Optimize previews of the ellipse selection and the shape tools

Before this commit, when these tools were being used on large areas, the software would start being very slow due to the polyline drawing. Now it simply draws an image.
TODO:
- Optimize the lasso, pixel and polygon select tools
- Mirror the previews of ellipse selection and shape tools, for consistency with the lasso, pixel and polygon select tools
- Perhaps somehow remove Previews.gd since its work is even more limited now.

src/Tools/BaseShapeDrawer.gd

@@ -153,26 +153,24 @@ func draw_end(pos: Vector2i) -> void:
 
 
 func draw_preview() -> void:
+	var canvas := Global.canvas.previews_sprite
 	if _drawing:
-		var canvas: CanvasItem = Global.canvas.previews
-		var indicator := BitMap.new()
 		var rect := _get_result_rect(_start, _dest)
 		var points := _get_points(rect.size)
-		var t_offset := _thickness - 1
+		var image := Image.create(
-		var t_offsetv := Vector2i(t_offset, t_offset)
+			Global.current_project.size.x, Global.current_project.size.y, false, Image.FORMAT_LA8
-		indicator.create(rect.size + t_offsetv)
-		for point in points:
-			indicator.set_bitv(point, 1)
-
-		var transform_pos := (
-			rect.position - t_offsetv + Vector2i((Vector2(0.5, 0.5) * (t_offset - 1)).ceil())
 		)
-		canvas.draw_set_transform(transform_pos, canvas.rotation, canvas.scale)
+		var thickness_vector := (
-
+			rect.position - Vector2i((Vector2(0.5, 0.5) * (_thickness - 1)).ceil())
-		for line in _create_polylines(indicator):
+		)
-			canvas.draw_polyline(PackedVector2Array(line), Color.BLACK)
+		for point in points:
-
+			var draw_pos := point + thickness_vector
-		canvas.draw_set_transform(canvas.position, canvas.rotation, canvas.scale)
+			if Rect2i(Vector2i.ZERO, image.get_size()).has_point(draw_pos):
+				image.set_pixelv(draw_pos, Color.WHITE)
+		var texture := ImageTexture.create_from_image(image)
+		canvas.texture = texture
+	else:
+		canvas.texture = null
 
 
 func _draw_shape(origin: Vector2i, dest: Vector2i) -> void:

src/Tools/DesignTools/CurveTool.gd

@@ -121,24 +121,24 @@ func draw_end(pos: Vector2i) -> void:
 
 
 func draw_preview() -> void:
+	var previews := Global.canvas.previews_sprite
 	if not _drawing:
+		previews.texture = null
 		return
-	var canvas: Node2D = Global.canvas.previews
-	var pos := canvas.position
-	var canvas_scale := canvas.scale
-	if Global.mirror_view:  # This fixes previewing in mirror mode
-		pos.x = pos.x + Global.current_project.size.x
-		canvas_scale.x = -1
-
 	var points := _bezier()
-	canvas.draw_set_transform(pos, canvas.rotation, canvas_scale)
+	var image := Image.create(
-	var indicator := _fill_bitmap_with_points(points, Global.current_project.size)
+		Global.current_project.size.x, Global.current_project.size.y, false, Image.FORMAT_LA8
-
+	)
-	for line in _create_polylines(indicator):
+	for point in points:
-		canvas.draw_polyline(PackedVector2Array(line), Color.BLACK)
+		var draw_point := point
-
+		if Global.mirror_view:  # This fixes previewing in mirror mode
-	canvas.draw_set_transform(canvas.position, canvas.rotation, canvas.scale)
+			draw_point.x = image.get_width() - point.x - 1
+		if Rect2i(Vector2i.ZERO, image.get_size()).has_point(draw_point):
+			image.set_pixelv(draw_point, Color.WHITE)
+	var texture := ImageTexture.create_from_image(image)
+	previews.texture = texture
 
+	var canvas := Global.canvas.previews
 	var circle_radius := Vector2.ONE * (5.0 / Global.camera.zoom.x)
 	if _is_hovering_first_position(_last_mouse_position) and _curve.point_count > 1:
 		var circle_center := _curve.get_point_position(0)

src/Tools/DesignTools/LineTool.gd

@@ -147,30 +147,19 @@ func draw_end(pos: Vector2i) -> void:
 
 
 func draw_preview() -> void:
+	var canvas := Global.canvas.previews_sprite
 	if _drawing:
-		var canvas: CanvasItem = Global.canvas.previews
-		var indicator := BitMap.new()
-		var start := _start
-		if _start.x > _dest.x:
-			start.x = _dest.x
-		if _start.y > _dest.y:
-			start.y = _dest.y
-
 		var points := _get_points()
-		var t_offset := _thickness - 1
+		var image := Image.create(
-		var t_offsetv := Vector2i(t_offset, t_offset)
+			Global.current_project.size.x, Global.current_project.size.y, false, Image.FORMAT_LA8
-		indicator.create((_dest - _start).abs() + t_offsetv * 2 + Vector2i.ONE)
+		)
-
 		for point in points:
-			var p := point - start + t_offsetv
+			if Rect2i(Vector2i.ZERO, image.get_size()).has_point(point):
-			indicator.set_bitv(p, 1)
+				image.set_pixelv(point, Color.WHITE)
-
+		var texture := ImageTexture.create_from_image(image)
-		canvas.draw_set_transform(start - t_offsetv, canvas.rotation, canvas.scale)
+		canvas.texture = texture
-
+	else:
-		for line in _create_polylines(indicator):
+		canvas.texture = null
-			canvas.draw_polyline(PackedVector2Array(line), Color.BLACK)
-
-		canvas.draw_set_transform(canvas.position, canvas.rotation, canvas.scale)
 
