Spritesheet Autoslicer (#893)

* Added autoSlicer

* Fixed the remaining things (Autoslicer fully functional)

* Update RegionUnpacker.gd

* Formatting

* formatting

* formatting

* neatify

* Update RegionUnpacker.gd

* formatting

* formatting

* Update RegionUnpacker.gd

* Update README.md

* Added region unpacker class

* Optimized the region unpacker, this should now be twice as fast

addon version: f01526e50db98eea6d4d69db3c241d360887af7f

* change Smart Slicer to 5745b26a6e0b7e10bc4a46d07b5f9f0dd8f26c96

5745b26a6e

* Delete addons/SmartSlicer/Shader directory

* removed shader

* Update SmartSlicer Version

278b1c5a80b2c8b89279e405156d556732ce98d2

* Formatting (This is torture LOL)

2578b74ba84289aa109ae715b4a6c90fd5e23126

* Delete addons/SmartSlicer/addons/SmartSlicer/Classes directory

* Formatting

Version remains same

* Delete SmartSlicePreview.gd

* use _draw instead of line2d

and moved SmartSlicerPreview.gd for better organization

* Formatting

* More formatting

* Fix bugs related to import

* fix crash on attempting to open empty image

as new spritesheet tab (smart)

* removed accidental print

* fix empty image warnings

addons/README.md

@@ -27,3 +27,10 @@ Files extracted from source:
 - Version: Based on git commit e5df60ed1d53246e03dba36053ff009846ba5174 with a modification on dockable_container.gd (lines 187-191).
 - License: [CC0-1.0](https://github.com/gilzoide/godot-dockable-container/blob/main/LICENSE)
 
+## SmartSlicer
+
+- Upstream: https://github.com/Variable-Interactive/SmartSlicer
+- Version: Based on git commit 2804e6109f9667022c66522ce88a99a56fd67ca8 with a modification on SmartSlicePreview.gd (lines 31-32). Only the contents of addons folder are used and the script SmartSlicePreview.gd is moved to res://src/UI/Dialogs/HelperScripts/ for better organization
+- License: [MIT](https://github.com/Variable-Interactive/SmartSlicer/blob/main/LICENSE)
+
+

