Add a way to invalidate preview cache

editor/editor_resource_preview.cpp

@@ -118,8 +118,6 @@ Variant EditorResourcePreviewGenerator::DrawRequester::_post_semaphore() const {
 	return Variant(); // Needed because of how the callback is used.
 }
 
-EditorResourcePreview *EditorResourcePreview::singleton = nullptr;
-
 bool EditorResourcePreview::is_threaded() const {
 	return RSG::texture_storage->can_create_resources_async();
 }
@@ -291,13 +289,17 @@ void EditorResourcePreview::_iterate() {
 		bool has_small_texture;
 		uint64_t last_modtime;
 		String hash;
-		_read_preview_cache(f, &tsize, &has_small_texture, &last_modtime, &hash, &preview_metadata);
+		bool outdated;
+		_read_preview_cache(f, &tsize, &has_small_texture, &last_modtime, &hash, &preview_metadata, &outdated);
 
 		bool cache_valid = true;
 
 		if (tsize != thumbnail_size) {
 			cache_valid = false;
 			f.unref();
+		} else if (outdated) {
+			cache_valid = false;
+			f.unref();
 		} else if (last_modtime != modtime) {
 			String last_md5 = f->get_line();
 			String md5 = FileAccess::get_md5(item.path);
@@ -357,14 +359,16 @@ void EditorResourcePreview::_write_preview_cache(Ref<FileAccess> p_file, int p_t
 	p_file->store_line(itos(p_modified_time));
 	p_file->store_line(p_hash);
 	p_file->store_line(VariantUtilityFunctions::var_to_str(p_metadata).replace("\n", " "));
+	p_file->store_line(itos(CURRENT_METADATA_VERSION));
 }
 
-void EditorResourcePreview::_read_preview_cache(Ref<FileAccess> p_file, int *r_thumbnail_size, bool *r_has_small_texture, uint64_t *r_modified_time, String *r_hash, Dictionary *r_metadata) {
+void EditorResourcePreview::_read_preview_cache(Ref<FileAccess> p_file, int *r_thumbnail_size, bool *r_has_small_texture, uint64_t *r_modified_time, String *r_hash, Dictionary *r_metadata, bool *r_outdated) {
 	*r_thumbnail_size = p_file->get_line().to_int();
 	*r_has_small_texture = p_file->get_line().to_int();
 	*r_modified_time = p_file->get_line().to_int();
 	*r_hash = p_file->get_line();
 	*r_metadata = VariantUtilityFunctions::str_to_var(p_file->get_line());
+	*r_outdated = p_file->get_line().to_int() < CURRENT_METADATA_VERSION;
 }
 
 void EditorResourcePreview::_thread() {

editor/editor_resource_preview.h

@@ -76,7 +76,8 @@ public:
 class EditorResourcePreview : public Node {
 	GDCLASS(EditorResourcePreview, Node);
 
-	static EditorResourcePreview *singleton;
+	inline static constexpr int CURRENT_METADATA_VERSION = 1; // Increment this number to invalidate all previews.
+	inline static EditorResourcePreview *singleton = nullptr;
 
 	struct QueueItem {
 		Ref<Resource> resource;
@@ -118,7 +119,7 @@ class EditorResourcePreview : public Node {
 	void _iterate();
 
 	void _write_preview_cache(Ref<FileAccess> p_file, int p_thumbnail_size, bool p_has_small_texture, uint64_t p_modified_time, const String &p_hash, const Dictionary &p_metadata);
-	void _read_preview_cache(Ref<FileAccess> p_file, int *r_thumbnail_size, bool *r_has_small_texture, uint64_t *r_modified_time, String *r_hash, Dictionary *r_metadata);
+	void _read_preview_cache(Ref<FileAccess> p_file, int *r_thumbnail_size, bool *r_has_small_texture, uint64_t *r_modified_time, String *r_hash, Dictionary *r_metadata, bool *r_outdated);
 
 	Vector<Ref<EditorResourcePreviewGenerator>> preview_generators;