/// <summary>
    /// 水印幫助類
    /// </summary>
    public class WaterMarkHelper
    {
        #region 設定水印
        /// <summary>
        /// 設定水印
        /// </summary>
        /// <param name="imgPath"></param>
        /// <param name="model"></param>
        /// <returns></returns>
        public static Image SetWaterMark(string imgPath, WaterMark model)
        {
            //獲取背景圖
            Image imgSource = Image.FromFile(imgPath);
            //獲取水印圖片
            Image markImg = null;

            //水印檢驗（文字，圖片[路徑下是否存在圖片]）
            #region 水印校驗+水印處理
            if (model == null)
            {
                return null;
            }
            //看看原圖是否存在
            if (!System.IO.File.Exists(imgPath))
            {
                return null;
            }
            //根據水印型別校驗+水印處理
            switch (model.WaterMarkType)
            {
                case WaterMarkAPP.Enums.WaterMarkTypeEnum.Text:
                    if (string.IsNullOrEmpty(model.Text))
                    {
                        return null;
                    }
                    else
                    {
                        markImg = TextToImager(model);//水印處理-如果是文字就轉換成圖片
                    }
                    break;
                case WaterMarkAPP.Enums.WaterMarkTypeEnum.Image:
                    if (!System.IO.File.Exists(model.ImgPath))
                    {
                        return null;
                    }
                    else
                    {
                        //獲得水印影象           
                        markImg = Image.FromFile(model.ImgPath);
                    }
                    break;
                case WaterMarkAPP.Enums.WaterMarkTypeEnum.NoneMark:
                    return imgSource;
            }
            #endregion

            #region 建立顏色矩陣
            //建立顏色矩陣
            float[][] ptsArray ={ 
                                 new float[] {1, 0, 0, 0, 0},
                                 new float[] {0, 1, 0, 0, 0},
                                 new float[] {0, 0, 1, 0, 0},
                                 new float[] {0, 0, 0, model.Transparency, 0}, //注意：0.0f為完全透明，1.0f為完全不透明
                                 new float[] {0, 0, 0, 0, 1}};
            ColorMatrix colorMatrix = new ColorMatrix(ptsArray);
            //新建一個Image屬性
            ImageAttributes imageAttributes = new ImageAttributes();
            //將顏色矩陣新增到屬性
            imageAttributes.SetColorMatrix(colorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Default);
            #endregion

            //原圖格式檢驗+水印
            #region 原圖格式檢驗+水印

            //判斷是否是索引影象格式
            if (imgSource.PixelFormat == PixelFormat.Format1bppIndexed || imgSource.PixelFormat == PixelFormat.Format4bppIndexed || imgSource.PixelFormat == PixelFormat.Format8bppIndexed)
            {
                #region 索引圖片,轉成點陣圖再加圖片
                //轉成點陣圖,這步很重要 
                Bitmap bitmap = new Bitmap(imgSource.Width, imgSource.Height);
                Graphics graphic = Graphics.FromImage(bitmap);

                #region 縮放處理
                //如果原圖小於水印圖片 等比縮放水印圖
                if (markImg.Width >= imgSource.Width || markImg.Height >= imgSource.Height)
                {
                    markImg = ImageShrink(imgSource, markImg);
                }
                #endregion

                #region 水印位置
                //水印位置
                int x;
                int y;
                WaterMarkLocations(model, imgSource, markImg, out x, out y);
                #endregion

                //將原圖畫在點陣圖上
                graphic.DrawImage(imgSource, new Point(0, 0));

                //將水印加在點陣圖上
                graphic.DrawImage(markImg, new Rectangle(x, y, markImg.Width, markImg.Height), 0, 0, markImg.Width, markImg.Height, GraphicsUnit.Pixel, imageAttributes);

                graphic.Dispose();
                return bitmap;
                #endregion
            }
            else
            {
                #region 非索引圖片,直接在上面加上水印
                Graphics graphic = Graphics.FromImage(imgSource);

                #region 縮放處理
                //如果原圖小於水印圖片 等比縮放水印圖
                if (markImg.Width >= imgSource.Width || markImg.Height >= imgSource.Height)
                {
                    markImg = ImageShrink(imgSource, markImg);
                }
                #endregion