addons/SmartSlicer/Classes/RegionUnpacker.gd

@@ -0,0 +1,251 @@
+class_name RegionUnpacker
+extends Reference
+
+# THIS CLASS TAKES INSPIRATION FROM PIXELORAMA'S FLOOD FILL
+# AND HAS BEEN MODIFIED FOR OPTIMIZATION
+
+var slice_thread := Thread.new()
+
+var _include_boundary_threshold: int  # the size of rect below which merging accounts for boundaty
+var _merge_dist: int  #  after crossing threshold the smaller image will merge with larger image
+# if it is within the _merge_dist
+
+# working array used as buffer for segments while flooding
+var _allegro_flood_segments: Array
+# results array per image while flooding
+var _allegro_image_segments: Array
+
+
+func _init(threshold: int, merge_dist: int) -> void:
+	_include_boundary_threshold = threshold
+	_merge_dist = merge_dist
+
+
+func get_used_rects(image: Image) -> Dictionary:
+	if OS.get_name() == "HTML5":
+		return get_rects(image)
+	else:
+		# If Thread model is set to "Multi-Threaded" in project settings>threads>thread model
+		if slice_thread.is_active():
+			slice_thread.wait_to_finish()
+		var error = slice_thread.start(self, "get_rects", image)
+		if error == OK:
+			return slice_thread.wait_to_finish()
+		else:
+			return get_rects(image)
+		# If Thread model is set to "Single-Safe" in project settings>threads>thread model then
+		# comment the above code and uncomment below
+		#return get_rects({"image": image})
+
+
+func get_rects(image: Image) -> Dictionary:
+	# make a smaller image to make the loop shorter
+	var used_rect = image.get_used_rect()
+	if used_rect.size == Vector2.ZERO:
+		return clean_rects([])
+	var test_image = image.get_rect(used_rect)
+	# prepare a bitmap to keep track of previous places
+	var scanned_area := BitMap.new()
+	scanned_area.create(test_image.get_size())
+	test_image.lock()
+	# Scan the image
+	var rects = []
+	var frame_size = Vector2.ZERO
+	for y in test_image.get_size().y:
+		for x in test_image.get_size().x:
+			var position = Vector2(x, y)
+			if test_image.get_pixelv(position).a > 0:  # used portion of image detected
+				if !scanned_area.get_bit(position):
+					var rect := _estimate_rect(test_image, position)
+					scanned_area.set_bit_rect(rect, true)
+					rect.position += used_rect.position
+					rects.append(rect)
+	test_image.unlock()
+	var rects_info = clean_rects(rects)
+	rects_info["rects"].sort_custom(self, "sort_rects")
+	return rects_info
+
+
+func clean_rects(rects: Array) -> Dictionary:
+	var frame_size = Vector2.ZERO
+	for i in rects.size():
+		var target: Rect2 = rects.pop_front()
+		var test_rect = target
+		if (
+			target.size.x < _include_boundary_threshold
+			or target.size.y < _include_boundary_threshold
+		):
+			test_rect.size += Vector2(_merge_dist, _merge_dist)
+			test_rect.position -= Vector2(_merge_dist, _merge_dist) / 2
+		var merged = false
+		for rect_i in rects.size():
+			if test_rect.intersects(rects[rect_i]):
+				rects[rect_i] = target.merge(rects[rect_i])
+				merged = true
+				break
+		if !merged:
+			rects.append(target)
+
+		# calculation for a suitable frame size
+		if target.size.x > frame_size.x:
+			frame_size.x = target.size.x
+		if target.size.y > frame_size.y:
+			frame_size.y = target.size.y
+	return {"rects": rects, "frame_size": frame_size}
+
+
+func sort_rects(rect_a: Rect2, rect_b: Rect2) -> bool:
+	# After many failed attempts, this version works for some reason (it's best not to disturb it)
+	if rect_a.end.y < rect_b.position.y:
+		return true
+	if rect_a.position.x < rect_b.position.x:
+		# if both lie in the same row
+		var start = rect_a.position
+		var size = Vector2(rect_b.end.x, rect_a.end.y)
+		if Rect2(start, size).intersects(rect_b):
+			return true
+	return false
+
+
+func _estimate_rect(image: Image, position: Vector2) -> Rect2:
+	var cel_image := Image.new()
+	cel_image.copy_from(image)
+	cel_image.lock()
+	var small_rect: Rect2 = _flood_fill(position, cel_image)
+	cel_image.unlock()
+	return small_rect
+
+
+# Add a new segment to the array
+func _add_new_segment(y: int = 0) -> void:
+	var segment = {}
+	segment.flooding = false
+	segment.todo_above = false
+	segment.todo_below = false
+	segment.left_position = -5  # anything less than -1 is ok
+	segment.right_position = -5
+	segment.y = y
+	segment.next = 0
+	_allegro_flood_segments.append(segment)
+
+
+# fill an horizontal segment around the specified position, and adds it to the
+# list of segments filled. Returns the first x coordinate after the part of the
+# line that has been filled.
+func _flood_line_around_point(position: Vector2, image: Image) -> int:
+	# this method is called by `_flood_fill` after the required data structures
+	# have been initialized
+	if not image.get_pixelv(position).a > 0:
+		return int(position.x) + 1
+	var west: Vector2 = position
+	var east: Vector2 = position
+	while west.x >= 0 && image.get_pixelv(west).a > 0:
+		west += Vector2.LEFT
+	while east.x < image.get_width() && image.get_pixelv(east).a > 0:
+		east += Vector2.RIGHT
+	# Make a note of the stuff we processed
+	var c = int(position.y)
+	var segment = _allegro_flood_segments[c]
+	# we may have already processed some segments on this y coordinate
+	if segment.flooding:
+		while segment.next > 0:
+			c = segment.next  # index of next segment in this line of image
+			segment = _allegro_flood_segments[c]
+		# found last current segment on this line
+		c = _allegro_flood_segments.size()
+		segment.next = c
+		_add_new_segment(int(position.y))
+		segment = _allegro_flood_segments[c]
+	# set the values for the current segment
+	segment.flooding = true
+	segment.left_position = west.x + 1
+	segment.right_position = east.x - 1
+	segment.y = position.y
+	segment.next = 0
+	# Should we process segments above or below this one?
+	# when there is a selected area, the pixels above and below the one we started creating this
+	# segment from may be outside it. It's easier to assume we should be checking for segments
+	# above and below this one than to specifically check every single pixel in it, because that
+	# test will be performed later anyway.
+	# On the other hand, this test we described is the same `project.can_pixel_get_drawn` does if
+	# there is no selection, so we don't need branching here.
+	segment.todo_above = position.y > 0
+	segment.todo_below = position.y < image.get_height() - 1
+	# this is an actual segment we should be coloring, so we add it to the results for the
+	# current image
+	if segment.right_position >= segment.left_position:
+		_allegro_image_segments.append(segment)
+	# we know the point just east of the segment is not part of a segment that should be
+	# processed, else it would be part of this segment
+	return int(east.x) + 1
+
+
+func _check_flooded_segment(y: int, left: int, right: int, image: Image) -> bool:
+	var ret = false
+	var c: int = 0
+	while left <= right:
+		c = y
+		while true:
+			var segment = _allegro_flood_segments[c]
+			if left >= segment.left_position and left <= segment.right_position:
+				left = segment.right_position + 2
+				break
+			c = segment.next
+			if c == 0:  # couldn't find a valid segment, so we draw a new one
+				left = _flood_line_around_point(Vector2(left, y), image)
+				ret = true
+				break
+	return ret
+
+
+func _flood_fill(position: Vector2, image: Image) -> Rect2:
+	# implements the floodfill routine by Shawn Hargreaves
+	# from https://www1.udel.edu/CIS/software/dist/allegro-4.2.1/src/flood.c
+	# init flood data structures
+	_allegro_flood_segments = []
+	_allegro_image_segments = []
+	_compute_segments_for_image(position, image)
+	# now actually color the image: since we have already checked a few things for the points
+	# we'll process here, we're going to skip a bunch of safety checks to speed things up.
+
+	var final_image = Image.new()
+	final_image.copy_from(image)
+	final_image.fill(Color.transparent)
+	final_image.lock()
+	_select_segments(final_image)
+	final_image.unlock()
+
+	return final_image.get_used_rect()
+
+
+func _compute_segments_for_image(position: Vector2, image: Image) -> void:
+	# initially allocate at least 1 segment per line of image
+	for j in image.get_height():
+		_add_new_segment(j)
+	# start flood algorithm
+	_flood_line_around_point(position, image)
+	# test all segments while also discovering more
+	var done := false
+	while not done:
+		done = true
+		var max_index = _allegro_flood_segments.size()
+		for c in max_index:
+			var p = _allegro_flood_segments[c]
+			if p.todo_below:  # check below the segment?
+				p.todo_below = false
+				if _check_flooded_segment(p.y + 1, p.left_position, p.right_position, image):
+					done = false
+			if p.todo_above:  # check above the segment?
+				p.todo_above = false
+				if _check_flooded_segment(p.y - 1, p.left_position, p.right_position, image):
+					done = false
+
+
+func _select_segments(map: Image) -> void:
+	# short circuit for flat colors
+	for c in _allegro_image_segments.size():
+		var p = _allegro_image_segments[c]
+		var rect = Rect2()
+		rect.position = Vector2(p.left_position, p.y)
+		rect.end = Vector2(p.right_position + 1, p.y + 1)
+		map.fill_rect(rect, Color.white)

project.godot

@@ -224,6 +224,11 @@ _global_script_classes=[ {
 "language": "GDScript",
 "path": "res://src/UI/ReferenceImages/ReferencesPanel.gd"
 }, {
+"base": "Reference",
+"class": "RegionUnpacker",
+"language": "GDScript",
+"path": "res://addons/SmartSlicer/Classes/RegionUnpacker.gd"
+}, {
 "base": "Image",
 "class": "SelectionMap",
 "language": "GDScript",
@@ -313,6 +318,7 @@ _global_script_class_icons={
 "Project": "",
 "ReferenceImage": "",
 "ReferencesPanel": "",
+"RegionUnpacker": "",
 "SelectionMap": "",
 "SelectionTool": "",
 "ShaderImageEffect": "",

src/Autoload/OpenSave.gd

@@ -470,14 +470,35 @@ func open_image_as_new_tab(path: String, image: Image) -> void:
 	set_new_imported_tab(project, path)
 
