Перерисовка фигуры на форме. Refresh и Invalid

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Collections;
 
namespace WpfApp1
{
    public partial class MainWindow : Window
    {
        Polygon myPolygon = new Polygon();
         
        double x1 = -50, x2 = 0, x3 = 50, rotate, rot = 0;
        int countResize = 0, countReplace = 0, stepShape = 1;
        double sxR = 1.2, syR = 1.2, sxP = 10, syP = 10;
        bool Place = true;
 
        public MainWindow()
        {
            InitializeComponent();
            printShape();
        }
        private void printShape()
        {
            myPolygon.Stroke = Brushes.Black;
            myPolygon.Fill = Brushes.LightSeaGreen;
            myPolygon.StrokeThickness = 2;
            myPolygon.HorizontalAlignment = HorizontalAlignment.Center;
            myPolygon.VerticalAlignment = VerticalAlignment.Center;
            Point Point1 = new Point(x1, x2);
            Point Point2 = new Point(x2, x3);
            Point Point3 = new Point(x3, x2);
            PointCollection myPointCollection = new PointCollection();
            myPointCollection.Add(Point1);
            myPointCollection.Add(Point2);
            myPointCollection.Add(Point3);
            myPolygon.Points = myPointCollection;
            grid1.Children.Add(myPolygon);
        }
        private void textBox(object sender, TextChangedEventArgs e) 
        {
            TextBox angle = (TextBox)sender;
            rotate = double.Parse(angle.Text);
        }
        private void turn(object sender, RoutedEventArgs e)
        {
            rot += rotate;
            RotateTransform rotateTransform = new RotateTransform(rot);
            rotateTransform.CenterX = 0;
            rotateTransform.CenterY = 0;
            myPolygon.RenderTransform = rotateTransform;
        }
        private void resize(object sender, RoutedEventArgs e)
        {
           
            if (countResize < 5) { sxR += 0.2; syR += 0.2; } else { sxR = syR = 1; countResize = 0; }
            ScaleTransform scaleTransform = new ScaleTransform(sxR, syR, 0, 0);
            myPolygon.RenderTransform = scaleTransform;
            countResize++;
        }
        private void replace(object sender, RoutedEventArgs e)
        { 
            if (Place) { sxP += 10; syP += 10; } else { sxP -= 10; syP -= 10; }
            TranslateTransform translateTransform = new TranslateTransform(sxP,syP);
            myPolygon.RenderTransform = translateTransform;
            countReplace += stepShape;
            if (countReplace > 5) { Place = false; stepShape *= (-1); }
            if (countReplace == 0) { Place = true; stepShape *= (-1); }
        }
    }   
}