几个比较实用的图形图像函数

ever__f

不错的总结，或许以后编写处理pdg的程序会使用到。
http://topic.csdn.net/u/20100207 ... 3882bac1.html?88639


C# code
/// <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;
}