Added an error indicator and error message box and refactored some code in the process - implements #21, prepares #16

src/Editor.gd

@@ -6,9 +6,17 @@ extends Control
 @onready var save_shader_dialog = %SaveShaderDialog
 @onready var ui_control_filesave = %SaveImageDialog
 
+@onready var status_indicator = %StatusIndicator
+@onready var error_msg_dialog = %ErrorMessageDialog
+
 @onready var image_viewport = get_tree().root.get_node("Main/%ImageViewport")
 @onready var camera = get_tree().root.get_node("Main/%Camera")
 
+#
+
+var status_okay_texture: CompressedTexture2D = preload("uid://m1omb6g45vst")
+var status_error_texture: CompressedTexture2D = preload("uid://04iv1gogpuhu")
+
 # # # # # # # # # # #
 # GDShader keywords #
 # https://github.com/godotengine/godot/blob/e96ad5af98547df71b50c4c4695ac348638113e0/servers/rendering/shader_language.cpp
@@ -173,7 +181,7 @@ func _on_code_edit_code_completion_requested():
 func _ready():
 	code_editor.code_completion_enabled = true
 	code_editor.syntax_highlighter = ShaderSyntaxHighlighter.new()
-	self.update()
+	self.update_code_edit()
 
 func _input(event):
 	if event.is_action_pressed("apply_shader"):
@@ -182,15 +190,32 @@ func _input(event):
 		accept_event() # Event is now handled.
 		_on_save_shader_button_pressed()
 
-func update():
+func update_code_edit():
 	code_editor.text = Filesystem.shader.code
 
+enum Status {OKAY, ERROR, UNKNOWN = -1}
+
+func update_status(status: Status, msg: String = ""):
+	error_msg_dialog.dialog_text = msg
+	error_msg_dialog.reset_size()
+	if status == Status.OKAY:
+		status_indicator.texture_normal = status_okay_texture
+	elif status == Status.ERROR:
+		status_indicator.texture_normal = status_error_texture
+	else:
+		status_indicator.texture_normal = null
+	if msg == "":
+		status_indicator.disabled = true
+	else:
+		status_indicator.disabled = false
+
 #
 
 func _on_new_shader_button_pressed():
 	Filesystem.reset()
-	self.update()
+	self.update_code_edit()
 	image_viewport.update()
+	update_status(Status.UNKNOWN)
 
 func _on_open_shader_button_pressed():
 	open_shader_dialog.show()
@@ -215,7 +240,11 @@ func _on_fit_image_button_pressed():
 
 func _on_apply_shader_button_pressed():
 	Filesystem.shader.code = code_editor.text
-	image_viewport.update()
+	var errors = await image_viewport.update()
+	if len(errors) > 0:
+		update_status(Status.ERROR, "\n".join(errors))
+	else:
+		update_status(Status.OKAY)
 
 func _on_save_image_button_pressed():
 	if Filesystem.result != null:
@@ -226,11 +255,16 @@ func _on_save_image_button_pressed():
 
 func _on_open_shader_dialog_file_selected(path: String):
 	Filesystem.load_shader(path)
-	image_viewport.update()
-	self.update()
+	self.update_code_edit()
+	self._on_apply_shader_button_pressed()
 
 func _on_save_shader_dialog_file_selected(path):
 	Filesystem.save_shader(path)
 
 func _on_save_image_dialog_file_selected(path):
 	Filesystem.save_result(path)
+
+#
+
+func _on_status_indicator_pressed() -> void:
+	error_msg_dialog.show()

src/Filesystem.gd

@@ -2,7 +2,9 @@ extends Node
 
 @onready var template_shader: Shader = load("res://src/shader/template.gdshader")
 @onready var shader: Shader = template_shader.duplicate()
+
 var original_image: ImageTexture
+var additional_images: Dictionary
 var result: Image
 
 var cwd = "."
@@ -24,8 +26,7 @@ func get_absolute_path(p: String) -> String:
 		return self.cwd + "/" + p.lstrip("./")
 	return p
 