 
-func open_image_as_spritesheet_tab(path: String, image: Image, horiz: int, vert: int) -> void:
+func open_image_as_spritesheet_tab_smart(
-	var project := Project.new([], path.get_file())
+	path: String, image: Image, sliced_rects: Array, frame_size: Vector2
+) -> void:
+	if sliced_rects.size() == 0:  # Image is empty sprite (manually set data to be consistent)
+		frame_size = image.get_size()
+		sliced_rects.append(Rect2(Vector2.ZERO, frame_size))
+	var project := Project.new([], path.get_file(), frame_size)
 	project.layers.append(PixelLayer.new(project))
 	Global.projects.append(project)
+	for rect in sliced_rects:
+		var offset: Vector2 = (0.5 * (frame_size - rect.size)).floor()
+		var frame := Frame.new()
+		var cropped_image := Image.new()
+		cropped_image.create(frame_size.x, frame_size.y, false, Image.FORMAT_RGBA8)
+		cropped_image.blit_rect(image, rect, offset)
+		cropped_image.convert(Image.FORMAT_RGBA8)
+		frame.cels.append(PixelCel.new(cropped_image, 1))
+		project.frames.append(frame)
+	set_new_imported_tab(project, path)
+
+
+func open_image_as_spritesheet_tab(path: String, image: Image, horiz: int, vert: int) -> void:
 	horiz = min(horiz, image.get_size().x)
 	vert = min(vert, image.get_size().y)
 	var frame_width := image.get_size().x / horiz
 	var frame_height := image.get_size().y / vert
+	var project := Project.new([], path.get_file(), Vector2(frame_width, frame_height))
+	project.layers.append(PixelLayer.new(project))
+	Global.projects.append(project)
 	for yy in range(vert):
 		for xx in range(horiz):
 			var frame := Frame.new()
@@ -492,6 +513,83 @@ func open_image_as_spritesheet_tab(path: String, image: Image, horiz: int, vert:
 	set_new_imported_tab(project, path)
 
 
+func open_image_as_spritesheet_layer_smart(
+	_path: String,
+	image: Image,
+	file_name: String,
+	sliced_rects: Array,
+	start_frame: int,
+	frame_size: Vector2
+) -> void:
+	# Resize canvas to if "frame_size.x" or "frame_size.y" is too large
+	var project: Project = Global.current_project
+	var project_width: int = max(frame_size.x, project.size.x)
+	var project_height: int = max(frame_size.y, project.size.y)
+	if project.size < Vector2(project_width, project_height):
+		DrawingAlgos.resize_canvas(project_width, project_height, 0, 0)
+
+	# Initialize undo mechanism
+	project.undos += 1
+	project.undo_redo.create_action("Add Spritesheet Layer")
+
+	# Create new frames (if needed)
+	var new_frames_size = max(project.frames.size(), start_frame + sliced_rects.size())
+	var frames := []
+	var frame_indices := []
+	if new_frames_size > project.frames.size():
+		var required_frames = new_frames_size - project.frames.size()
+		frame_indices = range(
+			project.current_frame + 1, project.current_frame + required_frames + 1
+		)
+		for i in required_frames:
+			var new_frame := Frame.new()
+			for l in range(project.layers.size()):  # Create as many cels as there are layers
+				new_frame.cels.append(project.layers[l].new_empty_cel())
+				if project.layers[l].new_cels_linked:
+					var prev_cel: BaseCel = project.frames[project.current_frame].cels[l]
+					if prev_cel.link_set == null:
+						prev_cel.link_set = {}
+						project.undo_redo.add_do_method(
+							project.layers[l], "link_cel", prev_cel, prev_cel.link_set
+						)
+						project.undo_redo.add_undo_method(
+							project.layers[l], "link_cel", prev_cel, null
+						)
+					new_frame.cels[l].set_content(prev_cel.get_content(), prev_cel.image_texture)
+					new_frame.cels[l].link_set = prev_cel.link_set
+			frames.append(new_frame)
+
+	# Create new layer for spritesheet
+	var layer := PixelLayer.new(project, file_name)
+	var cels := []
+	for f in new_frames_size:
+		if f >= start_frame and f < (start_frame + sliced_rects.size()):
+			# Slice spritesheet
+			var offset: Vector2 = (0.5 * (frame_size - sliced_rects[f - start_frame].size)).floor()
+			image.convert(Image.FORMAT_RGBA8)
+			var cropped_image := Image.new()
+			cropped_image.create(project_width, project_height, false, Image.FORMAT_RGBA8)
+			cropped_image.blit_rect(image, sliced_rects[f - start_frame], offset)
+			cels.append(PixelCel.new(cropped_image))
+		else:
+			cels.append(layer.new_empty_cel())
+
+	project.undo_redo.add_do_method(project, "add_frames", frames, frame_indices)
+	project.undo_redo.add_do_method(project, "add_layers", [layer], [project.layers.size()], [cels])
+	project.undo_redo.add_do_method(
+		project, "change_cel", new_frames_size - 1, project.layers.size()
+	)
+	project.undo_redo.add_do_method(Global, "undo_or_redo", false)
+
+	project.undo_redo.add_undo_method(project, "remove_layers", [project.layers.size()])
+	project.undo_redo.add_undo_method(project, "remove_frames", frame_indices)
+	project.undo_redo.add_undo_method(
+		project, "change_cel", project.current_frame, project.current_layer
+	)
+	project.undo_redo.add_undo_method(Global, "undo_or_redo", true)
+	project.undo_redo.commit_action()
+
+
 func open_image_as_spritesheet_layer(
 	_path: String, image: Image, file_name: String, horizontal: int, vertical: int, start_frame: int
 ) -> void:
@@ -547,12 +645,14 @@ func open_image_as_spritesheet_layer(
 			# Slice spritesheet
 			var xx: int = (f - start_frame) % horizontal
 			var yy: int = (f - start_frame) / horizontal
+			image.convert(Image.FORMAT_RGBA8)
 			var cropped_image := Image.new()
-			cropped_image = image.get_rect(
+			cropped_image.create(project_width, project_height, false, Image.FORMAT_RGBA8)
-				Rect2(frame_width * xx, frame_height * yy, frame_width, frame_height)
+			cropped_image.blit_rect(
+				image,
+				Rect2(frame_width * xx, frame_height * yy, frame_width, frame_height),
+				Vector2.ZERO
 			)
-			cropped_image.crop(project.size.x, project.size.y)
-			cropped_image.convert(Image.FORMAT_RGBA8)
 			cels.append(PixelCel.new(cropped_image))
 		else:
 			cels.append(layer.new_empty_cel())
@@ -585,8 +685,11 @@ func open_image_at_cel(image: Image, layer_index := 0, frame_index := 0) -> void
 	for i in project.frames.size():
 		if i == frame_index:
 			image.convert(Image.FORMAT_RGBA8)
+			var cel_image = Image.new()
+			cel_image.create(project_width, project_height, false, Image.FORMAT_RGBA8)
+			cel_image.blit_rect(image, Rect2(Vector2.ZERO, image.get_size()), Vector2.ZERO)
 			var cel: PixelCel = project.frames[i].cels[layer_index]
-			project.undo_redo.add_do_property(cel, "image", image)
+			project.undo_redo.add_do_property(cel, "image", cel_image)
 			project.undo_redo.add_undo_property(cel, "image", cel.image)
 
