add png load from buffer

though untested as yet

libvips/foreign/foreign.c

@@ -1583,6 +1583,7 @@ vips_foreign_operation_init( void )
 	extern GType vips_foreign_load_ppm_get_type( void ); 
 	extern GType vips_foreign_save_ppm_get_type( void ); 
 	extern GType vips_foreign_load_png_get_type( void ); 
+	extern GType vips_foreign_load_png_buffer_get_type( void ); 
 	extern GType vips_foreign_save_png_file_get_type( void ); 
 	extern GType vips_foreign_save_png_buffer_get_type( void ); 
 	extern GType vips_foreign_load_csv_get_type( void ); 
@@ -1623,6 +1624,7 @@ vips_foreign_operation_init( void )
 
 #ifdef HAVE_PNG
 	vips_foreign_load_png_get_type(); 
+	vips_foreign_load_png_buffer_get_type(); 
 	vips_foreign_save_png_file_get_type(); 
 	vips_foreign_save_png_buffer_get_type(); 
 #endif /*HAVE_PNG*/
@@ -2224,6 +2226,47 @@ vips_pngload( const char *filename, VipsImage **out, ... )
 	return( result );
 }
 
+/**
+ * vips_pngload_buffer:
+ * @buf: memory area to load
+ * @len: size of memory area
+ * @out: image to write
+ * @...: %NULL-terminated list of optional named arguments
+ *
+ * Read a PNG-formatted memory block into a VIPS image. It can read all png 
+ * images, including 8- and 16-bit images, 1 and 3 channel, with and without 
+ * an alpha channel.
+ *
+ * Any ICC profile is read and attached to the VIPS image.
+ *
+ * Caution: on return only the header will have been read, the pixel data is
+ * not decompressed until the first pixel is read. Therefore you must not free
+ * @buf until you have read pixel data from @out.
+ *
+ * See also: vips_pngload().
+ *
+ * Returns: 0 on success, -1 on error.
+ */
+int
+vips_pngload_buffer( void *buf, size_t len, VipsImage **out, ... )
+{
+	va_list ap;
+	VipsArea *area;
+	int result;
+
+	/* We don't take a copy of the data or free it.
+	 */
+	area = vips_area_new_blob( NULL, buf, len );
+
+	va_start( ap, out );
+	result = vips_call_split( "pngload_buffer", ap, area, out );
+	va_end( ap );
+
+	vips_area_unref( area );
+
+	return( result );
+}
+
 /**
  * vips_pngsave:
  * @in: image to save 

libvips/foreign/pngload.c

@@ -73,9 +73,9 @@ vips_foreign_load_png_get_flags_filename( const char *filename )
 
 	flags = 0;
 	if( vips__png_isinterlaced( filename ) )
-		flags = VIPS_FOREIGN_PARTIAL;
+		flags |= VIPS_FOREIGN_PARTIAL;
 	else
-		flags = VIPS_FOREIGN_SEQUENTIAL;
+		flags |= VIPS_FOREIGN_SEQUENTIAL;
 
 	return( flags );
 }
@@ -146,4 +146,72 @@ vips_foreign_load_png_init( VipsForeignLoadPng *png )
 {
 }
 