                #region 水印位置
                //水印位置
                int x;
                int y;
                WaterMarkLocations(model, imgSource, markImg, out x, out y);
                #endregion

                //將水印加在原圖上
                graphic.DrawImage(markImg, new Rectangle(x, y, markImg.Width, markImg.Height), 0, 0, markImg.Width, markImg.Height, GraphicsUnit.Pixel, imageAttributes);

                graphic.Dispose();
                return imgSource;
                #endregion
            }
            #endregion
        } 
        #endregion

        #region 水印處理-文字轉圖片
        /// <summary>
        /// 水印處理-文字轉圖片
        /// </summary>
        /// <param name="model"></param>
        /// <returns></returns>
        private static Image TextToImager(WaterMark model)
        {
            Font f = new Font(model.FontFamily, model.FontSize, model.FontStyle);
            Bitmap fbitmap = new Bitmap(Encoding.GetEncoding("GBK").GetByteCount(model.Text) / 2 * f.Height, f.Height);
            Graphics gh = Graphics.FromImage(fbitmap);//建立一個畫板;
            gh.SmoothingMode = SmoothingMode.AntiAlias;
            gh.DrawString(model.Text, f, model.BrushesColor, 0, 0);//畫字串
            return fbitmap as Image;
        }
        #endregion

        #region 水印位置
        /// <summary>
        /// 水印位置
        /// </summary>
        /// <param name="model"></param>
        /// <param name="imgSource"></param>
        /// <param name="markImg"></param>
        /// <param name="x"></param>
        /// <param name="y"></param>
        private static void WaterMarkLocations(WaterMark model, Image imgSource, Image markImg, out int x, out int y)
        {
            x = 0;
            y = 0;
            switch (model.WaterMarkLocation)
            {
                case WaterMarkLocationEnum.TopLeft:
                    x = 0;
                    y = 0;
                    break;
                case WaterMarkLocationEnum.TopCenter:
                    x = imgSource.Width / 2 - markImg.Width / 2;
                    y = 0;
                    break;
                case WaterMarkLocationEnum.TopRight:
                    x = imgSource.Width - markImg.Width;
                    y = 0;
                    break;
                case WaterMarkLocationEnum.CenterLeft:
                    x = 0;
                    y = imgSource.Height / 2 - markImg.Height / 2;
                    break;
                case WaterMarkLocationEnum.CenterCenter:
                    x = imgSource.Width / 2 - markImg.Width / 2;
                    y = imgSource.Height / 2 - markImg.Height / 2;
                    break;
                case WaterMarkLocationEnum.CenterRight:
                    x = imgSource.Width - markImg.Width;
                    y = imgSource.Height / 2 - markImg.Height / 2;
                    break;
                case WaterMarkLocationEnum.BottomLeft:
                    x = 0;
                    y = imgSource.Height - markImg.Height;
                    break;
                case WaterMarkLocationEnum.BottomCenter:
                    x = imgSource.Width / 2 - markImg.Width / 2;
                    y = imgSource.Height - markImg.Height;
                    break;
                case WaterMarkLocationEnum.BottomRight:
                    x = imgSource.Width - markImg.Width;
                    y = imgSource.Height - markImg.Height;
                    break;
            }
        }
        #endregion

        #region 縮放水印
        /// <summary>
        /// 等比縮放水印圖（縮小到原圖的1/3）
        /// </summary>
        /// <param name="imgSource"></param>
        /// <param name="successImage"></param>
        /// <returns></returns>
        private static Image ImageShrink(Image imgSource, Image markImg)
        {
            int w = 0;
            int h = 0;

            Image.GetThumbnailImageAbort callb = null;

            //對水印圖片生成縮圖,縮小到原圖的1/3(以短的一邊為準)                     
            if (imgSource.Width < imgSource.Height)
            {
                w = imgSource.Width / 3;
                h = markImg.Height * w / markImg.Width;
            }
            else
            {
                h = imgSource.Height / 3;
                w = markImg.Width * h / markImg.Height;
            }
            markImg = markImg.GetThumbnailImage(w, h, callb, new System.IntPtr());
            return markImg;
        }
        #endregion
    }