Make thumbnailers pass back raw images

fiv-browser.c

@@ -504,13 +504,23 @@ reload_thumbnails(FivBrowser *self)
 
 // --- Minion management -------------------------------------------------------
 
-static gboolean thumbnailer_next(Thumbnailer *thumbnailer);
+#if !GLIB_CHECK_VERSION(2, 70, 0)
+#define g_spawn_check_wait_status g_spawn_check_exit_status
+#endif
+
+static gboolean thumbnailer_next(Thumbnailer *t);
 
 static void
-thumbnailer_reprocess_entry(FivBrowser *self, Entry *entry)
+thumbnailer_reprocess_entry(FivBrowser *self, GBytes *output, Entry *entry)
 {
+	g_clear_object(&entry->icon);
+	g_clear_pointer(&entry->thumbnail, cairo_surface_destroy);
+	if (!output || !(entry->thumbnail = rescale_thumbnail(
+			fiv_io_deserialize(output), self->item_height))) {
 		entry_add_thumbnail(entry, self);
 		materialize_icon(self, entry);
+	}
+
 	gtk_widget_queue_resize(GTK_WIDGET(self));
 }
 
@@ -518,64 +528,75 @@ static void
 on_thumbnailer_ready(GObject *object, GAsyncResult *res, gpointer user_data)
 {
 	GSubprocess *subprocess = G_SUBPROCESS(object);
-	Thumbnailer *thumbnailer = user_data;
+	Thumbnailer *t = user_data;
 
+	// Reading out pixel data directly from a thumbnailer serves two purposes:
+	// 1. it avoids pointless delays with large thumbnail sizes,
+	// 2. it enables thumbnailing things that cannot be placed in the cache.
 	GError *error = NULL;
-	if (!g_subprocess_wait_check_finish(subprocess, res, &error)) {
+	GBytes *out = NULL;
+	if (!g_subprocess_communicate_finish(subprocess, res, &out, NULL, &error)) {
 		if (g_error_matches(error, G_IO_ERROR, G_IO_ERROR_CANCELLED)) {
 			g_error_free(error);
 			return;
 		}
-		if (!g_subprocess_get_if_exited(subprocess) ||
-			g_subprocess_get_exit_status(subprocess) != EXIT_FAILURE)
+	} else if (!g_subprocess_get_if_exited(subprocess)) {
+		// If it exited, it probably printed its own message.
+		g_spawn_check_wait_status(g_subprocess_get_status(subprocess), &error);
+	}
+
+	if (error) {
 		g_warning("%s", error->message);
 		g_error_free(error);
 	}
 
-	g_return_if_fail(subprocess == thumbnailer->minion);
+	g_return_if_fail(subprocess == t->minion);
 
 	gboolean succeeded = g_subprocess_get_if_exited(subprocess) &&
 		g_subprocess_get_exit_status(subprocess) == EXIT_SUCCESS;
-	g_clear_object(&thumbnailer->minion);
-	if (!thumbnailer->target) {
+	g_clear_object(&t->minion);
+	if (!t->target) {
 		g_warning("finished thumbnailing an unknown image");
+		g_clear_pointer(&out, g_bytes_unref);
 		return;
 	}
 
 	if (succeeded)
-		thumbnailer_reprocess_entry(thumbnailer->self, thumbnailer->target);
+		thumbnailer_reprocess_entry(t->self, out, t->target);
+	else
+		g_clear_pointer(&out, g_bytes_unref);
 
-	thumbnailer->target = NULL;
-	thumbnailer_next(thumbnailer);
+	t->target = NULL;
+	thumbnailer_next(t);
 }
 
 static gboolean
-thumbnailer_next(Thumbnailer *thumbnailer)
+thumbnailer_next(Thumbnailer *t)
 {
-	// TODO(p): Ideally, try to keep the minions alive.
-	FivBrowser *self = thumbnailer->self;
+	// TODO(p): Try to keep the minions alive (stdout will be a problem).
+	FivBrowser *self = t->self;
 	GList *link = self->thumbnailers_queue;
 	if (!link)
 		return FALSE;
 
