C#生成透明缩略图（转载）

页面调用:aspx.cs //上传文件

if (FileUpload1.HasFile)
{
isupload = mycomm.uploadThumbToServer(FileUpload1, strUpPath + "\" + tmpRdFile, this);
}

 

在页面调用的中转方法:

/// <summary>
/// 将图片以缩略图+水印的方式上传
/// </summary>
/// <param name="FileUpload1">要上传的对象</param>
/// <param name="warteImage">水印图片路径</param>
/// <param name="thumbImage">缩略图存储位置</param>
/// <returns></returns>
public static bool uploadThumbToServer(FileUpload FileUpload1,string warteImage,string thumbImage)
{
HttpPostedFile MyPostedFile = FileUpload1.PostedFile;
if (MyPostedFile.ContentType.ToString().ToLower().IndexOf("image") < 0)
{
return false;
}
return images.GetThumbNail(MyPostedFile.FileName, 320, 240,
MyPostedFile.ContentType.ToString(), false, MyPostedFile.InputStream, warteImage, thumbImage);
}
public static bool uploadThumbToServer(FileUpload FileUpload1, string thumbImage, Page pg)
{
string warteImage = pg.Server.MapPath("\images\qtk.png");//水印图
thumbImage = pg.Server.MapPath(thumbImage);
return uploadThumbToServer(FileUpload1, warteImage, thumbImage);
}

//---------------------------------

//主类详细代码-2007年9月24日 jace

using System;
using System.Data;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;

/// <summary>
/// images 的摘要说明
/// </summary>
public class images
{
public images()
{
//
// TODO: 在此处添加构造函数逻辑
//
}
/// <summary>
/// 图像文件imgFile的尺寸是否在imgWidth和imgHeight的控制范围外
/// </summary>
/// <param name="imgFile"></param>
/// <param name="imgWidth"></param>
/// <param name="imgHeight"></param>
/// <returns>width > imgWidth || height > imgHeight 返回真，反之</returns>
public static bool imageWH(string imgFile, int imgWidth, int imgHeight)
{
System.IO.FileStream fs = System.IO.File.Open(imgFile, System.IO.FileMode.Open, System.IO.FileAccess.Read);
System.Drawing.Image image = System.Drawing.Image.FromStream(fs);

// System.Drawing.Image image = System.Drawing.Image.FromFile(imgFile);
int width = image.Width;
int height = image.Height;
if (width > imgWidth || height > imgHeight)
{
// this.lb_msg.Text = "图像尺寸为200x160,请调整后再上传";
return true;
}
else
{
return false;
}

}

/// <summary>
/// 取得图片的格式
/// </summary>
/// <param name="strContentType"></param>
/// <returns></returns>
private static System.Drawing.Imaging.ImageFormat GetImageType(object strContentType)
{
if ((strContentType.ToString().ToLower()) == "image/pjpeg")
{
return System.Drawing.Imaging.ImageFormat.Jpeg;
}
else if ((strContentType.ToString().ToLower()) == "image/gif")
{
return System.Drawing.Imaging.ImageFormat.Gif;
}
else if ((strContentType.ToString().ToLower()) == "image/bmp")
{
return System.Drawing.Imaging.ImageFormat.Bmp;
}
else if ((strContentType.ToString().ToLower()) == "image/tiff")
{
return System.Drawing.Imaging.ImageFormat.Tiff;
}
else if ((strContentType.ToString().ToLower()) == "image/x-icon")
{
return System.Drawing.Imaging.ImageFormat.Icon;
}
else if ((strContentType.ToString().ToLower()) == "image/x-png")
{
return System.Drawing.Imaging.ImageFormat.Png;
}
else if ((strContentType.ToString().ToLower()) == "image/x-emf")
{
return System.Drawing.Imaging.ImageFormat.Emf;
}
else if ((strContentType.ToString().ToLower()) == "image/x-exif")
{
return System.Drawing.Imaging.ImageFormat.Exif;
}
else if ((strContentType.ToString().ToLower()) == "image/x-wmf")
{
return System.Drawing.Imaging.ImageFormat.Wmf;
}
else
{
return System.Drawing.Imaging.ImageFormat.MemoryBmp;
}
}