 	project.undo_redo.add_do_property(project, "selected_cels", [])
@@ -612,7 +715,10 @@ func open_image_as_new_frame(image: Image, layer_index := 0) -> void:
 	for i in project.layers.size():
 		if i == layer_index:
 			image.convert(Image.FORMAT_RGBA8)
-			frame.cels.append(PixelCel.new(image, 1))
+			var cel_image = Image.new()
+			cel_image.create(project_width, project_height, false, Image.FORMAT_RGBA8)
+			cel_image.blit_rect(image, Rect2(Vector2.ZERO, image.get_size()), Vector2.ZERO)
+			frame.cels.append(PixelCel.new(cel_image, 1))
 		else:
 			frame.cels.append(project.layers[i].new_empty_cel())
 
@@ -644,7 +750,10 @@ func open_image_as_new_layer(image: Image, file_name: String, frame_index := 0)
 	for i in project.frames.size():
 		if i == frame_index:
 			image.convert(Image.FORMAT_RGBA8)
-			cels.append(PixelCel.new(image, 1))
+			var cel_image = Image.new()
+			cel_image.create(project_width, project_height, false, Image.FORMAT_RGBA8)
+			cel_image.blit_rect(image, Rect2(Vector2.ZERO, image.get_size()), Vector2.ZERO)
+			cels.append(PixelCel.new(cel_image, 1))
 		else:
 			cels.append(layer.new_empty_cel())
 

src/UI/Dialogs/HelperScripts/RowColumnLines.gd

@@ -0,0 +1,39 @@
+extends Control
+
+var color: Color = Color("6680ff")  # Set this to a theme color later
+var _spritesheet_vertical
+var _spritesheet_horizontal
+
+
+func show_preview(spritesheet_vertical, spritesheet_horizontal) -> void:
+	_spritesheet_vertical = spritesheet_vertical
+	_spritesheet_horizontal = spritesheet_horizontal
+	update()
+
+
+func _draw() -> void:
+	var texture_rect: TextureRect = get_parent()
+	var image = texture_rect.texture.get_data()
+	var image_size_y = texture_rect.rect_size.y
+	var image_size_x = texture_rect.rect_size.x
+	if image.get_size().x > image.get_size().y:
+		var scale_ratio = image.get_size().x / image_size_x
+		image_size_y = image.get_size().y / scale_ratio
+	else:
+		var scale_ratio = image.get_size().y / image_size_y
+		image_size_x = image.get_size().x / scale_ratio
+
+	var offset_x = (texture_rect.rect_size.x - image_size_x) / 2
+	var offset_y = (texture_rect.rect_size.y - image_size_y) / 2
+
+	var line_distance_vertical = image_size_y / _spritesheet_vertical
+	var line_distance_horizontal = image_size_x / _spritesheet_horizontal
+
+	for i in range(1, _spritesheet_vertical):
+		var from = Vector2(offset_x, i * line_distance_vertical + offset_y)
+		var to = Vector2(image_size_x + offset_x, i * line_distance_vertical + offset_y)
+		draw_line(from, to, color)
+	for i in range(1, _spritesheet_horizontal):
+		var from = Vector2(i * line_distance_horizontal + offset_x, offset_y)
+		var to = Vector2(i * line_distance_horizontal + offset_x, image_size_y + offset_y)
+		draw_line(from, to, color)

src/UI/Dialogs/HelperScripts/SmartSlicePreview.gd

@@ -0,0 +1,36 @@
+extends Control
+
+# add this as a child of the texturerect that contains the main spritesheet
+var color: Color = Color("6680ff")  # Set this to a theme color later
+var _sliced_rects: Array
+var _stretch_amount: float
+var _offset: Vector2
+
+
+func show_preview(sliced_rects: Array) -> void:
+	var image = get_parent().texture.get_data()
+	if image.get_size().x > image.get_size().y:
+		_stretch_amount = rect_size.x / image.get_size().x
+	else:
+		_stretch_amount = rect_size.y / image.get_size().y
+	_sliced_rects = sliced_rects.duplicate()
+	_offset = (0.5 * (rect_size - (image.get_size() * _stretch_amount))).floor()
+	update()
+
+
+func _draw() -> void:
+	draw_set_transform(_offset, 0, Vector2.ONE)
+	for i in _sliced_rects.size():
+		var rect = _sliced_rects[i]
+		var scaled_rect: Rect2 = rect
+		scaled_rect.position = (scaled_rect.position * _stretch_amount)
+		scaled_rect.size *= _stretch_amount
+		draw_rect(scaled_rect, color, false)
+		# show number
+		draw_set_transform(_offset + scaled_rect.position, 0, Vector2.ONE)
+#		var font: Font = Control.new().get_font("font")
+		# replace with font used by pixelorama
+		var font: Font = Global.control.theme.default_font
+		var font_height := font.get_height()
+		draw_string(font, Vector2(1, font_height), str(i))
+		draw_set_transform(_offset, 0, Vector2.ONE)