+typedef struct _VipsForeignLoadPngBuffer {
+	VipsForeignLoad parent_object;
+
+	/* Load from a buffer.
+	 */
+	VipsArea *buf;
+
+} VipsForeignLoadPngBuffer;
+
+typedef VipsForeignLoadClass VipsForeignLoadPngBufferClass;
+
+G_DEFINE_TYPE( VipsForeignLoadPngBuffer, vips_foreign_load_png_buffer, 
+	VIPS_TYPE_FOREIGN_LOAD );
+
+static int
+vips_foreign_load_png_buffer_header( VipsForeignLoad *load )
+{
+	VipsForeignLoadPngBuffer *png = (VipsForeignLoadPngBuffer *) load;
+
+	if( vips__png_header_buffer( load->out, 
+		png->buf->data, png->buf->length ) )
+		return( -1 );
+
+	return( 0 );
+}
+
+static int
+vips_foreign_load_png_buffer_load( VipsForeignLoad *load )
+{
+	VipsForeignLoadPngBuffer *png = (VipsForeignLoadPngBuffer *) load;
+
+	if( vips__png_read_buffer( load->out, 
+		png->buf->data, png->buf->length ) )
+		return( -1 );
+
+	return( 0 );
+}
+
+static void
+vips_foreign_load_png_buffer_class_init( VipsForeignLoadPngBufferClass *class )
+{
+	GObjectClass *gobject_class = G_OBJECT_CLASS( class );
+	VipsObjectClass *object_class = (VipsObjectClass *) class;
+	VipsForeignLoadClass *load_class = (VipsForeignLoadClass *) class;
+
+	gobject_class->set_property = vips_object_set_property;
+	gobject_class->get_property = vips_object_get_property;
+
+	object_class->nickname = "pngload_buffer";
+	object_class->description = _( "load png from buffer" );
+
+	load_class->header = vips_foreign_load_png_buffer_header;
+	load_class->load = vips_foreign_load_png_buffer_load;
+
+	VIPS_ARG_BOXED( class, "buffer", 1, 
+		_( "Buffer" ),
+		_( "Buffer to load from" ),
+		VIPS_ARGUMENT_REQUIRED_INPUT, 
+		G_STRUCT_OFFSET( VipsForeignLoadPngBuffer, buf ),
+		VIPS_TYPE_BLOB );
+}
+
+static void
+vips_foreign_load_png_buffer_init( VipsForeignLoadPngBuffer *png )
+{
+}
+
 #endif /*HAVE_PNG*/
+

libvips/foreign/vipspng.c

@@ -125,11 +125,20 @@ typedef struct {
 	char *name;
 	VipsImage *out;
 
-	FILE *fp;
 	int y_pos;
 	png_structp pPng;
 	png_infop pInfo;
 	png_bytep *row_pointer;
+
+	/* For FILE input.
+	 */
+	FILE *fp;
+
+	/* For memory input.
+	 */
+	char *buffer;
+	size_t length;
+	size_t read_pos;
 } Read;
 
 static void
@@ -142,27 +151,27 @@ read_destroy( VipsImage *out, Read *read )
 }
 
 static Read *
-read_new( const char *name, VipsImage *out )
+read_new( VipsImage *out )
 {
 	Read *read;
 
 	if( !(read = VIPS_NEW( out, Read )) )
 		return( NULL );
 
-	read->name = vips_strdup( VIPS_OBJECT( out ), name );
+	read->name = NULL;
 	read->out = out;
-	read->fp = NULL;
 	read->y_pos = 0;
 	read->pPng = NULL;
 	read->pInfo = NULL;
 	read->row_pointer = NULL;
+	read->fp = NULL;
+	read->buffer = NULL;
+	read->length = 0;
+	read->read_pos = 0;
 
 	g_signal_connect( out, "close", 
 		G_CALLBACK( read_destroy ), read ); 
 
-        if( !(read->fp = vips__file_open_read( name, NULL, FALSE )) ) 
-		return( NULL );
-
 	if( !(read->pPng = png_create_read_struct( 
 		PNG_LIBPNG_VER_STRING, NULL,
 		user_error_function, user_warning_function )) ) 
@@ -176,6 +185,22 @@ read_new( const char *name, VipsImage *out )
 	if( !(read->pInfo = png_create_info_struct( read->pPng )) ) 
 		return( NULL );
 
+	return( read );
+}
+
+static Read *
+read_new_filename( VipsImage *out, const char *name )
+{
+	Read *read;
+
+	if( !(read = read_new( out )) )
+		return( NULL );
+
+	read->name = vips_strdup( VIPS_OBJECT( out ), name );
+
+        if( !(read->fp = vips__file_open_read( name, NULL, FALSE )) ) 
+		return( NULL );
+
 	/* Read enough of the file that png_get_interlace_type() will start
 	 * working.
 	 */
@@ -366,7 +391,7 @@ vips__png_header( const char *name, VipsImage *out )
 {
 	Read *read;
 
-	if( !(read = read_new( name, out )) ||
+	if( !(read = read_new_filename( out, name )) ||
 		png2vips_header( read, out ) ) 
 		return( -1 );
 
@@ -465,7 +490,7 @@ vips__png_isinterlaced( const char *filename )
 	int interlace_type;
 
 	image = vips_image_new();
-	if( !(read = read_new( filename, image )) ) {
+	if( !(read = read_new_filename( image, filename )) ) {
 		g_object_unref( image );
 		return( -1 );
 	}
@@ -475,24 +500,13 @@ vips__png_isinterlaced( const char *filename )
 	return( interlace_type != PNG_INTERLACE_NONE );
 }
 
