图片处理通用类

using System;
using System.IO;
using System.Text;

/// <summary>
/// 图形转换处理类
/// </summary>
public class ImageOperator
{
    public ImageOperator()
    {
    }

    /// <summary>
    /// 获取一个图片按等比例缩小后的大小。
    /// </summary>
    /// <param name="maxWidth">需要缩小到的宽度</param>
    /// <param name="maxHeight">需要缩小到的高度</param>
    /// <param name="imageOriginalWidth">图片的原始宽度</param>
    /// <param name="imageOriginalHeight">图片的原始高度</param>
    /// <returns>返回图片按等比例缩小后的实际大小</returns>
    public static Size GetNewSize(int maxWidth, int maxHeight, int imageOriginalWidth, int imageOriginalHeight)
    {
        double w = 0.0;
        double h = 0.0;
        double sw = Convert.ToDouble(imageOriginalWidth);
        double sh = Convert.ToDouble(imageOriginalHeight); double mw = Convert.ToDouble(maxWidth);
        double mh = Convert.ToDouble(maxHeight);

        if (sw < mw && sh < mh)
        {
            w = sw;
            h = sh;
        }
        else if ((sw / sh) > (mw / mh))
        {
            w = maxWidth;
            h = (w * sh) / sw;
        }
        else
        {
            h = maxHeight;
            w = (h * sw) / sh;
        }

        return new Size(Convert.ToInt32(w), Convert.ToInt32(h));
    }

    /// <summary>
    /// 对给定的一个图片（Image对象）生成一个指定大小的缩略图。
    /// </summary>
    /// <param name="originalImage">原始图片</param>
    /// <param name="thumMaxWidth">缩略图的宽度</param>
    /// <param name="thumMaxHeight">缩略图的高度</param>
    /// <returns>返回缩略图的Image对象</returns>
    public static System.Drawing.Image GetThumbNailImage(System.Drawing.Image originalImage, int thumMaxWidth, int thumMaxHeight)
    {
        Size thumRealSize = Size.Empty;
        System.Drawing.Image newImage = originalImage;
        Graphics graphics = null;

        try
        {
            thumRealSize = GetNewSize(thumMaxWidth, thumMaxHeight, originalImage.Width, originalImage.Height);
            newImage = new Bitmap(thumRealSize.Width, thumRealSize.Height);
            graphics = Graphics.FromImage(newImage);

            graphics.CompositingQuality = CompositingQuality.HighQuality;
            graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
            graphics.SmoothingMode = SmoothingMode.HighQuality;

            graphics.Clear(Color.Transparent);

            graphics.DrawImage(originalImage, new Rectangle(0, 0, thumRealSize.Width, thumRealSize.Height), new Rectangle(0, 0, originalImage.Width, originalImage.Height), GraphicsUnit.Pixel);
        }
        catch { }
        finally
        {
            if (graphics != null)
            {
                graphics.Dispose();
                graphics = null;
            }
        }

        return newImage;
    }
    /// <summary>
    /// 对给定的一个图片文件生成一个指定大小的缩略图。
    /// </summary>
    /// <param name="originalImage">图片的物理文件地址</param>
    /// <param name="thumMaxWidth">缩略图的宽度</param>
    /// <param name="thumMaxHeight">缩略图的高度</param>
    /// <returns>返回缩略图的Image对象</returns>
    public static System.Drawing.Image GetThumbNailImage(string imageFile, int thumMaxWidth, int thumMaxHeight)
    {
        System.Drawing.Image originalImage = null;
        System.Drawing.Image newImage = null;

        try
        {
            originalImage = System.Drawing.Image.FromFile(imageFile);
            newImage = GetThumbNailImage(originalImage, thumMaxWidth, thumMaxHeight);
        }
        catch { }
        finally
        {
            if (originalImage != null)
            {
                originalImage.Dispose();
                originalImage = null;
            }
        }

