Implement open polygon logic

src/app/app.v

@@ -41,8 +41,8 @@ fn create_widgets() []ui.Widget {
 	viewport_app := viewport.create_viewport_app()
 
 	return [
-		widgets.create_menubar_widget(viewport_app.open_work_sprite, viewport_app.set_polygon_file_path,
-			viewport_app.save_polygon),
+		widgets.create_menubar_widget(viewport_app.open_work_sprite, viewport_app.open_polygon,
+			viewport_app.set_polygon_file_path, viewport_app.save_polygon),
 		viewport.create_viewport_widget(viewport_app),
 	]
 }

src/viewport/viewport.v

@@ -7,6 +7,7 @@ import artemkakun.trnsfrm2d
 import os
 import x.json2
 import artemkakun.pcoll2d
+import json
 
 const viewport_z_index = 1
 
@@ -72,6 +73,25 @@ pub fn (mut app ViewportApp) open_work_sprite(path_to_sprite string) ! {
 	app.work_sprite = app.gg.create_image(path_to_sprite)!
 }
 
+// open_polygon opens a polygon shape from the provided path for editing in the viewport.
+pub fn (mut app ViewportApp) open_polygon(path_to_polygon string) ! {
+	polygon_data := os.read_file(path_to_polygon)!
+	polygon := json.decode(pcoll2d.Polygon, polygon_data)!
+	position := get_work_sprite_position(app)!
+
+	mut global_polygon_points := []trnsfrm2d.Position{}
+
+	for point in polygon.points {
+		global_polygon_points << trnsfrm2d.Position{
+			x: point.x * work_sprite_scale + position.x
+			y: point.y * work_sprite_scale + position.y
+		}
+	}
+
+	app.polygon_points = global_polygon_points
+	app.set_polygon_file_path(path_to_polygon)
+}
+
 // set_polygon_file_path sets the path to the polygon file that will be used for editing in the viewport.
 pub fn (mut app ViewportApp) set_polygon_file_path(path_to_polygon string) {
 	app.polygon_file_path = path_to_polygon
@@ -88,12 +108,7 @@ pub fn (app &ViewportApp) save_polygon() {
 }
 
 fn create_polygon_data_in_json_form(app ViewportApp) !string {
-	sprite_to_draw := app.work_sprite or {
-		return error("No work sprite, polygon points can't be calculated!")
-	}
-
-	position, _ := calculate_work_sprite_transforms(sprite_to_draw, app.bounds)
-
+	position := get_work_sprite_position(app)!
 	mut local_polygon_points := []trnsfrm2d.Position{}
 
 	for global_polygon_point in app.polygon_points {
@@ -106,3 +121,11 @@ fn create_polygon_data_in_json_form(app ViewportApp) !string {
 	polygon := pcoll2d.Polygon{local_polygon_points}
 	return json2.encode[pcoll2d.Polygon](polygon)
 }
+
+fn get_work_sprite_position(app ViewportApp) !trnsfrm2d.Position {
+	sprite_to_draw := app.work_sprite or { return error('No work sprite!') }
+
+	position, _ := calculate_work_sprite_transforms(sprite_to_draw, app.bounds)
+
+	return position
+}

src/widgets/menubar.v

@@ -11,29 +11,37 @@ const (
 )
 
 // create_menubar_widget returns menubar widget.
-pub fn create_menubar_widget(load_sprite_to_viewport_function fn (string) !, set_polygon_file_function fn (string), save_polygon fn ()) ui.Widget {
+pub fn create_menubar_widget(load_sprite_to_viewport_function fn (string) !, open_polygon_file fn (string) !, set_polygon_file_function fn (string), save_polygon fn ()) ui.Widget {
 	return ui.menubar(
 		height: widgets.menubar_height
 		z_index: widgets.menubar_z_index
 		items: [
 			ui.menuitem(
 				text: widgets.menubar_file_button_text
-				submenu: create_file_menu(load_sprite_to_viewport_function, set_polygon_file_function,
-					save_polygon)
+				submenu: create_file_menu(load_sprite_to_viewport_function, open_polygon_file,
+					set_polygon_file_function, save_polygon)
 			),
 		]
 	)
 }
 
-fn create_file_menu(load_sprite_to_viewport_function fn (string) !, set_polygon_file_function fn (string), save_polygon fn ()) &ui.Menu {
+fn create_file_menu(load_sprite_to_viewport_function fn (string) !, open_polygon_file fn (string) !, set_polygon_file_function fn (string), save_polygon fn ()) &ui.Menu {
 	open_sprite_file_function := fn [load_sprite_to_viewport_function] (_ &ui.MenuItem) {
-		sprite_path := open_sprite_file_dialog_with_kdialog()
+		sprite_path := open_file_dialog_with_kdialog('.png')
 
 		load_sprite_to_viewport_function(sprite_path) or {
 			eprintln('Failed to load sprite file from path ${sprite_path}: ${err}')
 		}
 	}
 
+	open_polygon_file_function := fn [open_polygon_file] (_ &ui.MenuItem) {
+		polygon_path := open_file_dialog_with_kdialog('.json')
+
+		open_polygon_file(polygon_path) or {
+			eprintln('Failed to load polygon file from path ${polygon_path}: ${err}')
+		}
+	}
+
 	create_polygon_file_function := fn [set_polygon_file_function] (_ &ui.MenuItem) {
 		polygon_path := open_polygon_file_save_dialog_with_kdialog() or {
 			eprintln('Error while selecting save path for new polygon file - ${err}')
@@ -48,7 +56,7 @@ fn create_file_menu(load_sprite_to_viewport_function fn (string) !, set_polygon_
 	}
 
 	file_menu_button_text_to_action_function_map := create_file_menu_button_text_to_action_function_map(open_sprite_file_function,
-		create_polygon_file_function, save_polygon_function)
+		open_polygon_file_function, create_polygon_file_function, save_polygon_function)
 
 	file_menu_buttons := create_file_menu_buttons(file_menu_button_text_to_action_function_map)
 
@@ -58,8 +66,8 @@ fn create_file_menu(load_sprite_to_viewport_function fn (string) !, set_polygon_
 	)
 }
 
-fn open_sprite_file_dialog_with_kdialog() string {
-	file_path_selection_result := os.execute("kdialog --getopenfilename . '*.png'")
+fn open_file_dialog_with_kdialog(file_extension string) string {
+	file_path_selection_result := os.execute("kdialog --getopenfilename . '*${file_extension}'")
 
 	return file_path_selection_result.output.trim_indent()
 }
@@ -80,11 +88,11 @@ fn open_polygon_file_save_dialog_with_kdialog() !string {
 	return save_path
 }
 
-fn create_file_menu_button_text_to_action_function_map(open_sprite_file_function fn (&ui.MenuItem), create_polygon_file_function fn (&ui.MenuItem), save_polygon_function fn (&ui.MenuItem)) map[string]fn (&ui.MenuItem) {
+fn create_file_menu_button_text_to_action_function_map(open_sprite_file_function fn (&ui.MenuItem), open_polygon_file_function fn (&ui.MenuItem), create_polygon_file_function fn (&ui.MenuItem), save_polygon_function fn (&ui.MenuItem)) map[string]fn (&ui.MenuItem) {
 	unsafe {
 		return {
 			'Open sprite file':   open_sprite_file_function
-			'Open polygon file':  nil
+			'Open polygon file':  open_polygon_file_function
 			'Create new polygon': create_polygon_file_function
 			'Save polygon':       save_polygon_function
 			'Save polygon as...': nil