C# 添加图片水印类的方法

///原图片地址
///水印图片地址
///
public void markwater(string filepath, string waterfile)
{
//gif不水印
int i = filepath.LastIndexOf(".");
string ex = filepath.Substring(i, filepath.Length - i);
if (string.Compare(ex, ".gif", true) == 0)
{
return;
}
string modifyimagepath = filepath;//修改的图像路径
int lucencypercent = 25;
Image modifyimage = null;
Image drawedimage = null;
Graphics g = null;
try
{
//建立图形对象
modifyimage = Image.FromFile(modifyimagepath, true);
drawedimage = Image.FromFile(waterfile, true);
g = Graphics.FromImage(modifyimage);
//获取要绘制图形坐标
int x = modifyimage.Width - drawedimage.Width;
int y = modifyimage.Height - drawedimage.Height; //设置颜色矩阵
float[][] matrixitems ={ new float[] { 1, 0, 0, 0, 0 }, new float[] { 0, 1, 0, 0, 0 }, new float[] { 0, 0, 1, 0, 0 }, new float[] { 0, 0, 0, (float)lucencypercent / 100f, 0 }, new float[] { 0, 0, 0, 0, 1 } };
ColorMatrix colormatrix = new ColorMatrix(matrixitems);
ImageAttributes imgattr = new ImageAttributes();
imgattr.SetColorMatrix(colormatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap); //绘制阴影图像
g.DrawImage(drawedimage, new Rectangle(x, y, drawedimage.Width, drawedimage.Height), 10, 10, drawedimage.Width, drawedimage.Height, GraphicsUnit.Pixel, imgattr); //保存文件
string[] allowimagetype ={ ".jpg", ".gif", ".png", ".bmp", ".tiff", ".wmf", ".ico" };
FileInfo fi = new FileInfo(modifyimagepath);
ImageFormat imagetype = ImageFormat.Gif;
switch (fi.Extension.ToLower())
{
case ".jpg":
imagetype = ImageFormat.Jpeg;
break;
case ".gif":
imagetype = ImageFormat.Gif;
break;
case ".png":
imagetype = ImageFormat.Png;
break;
case ".bmp":
imagetype = ImageFormat.Bmp;
break;
case ".tif":
imagetype = ImageFormat.Tiff;
break;
case ".wmf":
imagetype = ImageFormat.Wmf;
break;
case ".ico":
imagetype = ImageFormat.Icon;
break;
default: break;
}
MemoryStream ms = new MemoryStream();
modifyimage.Save(ms, imagetype);
byte[] imgdata = ms.ToArray();
modifyimage.Dispose();
drawedimage.Dispose();
g.Dispose();
FileStream fs = null;
//File.Delete(modifyimagepath);
fs = new FileStream(modifyimagepath, FileMode.Create, FileAccess.Write);
if (fs != null)
{
fs.Write(imgdata, 0, imgdata.Length);
fs.Close();
}
}
finally
{
try
{
drawedimage.Dispose();
modifyimage.Dispose();
g.Dispose();
}
catch
{ }
}
}
}
}

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