asp.net上传图片并同时生成缩略图
<%@ Page Language="C#" ResponseEncoding="gb2312" %>
<%@ Import Namespace="System" %>
<%@ Import Namespace="System.IO" %>
<%@ Import Namespace="System.Drawing" %>
<%@ Import Namespace="System.Drawing.Imaging" %>
<script runat="server">
void Page_Load(Object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
ImgPreview.Visible = false;
}
}
void GetThumbnailImage(int width, int height, string strInfo, int left, int right)
{
string file = "Uploads/" + uploadFile.PostedFile.FileName.Substring(uploadFile.PostedFile.FileName.LastIndexOf('\\') + 1);
string newfile = "Uploads/" + uploadFile.PostedFile.FileName.Substring(uploadFile.PostedFile.FileName.LastIndexOf('\\') + 1) + ".jpg";
string strAdd = strInfo;
System.Drawing.Image oldimage = System.Drawing.Image.FromFile(Server.MapPath(file));
System.Drawing.Image thumbnailImage =
oldimage.GetThumbnailImage(width, height, new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback), IntPtr.Zero);
Response.Clear();
Bitmap output = new Bitmap(thumbnailImage);
Graphics g = Graphics.FromImage(output);
g.DrawString(strAdd, new Font("Courier New", 14), new SolidBrush(Color.Red), left, right);
output.Save(Server.MapPath(newfile), System.Drawing.Imaging.ImageFormat.Jpeg);
Response.ContentType = "image/gif";
ImgPreview.Visible = true;
ImgPreview.ImageUrl = newfile;
}
bool ThumbnailCallback()
{
return true;
}
void Button_Click(object sender, EventArgs e)
{
int width, height, left, right;
string strAddInfo = txtAddInfo.Text;
width = Int32.Parse(txtWidth.Text);
height = Int32.Parse(txtHeight.Text);
left = Int32.Parse(txtLeft.Text);
right = Int32.Parse(txtRight.Text);
if (!(uploadFile.PostedFile.ContentLength > 0))
{
lblErrInfo.Text = "没有选择文件";
}
else
{
string path = Server.MapPath("./Uploads/" + uploadFile.PostedFile.FileName.Substring(uploadFile.PostedFile.FileName.LastIndexOf('\\') + 1));
if (File.Exists(path))
{
lblErrInfo.Text = "已经有同名文件";
}
else
{
uploadFile.PostedFile.SaveAs(path);
GetThumbnailImage(width, height, strAddInfo, left, right);
}
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title>上传图片并生成缩略图</title>
</head>
<body>
<form id="Form1" method="post" enctype="multipart/form-data" runat="server">
<p>
<input id="uploadFile" type="file" runat="server" />
<asp:Label ID="lblErrInfo" runat="server" ForeColor="Red"></asp:Label>
</p>
<p>
width:<asp:TextBox ID="txtWidth" runat="server" Width="40px">100</asp:TextBox>
height:<asp:TextBox ID="txtHeight" runat="server" Width="40px">150</asp:TextBox>
</p>
<p>
添加信息：<asp:TextBox ID="txtAddInfo" runat="server"> AspxBoy.Com</asp:TextBox>
</p>
<p>
信息位置：left:<asp:TextBox ID="txtLeft" runat="server" Width="40px">10</asp:TextBox>
right:<asp:TextBox ID="txtRight" runat="server" Width="40px">135</asp:TextBox>
</p>
<p>
<input id="button" type="button" value="上传生成所略图" onserverclick="Button_Click" runat="server" />
</p>
<p>
<asp:Image ID="ImgPreview" runat="server"></asp:Image>
</p>
<!-- Insert content here -->
</form>
</body>
</html>
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