[Targeted for 0.11.0] Export options to extension (#869)

* Added Export Options

* some improvements

* Improvements

* linting

* don't add format if it's already added

* Fix some more bugs

* fixed accidental change

* add accidentally deleted signal

src/Autoload/Export.gd

@@ -6,6 +6,12 @@ enum AnimationDirection { FORWARD = 0, BACKWARDS = 1, PING_PONG = 2 }
 # See file_format_string, file_format_description, and ExportDialog.gd
 enum FileFormat { PNG = 0, GIF = 1, APNG = 2 }
 
+# list of animated formats
+var animated_formats := [FileFormat.GIF, FileFormat.APNG]
+
+# A dictionary of custom exporter generators (Recieved from extensions)
+var custom_exporter_generators := {}
+
 var current_tab: int = ExportTab.IMAGE
 # All frames and their layers processed/blended into images
 var processed_images := []  # Image[]
@@ -40,6 +46,19 @@ func _exit_tree() -> void:
 		gif_export_thread.wait_to_finish()
 
 
+func add_file_format(name: String) -> int:
+	var id = FileFormat.size()
+	FileFormat.merge({name: id})
+	return id
+
+
+func remove_file_format(id: int) -> void:
+	for key in Export.FileFormat.keys():
+		if Export.FileFormat[key] == id:
+			Export.FileFormat.erase(key)
+			return
+
+
 func external_export(project := Global.current_project) -> void:
 	process_data(project)
 	export_processed_images(true, Global.export_dialog, project)
@@ -191,6 +210,29 @@ func export_processed_images(
 
 	scale_processed_images()
 
+	# override if a custom export is chosen
+	if project.file_format in custom_exporter_generators.keys():
+		# Divert the path to the custom exporter instead
+		var custom_exporter: Object = custom_exporter_generators[project.file_format][0]
+		if custom_exporter.has_method("override_export"):
+			var result := true
+			var details := {
+				"processed_images": processed_images,
+				"durations": durations,
+				"export_dialog": export_dialog,
+				"export_paths": export_paths,
+				"project": project
+			}
+			if OS.get_name() != "HTML5" and is_single_file_format(project):
+				if gif_export_thread.is_active():
+					gif_export_thread.wait_to_finish()
+				var error = gif_export_thread.start(custom_exporter, "override_export", details)
+				if error == OK:
+					result = gif_export_thread.wait_to_finish()
+			else:
+				result = custom_exporter.call("override_export", details)
+			return result
+
 	if is_single_file_format(project):
 		var exporter: AImgIOBaseExporter
 		if project.file_format == FileFormat.APNG:
@@ -304,11 +346,16 @@ func file_format_string(format_enum: int) -> String:
 		FileFormat.APNG:
 			return ".apng"
 		_:
+			# If a file format description is not found, try generating one
+			if custom_exporter_generators.has(format_enum):
+				return custom_exporter_generators[format_enum][1]
 			return ""
 
 
 func file_format_description(format_enum: int) -> String:
 	match format_enum:
+		#  these are overrides
+		#  (if they are not given, they will generate themselves based on the enum key name)
 		FileFormat.PNG:
 			return "PNG Image"
 		FileFormat.GIF:
@@ -316,13 +363,17 @@ func file_format_description(format_enum: int) -> String:
 		FileFormat.APNG:
 			return "APNG Image"
 		_:
+			# If a file format description is not found, try generating one
+			for key in FileFormat.keys():
+				if FileFormat[key] == format_enum:
+					return str(key.capitalize())
 			return ""
 
 
 func is_single_file_format(project := Global.current_project) -> bool:
 	# True when exporting to .gif and .apng (and potentially video formats in the future)
 	# False when exporting to .png, and other non-animated formats in the future
-	return project.file_format == FileFormat.GIF or project.file_format == FileFormat.APNG
+	return animated_formats.has(project.file_format)
 
 
 func create_export_path(multifile: bool, project: Project, frame: int = 0) -> String:

src/Autoload/ExtensionsAPI.gd

@@ -8,6 +8,7 @@ var panel := PanelAPI.new()
 var theme := ThemeAPI.new()
 var tools := ToolAPI.new()
 var project := ProjectAPI.new()
+var exports := ExportAPI.new()
 var signals := SignalsAPI.new()
 