/// <summary>
/// 生成高质量缩略图并加入透明图片水印
/// </summary>
/// <param name="strFileName">原始图片的文件名(全路径)</param>
/// <param name="iWidth">生成缩略图的宽</param>
/// <param name="iheight">生成缩略图的高</param>
/// <param name="strContentType">原始图片文件的文件类型</param>
/// <param name="blnGetFromFile">原始图来源于文件还是文件流,True=文件,False=流</param>
/// <param name="ImgStream">原始图片的文件流</param>
/// <param name="warteFile">水印文件的文件名(全路径)</param>
/// <param name="thumbSaveFile">生成的缩略图保存的位置(jpg格式)</param>
/// <returns>true=上传成功,false=失败</returns>
public static bool GetThumbNail(string strFileName, int iWidth, int iheight,
string strContentType, bool blnGetFromFile, System.IO.Stream ImgStream,
string warteFile, string thumbSaveFile)
{
try
{
if (!System.IO.File.Exists(strFileName))
{
return false;//原始文件不存在
}
System.Drawing.Image oImg;
#region 原始图来源于文件还是文件流
if (blnGetFromFile)
{
oImg = System.Drawing.Image.FromFile(strFileName);
}
else
{
oImg = System.Drawing.Image.FromStream(ImgStream);
}
#endregion
#region 高质量缩略图

//新建一个bmp图片
System.Drawing.Image bitmap = new System.Drawing.Bitmap(iWidth, iheight);

//新建一个画板
Graphics g = System.Drawing.Graphics.FromImage(bitmap);

//设置高质量插值法
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

//设置高质量,低速度呈现平滑程度
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

//清空画布并以透明背景色填充
g.Clear(Color.Transparent);

//在指定位置并且按指定大小绘制原图片的指定部分
g.DrawImage(oImg, new Rectangle(0, 0, iWidth, iheight),
new Rectangle(0, 0, oImg.Width, oImg.Height),
GraphicsUnit.Pixel);
#endregion
#region 普通质量的缩略图
//oImg = oImg.GetThumbnailImage(iWidth, iheight, null, IntPtr.Zero);//此法生成的图片丢失颜色比较多
#endregion
#region 加入文字水印

////新建一个画板
//System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(oImg);
//// new SolidBrush(Color.Red)
//g.DrawString("qiutianka.com", new Font("Arial Black", 80), new SolidBrush(Color.Red), 0, 0);
//g.Save();
//g.Dispose();
#endregion
#region 加入图片水印
//System.Drawing.Image image = System.Drawing.Image.FromFile(strFileName);
//Bitmap b = new Bitmap(oImg.Width, oImg.Height, PixelFormat.Format24bppRgb);
//Graphics g = Graphics.FromImage(b);
//g.Clear(Color.Transparent);
//g.SmoothingMode =System.Drawing.Drawing2D.SmoothingMode.HighQuality;
//g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
//g.DrawImage(oImg, 0, 0, oImg.Width, oImg.Height);

//System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(oImg);

//string mpath = @"E:projectweb_pos_Newimagesqtk.png"; //Server.MapPath("\images\qtk.png");//
////string mpath = Server.MapPath("\images\qtk.png");//水印文件位置
//addWatermarkImage(g, mpath, "WM_BOTTOM_RIGHT", iWidth, iheight);// 可以加入枚举来定位
addWatermarkImage(g, warteFile, "WM_BOTTOM_RIGHT", iWidth, iheight);// 可以加入枚举来定位
#endregion
#region 预览显示

//MemoryStream MemStream = new MemoryStream();

