图片打水印及缩放

于 2015-09-25 17:02:53 发布
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文章标签： .net c# 图片 代码 水印
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本文链接：https://blog.youkuaiyun.com/xuewuzhijing10/article/details/48734429

昨天公司客户要求在他们的商品图片上加水印。之前了解了点，但没有实际操作，昨天参照网上贴出来的代码，动手写了个demo，地址为：http://download.youkuaiyun.com/detail/xuewuzhijing10/9139455 。demo主要是一个工具类，下面就对工具类做一些解释</span>

先贴代码再解释：

using System;
using System.IO;
using System.Collections;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
namespace AddWarterMark
{
    /// <summary>
    /// 水印的类型
    /// </summary>
    public enum WaterMarkType
    {
        /// <summary>
        /// 文字水印
        /// </summary>
        TextMark,
        /// <summary>
        /// 图片水印
        /// </summary>
        ImageMark 
    };
    /// <summary>
    /// 水印的位置
    /// </summary>
    public enum WaterMarkPosition
    {
        /// <summary>
        /// 左上角
        /// </summary>
        WMP_Left_Top,
        /// <summary>
        /// 左下角
        /// </summary>
        WMP_Left_Bottom,
        /// <summary>
        /// 右上角
        /// </summary>
        WMP_Right_Top,
        /// <summary>
        /// 右下角
        /// </summary>
        WMP_Right_Bottom,
        /// <summary>
        /// 正中心
        /// </summary>
        WMP_Center_Center
    };
    /// <summary>
    /// 处理图片的类（包括加水印，生成缩略图）
    /// </summary>
    public class ImageWaterMark
    {
        public ImageWaterMark()
        {
            //
            // TODO: 在此处添加构造函数逻辑
            //
        }
        #region 给图片加水印
        /// <summary>
        /// 添加水印(分图片水印与文字水印两种)
        /// </summary>
        /// <param name="oldpath">原图片绝对地址</param>
        /// <param name="newpath">新图片放置的绝对地址</param>
        /// <param name="wmtType">要添加的水印的类型</param>
        /// <param name="sWaterMarkContent">水印内容，若添加文字水印，此即为要添加的文字；
        /// 若要添加图片水印，此为图片的路径</param>
        public void addWaterMark(string oldpath, string newpath,
         WaterMarkType wmtType, string sWaterMarkContent,WaterMarkPosition waterMarkPosition,float alpa = 0.5f)
        {
            try
            {
                Image image = Image.FromFile(oldpath);
                Bitmap b = new Bitmap(image.Width, image.Height,
                 PixelFormat.Format24bppRgb);
                Graphics g = Graphics.FromImage(b);
                g.Clear(Color.White);
                g.SmoothingMode = SmoothingMode.HighQuality;
                g.InterpolationMode = InterpolationMode.High;
                g.DrawImage(image, 0, 0, image.Width, image.Height);
                switch (wmtType)
                {