-int
+static int
-vips__png_read( const char *filename, VipsImage *out )
+read_all( Read *read, VipsImage *out )
 {
+	int interlace_type = png_get_interlace_type( read->pPng, read->pInfo );
 	VipsImage **t = (VipsImage **) 
 		vips_object_local_array( VIPS_OBJECT( out ), 3 );
 
-	Read *read;
-	int interlace_type;
-
-#ifdef DEBUG
-	printf( "vips__png_read: reading \"%s\"\n", filename );
-#endif /*DEBUG*/
-
-	if( !(read = read_new( filename, out )) )
-		return( -1 );
-
-	interlace_type = png_get_interlace_type( read->pPng, read->pInfo );
-
 	if( interlace_type != PNG_INTERLACE_NONE ) { 
 		/* Arg awful interlaced image. We have to load to a huge mem 
 		 * buffer, then copy to out.
@@ -516,6 +530,22 @@ vips__png_read( const char *filename, VipsImage *out )
 			return( -1 );
 	}
 
+	return( 0 );
+}
+
+int
+vips__png_read( const char *filename, VipsImage *out )
+{
+	Read *read;
+
+#ifdef DEBUG
+	printf( "vips__png_read: reading \"%s\"\n", filename );
+#endif /*DEBUG*/
+
+	if( !(read = read_new_filename( out, filename )) ||
+		read_all( read, out ) )
+		return( -1 ); 
+
 #ifdef DEBUG
 	printf( "vips__png_read: done\n" );
 #endif /*DEBUG*/
@@ -532,6 +562,63 @@ vips__png_ispng( const char *filename )
 		!png_sig_cmp( buf, 0, 8 ) );
 }
 
+static void
+vips_png_read_buffer( png_structp pPng, png_bytep data, png_size_t length )
+{
+	Read *read = png_get_io_ptr( pPng ); 
+
+	if( read->read_pos + length > read->length )
+		png_error( pPng, "not enough data in buffer" );
+
+	memcpy( data, read->buffer + read->read_pos, length );
+	read->read_pos += length;
+}
+
+static Read *
+read_new_buffer( VipsImage *out, char *buffer, size_t length )
+{
+	Read *read;
+
+	if( !(read = read_new( out )) )
+		return( NULL );
+
+	read->buffer = buffer;
+	read->length = length;
+
+	png_set_read_fn( read->pPng, read, vips_png_read_buffer ); 
+
+	/* Read enough of the file that png_get_interlace_type() will start
+	 * working.
+	 */
+	png_read_info( read->pPng, read->pInfo );
+
+	return( read );
+}
+
+int
+vips__png_header_buffer( VipsImage *out, char *buffer, size_t length )
+{
+	Read *read;
+
+	if( !(read = read_new_buffer( out, buffer, length )) ||
+		png2vips_header( read, out ) ) 
+		return( -1 );
+
+	return( 0 );
+}
+
+int
+vips__png_read_buffer( VipsImage *out, char *buffer, size_t length  )
+{
+	Read *read;
+
+	if( !(read = read_new_buffer( out, buffer, length )) ||
+		read_all( read, out ) )
+		return( -1 ); 
+
+	return( 0 );
+}
+
 const char *vips__png_suffs[] = { ".png", NULL };
 
 /* What we track during a PNG write.

libvips/foreign/vipspng.h

@@ -40,6 +40,8 @@ int vips__png_read( const char *name, VipsImage *out );
 int vips__png_ispng( const char *filename );
 gboolean vips__png_isinterlaced( const char *filename );
 extern const char *vips__png_suffs[];
+int vips__png_read_buffer( VipsImage *out, char *buffer, size_t length  );
+int vips__png_header_buffer( VipsImage *out, char *buffer, size_t length );
 
 int vips__png_write( VipsImage *in, const char *filename, 
 	int compress, int interlace );

libvips/include/vips/foreign.h

@@ -407,6 +407,8 @@ int vips_magickload( const char *filename, VipsImage **out, ... )
 
 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( VipsImage *in, const char *filename, ... )
 	__attribute__((sentinel));
 int vips_pngsave_buffer( VipsImage *in, void **buf, size_t *len, ... )