        return newImage;
    }
    /// <summary>
    /// 对给定的一个图片文件生成一个指定大小的缩略图，并将缩略图保存到指定位置。
    /// </summary>
    /// <param name="originalImageFile">图片的物理文件地址</param>
    /// <param name="thumbNailImageFile">缩略图的物理文件地址</param>
    /// <param name="thumMaxWidth">缩略图的宽度</param>
    /// <param name="thumMaxHeight">缩略图的高度</param>
    public static void MakeThumbNail(string originalImageFile, string thumbNailImageFile, int thumMaxWidth, int thumMaxHeight)
    {
        System.Drawing.Image newImage = GetThumbNailImage(originalImageFile, thumMaxWidth, thumMaxHeight);
        try
        {
            newImage.Save(thumbNailImageFile, ImageFormat.Jpeg);
        }
        catch
        { }
        finally
        {
            newImage.Dispose();
            newImage = null;
        }
    }
    /// <summary>
    /// 将一个图片的内存流调整为指定大小，并返回调整后的内存流。
    /// </summary>
    /// <param name="originalImageStream">原始图片的内存流</param>
    /// <param name="newWidth">新图片的宽度</param>
    /// <param name="newHeight">新图片的高度</param>
    /// <returns>返回调整后的图片的内存流</returns>
    public static MemoryStream ResizeImage(Stream originalImageStream, int newWidth, int newHeight)
    {
        MemoryStream newImageStream = null;

        System.Drawing.Image newImage = Globals.GetThumbNailImage(System.Drawing.Image.FromStream(originalImageStream), newWidth, newHeight);
        if (newImage != null)
        {
            newImageStream = new MemoryStream();
            newImage.Save(newImageStream, ImageFormat.Jpeg);
        }

        return newImageStream;
    }
    /// <summary>
    /// 将一个内存流保存为磁盘文件。
    /// </summary>
    /// <param name="stream">内存流</param>
    /// <param name="newFile">目标磁盘文件地址</param>
    public static void SaveStreamToFile(Stream stream, string newFile)
    {
        if (stream == null || stream.Length == 0 || string.IsNullOrEmpty(newFile))
        {
            return;
        }

        byte[] buffer = new byte[stream.Length];
        stream.Position = 0;
        stream.Read(buffer, 0, buffer.Length);
        FileStream fileStream = new FileStream(newFile, FileMode.OpenOrCreate, FileAccess.Write);
        fileStream.Write(buffer, 0, buffer.Length);
        fileStream.Flush();
        fileStream.Close();
        fileStream.Dispose();
    }
    /// <summary>
    /// 对一个指定的图片加上图片水印效果。
    /// </summary>
    /// <param name="imageFile">图片文件地址</param>
    /// <param name="waterImage">水印图片（Image对象）</param>
    public static void CreateImageWaterMark(string imageFile, System.Drawing.Image waterImage)
    {
        if (string.IsNullOrEmpty(imageFile) || !File.Exists(imageFile) || waterImage == null)
        {
            return;
        }

        System.Drawing.Image originalImage = System.Drawing.Image.FromFile(imageFile);

        if (originalImage.Width - 10 < waterImage.Width || originalImage.Height - 10 < waterImage.Height)
        {
            return;
        }

        Graphics graphics = Graphics.FromImage(originalImage);

        int x = originalImage.Width - waterImage.Width - 10;
        int y = originalImage.Height - waterImage.Height - 10;
        int width = waterImage.Width;
        int height = waterImage.Height;

        graphics.DrawImage(waterImage, new Rectangle(x, y, width, height), 0, 0, width, height, GraphicsUnit.Pixel);
        graphics.Dispose();

        MemoryStream stream = new MemoryStream();
        originalImage.Save(stream, ImageFormat.Jpeg);
        originalImage.Dispose();

        System.Drawing.Image imageWithWater = System.Drawing.Image.FromStream(stream);

        imageWithWater.Save(imageFile);
        imageWithWater.Dispose();
    }
    /// <summary>
    /// 对一个指定的图片加上文字水印效果。
    /// </summary>
    /// <param name="imageFile">图片文件地址</param>
    /// <param name="waterText">水印文字内容</param>
    public static void CreateTextWaterMark(string imageFile, string waterText)
    {
        if (string.IsNullOrEmpty(imageFile) || string.IsNullOrEmpty(waterText) || !File.Exists(imageFile))
        {
            return;
        }