-	thumbnailer->target = link->data;
+	t->target = link->data;
 	self->thumbnailers_queue =
 		g_list_delete_link(self->thumbnailers_queue, self->thumbnailers_queue);
 
 	GError *error = NULL;
-	thumbnailer->minion = g_subprocess_new(G_SUBPROCESS_FLAGS_NONE, &error,
+	t->minion = g_subprocess_new(G_SUBPROCESS_FLAGS_STDOUT_PIPE, &error,
 		PROJECT_NAME, "--thumbnail",
 		fiv_thumbnail_sizes[self->item_size].thumbnail_spec_name, "--",
-		thumbnailer->target->uri, NULL);
+		t->target->uri, NULL);
 	if (error) {
 		g_warning("%s", error->message);
 		g_error_free(error);
 		return FALSE;
 	}
 
-	thumbnailer->cancel = g_cancellable_new();
-	g_subprocess_wait_check_async(thumbnailer->minion, thumbnailer->cancel,
-		on_thumbnailer_ready, thumbnailer);
+	t->cancel = g_cancellable_new();
+	g_subprocess_communicate_async(
+		t->minion, NULL, t->cancel, on_thumbnailer_ready, t);
 	return TRUE;
 }
 
@@ -588,15 +609,15 @@ thumbnailers_abort(FivBrowser *self)
 	self->thumbnailers_queue = NULL;
 
 	for (size_t i = 0; i < self->thumbnailers_len; i++) {
-		Thumbnailer *thumbnailer = self->thumbnailers + i;
-		if (thumbnailer->cancel) {
-			g_cancellable_cancel(thumbnailer->cancel);
-			g_clear_object(&thumbnailer->cancel);
+		Thumbnailer *t = self->thumbnailers + i;
+		if (t->cancel) {
+			g_cancellable_cancel(t->cancel);
+			g_clear_object(&t->cancel);
 		}
 
 		// Just let them exit on their own.
-		g_clear_object(&thumbnailer->minion);
-		thumbnailer->target = NULL;
+		g_clear_object(&t->minion);
+		t->target = NULL;
 	}
 }
 

fiv-io.c

@@ -2703,13 +2703,77 @@ fiv_io_open_from_data(
 	return surface;
 }
 
+// --- Thumbnail passing utilities ---------------------------------------------
+
+typedef struct {
+	int width, height, stride, format;
+} CairoHeader;
+
+void
+fiv_io_serialize_to_stdout(cairo_surface_t *surface)
+{
+	if (!surface || cairo_surface_get_type(surface) != CAIRO_SURFACE_TYPE_IMAGE)
+		return;
+
+#ifdef G_OS_UNIX
+	// Common courtesy, this is never what the user wants.
+	if (isatty(fileno(stdout)))
+		return;
+#endif
+
+	CairoHeader h = {
+		.width = cairo_image_surface_get_width(surface),
+		.height = cairo_image_surface_get_height(surface),
+		.stride = cairo_image_surface_get_stride(surface),
+		.format = cairo_image_surface_get_format(surface),
+	};
+
+	// Cairo lets pixman initialize image surfaces.
+	// pixman allocates stride * height, not omitting those trailing bytes.
+	const unsigned char *data = cairo_image_surface_get_data(surface);
+	if (fwrite(&h, sizeof h, 1, stdout) == 1)
+		fwrite(data, 1, h.stride * h.height, stdout);
+}
+
+cairo_surface_t *
+fiv_io_deserialize(GBytes *bytes)
+{
+	CairoHeader h = {};
+	GByteArray *array = g_bytes_unref_to_array(bytes);
+	if (array->len < sizeof h) {
+		g_byte_array_unref(array);
+		return NULL;
+	}
+
+	h = *(CairoHeader *) array->data;
+	if (h.width < 1 || h.height < 1 || h.stride < h.width ||
+		G_MAXSIZE / (gsize) h.stride < (gsize) h.height ||
+		array->len - sizeof h < (gsize) h.stride * (gsize) h.height) {
+		g_byte_array_unref(array);
+		return NULL;
+	}
+
+	cairo_surface_t *surface = cairo_image_surface_create_for_data(
+		array->data + sizeof h, h.format, h.width, h.height, h.stride);
+	if (cairo_surface_status(surface) != CAIRO_STATUS_SUCCESS) {
+		cairo_surface_destroy(surface);
+		g_byte_array_unref(array);
+		return NULL;
+	}
+
+	static cairo_user_data_key_t key;
+	cairo_surface_set_user_data(
+		surface, &key, array, (cairo_destroy_func_t) g_byte_array_unref);
+	return surface;
+}
+
 // --- Filesystem --------------------------------------------------------------
 
