C#生成缩略图代码
2015-12-13 13:55
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/**//// <summary> /// 生成缩略图 /// </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) { Image originalImage = 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 Image bitmap = new System.Drawing.Bitmap(towidth,toheight); //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(originalImage, new Rectangle(0, 0, towidth, toheight), new Rectangle(x, y, ow,oh), GraphicsUnit.Pixel); 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(); } }
第二种
4个重载方法,有直接返回Image对象的,有生成缩略图,并且保存到指定目录的!
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
/// <summary>
/// 图片处理类
/// 1、生成缩略图片或按照比例改变图片的大小和画质
/// 2、将生成的缩略图放到指定的目录下
/// </summary>
public class ImageClass
{
public Image ResourceImage;
private int ImageWidth;
private int ImageHeight;
public string ErrMessage;
/// <summary>
/// 类的构造函数
/// </summary>
/// <param name="ImageFileName">图片文件的全路径名称</param>
public ImageClass(string ImageFileName)
{
ResourceImage=Image.FromFile(ImageFileName);
ErrMessage="";
}
public bool ThumbnailCallback()
{
return false;
}
/// <summary>
/// 生成缩略图重载方法1,返回缩略图的Image对象
/// </summary>
/// <param name="Width">缩略图的宽度</param>
/// <param name="Height">缩略图的高度</param>
/// <returns>缩略图的Image对象</returns>
public Image GetReducedImage(int Width,int Height)
{
try
{
Image ReducedImage;
Image.GetThumbnailImageAbort callb=new Image.GetThumbnailImageAbort(ThumbnailCallback);
ReducedImage=ResourceImage.GetThumbnailImage(Width,Height,callb,IntPtr.Zero);
return ReducedImage;
}
catch(Exception e)
{
ErrMessage=e.Message;
return null;
}
}
/// <summary>
/// 生成缩略图重载方法2,将缩略图文件保存到指定的路径
/// </summary>
/// <param name="Width">缩略图的宽度</param>
/// <param name="Height">缩略图的高度</param>
/// <param name="targetFilePath">缩略图保存的全文件名,(带路径),参数格式:D:\Images\filename.jpg</param>
/// <returns>成功返回true,否则返回false</returns>
public bool GetReducedImage(int Width,int Height,string targetFilePath)
{
try
{
Image ReducedImage;
Image.GetThumbnailImageAbort callb=new Image.GetThumbnailImageAbort(ThumbnailCallback);
ReducedImage=ResourceImage.GetThumbnailImage(Width,Height,callb,IntPtr.Zero);
ReducedImage.Save(@targetFilePath,ImageFormat.Jpeg);
ReducedImage.Dispose();
return true;
}
catch(Exception e)
{
ErrMessage=e.Message;
return false;
}
}
/// <summary>
/// 生成缩略图重载方法3,返回缩略图的Image对象
/// </summary>
/// <param name="Percent">缩略图的宽度百分比 如:需要百分之80,就填0.8</param>
/// <returns>缩略图的Image对象</returns>
public Image GetReducedImage(double Percent)
{
try
{
Image ReducedImage;
Image.GetThumbnailImageAbort callb=new Image.GetThumbnailImageAbort(ThumbnailCallback);
ImageWidth=Convert.ToInt32(ResourceImage.Width*Percent);
ImageHeight=Convert.ToInt32(ResourceImage.Width*Percent);
ReducedImage=ResourceImage.GetThumbnailImage(ImageWidth,ImageHeight,callb,IntPtr.Zero);
return ReducedImage;
}
catch(Exception e)
{
ErrMessage=e.Message;
return null;
}
}
/// <summary>
/// 生成缩略图重载方法4,返回缩略图的Image对象
/// </summary>
/// <param name="Percent">缩略图的宽度百分比 如:需要百分之80,就填0.8</param>
/// <param name="targetFilePath">缩略图保存的全文件名,(带路径),参数格式:D:\Images\filename.jpg</param>
/// <returns>成功返回true,否则返回false</returns>
public bool GetReducedImage(double Percent,string targetFilePath)
{
try
{
Image ReducedImage;
Image.GetThumbnailImageAbort callb=new Image.GetThumbnailImageAbort(ThumbnailCallback);
ImageWidth=Convert.ToInt32(ResourceImage.Width*Percent);
ImageHeight=Convert.ToInt32(ResourceImage.Width*Percent);
ReducedImage=ResourceImage.GetThumbnailImage(ImageWidth,ImageHeight,callb,IntPtr.Zero);
ReducedImage.Save(@targetFilePath,ImageFormat.Jpeg);
ReducedImage.Dispose();
return true;
}
catch(Exception e)
{
ErrMessage=e.Message;
return false;
}
}
}
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