3 files changed, 11 insertions, 6 deletions
diff --git a/fiv-io.c b/fiv-io.c
index b0766b9..916715b 100644
--- a/fiv-io.c
+++ b/fiv-io.c
@@ -2891,11 +2891,12 @@ fiv_io_open_from_data(
 // --- Thumbnail passing utilities ---------------------------------------------
 
 typedef struct {
+	guint64 user_data;
 	int width, height, stride, format;
 } CairoHeader;
 
 void
-fiv_io_serialize_to_stdout(cairo_surface_t *surface)
+fiv_io_serialize_to_stdout(cairo_surface_t *surface, guint64 user_data)
 {
 	if (!surface || cairo_surface_get_type(surface) != CAIRO_SURFACE_TYPE_IMAGE)
 		return;
@@ -2907,6 +2908,7 @@ fiv_io_serialize_to_stdout(cairo_surface_t *surface)
 #endif
 
 	CairoHeader h = {
+		.user_data = user_data,
 		.width = cairo_image_surface_get_width(surface),
 		.height = cairo_image_surface_get_height(surface),
 		.stride = cairo_image_surface_get_stride(surface),
@@ -2921,7 +2923,7 @@ fiv_io_serialize_to_stdout(cairo_surface_t *surface)
 }
 
 cairo_surface_t *
-fiv_io_deserialize(GBytes *bytes)
+fiv_io_deserialize(GBytes *bytes, guint64 *user_data)
 {
 	CairoHeader h = {};
 	GByteArray *array = g_bytes_unref_to_array(bytes);
@@ -2949,6 +2951,7 @@ fiv_io_deserialize(GBytes *bytes)
 	static cairo_user_data_key_t key;
 	cairo_surface_set_user_data(
 		surface, &key, array, (cairo_destroy_func_t) g_byte_array_unref);
+	*user_data = h.user_data;
 	return surface;
 }
 
diff --git a/fiv-io.h b/fiv-io.h
index 0c23799..dccdd31 100644
--- a/fiv-io.h
+++ b/fiv-io.h
@@ -102,8 +102,10 @@ cairo_surface_t *fiv_io_open_png_thumbnail(const char *path, GError **error);
 
 // --- Thumbnail passing utilities ---------------------------------------------
 
-void fiv_io_serialize_to_stdout(cairo_surface_t *surface);
-cairo_surface_t *fiv_io_deserialize(GBytes *bytes);
+enum { FIV_IO_SERIALIZE_LOW_QUALITY = 1 << 0 };
+
+void fiv_io_serialize_to_stdout(cairo_surface_t *surface, guint64 user_data);
+cairo_surface_t *fiv_io_deserialize(GBytes *bytes, guint64 *user_data);
 
 // --- Filesystem --------------------------------------------------------------
 
diff --git a/fiv-thumbnail.h b/fiv-thumbnail.h
index 822e609..35b93fe 100644
--- a/fiv-thumbnail.h
+++ b/fiv-thumbnail.h
@@ -45,10 +45,10 @@ typedef struct _FivThumbnailSizeInfo {
 	const char *thumbnail_spec_name;    ///< thumbnail-spec directory name
 } FivThumbnailSizeInfo;
 
-extern FivThumbnailSizeInfo fiv_thumbnail_sizes[FIV_THUMBNAIL_SIZE_COUNT];
-
 enum { FIV_THUMBNAIL_WIDE_COEFFICIENT = 2 };
 
+extern FivThumbnailSizeInfo fiv_thumbnail_sizes[FIV_THUMBNAIL_SIZE_COUNT];
+
 /// If non-NULL, indicates a thumbnail of insufficient quality.
 extern cairo_user_data_key_t fiv_thumbnail_key_lq;