                    case WaterMarkType.TextMark:
                        //文字水印
                        this.addWatermarkText(g, sWaterMarkContent,waterMarkPosition ,
                         image.Width, image.Height,alpa);
                        break;
                    case WaterMarkType.ImageMark:
                        this.addWatermarkImage(g,sWaterMarkContent,waterMarkPosition,image.Width,image.Height,alpa);
                        break;
                }
                b.Save(newpath);
                b.Dispose();
                image.Dispose();
            }
            catch (Exception exception)
            {
                //if (File.Exists(oldpath))
                //{
                //    File.Delete(oldpath);
                //}
            }
            finally
            {
                //if (File.Exists(oldpath))
                //{
                //    File.Delete(oldpath);
                //}
            }
        }
        /// <summary>
        ///   加水印文字
        /// </summary>
        /// <param name="picture">imge 对象</param>
        /// <param name="_watermarkText">水印文字内容</param>
        /// <param name="_watermarkPosition">水印位置</param>
        /// <param name="_width">被加水印图片的宽</param>
        /// <param name="_height">被加水印图片的高</param>
        private void addWatermarkText(Graphics picture, string _watermarkText,
         WaterMarkPosition watermarkPosition, int _width, int _height,float alpa)
        {
            // 确定水印文字的字体大小
            int[] sizes = new int[] { 32, 30, 28, 26, 24, 22, 20, 18, 16, 14, 12, 10, 8, 6, 4 };
            Font crFont = null;
            SizeF crSize = new SizeF();
            for (int i = 0; i < sizes.Length; i++)
            {
                crFont = new Font("Arial Black", sizes[i], FontStyle.Bold);
                crSize = picture.MeasureString(_watermarkText, crFont);
                if ((ushort)crSize.Width < (ushort)_width)
                {
                    break;
                }
            }
            // 生成水印图片（将文字写到图片中）
            Bitmap floatBmp = new Bitmap((int)crSize.Width + 3,
                  (int)crSize.Height + 3, PixelFormat.Format32bppArgb);
            Graphics fg = Graphics.FromImage(floatBmp);
            PointF pt = new PointF(0, 0);
            // 画阴影文字
            Brush TransparentBrush0 = new SolidBrush(Color.FromArgb(255, Color.Black));
            Brush TransparentBrush1 = new SolidBrush(Color.FromArgb(255, Color.Black));
            fg.DrawString(_watermarkText, crFont, TransparentBrush0, pt.X, pt.Y + 1);
            fg.DrawString(_watermarkText, crFont, TransparentBrush0, pt.X + 1, pt.Y);
            fg.DrawString(_watermarkText, crFont, TransparentBrush1, pt.X + 1, pt.Y + 1);
            fg.DrawString(_watermarkText, crFont, TransparentBrush1, pt.X, pt.Y + 2);
            fg.DrawString(_watermarkText, crFont, TransparentBrush1, pt.X + 2, pt.Y);
            TransparentBrush0.Dispose();
            TransparentBrush1.Dispose();
            // 画文字
            fg.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
            fg.DrawString(_watermarkText,
             crFont, new SolidBrush(Color.White),
             pt.X, pt.Y, StringFormat.GenericDefault);
            // 保存刚才的操作
            fg.Save();
            fg.Dispose();
            // floatBmp.Save("d:\\WebSite\\DIGITALKM\\ttt.jpg");
            // 将水印图片加到原图中
            this.addWatermarkImage(picture,new Bitmap(floatBmp),watermarkPosition,_width,_height,alpa);
        }

        /// <summary>
        ///   加水印图片
        /// </summary>
        /// <param name="picture">imge 对象</param>
        /// <param name="iTheImage">Image对象（以此图片为水印）</param>
        /// <param name="_watermarkPosition">水印位置</param>
        /// <param name="_width">被加水印图片的宽</param>
        /// <param name="_height">被加水印图片的高</param>
        private void addWatermarkImage(Graphics picture, Image iTheImage,
            WaterMarkPosition watermarkPosition, int _width, int _height,float alpa)
        {
            Image watermark = new Bitmap(iTheImage);
            ImageAttributes imageAttributes = new ImageAttributes();
            ColorMap colorMap = new ColorMap();
            colorMap.OldColor = Color.FromArgb(255, 0, 255, 0);
            colorMap.NewColor = Color.FromArgb(0, 0, 0, 0);
            ColorMap[] remapTable = {colorMap};
            imageAttributes.SetRemapTable(remapTable, ColorAdjustType.Bitmap);
            float[][] colorMatrixElements =
            {
                new float[] {1.0f, 0.0f, 0.0f, 0.0f, 0.0f},
                new float[] {0.0f, 1.0f, 0.0f, 0.0f, 0.0f},
                new float[] {0.0f, 0.0f, 1.0f, 0.0f, 0.0f},
                new float[] {0.0f, 0.0f, 0.0f, alpa, 0.0f},
                new float[] {0.0f, 0.0f, 0.0f, 0.0f, 1.0f}
            };

            ColorMatrix colorMatrix = new ColorMatrix(colorMatrixElements);

            imageAttributes.SetColorMatrix(colorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
            int xpos = 0;
            int ypos = 0;
            int WatermarkWidth = 0;
            int WatermarkHeight = 0;
            double bl = 1d;
            //计算水印图片的比率
            //取背景的1/4宽度来比较
            if ((_width > watermark.Width*4) && (_height > watermark.Height*4))
            {
                bl = 1;
            }
            else if ((_width > watermark.Width*4) && (_height < watermark.Height*4))
            {
                bl = Convert.ToDouble(_height/4)/Convert.ToDouble(watermark.Height);