//oImg.Save(MemStream, GetImageType(strContentType));
//b.Save(MemStream, GetImageType(strContentType));

//bitmap.Save(MemStream, GetImageType(strContentType));
//MemStream.WriteTo(Response.OutputStream);//不适合单独在一个类中,可放于aspx.cs页中使用
#endregion
#region 上传并保存

//上传
//string mp = Server.MapPath("1.jpg");
//oImg.Save(mp, System.Drawing.Imaging.ImageFormat.Jpeg);

//string mp = Server.MapPath("1.jpg");//不适合单独在一个类中,可放于aspx.cs页中使用
//string mp = @"c:1.jpg";
//bitmap.Save(mp, System.Drawing.Imaging.ImageFormat.Jpeg);

//保存缩略图位置的目录是否存在
string savedir = thumbSaveFile.Substring(0, thumbSaveFile.LastIndexOf('\'));
if (!System.IO.Directory.Exists(savedir))
{
//不存在就建立一个
System.IO.Directory.CreateDirectory(savedir);
}

bitmap.Save(thumbSaveFile, System.Drawing.Imaging.ImageFormat.Jpeg);
return true;
}
catch
{
return false;
}
#endregion
}
/// <summary>
/// 仅生成缩略图-高质量
/// </summary>
/// <param name="originalImagePath">源图路径（物理路径）</param>
/// <param name="thumbnailPath">缩略图路径（物理路径）</param>
/// <param name="width">缩略图宽度</param>
/// <param name="height">缩略图高度</param>
/// <param name="mode">生成缩略图的方式</param> 
public static void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode)
{
System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath);

int towidth = width;
int toheight = height;

int x = 0;
int y = 0;
int ow = originalImage.Width;
int oh = originalImage.Height;

switch (mode)
{
case "HW"://指定高宽缩放（可能变形） 
break;
case "W"://指定宽，高按比例 
toheight = originalImage.Height * width / originalImage.Width;
break;
case "H"://指定高，宽按比例
towidth = originalImage.Width * height / originalImage.Height;
break;
case "Cut"://指定高宽裁减（不变形） 
if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight)
{
oh = originalImage.Height;
ow = originalImage.Height * towidth / toheight;
y = 0;
x = (originalImage.Width - ow) / 2;
}
else
{
ow = originalImage.Width;
oh = originalImage.Width * height / towidth;
x = 0;
y = (originalImage.Height - oh) / 2;
}
break;
default:
break;
}

//新建一个bmp图片
System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);

//新建一个画板
System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);

//设置高质量插值法
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

//设置高质量,低速度呈现平滑程度
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

//清空画布并以透明背景色填充
g.Clear(Color.Transparent);

//在指定位置并且按指定大小绘制原图片的指定部分
g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight),
new Rectangle(x, y, ow, oh),
GraphicsUnit.Pixel);

//加入文字水印
//g.DrawString("qiutianka.com", new Font("Courier New", 14), new SolidBrush(Color.Red), 0, 100);

try
{
//以jpg格式保存缩略图
bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
catch (System.Exception e)
{
throw e;
}
finally
{
originalImage.Dispose();
bitmap.Dispose();
g.Dispose();
}
}
/// <summary>
/// 加水印文字
/// </summary>
/// <param name="picture">imge 对象</param>
/// <param name="_watermarkText">水印文字内容</param>
/// <param name="_watermarkPosition">水印位置</param>
/// <param name="_width">被加水印图片的宽</param>
/// <param name="_height">被加水印图片的高</param>
private static void addWatermarkText(Graphics picture, string _watermarkText, string _watermarkPosition, int _width, int _height)
{
int[] sizes = new int[] { 16, 14, 12, 10, 8, 6, 4 };
Font crFont = null;
SizeF crSize = new SizeF();
for (int i = 0; i < 7; i++)
{
crFont = new Font("arial", sizes[i], FontStyle.Bold);
crSize = picture.MeasureString(_watermarkText, crFont);

