本文实例讲述了C#利用原图和水印图的重叠简单实现水印的方法。分享给大家供大家参考，具体如下：
图片操作类
/// <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 ;
}
public class ImageHelper
{
#region " 水印存放的相对路径 "
public static string GetLogoPath()
{
return "/images/logo.png" ; ///水印图路径
}
#endregion
#region " 图片水印 "
// <summary>
// 在图片上生成图片水印,此方法不支持Gif类型的图片
// </summary>
// <param name="Path">原服务器图片路径</param>
// <param name="Path_syp">生成的带图片水印的图片路径</param>
// <param name="Path_sypf">水印图片路径</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
}
希望本文所述对大家C#程序设计有所帮助。
dy("nrwz");
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