昨天花了点时间写了几个比较实用的函数，分享给大家

ilovesijia 2010-02-07 02:07:45

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代码如下，因为觉得可能对大家有所帮助，所以不敢独享。



/// <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;

}

...全文

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aa627854273 2012-08-21

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好东西,就要收起来

gaotian20120604 2012-07-03

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楼主辛苦

jlwfl 2012-03-04

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收藏了，谢谢了.以后有用

my328420969 2012-02-28

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好东西方便

grok 2010-10-09

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顶,学习中

xinshouno7 2010-10-08

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学习了。3Q啊

zhuming8882000 2010-10-08

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低调接分，3qlz~

guolunfeng 2010-10-06

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mottoflies 2010-09-16