            }
            else if ((_width < watermark.Width*4) && (_height > watermark.Height*4))
            {
                bl = Convert.ToDouble(_width/4)/Convert.ToDouble(watermark.Width);
            }
            else
            {
                if ((_width*watermark.Height) > (_height*watermark.Width))
                {
                    bl = Convert.ToDouble(_height/4)/Convert.ToDouble(watermark.Height);
                }
                else
                {
                    bl = Convert.ToDouble(_width/4)/Convert.ToDouble(watermark.Width);
                }
            }
            WatermarkWidth = Convert.ToInt32(watermark.Width*bl);
            WatermarkHeight = Convert.ToInt32(watermark.Height*bl);
            switch (watermarkPosition)
            {
                case WaterMarkPosition.WMP_Left_Top:
                    xpos = 10;
                    ypos = 10;
                    break;
                case WaterMarkPosition.WMP_Right_Top:
                    xpos = _width - WatermarkWidth - 10;
                    ypos = 10;
                    break;
                case WaterMarkPosition.WMP_Right_Bottom:
                    xpos = _width - WatermarkWidth - 10;
                    ypos = _height - WatermarkHeight - 10;
                    break;
                case WaterMarkPosition.WMP_Left_Bottom:
                    xpos = 10;
                    ypos = _height - WatermarkHeight - 10;
                    break;
                case WaterMarkPosition.WMP_Center_Center:
                    xpos = (_width - WatermarkWidth)/2;
                    ypos = (_height - WatermarkHeight)/2;
                    break;
            }
            picture.DrawImage(watermark, new Rectangle(xpos, ypos, WatermarkWidth, WatermarkHeight), 0, 0,
                watermark.Width, watermark.Height, GraphicsUnit.Pixel, imageAttributes);
            watermark.Dispose();
            imageAttributes.Dispose();
        }

        /// <summary>
        ///   加水印图片
        /// </summary>
        /// <param name="picture">imge 对象</param>
        /// <param name="WaterMarkPicPath">水印图片的地址</param>
        /// <param name="_watermarkPosition">水印位置</param>
        /// <param name="_width">被加水印图片的宽</param>
        /// <param name="_height">被加水印图片的高</param>
        private void addWatermarkImage(Graphics picture, string WaterMarkPicPath,
         WaterMarkPosition _watermarkPosition, int _width, int _height,float alpa)
        {
            //var s = Image.FromFile(WaterMarkPicPath);
            Image watermark = new Bitmap(WaterMarkPicPath);
            
