Adding a user-selected watermark to a picture chosen by him?

The essence is simple. The picture is loaded into the picturebox, then at the touch of a button a watermark is added BUT! Now only the watermark and the watermark specified in the code are added, but it is necessary that the user himself can choose the picture and watermark he needs and all this with minimal code changes Actually, the code

using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Drawing.Imaging; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Windows.Forms; namespace FlipToFlip { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void openButton_Click(object sender, EventArgs e) //Открываем картинку { Bitmap image; //Bitmap для открываемого изображения { if (openFileDialog.ShowDialog() == DialogResult.OK) { textbox.Text = openFileDialog.FileName; } } { try { image = new Bitmap(openFileDialog.FileName); //Bitmap для открываемой картинки pictureBox1.Size = image.Size; //Картинка подгоняется под размер picturebox pictureBox1.Image = image; pictureBox1.Invalidate(); } catch { DialogResult result = MessageBox.Show("Невозможно открыть выбранный файл", "Ошибка", MessageBoxButtons.OK, MessageBoxIcon.Error); //Если это НЕ картинка } } } private void saveButton_Click(object sender, EventArgs e) //Сохранение повернутой картинки { Bitmap pngSave = (Bitmap)pictureBox1.Image; SaveFileDialog sfd = new SaveFileDialog(); sfd.DefaultExt = "png"; sfd.Filter = "Image files (*.png;*jpg;*gif)|*.png; *jpg; *gif;|All files (*.*)|*.*"; if (sfd.ShowDialog() == DialogResult.OK) pngSave.Save(sfd.FileName, ImageFormat.Png); } private void watermark_Click(object sender, EventArgs e) { using (Image watermarkImage = image.FromFile(@"C:\Users\User\Desktop\14829270527610.png")) using (Graphics imageGraphics = Graphics.FromImage(image)) using (TextureBrush watermarkBrush = new TextureBrush(watermarkImage)) { int x = (image.Width / 2 - watermarkImage.Width / 2); int y = (image.Height / 2 - watermarkImage.Height / 2); watermarkBrush.TranslateTransform(x, y); imageGraphics.FillRectangle(watermarkBrush, new Rectangle(new Point(x, y), new Size(watermarkImage.Width + 1, watermarkImage.Height))); } } } }