src/UI/Dialogs/PreviewDialog.gd

@@ -17,17 +17,28 @@ enum BrushTypes { FILE, PROJECT, RANDOM }
 var path: String
 var image: Image
 var current_import_option: int = ImageImportOptions.NEW_TAB
+var smart_slice = false
+var recycle_last_slice_result = false  # should we recycle the current sliced_rects
+var sliced_rects: Dictionary
 var spritesheet_horizontal := 1
 var spritesheet_vertical := 1
 var brush_type: int = BrushTypes.FILE
 var opened_once = false
 var is_master: bool = false
 var hiding: bool = false
+var _content_offset = rect_size - get_child(0).rect_size  # A workaround for a pixelorama bug
 
 onready var texture_rect: TextureRect = $VBoxContainer/CenterContainer/TextureRect
 onready var image_size_label: Label = $VBoxContainer/SizeContainer/ImageSizeLabel
 onready var frame_size_label: Label = $VBoxContainer/SizeContainer/FrameSizeLabel
-onready var spritesheet_tab_options = $VBoxContainer/HBoxContainer/SpritesheetTabOptions
+onready var smart_slice_checkbox = $VBoxContainer/HBoxContainer/SpritesheetTabOptions/SmartSlice
+onready var merge_threshold = $VBoxContainer/HBoxContainer/SpritesheetTabOptions/Smart/Threshold
+# gdlint: ignore=max-line-length
+onready var merge_dist: TextureProgress = $VBoxContainer/HBoxContainer/SpritesheetTabOptions/Smart/MergeDist
+# gdlint: ignore=max-line-length
+onready var spritesheet_manual_tab_options = $VBoxContainer/HBoxContainer/SpritesheetTabOptions/Manual
+onready var spritesheet_smart_tab_options = $VBoxContainer/HBoxContainer/SpritesheetTabOptions/Smart
+onready var spritesheet_tab_options = spritesheet_smart_tab_options.get_parent()
 onready var spritesheet_lay_opt = $VBoxContainer/HBoxContainer/SpritesheetLayerOptions
 onready var new_frame_options = $VBoxContainer/HBoxContainer/NewFrameOptions
 onready var replace_cel_options = $VBoxContainer/HBoxContainer/ReplaceCelOptions
@@ -62,11 +73,11 @@ func _on_PreviewDialog_about_to_show() -> void:
 	var img_texture := ImageTexture.new()
 	img_texture.create_from_image(image, 0)
 	texture_rect.texture = img_texture
-	spritesheet_tab_options.get_node("HorizontalFrames").max_value = min(
+	spritesheet_manual_tab_options.get_node("HorizontalFrames").max_value = min(
-		spritesheet_tab_options.get_node("HorizontalFrames").max_value, image.get_size().x
+		spritesheet_manual_tab_options.get_node("HorizontalFrames").max_value, image.get_size().x
 	)
-	spritesheet_tab_options.get_node("VerticalFrames").max_value = min(
+	spritesheet_manual_tab_options.get_node("VerticalFrames").max_value = min(
-		spritesheet_tab_options.get_node("VerticalFrames").max_value, image.get_size().y
+		spritesheet_manual_tab_options.get_node("VerticalFrames").max_value, image.get_size().y
 	)
 	image_size_label.text = (
 		tr("Image Size")
@@ -115,20 +126,39 @@ func _on_PreviewDialog_confirmed() -> void:
 			OpenSave.open_image_as_new_tab(path, image)
 
 		elif current_import_option == ImageImportOptions.SPRITESHEET_TAB:
-			OpenSave.open_image_as_spritesheet_tab(
+			if smart_slice:
-				path, image, spritesheet_horizontal, spritesheet_vertical
+				if !recycle_last_slice_result:
-			)
+					obtain_sliced_data()
+				OpenSave.open_image_as_spritesheet_tab_smart(
+					path, image, sliced_rects["rects"], sliced_rects["frame_size"]
+				)
+			else:
+				OpenSave.open_image_as_spritesheet_tab(
+					path, image, spritesheet_horizontal, spritesheet_vertical
+				)
 
 		elif current_import_option == ImageImportOptions.SPRITESHEET_LAYER:
 			var frame_index: int = spritesheet_lay_opt.get_node("AtFrameSpinbox").value - 1
-			OpenSave.open_image_as_spritesheet_layer(
+			if smart_slice:
-				path,
+				if !recycle_last_slice_result:
-				image,
+					obtain_sliced_data()
-				path.get_basename().get_file(),
+				OpenSave.open_image_as_spritesheet_layer_smart(
-				spritesheet_horizontal,
+					path,
-				spritesheet_vertical,
+					image,
-				frame_index
+					path.get_basename().get_file(),
-			)
+					sliced_rects["rects"],
+					frame_index,
+					sliced_rects["frame_size"]
+				)
+			else:
+				OpenSave.open_image_as_spritesheet_layer(
+					path,
+					image,
+					path.get_basename().get_file(),
+					spritesheet_horizontal,
+					spritesheet_vertical,
+					frame_index
+				)
 