            this.addWatermarkImage(picture, watermark, _watermarkPosition, _width,
             _height,alpa);
        }
        #endregion
        #region 生成缩略图
        /// <summary>
        /// 保存图片
        /// </summary>
        /// <param name="image">Image 对象</param>
        /// <param name="savePath">保存路径</param>
        /// <param name="ici">指定格式的编解码参数</param>
        private void SaveImage(Image image, string savePath, ImageCodecInfo ici)
        {
            //设置 原图片 对象的 EncoderParameters 对象
            EncoderParameters parameters = new EncoderParameters(1);
            parameters.Param[0] = new EncoderParameter(
             System.Drawing.Imaging.Encoder.Quality, ((long)90));
            image.Save(savePath, ici, parameters);
            parameters.Dispose();
        }
        /// <summary>
        /// 获取图像编码解码器的所有相关信息
        /// </summary>
        /// <param name="mimeType">包含编码解码器的多用途网际邮件扩充协议 (MIME) 类型的字符串</param>
        /// <returns>返回图像编码解码器的所有相关信息</returns>
        private ImageCodecInfo GetCodecInfo(string mimeType)
        {
            ImageCodecInfo[] CodecInfo = ImageCodecInfo.GetImageEncoders();
            foreach (ImageCodecInfo ici in CodecInfo)
            {
                if (ici.MimeType == mimeType)
                    return ici;
            }
            return null;
        }
        /// <summary>
        /// 生成缩略图
        /// </summary>
        /// <param name="sourceImagePath">原图片路径(相对路径)</param>
        /// <param name="thumbnailImagePath">生成的缩略图路径,如果为空则保存为原图片路径(相对路径)</param>
        /// <param name="thumbnailImageWidth">缩略图的宽度（高度与按源图片比例自动生成）</param>
        public void ToThumbnailImages(string SourceImagePath,string ThumbnailImagePath,int ThumbnailImageWidth)
        {
            Hashtable htmimes = new Hashtable();
            htmimes[".jpeg"] = "image/jpeg";
            htmimes[".jpg"] = "image/jpeg";
            htmimes[".png"] = "image/png";
            htmimes[".tif"] = "image/tiff";
            htmimes[".tiff"] = "image/tiff";
            htmimes[".bmp"] = "image/bmp";
            htmimes[".gif"] = "image/gif";
            // 取得原图片的后缀
            string sExt = SourceImagePath.Substring(
             SourceImagePath.LastIndexOf(".")).ToLower();
            //从 原图片 创建 Image 对象
            Image image = Image.FromFile(SourceImagePath);
            int num = ((ThumbnailImageWidth / 4) * 3);
            int width = image.Width;
            int height = image.Height;
            //计算图片的比例
            if ((((double)width) / ((double)height)) >= 1.3333333333333333f)
            {
                num = ((height * ThumbnailImageWidth) / width);
            }
            else
            {
                ThumbnailImageWidth = ((width * num) / height);
            }
            if ((ThumbnailImageWidth < 1) || (num < 1))
            {
                return;
            }
            //用指定的大小和格式初始化 Bitmap 类的新实例
            Bitmap bitmap = new Bitmap(ThumbnailImageWidth, num,
             PixelFormat.Format32bppArgb);
            //从指定的 Image 对象创建新 Graphics 对象
            Graphics graphics = Graphics.FromImage(bitmap);
            //清除整个绘图面并以透明背景色填充
            graphics.Clear(Color.Transparent);
            graphics.SmoothingMode = SmoothingMode.HighQuality;
            graphics.InterpolationMode = InterpolationMode.High;
            //在指定位置并且按指定大小绘制 原图片 对象
            graphics.DrawImage(image, new Rectangle(0, 0, ThumbnailImageWidth, num));
            image.Dispose();

            try
            {
                //将此 原图片 以指定格式并用指定的编解码参数保存到指定文件
                SaveImage(bitmap, ThumbnailImagePath,
                 GetCodecInfo((string)htmimes[sExt]));
            }
            catch (System.Exception e)
            {
                throw e;
            }
        }
        #endregion
    }
}
1、WaterMarkType：枚举，用于表示加水印的种类：文字水印还是图片水印

2、WaterMarkPosition：枚举，用于表示水印所在位置

3、ImageWaterMark：具体执行加水印和压缩的方法。总共两个公开的方法：addWaterMark、ToThumbnailImages

3.1、addWaterMark这个方法中，实现了对图片的加水印。

其加水印的原理是：先给一个用一个新的画布，将原图画上去，然后再将水印画上去，所以，按这个原理，水印相加几个就加几个。了解原理后，就只需要了解怎样将图片画到画布上，再将画布中图片保存就行了。

<span style="white-space:pre">		</span>Image image = Image.FromFile(oldpath);//从文件中读取原始图片
                Bitmap b = new Bitmap(image.Width, image.Height,
                 PixelFormat.Format24bppRgb);//根据原始图片，声明一个bitmap
                Graphics g = Graphics.FromImage(b);//
                g.Clear(Color.White);//清除整个绘图面并以指定背景色填充。
                g.SmoothingMode = SmoothingMode.HighQuality;
                g.InterpolationMode = InterpolationMode.High;
                g.DrawImage(image, 0, 0, image.Width, image.Height);//从（0,0）位置开始，以（height * weight）为区域大小，将原始图片绘制到声明的bitmap中，将图片保存到新的地址</span>

OK，现在知道怎么把Image通过Graphics保存到新的图片中，那么，加水印，就是在原来的Graphics上在绘制新的图片就行了：

picture.DrawImage(watermark, new Rectangle(xpos, ypos, WatermarkWidth, WatermarkHeight), 0, 0,
                watermark.Width, watermark.Height, GraphicsUnit.Pixel, imageAttributes);


引用：http://blog.youkuaiyun.com/yizhiduxiu11/article/details/3128005

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