 #include "xdg.h"
 
 #include <fnmatch.h>
 
-typedef struct _ModelEntry {
+typedef struct {
 	gchar *uri;                         ///< GIO URI
 	gchar *collate_key;                 ///< Collate key for the filename
 	gint64 mtime_msec;                  ///< Modification time in milliseconds

fiv-io.h

@@ -96,6 +96,11 @@ cairo_surface_t *fiv_io_open(const FivIoOpenContext *ctx, GError **error);
 cairo_surface_t *fiv_io_open_from_data(
 	const char *data, size_t len, const FivIoOpenContext *ctx, GError **error);
 
+// --- Thumbnail passing utilities ---------------------------------------------
+
+void fiv_io_serialize_to_stdout(cairo_surface_t *surface);
+cairo_surface_t *fiv_io_deserialize(GBytes *bytes);
+
 // --- Filesystem --------------------------------------------------------------
 
 typedef enum _FivIoModelSort {

fiv-thumbnail.c

@@ -230,7 +230,8 @@ save_thumbnail(cairo_surface_t *thumbnail, const char *path, GString *thum)
 }
 
 gboolean
-fiv_thumbnail_produce(GFile *target, FivThumbnailSize max_size, GError **error)
+fiv_thumbnail_produce(GFile *target, FivThumbnailSize max_size,
+	cairo_surface_t **max_size_surface, GError **error)
 {
 	g_return_val_if_fail(max_size >= FIV_THUMBNAIL_SIZE_MIN &&
 		max_size <= FIV_THUMBNAIL_SIZE_MAX, FALSE);
@@ -306,8 +307,12 @@ fiv_thumbnail_produce(GFile *target, FivThumbnailSize max_size, GError **error)
 		gchar *path = g_strdup_printf("%s/wide-%s/%s.webp", thumbnails_dir,
 			fiv_thumbnail_sizes[use].thumbnail_spec_name, sum);
 		save_thumbnail(scaled, path, thum);
-		cairo_surface_destroy(scaled);
 		g_free(path);
+
+		if (!*max_size_surface)
+			*max_size_surface = scaled;
+		else
+			cairo_surface_destroy(scaled);
 	}
 
 	g_string_free(thum, TRUE);

fiv-thumbnail.h

@@ -56,8 +56,9 @@ extern cairo_user_data_key_t fiv_thumbnail_key_lq;
 gchar *fiv_thumbnail_get_root(void);
 
 /// Generates wide thumbnails of up to the specified size, saves them in cache.
-gboolean fiv_thumbnail_produce(
-	GFile *target, FivThumbnailSize max_size, GError **error);
+/// Returns the surface used for the maximum size (if the pointer was NULL).
+gboolean fiv_thumbnail_produce(GFile *target, FivThumbnailSize max_size,
+	cairo_surface_t **max_size_surface, GError **error);
 
 /// Retrieves a thumbnail of the most appropriate quality and resolution
 /// for the target file.

fiv.c

@@ -1822,9 +1822,14 @@ main(int argc, char *argv[])
 			exit_fatal("unknown thumbnail size: %s", thumbnail_size);
 
 		GFile *target = g_file_new_for_commandline_arg(path_arg);
-		if (!fiv_thumbnail_produce(target, size, &error))
+		cairo_surface_t *surface = NULL;
+		if (!fiv_thumbnail_produce(target, size, &surface, &error))
 			exit_fatal("%s", error->message);
 		g_object_unref(target);
+		if (surface) {
+			fiv_io_serialize_to_stdout(surface);
+			cairo_surface_destroy(surface);
+		}
 		return 0;
 	}