 		elif current_import_option == ImageImportOptions.NEW_FRAME:
 			var layer_index: int = new_frame_options.get_node("AtLayerOption").get_selected_id()
@@ -200,11 +230,13 @@ func synchronize() -> void:
 				id == ImageImportOptions.SPRITESHEET_TAB
 				or id == ImageImportOptions.SPRITESHEET_LAYER
 			):
-				dialog.spritesheet_tab_options.get_node("HorizontalFrames").value = min(
+				dialog.spritesheet_manual_tab_options.get_node("HorizontalFrames").value = min(
-					spritesheet_tab_options.get_node("HorizontalFrames").value, image.get_size().x
+					spritesheet_manual_tab_options.get_node("HorizontalFrames").value,
+					image.get_size().x
 				)
-				dialog.spritesheet_tab_options.get_node("VerticalFrames").value = min(
+				dialog.spritesheet_manual_tab_options.get_node("VerticalFrames").value = min(
-					spritesheet_tab_options.get_node("VerticalFrames").value, image.get_size().y
+					spritesheet_manual_tab_options.get_node("VerticalFrames").value,
+					image.get_size().y
 				)
 				if id == ImageImportOptions.SPRITESHEET_LAYER:
 					dialog.spritesheet_lay_opt.get_node("AtFrameSpinbox").value = (spritesheet_lay_opt.get_node(
@@ -240,7 +272,10 @@ func synchronize() -> void:
 func _on_ImportOption_item_selected(id: int) -> void:
 	current_import_option = id
 	OpenSave.last_dialog_option = current_import_option
-	frame_size_label.visible = false
+	smart_slice_checkbox.pressed = false
+	apply_all.disabled = false
+	smart_slice = false
+	smart_slice_checkbox.visible = false
 	spritesheet_tab_options.visible = false
 	spritesheet_lay_opt.visible = false
 	new_frame_options.visible = false
@@ -249,22 +284,21 @@ func _on_ImportOption_item_selected(id: int) -> void:
 	new_brush_options.visible = false
 	texture_rect.get_child(0).visible = false
 	texture_rect.get_child(1).visible = false
-	rect_size.x = 550
 
 	if id == ImageImportOptions.SPRITESHEET_TAB:
 		frame_size_label.visible = true
+		smart_slice_checkbox.visible = true
 		spritesheet_tab_options.visible = true
 		texture_rect.get_child(0).visible = true
 		texture_rect.get_child(1).visible = true
-		rect_size.x = spritesheet_tab_options.rect_size.x
 
 	elif id == ImageImportOptions.SPRITESHEET_LAYER:
 		frame_size_label.visible = true
-		spritesheet_tab_options.visible = true
+		smart_slice_checkbox.visible = true
 		spritesheet_lay_opt.visible = true
+		spritesheet_tab_options.visible = true
 		texture_rect.get_child(0).visible = true
 		texture_rect.get_child(1).visible = true
-		rect_size.x = spritesheet_lay_opt.rect_size.x
 
 	elif id == ImageImportOptions.NEW_FRAME:
 		new_frame_options.visible = true
@@ -306,59 +340,68 @@ func _on_ImportOption_item_selected(id: int) -> void:
 	elif id == ImageImportOptions.BRUSH:
 		new_brush_options.visible = true
 
+	rect_size = get_child(0).rect_size + _content_offset
+	update()
+
+
+func _on_SmartSlice_toggled(button_pressed: bool) -> void:
+	setup_smart_slice(button_pressed)
+
+
+func setup_smart_slice(enabled: bool) -> void:
+	spritesheet_smart_tab_options.visible = enabled
+	spritesheet_manual_tab_options.visible = !enabled
+	if is_master:  # disable apply all (the algorithm is not fast enough for this)
+		apply_all.pressed = false
+	apply_all.disabled = enabled
+	smart_slice = enabled
+	if !recycle_last_slice_result and enabled:
+		slice_preview()
+	update()
+
+
+func obtain_sliced_data() -> void:
+	var unpak := RegionUnpacker.new(merge_threshold.value, merge_dist.value)
+	sliced_rects = unpak.get_used_rects(texture_rect.texture.get_data())
+
+
+func slice_preview():
+	sliced_rects.clear()
+	obtain_sliced_data()
+	recycle_last_slice_result = true
+	var size = sliced_rects["frame_size"]
+	frame_size_label.text = tr("Frame Size") + ": " + str(size.x) + "×" + str(size.y)
+
+
+func _on_Threshold_value_changed(_value: float) -> void:
+	recycle_last_slice_result = false
+
+
+func _on_MergeDist_value_changed(_value: float) -> void:
+	recycle_last_slice_result = false
+
+
+func _on_Slice_pressed() -> void:
+	if !recycle_last_slice_result:
+		slice_preview()
+	update()
+
 
 func _on_HorizontalFrames_value_changed(value: int) -> void:
 	spritesheet_horizontal = value
-	for child in texture_rect.get_node("HorizLines").get_children():
+	spritesheet_frame_value_changed()
-		child.queue_free()
-
-	spritesheet_frame_value_changed(value, false)
 
 
 func _on_VerticalFrames_value_changed(value: int) -> void:
 	spritesheet_vertical = value
-	for child in texture_rect.get_node("VerticalLines").get_children():
+	spritesheet_frame_value_changed()
-		child.queue_free()
-
-	spritesheet_frame_value_changed(value, true)
 
 
-func spritesheet_frame_value_changed(value: int, vertical: bool) -> void:
+func spritesheet_frame_value_changed() -> void:
-	var image_size_y = texture_rect.rect_size.y
-	var image_size_x = texture_rect.rect_size.x
-	if image.get_size().x > image.get_size().y:
-		var scale_ratio = image.get_size().x / image_size_x
-		image_size_y = image.get_size().y / scale_ratio
-	else:
-		var scale_ratio = image.get_size().y / image_size_y
-		image_size_x = image.get_size().x / scale_ratio
-
-	var offset_x = (texture_rect.rect_size.x - image_size_x) / 2
-	var offset_y = (texture_rect.rect_size.y - image_size_y) / 2
-
-	if value > 1:
-		var line_distance
-		if vertical:
-			line_distance = image_size_y / value
-		else:
-			line_distance = image_size_x / value
-
-		for i in range(1, value):
-			var line_2d := Line2D.new()
-			line_2d.width = 1
-			line_2d.position = Vector2.ZERO
-			if vertical:
-				line_2d.add_point(Vector2(offset_x, i * line_distance + offset_y))
-				line_2d.add_point(Vector2(image_size_x + offset_x, i * line_distance + offset_y))
-				texture_rect.get_node("VerticalLines").add_child(line_2d)
-			else:
-				line_2d.add_point(Vector2(i * line_distance + offset_x, offset_y))
-				line_2d.add_point(Vector2(i * line_distance + offset_x, image_size_y + offset_y))
-				texture_rect.get_node("HorizLines").add_child(line_2d)
-
 	var frame_width = floor(image.get_size().x / spritesheet_horizontal)
 	var frame_height = floor(image.get_size().y / spritesheet_vertical)
 	frame_size_label.text = tr("Frame Size") + ": " + str(frame_width) + "×" + str(frame_height)
+	update()
 
