/// <summary>
/// 獲取一個(gè)圖片按等比例縮小后的大小。
/// </summary>
/// <param name="maxWidth">需要縮小到的寬度</param>
/// <param name="maxHeight">需要縮小到的高度</param>
/// <param name="imageOriginalWidth">圖片的原始寬度</param>
/// <param name="imageOriginalHeight">圖片的原始高度</param>
/// <returns>返回圖片按等比例縮小后的實(shí)際大小</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>
/// 對給定的一個(gè)圖片（Image對象）生成一個(gè)指定大小的縮略圖。
/// </summary>
/// <param name="originalImage">原始圖片</param>
/// <param name="thumMaxWidth">縮略圖的寬度</param>
/// <param name="thumMaxHeight">縮略圖的高度</param>
/// <returns>返回縮略圖的Image對象</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>
/// 對給定的一個(gè)圖片文件生成一個(gè)指定大小的縮略圖。
/// </summary>
/// <param name="originalImage">圖片的物理文件地址</param>
/// <param name="thumMaxWidth">縮略圖的寬度</param>
/// <param name="thumMaxHeight">縮略圖的高度</param>
/// <returns>返回縮略圖的Image對象</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>
/// 對給定的一個(gè)圖片文件生成一個(gè)指定大小的縮略圖，并將縮略圖保存到指定位置。
/// </summary>
/// <param name="originalImageFile">圖片的物理文件地址</param>
/// <param name="thumbNailImageFile">縮略圖的物理文件地址</param>
/// <param name="thumMaxWidth">縮略圖的寬度</param>
/// <param name="thumMaxHeight">縮略圖的高度</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>
/// 將一個(gè)圖片的內(nèi)存流調(diào)整為指定大小，并返回調(diào)整后的內(nèi)存流。
/// </summary>
/// <param name="originalImageStream">原始圖片的內(nèi)存流</param>
/// <param name="newWidth">新圖片的寬度</param>
/// <param name="newHeight">新圖片的高度</param>
/// <returns>返回調(diào)整后的圖片的內(nèi)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>
/// 將一個(gè)內(nèi)存流保存為磁盤文件。
/// </summary>
/// <param name="stream">內(nèi)存流</param>
/// <param name="newFile">目標(biāo)磁盤文件地址</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>
/// 對一個(gè)指定的圖片加上圖片水印效果。
/// </summary>
/// <param name="imageFile">圖片文件地址</param>
/// <param name="waterImage">水印圖片（Image對象）</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>
/// 對一個(gè)指定的圖片加上文字水印效果。
/// </summary>
/// <param name="imageFile">圖片文件地址</param>
/// <param name="waterText">水印文字內(nèi)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>
/// 判斷上傳組件是否包含內(nèi)容。
/// </summary>
/// <param name="fileUpload">ASP.NET 2.0標(biāo)準(zhǔn)上傳組件</param>
/// <returns>如果數(shù)據(jù)有效，則返回True，否則返回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;
}

public class ImageHelper
{
  #region " 水印存放的相對路徑 "
  public static string GetLogoPath()
  {
    return "/images/logo.png";  ///水印圖路徑
  }
  #endregion
  #region " 圖片水印 "
  // <summary>
  // 在圖片上生成圖片水印,此方法不支持Gif類型的圖片
  // </summary>
  // <param name="Path">原服務(wù)器圖片路徑</param>
  // <param name="Path_syp">生成的帶圖片水印的圖片路徑</param>
  // <param name="Path_sypf">水印圖片路徑</param>
  public static void MarkImage(Stream InUploadImagePath, string inLogoImagePath, string InSavePath)
  {
    System.Drawing.Image Image = System.Drawing.Image.FromStream(InUploadImagePath);
    System.Drawing.Image newimage = Image.FromFile(Current.Server.MapPath(inLogoImagePath));
    Graphics g = Graphics.FromImage(Image);
    g.DrawImage(newimage, new Rectangle(Image.Width - newimage.Width, Image.Height - newimage.Height, newimage.Width, newimage.Height), 0, 0, newimage.Width, newimage.Height, GraphicsUnit.Pixel);
    try {
      Image.Save(Current.Server.MapPath(InSavePath));
    }
    catch (Exception ex) {
    }
    finally {
      g.Dispose();
      Image.Dispose();
      newimage.Dispose();
    }
  }
  #endregion
}