asp.net上传图片并作处理水印与缩略图的实例代码

复制代码 代码如下:

upFileClass.cs

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

/// <summary>
/// upFileClass 的摘要说明
/// </summary>
public class upFileClass
{
    public upFileClass()
    {
        //
        // TODO: 在此处添加构造函数逻辑
        //
    }

/// <summary>
    /// 生成缩略图
    /// </summary>
    /// <param>源图路径（物理路径）</param>
    /// <param>缩略图路径（物理路径）</param>
    /// <param>缩略图宽度</param>
    /// <param>缩略图高度</param>
    /// <param>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(System.Drawing.Color.Transparent);