
+
+	gobject_class->set_property = vips_object_set_property;
+	gobject_class->get_property = vips_object_get_property;
+
+	object_class->nickname = "pngsave_stream";
+	object_class->description = _( "save image to png stream" );
+	object_class->build = vips_foreign_save_png_stream_build;
+
+	VIPS_ARG_OBJECT( class, "output", 1,
+		_( "Output" ),
+		_( "Stream to save to" ),
+		VIPS_ARGUMENT_REQUIRED_INPUT, 
+		G_STRUCT_OFFSET( VipsForeignSavePngStream, output ),
+		VIPS_TYPE_STREAM_OUTPUT );
+
+}
+
+static void
+vips_foreign_save_png_stream_init( VipsForeignSavePngStream *stream )
+{
+}
+
 typedef struct _VipsForeignSavePngFile {
 	VipsForeignSavePng parent_object;
 
@@ -197,15 +254,23 @@ vips_foreign_save_png_file_build( VipsObject *object )
 	VipsForeignSavePng *png = (VipsForeignSavePng *) object;
 	VipsForeignSavePngFile *png_file = (VipsForeignSavePngFile *) object;
 
+	VipsStreamOutput *output;
+
 	if( VIPS_OBJECT_CLASS( vips_foreign_save_png_file_parent_class )->
 		build( object ) )
 		return( -1 );
 
-	if( vips__png_write( save->ready, 
+	if( !(output = vips_stream_output_new_from_filename( 
-		png_file->filename, png->compression, png->interlace, 
+		png_file->filename )) )
-		png->profile, png->filter, save->strip, png->palette,
-		png->colours, png->Q, png->dither ) )
 		return( -1 );
+	if( vips__png_write_stream( save->ready, output, 
+		png->compression, png->interlace, 
+		png->profile, png->filter, save->strip, png->palette,
+		png->colours, png->Q, png->dither ) ) {
+		VIPS_UNREF( output );
+		return( -1 );
+	}
+	VIPS_UNREF( output );
 
 	return( 0 );
 }
@@ -252,27 +317,32 @@ vips_foreign_save_png_buffer_build( VipsObject *object )
 {
 	VipsForeignSave *save = (VipsForeignSave *) object;
 	VipsForeignSavePng *png = (VipsForeignSavePng *) object;
+	VipsForeignSavePngBuffer *buffer = (VipsForeignSavePngBuffer *) object;
 
-	void *obuf;
+	VipsStreamOutput *output;
-	size_t olen;
 	VipsBlob *blob;
 
 	if( VIPS_OBJECT_CLASS( vips_foreign_save_png_buffer_parent_class )->
 		build( object ) )
 		return( -1 );
 
-	if( vips__png_write_buf( save->ready, &obuf, &olen,
+	if( !(output = vips_stream_output_new_memory()) )
-		png->compression, png->interlace, png->profile, png->filter,
-		save->strip, png->palette, png->colours, png->Q, png->dither ) )
 		return( -1 );
 
-	/* vips__png_write_buf() makes a buffer that needs g_free(), not
+	if( vips__png_write_stream( save->ready, output,
-	 * vips_free().
+		png->compression, png->interlace, png->profile, png->filter,
-	 */
+		save->strip, png->palette, png->colours, png->Q, 
-	blob = vips_blob_new( (VipsCallbackFn) g_free, obuf, olen );
+		png->dither ) ) {
-	g_object_set( object, "buffer", blob, NULL );
+		VIPS_UNREF( output );
+		return( -1 );
+	}
+
+	g_object_get( output, "blob", &blob, NULL );
+	g_object_set( buffer, "buffer", blob, NULL );
 	vips_area_unref( VIPS_AREA( blob ) );
 
+	VIPS_UNREF( output );
+
 	return( 0 );
 }
 
@@ -427,3 +497,39 @@ vips_pngsave_buffer( VipsImage *in, void **buf, size_t *len, ... )
 
 	return( result );
 }
+
+/**
+ * vips_pngsave_stream: (method)
+ * @in: image to save 
+ * @output: save image to this stream
+ * @...: %NULL-terminated list of optional named arguments
+ *
+ * Optional arguments:
+ *
+ * * @compression: compression level
+ * * @interlace: interlace image
+ * * @profile: ICC profile to embed
+ * * @filter: libpng row filter flag(s)
+ * * @palette: enable quantisation to 8bpp palette
+ * * @colours: max number of palette colours for quantisation
+ * * @Q: quality for 8bpp quantisation (does not exceed @colours)
+ * * @dither: amount of dithering for 8bpp quantization
+ *
+ * As vips_pngsave(), but save to a stream.
+ *
+ * See also: vips_pngsave(), vips_image_write_to_stream().
+ *
+ * Returns: 0 on success, -1 on error.
+ */
+int
+vips_pngsave_stream( VipsImage *in, VipsStreamOutput *output, ... )
+{
+	va_list ap;
+	int result;
+
+	va_start( ap, output );
+	result = vips_call_split( "pngsave_stream", ap, in, output );
+	va_end( ap );
+
+	return( result );
+}

libvips/foreign/vipspng.c

@@ -780,8 +780,7 @@ typedef struct {
 	VipsImage *in;
 	VipsImage *memory;
 
