vba - 使用存储在 CustomXMLPart 中的 base64 数据作为 Office 中的图像

Question

作为有关使用存储在功能区按钮上的 Excel 文件中的图像的问题的后续行动：

是否可以使用以 base64 编码字符串存储在 CustomXMLPart/CustomXMLNode 中的图像作为 Office 文档中的图像，而无需先将其保存到磁盘并重新加载？

我想使用图像的地方将一个IPictureDisp对象作为参数（就像LoadPicture函数返回一样，但这只会从磁盘加载文件）。

Answer 1

首先，您需要将 base_64 数据转换为字节数组：

Private Function decodeBase64(ByVal strData As String) As Byte()
    Dim objXML As MSXML2.DOMDocument
    Dim objNode As MSXML2.IXMLDOMElement

    Set objXML = New MSXML2.DOMDocument
    Set objNode = objXML.createElement("b64")
    objNode.DataType = "bin.base64"
    objNode.Text = strData
    decodeBase64 = objNode.nodeTypedValue

    Set objNode = Nothing
    Set objXML = Nothing
End Function

来自：http ://thydzik.com/vb6vba-functions-to-convert-binary-string-to-base64-string/

然后您可以将其加载到内存中并使用有关此主题的信息创建您的 IPictureDisp：http ://www.xtremevbtalk.com/showthread.php?t=137857

Type GUID
  Data1 As Long
  Data2 As Integer
  Data3 As Integer
  Data4(7) As Byte
End Type

Private Declare Function CreateStreamOnHGlobal Lib "ole32.dll" (ByRef hGlobal As Any,     ByVal fDeleteOnResume As Long, ByRef ppstr As Any) As Long
Private Declare Function OleLoadPicture Lib "olepro32.dll" (ByVal lpStream As IUnknown, ByVal lSize As Long, ByVal fRunMode As Long, ByRef riid As GUID, ByRef lplpObj As Any) As Long
Private Declare Function CLSIDFromString Lib "ole32.dll" (ByVal lpsz As Long, ByRef pclsid As GUID) As Long

Private Const SIPICTURE As String = "{7BF80980-BF32-101A-8BBB-00AA00300CAB}"

Public Function PictureFromArray(ByRef b() As Byte) As IPicture
  On Error GoTo errorhandler

  Dim istrm As IUnknown
  Dim tGuid As GUID

  If Not CreateStreamOnHGlobal(b(LBound(b)), False, istrm) Then
    CLSIDFromString StrPtr(SIPICTURE), tGuid
    OleLoadPicture istrm, UBound(b) - LBound(b) + 1, False, tGuid, PictureFromArray
  End If

  Set istrm = Nothing
  Exit Function
errorhandler:
  Debug.Print "Could not convert to IPicture!"
End Function