record the image loader

and display in header too

ChangeLog

@@ -3,6 +3,8 @@
   raised an error (thanks Todd)
 - fix another dzsave corner-case (thanks Martin)
 - neater output for "header"
+- added VIPS_META_LOADER: record the loader name
+= header displays this hint
 
 31/8/12 started 7.31.0
 - redone im_Lab2XYZ(), im_XYZ2Lab(), im_Lab2LCh(), im_LCh2Lab(), im_UCS2LCh, 

libvips/foreign/foreign.c

@@ -850,6 +850,9 @@ vips_foreign_load_build( VipsObject *object )
 
 	g_object_set( object, "out", vips_image_new(), NULL ); 
 
+	vips_image_set_string( load->out, 
+		VIPS_META_LOADER, class->nickname );
+
 #ifdef DEBUG
 	printf( "vips_foreign_load_build: triggering ->header()\n" );
 #endif /*DEBUG*/

libvips/include/vips/header.h

@@ -84,6 +84,14 @@ extern "C" {
  */
 #define VIPS_META_RESOLUTION_UNIT "resolution-unit"
 
+/**
+ * VIPS_META_LOADER:
+ *
+ * Record the name of the original loader here. Handy for hinting file formats
+ * and for debugging.
+ */
+#define VIPS_META_LOADER "vips-loader"
+
 guint64 vips_format_sizeof( VipsBandFormat format );
 
 int vips_image_get_width( const VipsImage *image );

libvips/iofuncs/image.c

@@ -395,6 +395,7 @@ static void
 vips_image_summary( VipsObject *object, VipsBuf *buf )
 {
 	VipsImage *image = VIPS_IMAGE( object );
+	char *p;
 
 	vips_buf_appendf( buf, "%dx%d",
 		vips_image_get_width( image ), vips_image_get_height( image ) );
@@ -416,6 +417,10 @@ vips_image_summary( VipsObject *object, VipsBuf *buf )
 				vips_image_get_coding( image ) ) );
 	}
 
+	if( vips_image_get_typeof( image, VIPS_META_LOADER ) &&
+		!vips_image_get_string( image, VIPS_META_LOADER, &p ) ) 
+		vips_buf_appendf( buf, ", %s", p );
+
 	VIPS_OBJECT_CLASS( vips_image_parent_class )->summary( object, buf );
 }
 

tools/header.c

@@ -36,6 +36,8 @@
  * 6/11/09
  * 	- added im_history_get(), im_getexp(), im_printdesc() as wrapped
  * 	  functions, so "header" is now obsolete
+ * 27/2/13
+ * 	- convert to vips8 API
  */
 
 /*
@@ -95,8 +97,8 @@ static GOptionEntry main_option[] = {
 static void
 print_error( void )
 {
-        fprintf( stderr, "%s: %s", g_get_prgname(), im_error_buffer() );
-	im_error_clear();
+        fprintf( stderr, "%s: %s", g_get_prgname(), vips_error_buffer() );
+	vips_error_clear();
 }
 
 static void *
@@ -137,7 +139,7 @@ print_field_fn( VipsImage *image, const char *field, GValue *value, void *a )
 /* Print header, or parts of header.
  */
 static int
-print_header( IMAGE *im, gboolean many )
+print_header( VipsImage *im, gboolean many )
 {
 	if( !main_option_field ) {
 		printf( "%s: ", im->filename );
@@ -148,47 +150,25 @@ print_header( IMAGE *im, gboolean many )
 			(void) vips_image_map( im, print_field_fn, &many );
 	}
 	else if( strcmp( main_option_field, "getext" ) == 0 ) {
-		if( im__has_extension_block( im ) ) {
+		if( vips__has_extension_block( im ) ) {
 			void *buf;
 			int size;
 
-			if( !(buf = im__read_extension_block( im, &size )) )
+			if( !(buf = vips__read_extension_block( im, &size )) )
 				return( -1 );
 			printf( "%s", (char *) buf );
-			im_free( buf );
+			g_free( buf );
 		}
 	}
 	else if( strcmp( main_option_field, "Hist" ) == 0 ) 
-		printf( "%s", im_history_get( im ) );
+		printf( "%s", vips_image_get_history( im ) );
 	else {
-		GValue value = { 0 };
-		GType type;
+		char *str;
 
-		if( im_header_get( im, main_option_field, &value ) )
+		if( vips_image_get_as_string( im, main_option_field, &str ) )
 			return( -1 );
-
-		/* Display the save form, if there is one. This way we display
-		 * something useful for ICC profiles, xml fields, etc.
-		 */
-		type = G_VALUE_TYPE( &value );
-		if( g_value_type_transformable( type, IM_TYPE_SAVE_STRING ) ) {
-			GValue save_value = { 0 };
-
-			g_value_init( &save_value, IM_TYPE_SAVE_STRING );
-			if( !g_value_transform( &value, &save_value ) ) 
-				return( -1 );
-			printf( "%s\n", im_save_string_get( &save_value ) );
-			g_value_unset( &save_value );
-		}
-		else {
-			char *str_value;
-
-			str_value = g_strdup_value_contents( &value );
-			printf( "%s\n", str_value );
-			g_free( str_value );
-		}
-
-		g_value_unset( &value );
+		printf( "%s\n", str );
+		g_free( str );
 	}
 
 	return( 0 );
@@ -202,8 +182,8 @@ main( int argc, char *argv[] )
 	int i;
 	int result;
 
-	if( im_init_world( argv[0] ) )
-	        error_exit( "unable to start VIPS" );
+	if( vips_init( argv[0] ) )
+	        vips_error_exit( "unable to start VIPS" );
 	textdomain( GETTEXT_PACKAGE );
 	setlocale( LC_ALL, "" );
 
@@ -211,7 +191,7 @@ main( int argc, char *argv[] )
 
 	g_option_context_add_main_entries( context,
 		main_option, GETTEXT_PACKAGE );
-	g_option_context_add_group( context, im_get_option_group() );
+	g_option_context_add_group( context, vips_get_option_group() );
 
 	if( !g_option_context_parse( context, &argc, &argv, &error ) ) {
 		if( error ) {
@@ -219,7 +199,7 @@ main( int argc, char *argv[] )
 			g_error_free( error );
 		}
 
-		error_exit( "try \"%s --help\"", g_get_prgname() );
+		vips_error_exit( "try \"%s --help\"", g_get_prgname() );
 	}
 
 	g_option_context_free( context );
@@ -227,9 +207,9 @@ main( int argc, char *argv[] )
 	result = 0;
 
 	for( i = 1; i < argc; i++ ) {
-		IMAGE *im;
+		VipsImage *im;
 
-		if( !(im = im_open( argv[i], "r" )) ) {
+		if( !(im = vips_image_new_from_file( argv[i] )) ) {
 			print_error();
 			result = 1;
 		}
@@ -241,7 +221,7 @@ main( int argc, char *argv[] )
 		}
 
 		if( im )
-			im_close( im );
+			g_object_unref( im );
 	}
 
 	vips_shutdown();