 # This fail-safe below is designed to work ONLY if Pixelorama is launched in Godot Editor
@@ -365,6 +366,65 @@ class ProjectAPI:
 			print("cel at frame ", frame, ", layer ", layer, " is not a PixelCel")
 
 
+class ExportAPI:
+	# gdlint: ignore=class-variable-name
+	var ExportTab := Export.ExportTab
+
+	func add_export_option(
+		format_info: Dictionary, exporter_generator, tab := ExportTab.IMAGE, is_animated := true
+	) -> int:
+		# separate enum name and file name
+		var extension = ""
+		var format_name = ""
+		if format_info.has("extension"):
+			extension = format_info["extension"]
+		if format_info.has("description"):
+			format_name = format_info["description"].to_upper().replace(" ", "_")
+		# change format name if another one uses the same name
+		for i in range(Export.FileFormat.size()):
+			var test_name = format_name
+			if i != 0:
+				test_name = str(test_name, "_", i)
+			if !Export.FileFormat.keys().has(test_name):
+				format_name = test_name
+				break
+		#  add to FileFormat enum
+		var id := Export.FileFormat.size()
+		for i in Export.FileFormat.size():  # use an empty id if it's available
+			if !Export.FileFormat.values().has(i):
+				id = i
+		Export.FileFormat.merge({format_name: id})
+		#  add exporter generator
+		Export.custom_exporter_generators.merge({id: [exporter_generator, extension]})
+		#  add to animated (or not)
+		if is_animated:
+			Export.animated_formats.append(id)
+		#  add to export dialog
+		match tab:
+			ExportTab.IMAGE:
+				Global.export_dialog.image_exports.append(id)
+			ExportTab.SPRITESHEET:
+				Global.export_dialog.spritesheet_exports.append(id)
+			_:  # Both
+				Global.export_dialog.image_exports.append(id)
+				Global.export_dialog.spritesheet_exports.append(id)
+		ExtensionsApi.add_action("add_exporter")
+		return id
+
+	func remove_export_option(id: int):
+		if Export.custom_exporter_generators.has(id):
+			# remove enum
+			Export.remove_file_format(id)
+			# remove exporter generator
+			Export.custom_exporter_generators.erase(id)
+			#  remove from animated (or not)
+			Export.animated_formats.erase(id)
+			#  add to export dialog
+			Global.export_dialog.image_exports.erase(id)
+			Global.export_dialog.spritesheet_exports.erase(id)
+			ExtensionsApi.remove_action("add_exporter")
+
+
 class SignalsAPI:
 	# system to auto-adjust texture_changed to the "current cel"
 	signal texture_changed

src/UI/Dialogs/ExportDialog.gd

@@ -6,6 +6,10 @@ signal resume_export_function
 var preview_current_frame := 0
 var preview_frames := []
 
+# allow custom exporters to be added
+var image_exports := [Export.FileFormat.PNG, Export.FileFormat.GIF, Export.FileFormat.APNG]
+var spritesheet_exports := [Export.FileFormat.PNG]
+
 onready var tabs: Tabs = $VBoxContainer/Tabs
 onready var checker: ColorRect = $"%TransparentChecker"
 onready var previews: GridContainer = $"%Previews"
@@ -164,11 +168,9 @@ func remove_previews() -> void:
 func set_file_format_selector() -> void:
 	match Export.current_tab:
 		Export.ExportTab.IMAGE:
-			_set_file_format_selector_suitable_file_formats(
-				[Export.FileFormat.PNG, Export.FileFormat.GIF, Export.FileFormat.APNG]
-			)
+			_set_file_format_selector_suitable_file_formats(image_exports)
 		Export.ExportTab.SPRITESHEET:
-			_set_file_format_selector_suitable_file_formats([Export.FileFormat.PNG])
+			_set_file_format_selector_suitable_file_formats(spritesheet_exports)
 
 
 # Updates the suitable list of file formats. First is preferred.