Asp.net 生成高清缩略图

Asp.net 生成高清缩略图

    生成高清缩略图,原创代码如下所示：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Drawing;

namespace WebApplication
{
	public class Images
	{
		#region 生成缩略图(图片压缩裁剪)
		/// <summary>
		/// 生成缩略图(图片压缩裁剪)
		/// </summary>
		/// <param name="serverImagePath">原始图片地址</param>
		/// <param name="thumbnailImagePath">新图保存地址</param>
		/// <param name="width">宽</param>
		/// <param name="height">高</param>
		/// <param name="p">操作类型</param>
		/// <param name="type">图片类型</param>
		public static void GetThumbnail(string serverImagePath, string thumbnailImagePath, int width, int height, string p, string type)
		{
			Image serverImage = Image.FromFile(serverImagePath);

			//画板大小
			int towidth = width;
			int toheight = height;

			//缩略图矩形框的像素点
			int x = 0;
			int y = 0;
			int ow = serverImage.Width;
			int oh = serverImage.Height;

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

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

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

			//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(System.Drawing.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(serverImage, new System.Drawing.Rectangle(0, 0, towidth, toheight),
				new System.Drawing.Rectangle(x, y, ow, oh),
				System.Drawing.GraphicsUnit.Pixel);

			try
			{
				System.Drawing.Imaging.ImageFormat imgtype = null;
				switch (type)
				{
					case ".jpg":
					case ".jpeg":
						imgtype = System.Drawing.Imaging.ImageFormat.Jpeg;
						break;
					case ".gif":
						imgtype = System.Drawing.Imaging.ImageFormat.Gif;
						break;
					case ".png":
						imgtype = System.Drawing.Imaging.ImageFormat.Png;
						break;
					case "*.bmp":
						imgtype = System.Drawing.Imaging.ImageFormat.Bmp;
						break;
					default:
						imgtype = System.Drawing.Imaging.ImageFormat.Jpeg;
						break;
				}

				//保存缩略图
				bm.Save(thumbnailImagePath, imgtype);
			}
			catch (System.Exception e)
			{
				throw e;
			}
			finally
			{
				serverImage.Dispose();
				bm.Dispose();
				g.Dispose();
			}
		}
		#endregion
	}
}