 
 func _draw_shape() -> void:

src/Tools/SelectionTools/EllipseSelect.gd

@@ -48,24 +48,24 @@ func draw_end(pos: Vector2i) -> void:
 
 
 func draw_preview() -> void:
+	var canvas := Global.canvas.previews_sprite
 	if !_move && _rect.has_area():
-		var canvas: Node2D = Global.canvas.previews
-		var pos := canvas.position
-		var canvas_scale := canvas.scale
 		var temp_rect := _rect
-		if Global.mirror_view:
-			pos.x = pos.x + Global.current_project.size.x
-			temp_rect.position.x = Global.current_project.size.x - temp_rect.position.x
-			canvas_scale.x = -1
 
-		var border := DrawingAlgos.get_ellipse_points_filled(Vector2.ZERO, temp_rect.size)
+		var points := DrawingAlgos.get_ellipse_points(Vector2.ZERO, temp_rect.size)
-		var indicator := _fill_bitmap_with_points(border, temp_rect.size)
+		var image := Image.create(
-
+			Global.current_project.size.x, Global.current_project.size.y, false, Image.FORMAT_LA8
-		canvas.draw_set_transform(temp_rect.position, canvas.rotation, canvas_scale)
+		)
-		for line in _create_polylines(indicator):
+		for point in points:
-			canvas.draw_polyline(PackedVector2Array(line), Color.BLACK)
+			var draw_point := point + temp_rect.position
-
+			if Global.mirror_view:  # This fixes previewing in mirror mode
-		canvas.draw_set_transform(canvas.position, canvas.rotation, canvas.scale)
+				draw_point.x = image.get_width() - draw_point.x - 1
+			if Rect2i(Vector2i.ZERO, image.get_size()).has_point(draw_point):
+				image.set_pixelv(draw_point, Color.WHITE)
+		var texture := ImageTexture.create_from_image(image)
+		canvas.texture = texture
+	else:
+		canvas.texture = null
 
 
 func apply_selection(_position: Vector2i) -> void:

src/UI/Canvas/Canvas.gd

@@ -23,6 +23,7 @@ var layer_metadata_texture := ImageTexture.new()
 @onready var crop_rect := $CropRect as CropRect
 @onready var indicators := $Indicators as Node2D
 @onready var previews := $Previews as Node2D
+@onready var previews_sprite := $PreviewsSprite as Sprite2D
 @onready var mouse_guide_container := $MouseGuideContainer as Node2D
 @onready var gizmos_3d := $Gizmos3D as Node2D
 @onready var measurements := $Measurements as Node2D

src/UI/Canvas/Canvas.tscn

@@ -1,4 +1,4 @@
-[gd_scene load_steps=22 format=3 uid="uid://ba24iuv55m4l3"]
+[gd_scene load_steps=23 format=3 uid="uid://ba24iuv55m4l3"]
 
 [ext_resource type="Script" path="res://src/UI/Canvas/Canvas.gd" id="1"]
 [ext_resource type="Shader" path="res://src/Shaders/BlendLayers.gdshader" id="1_253dh"]
@@ -10,12 +10,12 @@
 [ext_resource type="Script" path="res://src/UI/Canvas/Previews.gd" id="7"]
 [ext_resource type="Script" path="res://src/UI/Canvas/Selection.gd" id="8"]
 [ext_resource type="Shader" path="res://src/Shaders/MarchingAntsOutline.gdshader" id="9"]
-[ext_resource type="Shader" path="res://src/Shaders/AutoInvertColors.gdshader" id="10"]
 [ext_resource type="PackedScene" uid="uid://no3w7e2264u4" path="res://src/UI/Canvas/MouseGuideContainer.tscn" id="11"]
 [ext_resource type="Script" path="res://src/UI/Canvas/OnionSkinning.gd" id="12"]
 [ext_resource type="Script" path="res://src/UI/Canvas/CropRect.gd" id="13"]
 [ext_resource type="Script" path="res://src/UI/Canvas/Gizmos3D.gd" id="14"]
 [ext_resource type="Script" path="res://src/UI/Canvas/Measurements.gd" id="16_nxilb"]
+[ext_resource type="Shader" path="res://src/Shaders/AutoInvertColors.gdshader" id="17_lowhf"]
 [ext_resource type="Script" path="res://src/UI/Canvas/ReferenceImages.gd" id="17_qfjb4"]
 
 [sub_resource type="ShaderMaterial" id="ShaderMaterial_6b0ox"]
@@ -36,7 +36,10 @@ shader_parameter/frequency = 200.0
 shader_parameter/stripe_direction = 0.5
 
 [sub_resource type="ShaderMaterial" id="3"]
-shader = ExtResource("10")
+shader = ExtResource("17_lowhf")
+
+[sub_resource type="ShaderMaterial" id="ShaderMaterial_tb70k"]
+shader = ExtResource("17_lowhf")
 
 [node name="Canvas" type="Node2D"]
 material = SubResource("ShaderMaterial_6b0ox")
@@ -81,6 +84,10 @@ script = ExtResource("3")
 material = SubResource("3")
 script = ExtResource("7")
 
+[node name="PreviewsSprite" type="Sprite2D" parent="."]
+material = SubResource("ShaderMaterial_tb70k")
+centered = false
+
 [node name="OnionPast" type="Node2D" parent="."]
 script = ExtResource("12")