本文實例講述了C#利用原圖和水印圖的重疊簡單實現水印的方法。分享給大家供大家參考，具體如下：
圖片操作類
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/// <summary>
/// 獲取一個圖片按等比例縮小後的大小。
/// </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後的實際大小</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>
/// 對給定的一個圖片（Image對象）生成一個指定大小的縮略圖。
/// </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>
/// 對給定的一個圖片文件生成一個指定大小的縮略圖。
/// </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>
/// 對給定的一個圖片文件生成一個指定大小的縮略圖，並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>
/// 將一個圖片的內存流調整為指定大小，並返回調整後的內存流。
/// </summary>
/// <param name="originalImageStream">原始圖片的內存流</param>
/// <param name="newWidth">新圖片的寬度</param>
/// <param name="newHeight">新圖片的高度</param>
/// <returns>返回調整後的圖片的內存流</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>
/// 將一個內存流保存為磁盤文件。
/// </summary>
/// <param name="stream">內存流</param>
/// <param name="newFile">目標磁盤文件地址</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容。
/// </summary>
/// <param name="fileUpload">ASP.Net 2.0標准上傳組件</param>
/// <returns>如果數據有效，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;
}
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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
}