        System.Drawing.Image originalImage = System.Drawing.Image.FromFile(imageFile);

        Graphics graphics = Graphics.FromImage(originalImage);

        graphics.SmoothingMode = SmoothingMode.HighQuality;
        graphics.TextRenderingHint = TextRenderingHint.ClearTypeGridFit;
        graphics.CompositingQuality = CompositingQuality.HighQuality;
        graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;

        SolidBrush brush = new SolidBrush(Color.FromArgb(153, 255, 255, 255));
        Font waterTextFont = new Font("Arial", 16, FontStyle.Regular);
        SizeF waterTextSize = graphics.MeasureString(waterText, waterTextFont);

        float x = (float)originalImage.Width - waterTextSize.Width - 10F;
        float y = (float)originalImage.Height - waterTextSize.Height - 10F;

        graphics.DrawString(waterText, waterTextFont, brush, x, y);

        graphics.Dispose();
        brush.Dispose();

        MemoryStream stream = new MemoryStream();
        originalImage.Save(stream, ImageFormat.Jpeg);
        originalImage.Dispose();

        System.Drawing.Image imageWithWater = System.Drawing.Image.FromStream(stream);

        imageWithWater.Save(imageFile);
        imageWithWater.Dispose();
    }

    /// <summary>
    /// 判断上传组件是否包含内容。
    /// </summary>
    /// <param name="fileUpload">ASP.NET 2.0标准上传组件</param>
    /// <returns>如果数据有效，则返回True，否则返回False</returns>
    public static bool IsAttachmentValid(FileUpload fileUpload)
    {
        if (fileUpload != null &&
            fileUpload.PostedFile != null &&
            !string.IsNullOrEmpty(fileUpload.PostedFile.FileName) &&
            fileUpload.PostedFile.ContentLength > 0)
        {
            return true;
        }
        return false;
    }

    /// <summary>
    /// 将 Stream 转成 byte[]
    /// </summary>
    public byte[] StreamToBytes(Stream stream)
    {
        byte[] bytes = new byte[stream.Length];
        stream.Read(bytes, 0, bytes.Length);
        // 设置当前流的位置为流的开始
        stream.Seek(0, SeekOrigin.Begin);
        return bytes;
    }

    /// <summary>
    /// 将 byte[] 转成 Stream
    /// </summary>
    public Stream BytesToStream(byte[] bytes)
    {
        Stream stream = new MemoryStream(bytes);
        return stream;
    }

    /// <summary>
    /// 将 string 转 byte[] 
    /// </summary>
    /// <param name="str"></param>
    /// <returns></returns>
    public byte[] StringToBytes(string inputString)
    {
        System.Text.UnicodeEncoding converter = new System.Text.UnicodeEncoding();
        byte[] inputBytes = converter.GetBytes(inputString);
        return inputBytes;
    }

    /// <summary>
    /// 将 byte[] 转 string 
    /// </summary>
    /// <param name="bytes"></param>
    /// <returns></returns>
    public string BytesToString(byte[] inputBytes)
    {
        System.Text.UnicodeEncoding converter = new System.Text.UnicodeEncoding();
         string inputString = converter.GetString(inputBytes);
         return inputString;
    }

    /// <summary>
    /// 将 string 转 byte[] FromBase64
    /// </summary>
    /// <param name="str"></param>
    /// <returns></returns>
    public byte[] StringToBytesFromBase64(string inputString)
    {
        System.Text.UnicodeEncoding converter = new System.Text.UnicodeEncoding();
        byte[] inputBytes = System.Convert.FromBase64String(inputString);
        return inputBytes;

    }

    /// <summary>
    /// 将 byte[] 转 string FromBase64
    /// </summary>
    /// <param name="bytes"></param>
    /// <returns></returns>
    public string BytesToStringFromBase64(byte[] inputBytes)
    {
        System.Text.UnicodeEncoding converter = new System.Text.UnicodeEncoding();
        string inputString = System.Convert.ToBase64String(inputBytes);
        return inputString;
    }

}