improve orientation fetch

we were generating some annoying messages

TODO

@@ -7,30 +7,6 @@
 
   try other files in test/images
 
-- try
-
-	http://www.camerafv5.com/files/photos/raw1/rope.dng
-	$ vips colourspace rope.dng 3.tif[compression=jpeg,Q=90,tile,tile-width=512,tile-height=512] srgb
-
-  tries to save a 16-bit image?
-
-  hangs 50% of the time, the other 50 it fails with a 16-bit error
-
-  save a 16-bit image to tiff with jpg compression ... should it autoconvert?
-
-  tiff should use convert for save in jpeg mode if jpeg compression is enabled
-
-- try
-
-	$ vipsthumbnail ~/pics/*.jpg
-	vips warning: vips_image_get: field "orientation" not found
-	vips_image_get: field "orientation" not found
-	vips_image_get: field "orientation" not found
-	vips_image_get: field "orientation" not found
-	...
-
-  ugly!
-
 - try adding a coz progress point to vipsthumbnail's main loop
 
   see

libvips/conversion/autorot.c

@@ -76,7 +76,8 @@ vips_autorot_get_angle( VipsImage *im )
 	int orientation;
 	VipsAngle angle;
 
-	if( vips_image_get_int( im, VIPS_META_ORIENTATION, &orientation ) )
+	if( !vips_image_get_typeof( im, VIPS_META_ORIENTATION ) ||
+		vips_image_get_int( im, VIPS_META_ORIENTATION, &orientation ) )
 		orientation = 1;
 
 	switch( orientation ) {

libvips/foreign/tiff2vips.c

@@ -2051,6 +2051,7 @@ vips__tiff_read_header_orientation( ReadTiff *rtiff, VipsImage *out )
 	int orientation;
 
 	if( rtiff->autorotate &&
+		vips_image_get_typeof( out, VIPS_META_ORIENTATION ) &&
 		!vips_image_get_int( out, 
 			VIPS_META_ORIENTATION, &orientation ) ) {
 		if( orientation == 3 || 

libvips/foreign/vips2jpeg.c

@@ -543,7 +543,8 @@ set_exif_orientation( ExifData *ed, VipsImage *im )
 	/* We set the tag, even if it's been deleted, since it's a required
 	 * field.
 	 */
-	if( vips_image_get_int( im, VIPS_META_ORIENTATION, &orientation ) ) 
+	if( !vips_image_get_typeof( im, VIPS_META_ORIENTATION ) ||
+		vips_image_get_int( im, VIPS_META_ORIENTATION, &orientation ) ) 
 		orientation = 1;
 
 	VIPS_DEBUG_MSG( "set_exif_orientation: %d\n", orientation );

libvips/foreign/vips2tiff.c

@@ -585,8 +585,9 @@ write_tiff_header( Write *write, Layer *layer )
 		write_embed_imagedescription( write, tif ) )
 		return( -1 ); 
 
-	if( !vips_image_get_int( write->im, 
-		VIPS_META_ORIENTATION, &orientation ) )
+	if( vips_image_get_typeof( write->im, VIPS_META_ORIENTATION ) &&
+		!vips_image_get_int( write->im, 
+			VIPS_META_ORIENTATION, &orientation ) )
 		TIFFSetField( tif, TIFFTAG_ORIENTATION, orientation );
 
 	/* And colour fields.