-func load_original_image(path: String):
-	print("Load ", path)
+func load_original_image(path: String) -> String: # returns an error message
 	var img = Image.new()
 	var err = img.load(path)
 	if err == OK:
@@ -34,12 +35,20 @@ func load_original_image(path: String):
 			self.last_original_image_path = path
 		if self.last_image_savepath == "":
 			self.last_image_savepath = path
-	else:
-		print("An error occured!")
+		return ""
+	return error_string(err) + " " + path
 
-func load_image(path: String) -> ImageTexture:
-	print("Load ", path)
-	return ImageTexture.create_from_image(Image.load_from_file(path))
+func clear_additional_images():
+	additional_images.clear()
+
+func load_additional_image(key: String, path: String) -> String: # returns Error Message String
+	var img = Image.new()
+	var err = img.load(path)
+	if err == OK:
+		additional_images[key] = ImageTexture.create_from_image(img)
+		return ""
+	else:
+		return error_string(err) + " " + path
 
 func save_result(path: String):
 	print("Export ", path)

src/ImageViewport.gd

@@ -4,31 +4,42 @@ extends SubViewport
 @onready var image_sprite = %ImageSprite
 @onready var image_viewport_display = %ImageViewportDisplay
 
-func update():
+func update() -> Array: # returns error messages (strings)
+	var errors = []
 	var fit_image = false
-	# load image from //!load directive -> TEXTURE
+	# load texture(s)
+	Filesystem.clear_additional_images()
+	# ... from //!load directive -> TEXTURE
 	var m = ShaderDirectiveParser.parse_load_directive(Filesystem.shader)
 	if len(m) < 1:
-		return # AAAAAAAa
+		errors.append("Didn't find a load directive!")
+		return errors
 	var original_image_path = Filesystem.get_absolute_path(m[1])
 	if original_image_path != Filesystem.last_original_image_path:
 		fit_image = true
-	Filesystem.load_original_image(original_image_path)
-	if Filesystem.original_image == null:
+	var err = Filesystem.load_original_image(original_image_path)
+	if err != "":
+		errors.append(err)
 		image_viewport_display.hide()
-		return
+		return errors
+	# ... from //!load+ directives
+	for n in ShaderDirectiveParser.parse_load_additional_directive(Filesystem.shader):
+		err = Filesystem.load_additional_image(n[1], Filesystem.get_absolute_path(n[2]))
+		if err != "":
+			errors.append(err)
+	if len(errors) > 0:
+		return errors
+	# apply textures
 	image_sprite.texture = Filesystem.original_image
 	image_sprite.offset = Filesystem.original_image.get_size() / 2
 	self.size = Filesystem.original_image.get_size()
 	var mat = ShaderMaterial.new()
 	mat.shader = Filesystem.shader
-	# load images from //!load+ directives and apply them to
-	# the material as shader parameters
-	for n in ShaderDirectiveParser.parse_load_additional_directive(Filesystem.shader):
+	# ... as shader parameters
+	for key in Filesystem.additional_images:
 		mat.set_shader_parameter(
-			n[1], # uniform param name
-			Filesystem.load_image(Filesystem.get_absolute_path(n[2]))
-		)
+			key, # uniform param name
+			Filesystem.additional_images[key])
 	# assign material
 	image_sprite.material = mat
 	# Get viewport texture
@@ -39,3 +50,5 @@ func update():
 	if fit_image:
 		camera.fit_image()
 	image_viewport_display.show()
+	# done
+	return errors

src/ShaderDirectiveParser.gd

@@ -11,8 +11,7 @@ func _ready():
 
 func parse_load_directive(shader: Shader) -> PackedStringArray:
 	var regex_match = self._load_regex.search(Filesystem.shader.code)
-	if regex_match == null: # Error!
-		printerr("Didn't find any load directives!")
+	if regex_match == null:
 		return []
 	return regex_match.strings