将Canvas画布内容保存为jpg格式图片

/// <summary>
        /// 功能：将Canvas画布内容保存为jpg格式图片
        /// 作者：GYS | 日期：2013年9月9日
        /// </summary>
        /// <param name="filePath"></param>
        /// <param name="pixBox"></param>
        private void SaveAsJpeg(string filePath, Canvas pixBox)
        {
            try
            {
                RenderTargetBitmap bmp = new RenderTargetBitmap((int)picBox.Width, (int)picBox.Height, 96, 96, PixelFormats.Pbgra32);
                bmp.Render(pixBox);

string Extension = System.IO.Path.GetExtension(filePath).ToLower();
                BitmapEncoder encoder = new JpegBitmapEncoder();

encoder.Frames.Add(BitmapFrame.Create(bmp));
                using (Stream stm = File.Create(filePath))
                {
                    encoder.Save(stm);
                }
            }
            catch
            {
                System.Windows.Forms.MessageBox.Show("图片保存失败");
            }
        }