-	FILE *fp;
+	VipsStreamOutput *output;
-	VipsDbuf dbuf;
 
 	png_structp pPng;
 	png_infop pInfo;
@@ -791,9 +790,8 @@ typedef struct {
 static void
 write_finish( Write *write )
 {
-	VIPS_FREEF( fclose, write->fp );
 	VIPS_UNREF( write->memory );
-	vips_dbuf_destroy( &write->dbuf );
+	VIPS_UNREF( write->output );
 	if( write->pPng )
 		png_destroy_write_struct( &write->pPng, &write->pInfo );
 }
@@ -804,8 +802,17 @@ write_destroy( VipsImage *out, Write *write )
 	write_finish( write ); 
 }
 
+static void
+user_write_data( png_structp pPng, png_bytep data, png_size_t length )
+{
+	Write *write = (Write *) png_get_io_ptr( pPng );
+
+	if( vips_stream_output_write( write->output, data, length ) ) 
+		png_error( pPng, "not enough data" );
+}
+
 static Write *
-write_new( VipsImage *in )
+write_new( VipsImage *in, VipsStreamOutput *output )
 {
 	Write *write;
 
@@ -814,8 +821,8 @@ write_new( VipsImage *in )
 	memset( write, 0, sizeof( Write ) );
 	write->in = in;
 	write->memory = NULL;
-	write->fp = NULL;
+	write->output = output;
-	vips_dbuf_init( &write->dbuf );
+	g_object_ref( output );
 	g_signal_connect( in, "close", 
 		G_CALLBACK( write_destroy ), write ); 
 
@@ -833,6 +840,8 @@ write_new( VipsImage *in )
 		PNG_SKIP_sRGB_CHECK_PROFILE, PNG_OPTION_ON );
 #endif /*PNG_SKIP_sRGB_CHECK_PROFILE*/
 
+	png_set_write_fn( write->pPng, write, user_write_data, NULL );
+
 	/* Catch PNG errors from png_create_info_struct().
 	 */
 	if( setjmp( png_jmpbuf( write->pPng ) ) ) 
@@ -1176,80 +1185,25 @@ write_vips( Write *write,
 }
 
 int
-vips__png_write( VipsImage *in, const char *filename, 
+vips__png_write_stream( VipsImage *in, VipsStreamOutput *output,
-	int compress, int interlace, const char *profile,
+	int compression, int interlace,
-	VipsForeignPngFilter filter, gboolean strip,
-	gboolean palette, int colours, int Q, double dither )
-{
-	Write *write;
-
-#ifdef DEBUG
-	printf( "vips__png_write: writing \"%s\"\n", filename );
-#endif /*DEBUG*/
-
-	if( !(write = write_new( in )) )
-		return( -1 );
-
-	/* Make output.
-	 */
-        if( !(write->fp = vips__file_open_write( filename, FALSE )) ) 
-		return( -1 );
-	png_init_io( write->pPng, write->fp );
-
-	/* Convert it!
-	 */
-	if( write_vips( write, 
-		compress, interlace, profile, filter, strip, palette,
-		colours, Q, dither ) ) {
-		vips_error( "vips2png", 
-			_( "unable to write \"%s\"" ), filename );
-
-		return( -1 );
-	}
-
-	write_finish( write );
-
-#ifdef DEBUG
-	printf( "vips__png_write: done\n" ); 
-#endif /*DEBUG*/
-
-	return( 0 );
-}
-
-static void
-user_write_data( png_structp png_ptr, png_bytep data, png_size_t length )
-{
-	Write *write = (Write *) png_get_io_ptr( png_ptr );
-
-	vips_dbuf_write( &write->dbuf, data, length ); 
-}
-
-int
-vips__png_write_buf( VipsImage *in, 
-	void **obuf, size_t *olen, int compression, int interlace,
 	const char *profile, VipsForeignPngFilter filter, gboolean strip,
 	gboolean palette, int colours, int Q, double dither )
 {
 	Write *write;
 
-	if( !(write = write_new( in )) ) 
+	if( !(write = write_new( in, output )) ) 
 		return( -1 );
 
-	png_set_write_fn( write->pPng, write, user_write_data, NULL );
-
-	/* Convert it!
-	 */
 	if( write_vips( write, 
 		compression, interlace, profile, filter, strip, palette,
 		colours, Q, dither ) ) {
+		write_finish( write );
 		vips_error( "vips2png", 
 			"%s", _( "unable to write to buffer" ) );
-
 		return( -1 );
 	}
 
-	*obuf = vips_dbuf_steal( &write->dbuf, olen );
-
 	write_finish( write );
 
 	return( 0 );

libvips/include/vips/foreign.h

@@ -369,6 +369,8 @@ int vips_jpegload( const char *filename, VipsImage **out, ... )
 int vips_jpegload_buffer( void *buf, size_t len, VipsImage **out, ... )
 	__attribute__((sentinel));
 
+int vips_jpegsave_stream( VipsImage *in, VipsStreamOutput *output, ... )
+	__attribute__((sentinel));
 int vips_jpegsave( VipsImage *in, const char *filename, ... )
 	__attribute__((sentinel));
 int vips_jpegsave_buffer( VipsImage *in, void **buf, size_t *len, ... )
@@ -547,6 +549,8 @@ int vips_pngload( const char *filename, VipsImage **out, ... )
 	__attribute__((sentinel));
 int vips_pngload_buffer( void *buf, size_t len, VipsImage **out, ... )
 	__attribute__((sentinel));
+int vips_pngsave_stream( VipsImage *in, VipsStreamOutput *output, ... )
+	__attribute__((sentinel));
 int vips_pngsave( VipsImage *in, const char *filename, ... )
 	__attribute__((sentinel));
 int vips_pngsave_buffer( VipsImage *in, void **buf, size_t *len, ... )