C＃ 给图片画 矩形，椭圆形，文字

代码

        private void Button_Test_Click(object sender, EventArgs e)
        {
            string path = TextBox_Img1Path.Text;
            if (string.IsNullOrEmpty(path))
            {
                Console.WriteLine("路径不能为空");
                return;
            }
            if (!System.IO.File.Exists(path))
            {
                Console.WriteLine("图片不存在");
                return;
            }

            Bitmap bitmap = new Bitmap(path);
            Point point1 = new Point(100, 100);
            Point point2 = new Point(120, 120);

            //bitmap = DrawRoundInPicture(bitmap, point1, point2, Color.Red, 3, "起泡");
            //pictureBox1.Image = bitmap;

            Size size = new Size();
            size.Width = 200;
            size.Height = 200;
            Bitmap bitmap1 = DrawRectangleInPicture(bitmap, point1, size, Color.Red, 2, "气泡", 13);
            pictureBox1.Image = bitmap1;

            //Point point3 = new Point(200, 200);
            //Point point4 = new Point(210, 210);
            //bitmap = DrawRoundInPicture(bitmap, point3, point4, Color.AntiqueWhite, 3, "破裂");
            //bitmap.Save(path, System.Drawing.Imaging.ImageFormat.Bmp);
        }

        /// <summary>
        /// 在图片上画椭圆
        /// </summary>
        /// <param name="bmp">图片的bitmap</param>
        /// <param name="p0">位置</param>
        /// <param name="lineColor">颜色</param>
        /// <param name="lineWidth">圆圈厚度</param>
        /// <param name="text">标题</param>
        /// <param name="ds">线条的线型</param>
        /// <returns></returns>
        public static Bitmap DrawRoundInPicture(Bitmap bmp, Point p0, Point p1, Color lineColor, int lineWidth, string text, DashStyle ds = DashStyle.Solid)
        {
            if (bmp == null) return null;

            Graphics g = Graphics.FromImage(bmp);

            Brush brush = new SolidBrush(lineColor);
            Pen pen = new Pen(brush, lineWidth);
            pen.DashStyle = ds;

            //画椭圆
            //g.DrawEllipse(pen, new Rectangle(p0.X, p0.Y, Math.Abs(p0.X - p1.X), Math.Abs(p0.Y - p1.Y)));
            //画矩形
            g.DrawRectangle(pen, p0.X, p0.Y, 20, 20);

            Font myFont = new Font("宋体", 30, FontStyle.Bold);
            Brush bush = new SolidBrush(lineColor);//填充的颜色
            g.DrawString(text, myFont, bush, p0.X - 30, p1.Y + 10);

            g.Dispose();

            return bmp;
        }

        /// <summary>
        /// 图片上画矩形和标记文字
        /// </summary>
        /// <param name="bmp">图片bitmap</param>
        /// <param name="pos">矩形的坐标位置</param>
        /// <param name="size">矩形的宽高</param>
        /// <param name="lineColor">线条的颜色</param>
        /// <param name="lineWidth">线条</param>
        /// <param name="text">矩形的文本</param>
        /// <param name="fontSize">字体大小</param>
        /// <param name="ds">线条的线型</param>
        /// <returns></returns>
        public static Bitmap DrawRectangleInPicture(Bitmap bmp, Point pos, Size size, Color lineColor, int lineWidth, string text, int fontSize, DashStyle ds = DashStyle.Solid)
        {
            if (bmp == null) return null;

            Graphics g = Graphics.FromImage(bmp);

            Brush brush = new SolidBrush(lineColor);
            Pen pen = new Pen(brush, lineWidth);
            pen.DashStyle = ds;

            //画中心点（用于测试）
            //g.DrawEllipse(pen, new Rectangle(pos.X, pos.Y, 3, 3));

            //画矩形
            int rectX = pos.X - (size.Width / 2);
            int rectY = pos.Y - (size.Height / 2);
            //g.DrawRectangle(pen, pos.X, pos.Y, size.Width, size.Height);
            g.DrawRectangle(pen, rectX, rectY, size.Width, size.Height);

            Font myFont = new Font("宋体", fontSize, FontStyle.Regular);
            Brush bush = new SolidBrush(lineColor);//填充的颜色

            //计算字体的长度
            SizeF sizeF = g.MeasureString(text, myFont);
            int fontPosX = (int)(pos.X - (sizeF.Width / 2));
            int fontPosY = (int)(pos.Y + (sizeF.Height / 2) + (size.Height / 2));
            Console.WriteLine();
            g.DrawString(text, myFont, bush, fontPosX, fontPosY);
            g.Dispose();

            return bmp;
        }

end