 
 func _on_BrushTypeOption_item_selected(index: int) -> void:
@@ -428,3 +471,21 @@ func file_name_replace(name: String, folder: String) -> String:
 		temp_name += "." + file_ext
 	name = temp_name
 	return name
+
+
+func _on_PreviewDialog_item_rect_changed() -> void:
+	update()
+
+
+func _draw() -> void:
+	$"%SmartSlice".show_preview([])
+	$"%RowColumnLines".show_preview(1, 1)
+	if (
+		current_import_option == ImageImportOptions.SPRITESHEET_TAB
+		or current_import_option == ImageImportOptions.SPRITESHEET_LAYER
+	):
+		if smart_slice:
+			if "rects" in sliced_rects.keys():
+				$"%SmartSlice".show_preview(sliced_rects["rects"])
+		else:
+			$"%RowColumnLines".show_preview(spritesheet_vertical, spritesheet_horizontal)

src/UI/Dialogs/PreviewDialog.tscn

@@ -1,18 +1,18 @@
-[gd_scene load_steps=2 format=2]
+[gd_scene load_steps=5 format=2]
 
 [ext_resource path="res://src/UI/Dialogs/PreviewDialog.gd" type="Script" id=1]
+[ext_resource path="res://src/UI/Nodes/ValueSlider.tscn" type="PackedScene" id=2]
+[ext_resource path="res://src/UI/Dialogs/HelperScripts/SmartSlicePreview.gd" type="Script" id=3]
+[ext_resource path="res://src/UI/Dialogs/HelperScripts/RowColumnLines.gd" type="Script" id=4]
 
 [node name="PreviewDialog" type="ConfirmationDialog"]
-margin_right = 550.0
+margin_right = 629.0
-margin_bottom = 410.0
+margin_bottom = 513.0
 rect_min_size = Vector2( 550, 70 )
 popup_exclusive = true
 window_title = "Import Options"
 resizable = true
 script = ExtResource( 1 )
-__meta__ = {
-"_edit_use_anchors_": false
-}
 
 [node name="VBoxContainer" type="VBoxContainer" parent="."]
 anchor_right = 1.0
@@ -21,23 +21,16 @@ margin_left = 8.0
 margin_top = 8.0
 margin_right = -8.0
 margin_bottom = -36.0
-__meta__ = {
-"_edit_use_anchors_": false
-}
 
-[node name="CenterContainer" type="CenterContainer" parent="VBoxContainer"]
+[node name="CenterContainer" type="AspectRatioContainer" parent="VBoxContainer"]
-margin_right = 534.0
+margin_right = 613.0
-margin_bottom = 324.0
+margin_bottom = 395.0
 size_flags_vertical = 3
-__meta__ = {
-"_edit_use_anchors_": false
-}
 
 [node name="TextureRect" type="TextureRect" parent="VBoxContainer/CenterContainer"]
-margin_left = 117.0
+margin_left = 109.0
-margin_top = 12.0
+margin_right = 504.0
-margin_right = 417.0
+margin_bottom = 395.0
-margin_bottom = 312.0
 rect_min_size = Vector2( 300, 300 )
 expand = true
 stretch_mode = 6
@@ -45,12 +38,15 @@ __meta__ = {
 "_edit_use_anchors_": false
 }
 
-[node name="HorizLines" type="Control" parent="VBoxContainer/CenterContainer/TextureRect"]
+[node name="RowColumnLines" type="Control" parent="VBoxContainer/CenterContainer/TextureRect"]
-__meta__ = {
+unique_name_in_owner = true
-"_edit_use_anchors_": false
+script = ExtResource( 4 )
-}
 
-[node name="VerticalLines" type="Control" parent="VBoxContainer/CenterContainer/TextureRect"]
+[node name="SmartSlice" type="Control" parent="VBoxContainer/CenterContainer/TextureRect"]
+unique_name_in_owner = true
+anchor_right = 1.0
+anchor_bottom = 1.0
+script = ExtResource( 3 )
 
 [node name="ApplyAll" type="CheckBox" parent="VBoxContainer"]
 visible = false
@@ -60,9 +56,9 @@ margin_bottom = 324.0
 text = "Apply to all"
 
 [node name="SizeContainer" type="HBoxContainer" parent="VBoxContainer"]
-margin_top = 328.0
+margin_top = 399.0
-margin_right = 534.0
+margin_right = 613.0
-margin_bottom = 342.0
+margin_bottom = 413.0
 custom_constants/separation = 32
 
 [node name="ImageSizeLabel" type="Label" parent="VBoxContainer/SizeContainer"]
@@ -78,14 +74,14 @@ margin_bottom = 14.0
 text = "Frame size: 64×64"
 
 [node name="HBoxContainer" type="HBoxContainer" parent="VBoxContainer"]
-margin_top = 346.0
+margin_top = 417.0
-margin_right = 534.0
+margin_right = 613.0
-margin_bottom = 366.0
+margin_bottom = 469.0
 
 [node name="Label" type="Label" parent="VBoxContainer/HBoxContainer"]
-margin_top = 3.0
 margin_right = 66.0
-margin_bottom = 17.0
+margin_bottom = 14.0
+size_flags_vertical = 0
 text = "Import as:"
 
 [node name="ImportOption" type="OptionButton" parent="VBoxContainer/HBoxContainer"]
@@ -93,21 +89,27 @@ margin_left = 70.0
 margin_right = 151.0
 margin_bottom = 20.0
 mouse_default_cursor_shape = 2
+size_flags_vertical = 0
 text = "New tab"
 
-[node name="SpritesheetTabOptions" type="HBoxContainer" parent="VBoxContainer/HBoxContainer"]
+[node name="SpritesheetTabOptions" type="GridContainer" parent="VBoxContainer/HBoxContainer"]
-visible = false
 margin_left = 155.0
-margin_right = 533.0
+margin_right = 613.0
+margin_bottom = 52.0
+rect_min_size = Vector2( 380, 0 )
+size_flags_horizontal = 3
+
+[node name="Manual" type="HBoxContainer" parent="VBoxContainer/HBoxContainer/SpritesheetTabOptions"]
+margin_right = 378.0
 margin_bottom = 24.0
 
