Downscale embedded thumbnails within minions

Otherwise the UI would become unresponsive during loading.

fiv-thumbnail.c

@@ -130,69 +130,6 @@ render(GFile *target, GBytes *data, gboolean *color_managed, GError **error)
 	return surface;
 }
 
-cairo_surface_t *
-fiv_thumbnail_extract(GFile *target, GError **error)
-{
-	const char *path = g_file_peek_path(target);
-	if (!path) {
-		set_error(error, "thumbnails will only be extracted from local files");
-		return NULL;
-	}
-
-	GMappedFile *mf = g_mapped_file_new(path, FALSE, error);
-	if (!mf)
-		return NULL;
-
-	cairo_surface_t *surface = NULL;
-#ifndef HAVE_LIBRAW
-	// TODO(p): Implement our own thumbnail extractors.
-	set_error(error, "unsupported file");
-#else  // HAVE_LIBRAW
-	libraw_data_t *iprc = libraw_init(
-		LIBRAW_OPIONS_NO_MEMERR_CALLBACK | LIBRAW_OPIONS_NO_DATAERR_CALLBACK);
-	if (!iprc) {
-		set_error(error, "failed to obtain a LibRaw handle");
-		goto fail;
-	}
-
-	int err = 0;
-	if ((err = libraw_open_buffer(iprc, (void *) g_mapped_file_get_contents(mf),
-			 g_mapped_file_get_length(mf))) ||
-		(err = libraw_unpack_thumb(iprc))) {
-		set_error(error, libraw_strerror(err));
-		goto fail_libraw;
-	}
-
-	libraw_processed_image_t *image = libraw_dcraw_make_mem_thumb(iprc, &err);
-	if (!image) {
-		set_error(error, libraw_strerror(err));
-		goto fail_libraw;
-	}
-
-	gboolean dummy = FALSE;
-	switch (image->type) {
-	case LIBRAW_IMAGE_JPEG:
-		surface = render(
-			target, g_bytes_new(image->data, image->data_size), &dummy, error);
-		break;
-	case LIBRAW_IMAGE_BITMAP:
-		// TODO(p): Implement this one as well.
-	default:
-		set_error(error, "unsupported embedded thumbnail");
-	}
-
-	libraw_dcraw_clear_mem(image);
-fail_libraw:
-	libraw_close(iprc);
-#endif  // HAVE_LIBRAW
-
-fail:
-	g_mapped_file_unref(mf);
-	return surface;
-}
-
-// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-
 // In principle similar to rescale_thumbnail() from fiv-browser.c.
 static cairo_surface_t *
 adjust_thumbnail(cairo_surface_t *thumbnail, double row_height)
@@ -264,6 +201,76 @@ adjust_thumbnail(cairo_surface_t *thumbnail, double row_height)
 	return scaled;
 }
 
+cairo_surface_t *
+fiv_thumbnail_extract(GFile *target, FivThumbnailSize max_size, GError **error)
+{
+	const char *path = g_file_peek_path(target);
+	if (!path) {
+		set_error(error, "thumbnails will only be extracted from local files");
+		return NULL;
+	}
+
+	GMappedFile *mf = g_mapped_file_new(path, FALSE, error);
+	if (!mf)
+		return NULL;
+
+	cairo_surface_t *surface = NULL;
+#ifndef HAVE_LIBRAW
+	// TODO(p): Implement our own thumbnail extractors.
+	set_error(error, "unsupported file");
+#else  // HAVE_LIBRAW
+	libraw_data_t *iprc = libraw_init(
+		LIBRAW_OPIONS_NO_MEMERR_CALLBACK | LIBRAW_OPIONS_NO_DATAERR_CALLBACK);
+	if (!iprc) {
+		set_error(error, "failed to obtain a LibRaw handle");
+		goto fail;
+	}
+
+	int err = 0;
+	if ((err = libraw_open_buffer(iprc, (void *) g_mapped_file_get_contents(mf),
+			 g_mapped_file_get_length(mf))) ||
+		(err = libraw_unpack_thumb(iprc))) {
+		set_error(error, libraw_strerror(err));
+		goto fail_libraw;
+	}
+
+	libraw_processed_image_t *image = libraw_dcraw_make_mem_thumb(iprc, &err);
+	if (!image) {
+		set_error(error, libraw_strerror(err));
+		goto fail_libraw;
+	}
+
+	gboolean dummy = FALSE;
+	switch (image->type) {
+	case LIBRAW_IMAGE_JPEG:
+		surface = render(
+			target, g_bytes_new(image->data, image->data_size), &dummy, error);
+		break;
+	case LIBRAW_IMAGE_BITMAP:
+		// TODO(p): Implement this one as well.
+	default:
+		set_error(error, "unsupported embedded thumbnail");
+	}
+
+	libraw_dcraw_clear_mem(image);
+fail_libraw:
+	libraw_close(iprc);
+#endif  // HAVE_LIBRAW
+
+fail:
+	g_mapped_file_unref(mf);
+	if (!surface || max_size < FIV_THUMBNAIL_SIZE_MIN ||
+		max_size > FIV_THUMBNAIL_SIZE_MAX)
+		return surface;
+
+	cairo_surface_t *result =
+		adjust_thumbnail(surface, fiv_thumbnail_sizes[max_size].size);
+	cairo_surface_destroy(surface);
+	return result;
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
 static WebPData
 encode_thumbnail(cairo_surface_t *surface)
 {

fiv-thumbnail.h

@@ -56,7 +56,9 @@ extern cairo_user_data_key_t fiv_thumbnail_key_lq;
 gchar *fiv_thumbnail_get_root(void);
 
 /// Attempts to extract any low-quality thumbnail from fast targets.
-cairo_surface_t *fiv_thumbnail_extract(GFile *target, GError **error);
+/// If `max_size` is a valid value, the image will be downscaled as appropriate.
+cairo_surface_t *fiv_thumbnail_extract(
+	GFile *target, FivThumbnailSize max_size, GError **error);
 
 /// Generates wide thumbnails of up to the specified size, saves them in cache.
 /// Returns the surface used for the maximum size, or an error.

fiv.c

@@ -1773,9 +1773,9 @@ output_thumbnail(const char *path_arg, gboolean extract, const char *size_arg)
 	if (!path_arg)
 		exit_fatal("no path given");
 
-	FivThumbnailSize size = 0;
+	FivThumbnailSize size = FIV_THUMBNAIL_SIZE_COUNT;
 	if (size_arg) {
-		for (; size < FIV_THUMBNAIL_SIZE_COUNT; size++) {
+		for (size = 0; size < FIV_THUMBNAIL_SIZE_COUNT; size++) {
 			if (!strcmp(
 					fiv_thumbnail_sizes[size].thumbnail_spec_name, size_arg))
 				break;
@@ -1787,7 +1787,7 @@ output_thumbnail(const char *path_arg, gboolean extract, const char *size_arg)
 	GError *error = NULL;
 	GFile *file = g_file_new_for_commandline_arg(path_arg);
 	cairo_surface_t *surface = NULL;
-	if (extract && (surface = fiv_thumbnail_extract(file, &error)))
+	if (extract && (surface = fiv_thumbnail_extract(file, size, &error)))
 		fiv_io_serialize_to_stdout(surface, FIV_IO_SERIALIZE_LOW_QUALITY);
 	else if (size_arg &&
 		(g_clear_error(&error),