Implementation Method of Webform Image Watermark and Image Verification Code in Asp.net Development

Both need to import the namespace: using System.Drawing;

I. Image Watermark

Front-end PhotoWatermark.aspx Code:

<div>
<asp:FileUpload ID="FileUpload1" runat="server" />
<asp:Button ID="Button1" runat="server" Text="Upload" /><br />
<asp:Image ID="Image1" runat="server" />
</div>

Back-end PhotoWatermark.aspx.cs Code:

protected void Page_Load(object sender, EventArgs e)
{
Button1.Click += Button1_Click;
}
void Button1_Click(object sender, EventArgs e)
{
//1、Create Canvas
System.Drawing.Image img = System.Drawing.Image.FromStream(FileUpload1.FileContent);
Graphics g = Graphics.FromImage(img);
//Watermark Style: Draw what
string a = "http://www.itnba.com";
//Font, Size
Font f = new Font("黑体", 30);
//Color
Brush b = new SolidBrush(Color.Red);
//0,0——Start position of watermark drawing
g.DrawString(a, f, b, 0, 0);
//Save Path
string path = "images"/" + FileUpload1.FileName;
img.Save(Server.MapPath(path));
//Display in the image control
Image1.ImageUrl = path;
}

Effect Display:

II. Image Verification Code

Front-end Photo Verification Code Code:

<form id="form1" runat="server">
<div>
Username:<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<br />
Password:<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
<br />
Captcha:<asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
<asp:Image ID="Image1" runat="server" ImageUrl="YZM.aspx" />
<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
<br />
<asp:Button ID="Button1" runat="server" Text="Button" />
</div>
</form>
</body>
</html>
<script type="text/javascript">
var aaa = 1;
document.getElementById("Image1").onclick = function () {
this.setAttribute("src", "YZM.aspx?id=" + aaa);
aaa++;
};
</script>

Link page "YZM.aspx"——No front-end code, the back-end code is:

protected void Page_Load(object sender, EventArgs e)
{
Random r = new Random();
string aaa = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
//Generate canvas
Bitmap img = new Bitmap(80, 30);
//Canvas background color mixture
List<Color> Clist = new List<Color>();
Clist.Add(Color.Yellow);
Clist.Add(Color.Green);
Clist.Add(Color.Blue);
Clist.Add(Color.Aqua);
Clist.Add(Color.Orange);
Clist.Add(Color.Pink);
Graphics g = Graphics.FromImage(img);
g.FillRectangle(new SolidBrush(Clist[r.Next(0, Clist.Count)]), 0, 0, 80, 30);
//Randomly generate the display code combination
string str = "";
for (int i = 0; i < 4; i}}++)
{
str += aaa.Substring(r.Next(0, aaa.Length), 1
}
Session["YZM"] = str;
Font f = new Font("黑体", 20);
Brush b = new SolidBrush(Color.Red);
//
g.DrawString(str, f, b, 10, 0);
//
for (int i = 0; i < r.Next(6, 20); i++)
{

Pen p = new Pen(bb, 1
 80), r.Next(0, 30), r.Next(0, 80), r.Next(0, 30));
}
//Save completed
img.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
Response.End();
}

Effect Display:

The above-mentioned methods of implementing image watermark and image verification code in Asp.net development webform introduced by the editor are for your reference. I hope it will be helpful to you. If you have any questions, please leave a message, and the editor will reply to you in time. At the same time, I would also like to express my heartfelt thanks to everyone for their support of the Yell Tutorial website!

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