if ((ushort)crSize.Width < (ushort)_width)
break;
}

float xpos = 0;
float ypos = 0;

switch (_watermarkPosition)
{
case "WM_TOP_LEFT":
xpos = ((float)_width * (float).01) + (crSize.Width / 2);
ypos = (float)_height * (float).01;
break;
case "WM_TOP_RIGHT":
xpos = ((float)_width * (float).99) - (crSize.Width / 2);
ypos = (float)_height * (float).01;
break;
case "WM_BOTTOM_RIGHT":
xpos = ((float)_width * (float).99) - (crSize.Width / 2);
ypos = ((float)_height * (float).99) - crSize.Height;
break;
case "WM_BOTTOM_LEFT":
xpos = ((float)_width * (float).01) + (crSize.Width / 2);
ypos = ((float)_height * (float).99) - crSize.Height;
break;
}

StringFormat StrFormat = new StringFormat();
StrFormat.Alignment = StringAlignment.Center;

SolidBrush semiTransBrush2 = new SolidBrush(Color.FromArgb(153, 0, 0, 0));
picture.DrawString(_watermarkText, crFont, semiTransBrush2, xpos + 1, ypos + 1, StrFormat);

SolidBrush semiTransBrush = new SolidBrush(Color.FromArgb(153, 255, 255, 255));
picture.DrawString(_watermarkText, crFont, semiTransBrush, xpos, ypos, StrFormat);

semiTransBrush2.Dispose();
semiTransBrush.Dispose();

}//代码已经修改，可以按比率还填加图片水印，不过如果背景图片和水印图片太不成比率的话（指水印图片要大于背景图片的1/4），出来的效果不是很好。
/// <summary>
/// 加水印图片
/// </summary>
/// <param name="picture">imge 对象</param>
/// <param name="WaterMarkPicPath">水印图片的地址</param>
/// <param name="_watermarkPosition">水印位置</param>
/// <param name="_width">被加水印图片的宽</param>
/// <param name="_height">被加水印图片的高</param>
private static void addWatermarkImage(Graphics picture, string WaterMarkPicPath, string _watermarkPosition, int _width, int _height)
{
System.Drawing.Image watermark = new System.Drawing.Bitmap(WaterMarkPicPath);

System.Drawing.Imaging.ImageAttributes imageAttributes = new System.Drawing.Imaging.ImageAttributes();
System.Drawing.Imaging.ColorMap colorMap = new System.Drawing.Imaging.ColorMap();

colorMap.OldColor = Color.FromArgb(255, 0, 255, 0);
colorMap.NewColor = Color.FromArgb(0, 0, 0, 0);
System.Drawing.Imaging.ColorMap[] remapTable = { colorMap };

imageAttributes.SetRemapTable(remapTable, ColorAdjustType.Bitmap);

float[][] colorMatrixElements = {
new float[] {1.0f, 0.0f, 0.0f, 0.0f, 0.0f},
new float[] {0.0f, 1.0f, 0.0f, 0.0f, 0.0f},
new float[] {0.0f, 0.0f, 1.0f, 0.0f, 0.0f},
new float[] {0.0f, 0.0f, 0.0f, 0.3f, 0.0f},
new float[] {0.0f, 0.0f, 0.0f, 0.0f, 1.0f}
};

System.Drawing.Imaging.ColorMatrix colorMatrix = new System.Drawing.Imaging.ColorMatrix(colorMatrixElements);

imageAttributes.SetColorMatrix(colorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
//设置水印图片中被透明的色值,low=hight
imageAttributes.SetColorKey(Color.Black, Color.Black, ColorAdjustType.Bitmap);

int xpos = 0;
int ypos = 0;
int WatermarkWidth = 0;
int WatermarkHeight = 0;
double bl = 1d;//默认比率=1,不进行水印的大小改变,而直接使用水印图真实大小加入背景
#region 计算水印图片的比率
//取背景的1/4宽度来比较
//if ((_width > watermark.Width * 4) && (_height > watermark.Height * 4))
//{
// bl = 1;
//}
//else if ((_width > watermark.Width * 4) && (_height < watermark.Height * 4))
//{
// bl = Convert.ToDouble(_height / 4) / Convert.ToDouble(watermark.Height);

