C#使用GDI+同时绘制图像和ROI在picturebox上

        Bitmap bmp;
        /// <summary>
        /// 绘制图像
        /// </summary>
        /// <param name="g">Graphics</param>
        /// <param name="Width">图像宽</param>
        /// <param name="Height">图像高</param>
        /// <param name="ScaleX">缩放X</param>
        /// <param name="ScaleY">缩放Y</param>
        public void DrawImage(Graphics g,Bitmap bitmap, int Width, int Height, float ScaleX = 1, float ScaleY = 1)
        {
            if (bitmap != null)
            {
                if (bmp == null)
                {
                    bmp = new Bitmap(Width, Height);
                }
                g = Graphics.FromImage(bmp);
                picturebox.BeginInvoke(new Action(() =>
                {
                    this.picturebox.Image = bmp;
                }));
                g.DrawImage(bitmap, 0, 0, Width * ScaleX, Height * ScaleY);
            }
        }