C#のWinFormsでワールド変換で図形を回転4「カーソルキーで図形を移動する」

namespace Kaiten02;

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

        this.ClientSize = new Size(640, 480);
        this.KeyPreview = true;

        Bitmap bmp1 = new (64, 64);
        using(Graphics bmp_g = Graphics.FromImage(bmp1))
        {
            // 矢印
            PointF[] points = [
                new PointF(bmp1.Width/2, 0),
                new PointF(bmp1.Width-1, bmp1.Height-1),
                new PointF(bmp1.Width/2, bmp1.Height*2/3),
                new PointF(0, bmp1.Height-1),
                new PointF(bmp1.Width/2, 0),
            ];
            // 三角
            PointF[] points2 = [
                new PointF(0, 0),
                new PointF(8, 0),
                new PointF(0, 8),
                new PointF(0, 0),
            ];

            bmp_g.FillPolygon(Brushes.White, points); // 塗潰し
            bmp_g.DrawLines(Pens.Black, points); // 縁取り
            bmp_g.FillPolygon(Brushes.Pink, points2); // 中心
        }
        PictureBox picbox = new()
        {
            BackColor = Color.Navy,
            Parent = this,
            Size = new Size(640, 480),
        };

        int r = 0;
        int x = 0;
        int y = 0;

        picbox.Paint += (s, e) =>
        {
            var g = e.Graphics;

            g.ResetTransform();

            // 中心へ移動
            g.TranslateTransform(picbox.Width/2-bmp1.Width/2+x, picbox.Height/2-bmp1.Height/2+y);

            // 回転
            g.TranslateTransform(bmp1.Width/2, (bmp1.Height/2));

            g.RotateTransform(r);

            g.TranslateTransform(-bmp1.Width/2, -(bmp1.Height/2));

            // 描画
            g.DrawImage(bmp1, 0, 0);
        };
        this.KeyDown += (s, e) =>
        {
            if (e.KeyCode == Keys.Left)
            {
                // 左
                r = 270;
                x -= bmp1.Width/8;
                picbox.Invalidate();
            }
            else if (e.KeyCode == Keys.Right)
            {
                // 右
                r = 90;
                x += bmp1.Width/8;
                picbox.Invalidate();
            }
            else if (e.KeyCode == Keys.Up)
            {
                // 上
                r = 0;
                y -= bmp1.Height/8;
                picbox.Invalidate();
            }
            else if (e.KeyCode == Keys.Down)
            {
                // 下
                r = 180;
                y += bmp1.Height/8;
                picbox.Invalidate();
            }
        };
    }
}