Keep the aspect ratio correctly in the image effect dialog previews

src/Classes/ImageEffect.gd

@@ -9,6 +9,7 @@ var affect: int = SELECTED_CELS
 var selected_cels := Image.create(1, 1, false, Image.FORMAT_RGBA8)
 var current_frame := Image.create(1, 1, false, Image.FORMAT_RGBA8)
 var preview_image := Image.new()
+var aspect_ratio_container: AspectRatioContainer
 var preview: TextureRect
 var selection_checkbox: CheckBox
 var affect_option_button: OptionButton
@@ -38,7 +39,7 @@ func _about_to_popup() -> void:
 	Global.canvas.selection.transform_content_confirm()
 	prepare_animator(Global.current_project)
 	set_and_update_preview_image(Global.current_project.current_frame)
-	update_transparent_background_size()
+	aspect_ratio_container.ratio = float(preview_image.get_width()) / preview_image.get_height()
 
 
 # prepares "animate_panel.frames" according to affect
@@ -131,6 +132,7 @@ func commit_action(_cel: Image, _project := Global.current_project) -> void:
 
 
 func set_nodes() -> void:
+	aspect_ratio_container = $VBoxContainer/AspectRatioContainer
 	preview = $VBoxContainer/AspectRatioContainer/Preview
 	selection_checkbox = $VBoxContainer/OptionsContainer/SelectionCheckBox
 	affect_option_button = $VBoxContainer/OptionsContainer/AffectOptionButton
@@ -214,22 +216,6 @@ func update_preview() -> void:
 	preview.texture = ImageTexture.create_from_image(preview_image)
 
 
-func update_transparent_background_size() -> void:
-	if !preview:
-		return
-	var image_size_y := preview.size.y
-	var image_size_x := preview.size.x
-	if preview_image.get_size().x > preview_image.get_size().y:
-		var scale_ratio := preview_image.get_size().x / image_size_x
-		image_size_y = preview_image.get_size().y / scale_ratio
-	else:
-		var scale_ratio := preview_image.get_size().y / image_size_y
-		image_size_x = preview_image.get_size().x / scale_ratio
-
-	preview.get_node("TransparentChecker").size.x = image_size_x
-	preview.get_node("TransparentChecker").size.y = image_size_y
-
-
 func _visibility_changed() -> void:
 	if visible:
 		return

src/UI/Dialogs/ImageEffects/ResizeCanvas.gd

@@ -10,6 +10,7 @@ var image := Image.create(1, 1, false, Image.FORMAT_RGBA8)
 @onready var height_spinbox: SpinBox = $VBoxContainer/OptionsContainer/HeightValue
 @onready var x_spinbox: SpinBox = $VBoxContainer/OptionsContainer/XSpinBox
 @onready var y_spinbox: SpinBox = $VBoxContainer/OptionsContainer/YSpinBox
+@onready var aspect_ratio_container: AspectRatioContainer = $VBoxContainer/AspectRatioContainer
 @onready var preview_rect: TextureRect = $VBoxContainer/AspectRatioContainer/Preview
 
 
@@ -82,21 +83,7 @@ func update_preview() -> void:
 		image, Rect2i(Vector2i.ZERO, Global.current_project.size), Vector2i(offset_x, offset_y)
 	)
 	preview_rect.texture = ImageTexture.create_from_image(preview_image)
-	update_transparent_background_size(preview_image)
-
-
-func update_transparent_background_size(preview_image: Image) -> void:
-	var image_size_y := preview_rect.size.y
-	var image_size_x := preview_rect.size.x
-	if preview_image.get_size().x > preview_image.get_size().y:
-		var scale_ratio := preview_image.get_size().x / image_size_x
-		image_size_y = preview_image.get_size().y / scale_ratio
-	else:
-		var scale_ratio := preview_image.get_size().y / image_size_y
-		image_size_x = preview_image.get_size().x / scale_ratio
-
-	preview_rect.get_node("TransparentChecker").size.x = image_size_x
-	preview_rect.get_node("TransparentChecker").size.y = image_size_y
+	aspect_ratio_container.ratio = float(preview_image.get_width()) / preview_image.get_height()
 
 
 func _on_visibility_changed() -> void: