在 VBScript 中将十六进制字符串(图像)转换为 base64(用于浏览器渲染) [英] Convert hex string (image) to base64 (for browser rendering) in VBScript

问题描述

我有一个输出 .bmp 验证码图像的脚本.

I have a script that outputs a .bmp captcha image.

图片为16进制，转成二进制后通过response.binaryWrite chrB(CByte(myHexImage))(作为图片mime type = bmp)发送给浏览器

The image is built in hexadecimal, and converted to binary and sent to the browser via response.binaryWrite chrB(CByte(myHexImage)) (as an image mime type = bmp)

我希望选择摆脱这种情况(更改 mime 类型等)，而只向输出发送一些内容，如下所示:

I want the option to move away from that (changing mime type, etc) and toward just sending something to the output like this:

data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD/2 ...

(除了我的图片是 BMP)

(except that my images are BMP)

是否有一种快速简便的方法可以在 vbscript 中将该十六进制或二进制转换为 base64?这是我现在实施的内容的片段，如上所述.

Is there a quick and easy way to convert that hex or binary to base64 in vbscript? Here is a snippet of what I have implmented now as described above.

如何更改此设置以便将有效的十六进制格式(然后我可以轻松转换为 base64)或直接将 base64 输出到屏幕?

how can I change this so I output, to the screen, valid hex format (which i can then easily convert to base64) or base64 directly?

    Dim sBmpEndLine, sBmpInfoHeader, sBmpHeader, sTmpHex

    If (m_iBmpWidth Mod 4) <> 0 Then
        sBmpEndLine = string((4 - (m_iBmpWidth Mod 4)) * 2, "0")
    Else
        sBmpEndLine = vbNullString
    End If

    sBmpInfoHeader = array("28000000", "00000000", "00000000", "0100", "0800", "00000000", "00000000", "120B0000", "120B0000", "00000000", "00000000")
    sBmpInfoHeader(1) = formatHex(hex(m_iBmpWidth), 4, 0, True)
    sBmpInfoHeader(2) = formatHex(hex(m_iBmpHeight), 4, 0, True)
    sBmpInfoHeader(6) = formatHex(hex((m_iBmpHeight * m_iBmpWidth) + (m_iBmpHeight * (len(sBmpEndLine) / 2))), 4, 0, True)
    sBmpInfoHeader(9) = formatHex(hex(len(m_sBmpColorMap) / 8), 4, 0, True)
    sBmpInfoHeader(10) = sBmpInfoHeader(9)
    sBmpHeader = array("424D", "00000000", "0000", "0000", "00000000")
    sBmpHeader(1) = formatHex(hex((len(join(sBmpHeader, "")) / 2) + (len(join(sBmpInfoHeader, "")) / 2) + (len(m_sBmpColorMap) / 2) + (m_iBmpHeight * m_iBmpWidth) + (m_iBmpHeight * (len(sBmpEndLine) / 2))), 4, 0, True)
    sBmpHeader(4) = formatHex(hex((len(join(sBmpHeader, "")) / 2) + (len(join(sBmpInfoHeader, "")) / 2) + (len(m_sBmpColorMap) / 2)), 4, 0, True)

    sendHex(join(sBmpHeader, ""))
    sendHex(join(sBmpInfoHeader, ""))
    sendHex(m_sBmpColorMap)
    For y = m_iBmpHeight To 1 Step -1
        For x = 1 To m_iBmpWidth
            sTmpHex = m_aBitmap(y, x)
            If sTmpHex = vbNullString Then
                sendHex(m_sBgColor)
            Else
                sendHex(sTmpHex)
            End If
        Next
        sendHex(sBmpEndLine)
    Next

    Response.Flush

这里是 sendHex() 函数:

Private Sub sendHex(valHex)

    Dim iCntHex
    For iCntHex = 1 To len(valHex) Step 2
        'Response.BinaryWrite chrB(CByte("&H" & mid(valHex, iCntHex, 2)))
        response.Write "&H" & mid(valHex, iCntHex, 2)
    Next
End Sub

推荐答案

我能够让它工作.方法如下.

I was able to get this working. Here is how.

在 sendHex 中，我删除了 &H 部分，并将我的字符串包裹在 hex() 中:

In sendHex, I removed the &H portion, and wrapped my string in hex():

Private Sub sendHex(valHex)
    Dim iCntHex
    For iCntHex = 1 To len(valHex) Step 2
    If len( mid(valHex, iCntHex, 2)) = 1 Then 
        response.write "0"
    end if 
    response.write mid(valHex, iCntHex, 2)
    Next
End Sub

这会导致这样的字符串输出(以 2 个十六进制字符的字节字符串形式):

This results in a string output like this (in byte strings of 2 hexidecimal chars):

424d1e050000000000003e00000028000000340000001800000001000

然后我可以将正确的十六进制字符串转储到 HEX 到 base64 函数如下(不是由我写的，而是由 Richard Mueller - http://www.rlmueller.net/Base64.htm)

I can then dump that proper hex string into a HEX to base64 function as follows (not written by me, but rather, by Richard Mueller - http://www.rlmueller.net/Base64.htm)

Function HexToBase64(strHex)
    ' Function to convert a hex string into a base64 encoded string.
    ' Constant B64 has global scope.
    Dim lngValue, lngTemp, lngChar, intLen, k, j, strWord, str64, intTerm

    intLen = Len(strHex)

    ' Pad with zeros to multiple of 3 bytes.
    intTerm = intLen Mod 6
    If (intTerm = 4) Then
        strHex = strHex & "00"
        intLen = intLen + 2
    End If
    If (intTerm = 2) Then
        strHex = strHex & "0000"
        intLen = intLen + 4
    End If

    ' Parse into groups of 3 hex bytes.
    j = 0
    strWord = ""
    HexToBase64 = ""
    For k = 1 To intLen Step 2
        j = j + 1
        strWord = strWord & Mid(strHex, k, 2)
        If (j = 3) Then
            ' Convert 3 8-bit bytes into 4 6-bit characters.
            lngValue = CCur("&H" & strWord)

            lngTemp = Fix(lngValue / 64)
            lngChar = lngValue - (64 * lngTemp)
            str64 = Mid(B64, lngChar + 1, 1)
            lngValue = lngTemp

            lngTemp = Fix(lngValue / 64)
            lngChar = lngValue - (64 * lngTemp)
            str64 = Mid(B64, lngChar + 1, 1) & str64
            lngValue = lngTemp

            lngTemp = Fix(lngValue / 64)
            lngChar = lngValue - (64 * lngTemp)
            str64 = Mid(B64, lngChar + 1, 1) & str64

            str64 = Mid(B64, lngTemp + 1, 1) & str64

            HexToBase64 = HexToBase64 & str64
            j = 0
            strWord = ""
        End If
    Next
    ' Account for padding.
    If (intTerm = 4) Then
        HexToBase64 = Left(HexToBase64, Len(HexToBase64) - 1) & "="
    End If
    If (intTerm = 2) Then
        HexToBase64 = Left(HexToBase64, Len(HexToBase64) - 2) & "=="
    End If

End Function

这会将上述内容转换为 base64，我可以使用这样的输出(例如在浏览器 url 栏中)将其作为图像查看:

This converts the above to base64, and I can use the output like this (e.g. in a browser url bar) to view it as an image:

data:image/bmp;base64,Qk0eBQAAAAAAAD4AAAAo...

这篇关于在 VBScript 中将十六进制字符串(图像)转换为 base64(用于浏览器渲染)的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！