//}
//else

// if ((_width < watermark.Width * 4) && (_height > watermark.Height * 4))
// {
// bl = Convert.ToDouble(_width / 4) / Convert.ToDouble(watermark.Width);
// }
// else
// {
// if ((_width * watermark.Height) > (_height * watermark.Width))
// {
// bl = Convert.ToDouble(_height / 4) / Convert.ToDouble(watermark.Height);

// }
// else
// {
// bl = Convert.ToDouble(_width / 4) / Convert.ToDouble(watermark.Width);

// }

// }
#endregion
WatermarkWidth = Convert.ToInt32(watermark.Width * bl);
WatermarkHeight = Convert.ToInt32(watermark.Height * bl);

#region 水印在背景图中的位置

switch (_watermarkPosition)
{
case "WM_TOP_LEFT":
xpos = 10;
ypos = 10;
break;
case "WM_TOP_RIGHT":
xpos = _width - WatermarkWidth - 10;
ypos = 10;
break;
case "WM_BOTTOM_RIGHT":
xpos = _width - WatermarkWidth - 10;
ypos = _height - WatermarkHeight - 10;
break;
case "WM_BOTTOM_LEFT":
xpos = 10;
ypos = _height - WatermarkHeight - 10;
break;
}
#endregion
picture.DrawImage(watermark, new Rectangle(xpos, ypos, WatermarkWidth, WatermarkHeight), 0, 0, watermark.Width, watermark.Height, GraphicsUnit.Pixel, imageAttributes);

watermark.Dispose();
imageAttributes.Dispose();
}
#region 直接将本地的图片生成缩略图

/// <summary>
/// 直接将本地的图片生成缩略图(不加水印,不进行文件类型处理),
/// 并存放于新位置(换个用法也可以在Asp.net中使用)
/// 2007年9月24日 14时42分45秒 jace未调试
/// </summary>
/// <param name="oldpath">原图片地址</param>
/// <param name="newpath">新图片地址</param>
/// <param name="tWidth">缩略图的宽</param>
/// <param name="tHeight">缩略图的高</param>
public static void GreateMiniImage(string oldpath, string newpath, int tWidth, int tHeight)
{

try
{

System.Drawing.Image image = System.Drawing.Image.FromFile(oldpath);
double bl = 1d;
if ((image.Width <= image.Height) && (tWidth >= tHeight))
{
bl = Convert.ToDouble(image.Height) / Convert.ToDouble(tHeight);
}
else if ((image.Width > image.Height) && (tWidth < tHeight))
{
bl = Convert.ToDouble(image.Width) / Convert.ToDouble(tWidth);
}
else

if ((image.Width <= image.Height) && (tWidth <= tHeight))
{
if (image.Height / tHeight >= image.Width / tWidth)
{
bl = Convert.ToDouble(image.Width) / Convert.ToDouble(tWidth);
}
else
{
bl = Convert.ToDouble(image.Height) / Convert.ToDouble(tHeight);
}
}
else
{
if (image.Height / tHeight >= image.Width / tWidth)
{
bl = Convert.ToDouble(image.Height) / Convert.ToDouble(tHeight);

}
else
{
bl = Convert.ToDouble(image.Width) / Convert.ToDouble(tWidth);

}
}
Bitmap b = new Bitmap(image, Convert.ToInt32(image.Width / bl), Convert.ToInt32(image.Height / bl));

b.Save(newpath);
b.Dispose();
image.Dispose();

}
catch
{

}

}
#endregion
}

 

转自：http://blog.163.com/alex_kame/blog/static/14546748200972953344109/