技术文章 > 生成图象验证码函数

生成图象验证码函数

2018-12-12 08:31

文档管理软件,文档管理系统,知识管理系统,档案管理系统的技术资料:

““生成图象验证码函数

Sub ValidateCode(ByVal VNum As String)

Dim Img As System.Drawing.Bitmap

Dim g As Graphics

Dim ms As System.IO.MemoryStream

““gheight为图片宽度,根据字符长度自动更改图片宽度

Dim gheight As Integer = Int(Len(VNum) * 11.5)

““创建一个宽度已定,高度为20的图像

Img = New Bitmap(gheight, 20)

g = Graphics.FromImage(Img)

““在矩形内绘制字串(字串,字体,画笔颜色,左上x.左上y)

g.DrawString(VNum, (New Font(“宋体“, 12)), (New SolidBrush(Color.Blue)), 3, 3)

ms = New System.IO.MemoryStream

Img.Save(ms, System.Drawing.Imaging.ImageFormat.Png)

Response.ClearContent() ““需要输出图象信息 要修改HTTP头

Response.ContentType = “image/Png“

Response.BinaryWrite(ms.ToArray())

g.Dispose()

Img.Dispose()

Response.End()

End Sub