Support draw tiles mode in the magic wand tool

Now all selection tools are supported. They can all move, but not yet resize.

src/Tools/SelectionTools/MagicWand.gd

@@ -34,10 +34,10 @@ func apply_selection(pos: Vector2i) -> void:
 
 	var cel_image := Image.new()
 	cel_image.copy_from(_get_draw_image())
-	_flood_fill(pos, cel_image, project.selection_map, previous_selection_map)
+	_flood_fill(pos, cel_image, project, previous_selection_map)
 	# Handle mirroring
 	for mirror_pos in Tools.get_mirrored_positions(pos):
-		_flood_fill(mirror_pos, cel_image, project.selection_map, previous_selection_map)
+		_flood_fill(mirror_pos, cel_image, project, previous_selection_map)
 
 	Global.canvas.selection.big_bounding_rectangle = project.selection_map.get_used_rect()
 	Global.canvas.selection.commit_undo("Select", undo_data)
@@ -59,6 +59,39 @@ func update_config() -> void:
 	$ToleranceSlider.value = _tolerance * 255.0
 
 
+func _on_tolerance_slider_value_changed(value: float) -> void:
+	_tolerance = value / 255.0
+	update_config()
+	save_config()
+
+
+func _flood_fill(
+	pos: Vector2i, image: Image, project: Project, previous_selection_map: SelectionMap
+) -> void:
+	# implements the floodfill routine by Shawn Hargreaves
+	# from https://www1.udel.edu/CIS/software/dist/allegro-4.2.1/src/flood.c
+	var selection_map := project.selection_map
+	if Tools.is_placing_tiles():
+		for cel in _get_selected_draw_cels():
+			if cel is not CelTileMap:
+				continue
+			var tile_index := (cel as CelTileMap).get_cell_index_at_coords(pos)
+			# init flood data structures
+			_allegro_flood_segments = []
+			_allegro_image_segments = []
+			_compute_segments_for_tilemap(pos, cel, tile_index)
+			_select_segments_tilemap(project, previous_selection_map)
+		return
+	var color := image.get_pixelv(pos)
+	# init flood data structures
+	_allegro_flood_segments = []
+	_allegro_image_segments = []
+	_compute_segments_for_image(pos, project, image, color)
+	# 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.
+	_select_segments(selection_map, previous_selection_map)
+
+
 # Add a new segment to the array
 func _add_new_segment(y := 0) -> void:
 	_allegro_flood_segments.append(Segment.new(y))
@@ -140,22 +173,6 @@ func _check_flooded_segment(
 	return ret
 
 
-func _flood_fill(
-	pos: Vector2i, image: Image, selection_map: SelectionMap, previous_selection_map: SelectionMap
-) -> void:
-	# implements the floodfill routine by Shawn Hargreaves
-	# from https://www1.udel.edu/CIS/software/dist/allegro-4.2.1/src/flood.c
-	var project := Global.current_project
-	var color := image.get_pixelv(pos)
-	# init flood data structures
-	_allegro_flood_segments = []
-	_allegro_image_segments = []
-	_compute_segments_for_image(pos, project, image, color)
-	# 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.
-	_select_segments(selection_map, previous_selection_map)
-
-
 func _compute_segments_for_image(
 	pos: Vector2i, project: Project, image: Image, src_color: Color
 ) -> void:
@@ -201,7 +218,128 @@ func _set_bit(p: Vector2i, selection_map: SelectionMap, prev_selection_map: Sele
 		selection_map.select_pixel(p, !_subtract)
 
 
-func _on_tolerance_slider_value_changed(value: float) -> void:
+func _compute_segments_for_tilemap(pos: Vector2i, cel: CelTileMap, src_index: int) -> void:
-	_tolerance = value / 255.0
+	# initially allocate at least 1 segment per line of the tilemap
-	update_config()
+	for j in cel.vertical_cells:
-	save_config()
+		_add_new_segment(j)
+	pos /= cel.tileset.tile_size
+	# start flood algorithm
+	_flood_line_around_point_tilemap(pos, cel, src_index)
+	# 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_tilemap(
+					p.y + 1, p.left_position, p.right_position, cel, src_index
+				):
+					done = false
+			if p.todo_above:  # check above the segment?
+				p.todo_above = false
+				if _check_flooded_segment_tilemap(
+					p.y - 1, p.left_position, p.right_position, cel, src_index
+				):
+					done = false
+
+
+## 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.
+## Τhis method is called by [method _flood_fill] after the required data structures
+## have been initialized.
+func _flood_line_around_point_tilemap(pos: Vector2i, cel: CelTileMap, src_index: int) -> int:
+	if cel.get_cell_index_at_coords_in_tilemap_space(pos) != src_index:
+		return pos.x + 1
+	var west := pos
+	var east := pos
+	while west.x >= 0 && cel.get_cell_index_at_coords_in_tilemap_space(west) == src_index:
+		west += Vector2i.LEFT
+	while (
+		east.x < cel.horizontal_cells
+		&& cel.get_cell_index_at_coords_in_tilemap_space(east) == src_index
+	):
+		east += Vector2i.RIGHT
+	# Make a note of the stuff we processed
+	var c := pos.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(pos.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 = pos.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 = pos.y > 0
+	segment.todo_below = pos.y < cel.vertical_cells - 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 east.x + 1
+
+
+func _check_flooded_segment_tilemap(
+	y: int, left: int, right: int, cel: CelTileMap, src_index: int
+) -> bool:
+	var ret := false
+	var c := 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_tilemap(Vector2i(left, y), cel, src_index)
+				ret = true
+				break
+	return ret
+
+
+func _select_segments_tilemap(project: Project, previous_selection_map: SelectionMap) -> void:
+	# short circuit for flat colors
+	for c in _allegro_image_segments.size():
+		var p := _allegro_image_segments[c]
+		for px in range(p.left_position, p.right_position + 1):
+			# We don't have to check again whether the point being processed is within the bounds
+			_set_bit_rect(Vector2i(px, p.y), project, previous_selection_map)
+
+
+func _set_bit_rect(p: Vector2i, project: Project, prev_selection_map: SelectionMap) -> void:
+	var selection_map := project.selection_map
+	var tilemap := project.get_current_cel() as CelTileMap
+	var cell_position := tilemap.get_cell_position_in_tilemap_space(p)
+	if _intersect:
+		var image_coords := tilemap.get_cell_coords_in_image(cell_position)
+		select_tilemap_cell(
+			tilemap,
+			cell_position,
+			project.selection_map,
+			prev_selection_map.is_pixel_selected(image_coords)
+		)
+	else:
+		select_tilemap_cell(tilemap, cell_position, project.selection_map, !_subtract)