ASP.NET下实现图片等比例缩放和裁剪

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

----------------------------------------------------------------------------------------------------------

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Drawing;
using System.Drawing.Imaging;
using System.Collections;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
    }
    protected void BtnSend_Click(object sender, EventArgs e)
    {
        //int towidth = width;
        //int toheight = height;

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

        //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;
        //}

        //Image.GetThumbnailImageAbort myCallback = new Image.GetThumbnailImageAbort(ThumbnailCallback);
        //Bitmap myBitmap = new Bitmap(this.File1.PostedFile.FileName);
        //Image myThumbnail = myBitmap.GetThumbnailImage(120, 120, myCallback, IntPtr.Zero);

//myThumbnail.Save(Server.MapPath("file/" + DateTime.Now.ToString("yyyyMMddHHmmssffff") + ".gif"));
//myThumbnail.Dispose();

MakeThumbnail(this.File1.PostedFile.FileName, Server.MapPath("file"), 100, 100, "A");
}

    public bool ThumbnailCallback()
    {
        return false;
    }

///<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 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 "A":
                if (originalImage.Width / originalImage.Height >= width / height)
                {
                    if (originalImage.Width > width)
                    {
                        towidth = width;
                        toheight = (originalImage.Height * width) / originalImage.Width;
                    }
                    else
                    {
                        towidth = originalImage.Width;
                        toheight = originalImage.Height;
                    }
                }
                else
                {
                    if (originalImage.Height > height)
                    {
                        toheight = height;
                        towidth = (originalImage.Width * height) / originalImage.Height;
                    }
                    else
                    {
                        towidth = originalImage.Width;
                        toheight = 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
Graphics g = System.Drawing.Graphics.FromImage(bitmap);

       //设置高质量插值法
       g.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.Half;
       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.AntiAlias;

//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(Server.MapPath("file/" + DateTime.Now.ToString("yyyyMMddHHmmssffff") + ".jpg"), System.Drawing.Imaging.ImageFormat.Jpeg);
        //outthumbnailPath=thumbnailPath;
       }
       catch(System.Exception e)
       {
        throw e;
       }
       finally
       {
        originalImage.Dispose();
        bitmap.Dispose();
        g.Dispose();
       }
}
}

posted @ 2008-05-21 19:13 supers 阅读(1867) 评论(0) 收藏举报

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ASP.NET下实现图片等比例缩放和裁剪

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