-[node name="Label" type="Label" parent="VBoxContainer/HBoxContainer/SpritesheetTabOptions"]
+[node name="Label" type="Label" parent="VBoxContainer/HBoxContainer/SpritesheetTabOptions/Manual"]
 margin_top = 5.0
 margin_right = 118.0
 margin_bottom = 19.0
 text = "Horizontal frames:"
 
-[node name="HorizontalFrames" type="SpinBox" parent="VBoxContainer/HBoxContainer/SpritesheetTabOptions"]
+[node name="HorizontalFrames" type="SpinBox" parent="VBoxContainer/HBoxContainer/SpritesheetTabOptions/Manual"]
 margin_left = 122.0
 margin_right = 196.0
 margin_bottom = 24.0
@@ -115,14 +117,14 @@ mouse_default_cursor_shape = 2
 min_value = 1.0
 value = 1.0
 
-[node name="Label2" type="Label" parent="VBoxContainer/HBoxContainer/SpritesheetTabOptions"]
+[node name="Label2" type="Label" parent="VBoxContainer/HBoxContainer/SpritesheetTabOptions/Manual"]
 margin_left = 200.0
 margin_top = 5.0
 margin_right = 300.0
 margin_bottom = 19.0
 text = "Vertical frames:"
 
-[node name="VerticalFrames" type="SpinBox" parent="VBoxContainer/HBoxContainer/SpritesheetTabOptions"]
+[node name="VerticalFrames" type="SpinBox" parent="VBoxContainer/HBoxContainer/SpritesheetTabOptions/Manual"]
 margin_left = 304.0
 margin_right = 378.0
 margin_bottom = 24.0
@@ -130,11 +132,47 @@ mouse_default_cursor_shape = 2
 min_value = 1.0
 value = 1.0
 
+[node name="Smart" type="HBoxContainer" parent="VBoxContainer/HBoxContainer/SpritesheetTabOptions"]
+visible = false
+margin_top = 28.0
+margin_right = 458.0
+margin_bottom = 52.0
+size_flags_horizontal = 3
+
+[node name="Threshold" parent="VBoxContainer/HBoxContainer/SpritesheetTabOptions/Smart" instance=ExtResource( 2 )]
+margin_right = 195.0
+hint_tooltip = "Image having any one side smaller than this value will closs the threshold"
+min_value = 1.0
+value = 10.0
+allow_greater = true
+prefix = "Threshold:"
+
+[node name="MergeDist" parent="VBoxContainer/HBoxContainer/SpritesheetTabOptions/Smart" instance=ExtResource( 2 )]
+margin_left = 199.0
+margin_right = 394.0
+hint_tooltip = "image (that crossed the threshold), this distance apart to any other image
+will get merged with that image"
+value = 3.0
+prefix = "Merge distance:"
+
+[node name="Slice" type="Button" parent="VBoxContainer/HBoxContainer/SpritesheetTabOptions/Smart"]
+margin_left = 398.0
+margin_right = 458.0
+margin_bottom = 24.0
+text = "Refresh"
+
+[node name="SmartSlice" type="CheckBox" parent="VBoxContainer/HBoxContainer/SpritesheetTabOptions"]
+margin_top = 28.0
+margin_right = 378.0
+margin_bottom = 52.0
+text = "Smart Slice"
+
 [node name="SpritesheetLayerOptions" type="HBoxContainer" parent="VBoxContainer/HBoxContainer"]
 visible = false
 margin_left = 155.0
 margin_right = 307.0
 margin_bottom = 24.0
+size_flags_vertical = 0
 
 [node name="Label3" type="Label" parent="VBoxContainer/HBoxContainer/SpritesheetLayerOptions"]
 margin_top = 5.0
@@ -264,9 +302,14 @@ margin_bottom = 24.0
 
 [connection signal="about_to_show" from="." to="." method="_on_PreviewDialog_about_to_show"]
 [connection signal="confirmed" from="." to="." method="_on_PreviewDialog_confirmed"]
+[connection signal="item_rect_changed" from="." to="." method="_on_PreviewDialog_item_rect_changed"]
 [connection signal="popup_hide" from="." to="." method="_on_PreviewDialog_popup_hide"]
 [connection signal="toggled" from="VBoxContainer/ApplyAll" to="." method="_on_ApplyAll_toggled"]
 [connection signal="item_selected" from="VBoxContainer/HBoxContainer/ImportOption" to="." method="_on_ImportOption_item_selected"]
-[connection signal="value_changed" from="VBoxContainer/HBoxContainer/SpritesheetTabOptions/HorizontalFrames" to="." method="_on_HorizontalFrames_value_changed"]
+[connection signal="value_changed" from="VBoxContainer/HBoxContainer/SpritesheetTabOptions/Manual/HorizontalFrames" to="." method="_on_HorizontalFrames_value_changed"]
-[connection signal="value_changed" from="VBoxContainer/HBoxContainer/SpritesheetTabOptions/VerticalFrames" to="." method="_on_VerticalFrames_value_changed"]
+[connection signal="value_changed" from="VBoxContainer/HBoxContainer/SpritesheetTabOptions/Manual/VerticalFrames" to="." method="_on_VerticalFrames_value_changed"]
+[connection signal="value_changed" from="VBoxContainer/HBoxContainer/SpritesheetTabOptions/Smart/Threshold" to="." method="_on_Threshold_value_changed"]
+[connection signal="value_changed" from="VBoxContainer/HBoxContainer/SpritesheetTabOptions/Smart/MergeDist" to="." method="_on_MergeDist_value_changed"]
+[connection signal="pressed" from="VBoxContainer/HBoxContainer/SpritesheetTabOptions/Smart/Slice" to="." method="_on_Slice_pressed"]
+[connection signal="toggled" from="VBoxContainer/HBoxContainer/SpritesheetTabOptions/SmartSlice" to="." method="_on_SmartSlice_toggled"]
 [connection signal="item_selected" from="VBoxContainer/HBoxContainer/NewBrushOptions/BrushTypeOption" to="." method="_on_BrushTypeOption_item_selected"]