C# 生成各种格式各种大小的图片类

using System; using System.Collections.Generic; using System.Text; using System.Drawing; using System.Drawing.Drawing2D; using System.Drawing.Imaging; namespace Chen { public class Thumbnail { #region 生成缩略图 ///summary /// 生成缩略图 /

using System;
using System.Collections.Generic;
using System.Text;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;

namespace Chen
{
public class Thumbnail
{
#region 生成缩略图
///

/// 生成缩略图
///

/// 源图路径（物理路径）
/// 缩略图路径（物理路径）
/// 缩略图宽度
/// 缩略图高度
/// 生成缩略图的方式
/// 生成缩略图的类型
public void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode, out string outthumbnailPath, string thumbnailType)
{
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 Bitmap(towidth, toheight);

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

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

//设置高质量,低速度呈现平滑程度
g.SmoothingMode = 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
{
//以各种格式保存缩略图
switch (thumbnailType)
{
case "ico":
bitmap.Save(thumbnailPath, ImageFormat.Icon);
break;
case "jpg":
bitmap.Save(thumbnailPath, ImageFormat.Jpeg);
break;
case "bmp":
bitmap.Save(thumbnailPath, ImageFormat.Bmp);
break;
case "gif":
bitmap.Save(thumbnailPath, ImageFormat.Gif);
break;
default:
bitmap.Save(thumbnailPath, ImageFormat.Jpeg);
break;
}
outthumbnailPath = thumbnailPath;
}
catch (System.Exception e)
{
throw e;
}
finally
{
originalImage.Dispose();
bitmap.Dispose();
g.Dispose();
}
}
}
#endregion
}