在asp.net中，上傳圖片功能或者是常用的，生成縮略圖也是常用的。baidu或者google，c#的方法也是很多的，但是一用卻發(fā)現(xiàn)縮略圖不清晰啊，縮略圖片太大之類的事情，下面是我在處理圖片上的代碼，效果不錯(cuò)，所以拿出來(lái)分享，(效果能達(dá)到一些繪圖軟件的效果)
/// summary>
/// asp.net上傳圖片并生成縮略圖
/// /summary>
/// param name="upImage">HtmlInputFile控件/param>
/// param name="sSavePath">保存的路徑,些為相對(duì)服務(wù)器路徑的下的文件夾/param>
/// param name="sThumbExtension">縮略圖的thumb/param>
/// param name="intThumbWidth">生成縮略圖的寬度/param>
/// param name="intThumbHeight">生成縮略圖的高度/param>
/// returns>縮略圖名稱/returns>
public string UpLoadImage(HtmlInputFile upImage, string sSavePath, string sThumbExtension, int intThumbWidth, int intThumbHeight)
{
string sThumbFile = "";
string sFilename = "";
if (upImage.PostedFile != null)
{
HttpPostedFile myFile = upImage.PostedFile;
int nFileLen = myFile.ContentLength;
if (nFileLen == 0)
return "沒有選擇上傳圖片";
//獲取upImage選擇文件的擴(kuò)展名
string extendName = System.IO.Path.GetExtension(myFile.FileName).ToLower();
//判斷是否為圖片格式
if (extendName != ".jpg" extendName != ".jpge" extendName != ".gif" extendName != ".bmp" extendName != ".png")
return "圖片格式不正確";
byte[] myData = new Byte[nFileLen];
myFile.InputStream.Read(myData, 0, nFileLen);
sFilename = System.IO.Path.GetFileName(myFile.FileName);
int file_append = 0;
//檢查當(dāng)前文件夾下是否有同名圖片,有則在文件名+1
while (System.IO.File.Exists(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename)))
{
file_append++;
sFilename = System.IO.Path.GetFileNameWithoutExtension(myFile.FileName)
+ file_append.ToString() + extendName;
}
System.IO.FileStream newFile
= new System.IO.FileStream(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename),
System.IO.FileMode.Create, System.IO.FileAccess.Write);
newFile.Write(myData, 0, myData.Length);
newFile.Close();
//以上為上傳原圖
try
{
//原圖加載
using (System.Drawing.Image sourceImage = System.Drawing.Image.FromFile(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename)))
{
//原圖寬度和高度
int width = sourceImage.Width;
int height = sourceImage.Height;
int smallWidth;
int smallHeight;
//獲取第一張繪制圖的大小,(比較 原圖的寬/縮略圖的寬 和 原圖的高/縮略圖的高)
if (((decimal)width) / height = ((decimal)intThumbWidth) / intThumbHeight)
{
smallWidth = intThumbWidth;
smallHeight = intThumbWidth * height / width;
}
else
{
smallWidth = intThumbHeight * width / height;
smallHeight = intThumbHeight;
}
//判斷縮略圖在當(dāng)前文件夾下是否同名稱文件存在
file_append = 0;
sThumbFile = sThumbExtension + System.IO.Path.GetFileNameWithoutExtension(myFile.FileName) + extendName;
while (System.IO.File.Exists(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sThumbFile)))
{
file_append++;
sThumbFile = sThumbExtension + System.IO.Path.GetFileNameWithoutExtension(myFile.FileName) +
file_append.ToString() + extendName;
}
//縮略圖保存的絕對(duì)路徑
string smallImagePath = System.Web.HttpContext.Current.Server.MapPath(sSavePath) + sThumbFile;
//新建一個(gè)圖板,以最小等比例壓縮大小繪制原圖
using (System.Drawing.Image bitmap = new System.Drawing.Bitmap(smallWidth, smallHeight))
{
//繪制中間圖
using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap))
{
//高清,平滑
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
g.Clear(Color.Black);
g.DrawImage(
sourceImage,
new System.Drawing.Rectangle(0, 0, smallWidth, smallHeight),
new System.Drawing.Rectangle(0, 0, width, height),
System.Drawing.GraphicsUnit.Pixel
);
}
//新建一個(gè)圖板,以縮略圖大小繪制中間圖
using (System.Drawing.Image bitmap1 = new System.Drawing.Bitmap(intThumbWidth, intThumbHeight))
{
//繪制縮略圖 http://www.cnblogs.com/sosoft/
using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap1))
{
//高清,平滑
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
g.Clear(Color.Black);
int lwidth = (smallWidth - intThumbWidth) / 2;
int bheight = (smallHeight - intThumbHeight) / 2;
g.DrawImage(bitmap, new Rectangle(0, 0, intThumbWidth, intThumbHeight), lwidth, bheight, intThumbWidth, intThumbHeight, GraphicsUnit.Pixel);
g.Dispose();
bitmap1.Save(smallImagePath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
}
}
}
}
catch
{
//出錯(cuò)則刪除
System.IO.File.Delete(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename));
return "圖片格式不正確";
}
//返回縮略圖名稱
return sThumbFile;
}
return "沒有選擇圖片";
}
HtmlInputFile控件我想大家都應(yīng)該知道的，就是input type=file....
%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="Default2" %>
!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
html xmlns="http://www.w3.org/1999/xhtml" >
head runat="server">
title>圖片上傳-柯樂(lè)義/title>
/head>
body>
form id="form1" runat="server">
div>
input id="File1" runat="server" type="file" />/div>asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Button" />
/form>
/body>
/html>
protected void Button1_Click(object sender, EventArgs e)
{
string a = this.UpLoadImage(this.File1, "UpLoad/", "thumb_", 118, 118);
}
例如：原圖為500*500 我要縮略成100*80,上面代碼程序會(huì)先繪制一張100*100的中間圖，再在這圖片上繪制100*80的，在繪制100*100中間圖之前如果先繪300*300的中間圖，再在300*300的基礎(chǔ)上再繪100*100然后再繪100*80這樣會(huì)比我上面的代碼效果更好，圖片更清晰，即中間圖越多，效果越好，大家可以去試試。
