在VB允许你判别标准的、认可的格式是否在剪贴板上的同时，你无法判别是否有其它格式出现。所以，举例来说，如果你想知道剪贴板上是否包含来自Excel的数据(which always pastes at least its own customised format called ''''Wk1'''')，或者你想判别Rich Text格式是否可用以激活粘贴菜单时，你无法办到。 这则技巧告诉你如何判别当前剪贴板上所有可用的格式，包括自定义格式。 开始一个新项目，在窗体上放置一个Command和一个ListBox，然后加入下列代码：
Private Declare Function CountClipboardFormats Lib "USER32" () As Long Private Declare Function EnumClipboardFormats Lib "USER32" (ByVal wFormat As Long) As Long Private Declare Function OpenClipboard Lib "USER32" (ByVal hWnd As Long) As Long Private Declare Function CloseClipboard Lib "USER32" () As Long Private Declare Function GetClipboardFormatName Lib "USER32" Alias "GetClipboardFormatNameA" (ByVal wFormat As Long, ByVal lpString As String, ByVal nMaxCount As Long) As Long Private Enum EPredefinedClipboardFormatConstants [_First] = 1 CF_TEXT = 1 CF_BITMAP = 2 CF_METAFILEPICT = 3 CF_SYLK = 4 CF_DIF = 5 CF_TIFF = 6 CF_OEMTEXT = 7 CF_DIB = 8 CF_PALETTE = 9 CF_PENDATA = 10 CF_RIFF = 11 CF_WAVE = 12 CF_UNICODETEXT = 13 CF_ENHMETAFILE = 14 CF_HDROP = 15 CF_LOCALE = 16 CF_MAX = 17 [_Last] = 17 End Enum
Private Property Get FormatName(ByVal lFormatId As Long) As String ''''返回一个见剪贴板格式id的格式名： Dim lSize As Long Dim sBuf As String Dim lR As Long
If (lFormatId >= EPredefinedClipboardFormatConstants.[_First] And _ lFormatId <= EPredefinedClipboardFormatConstants.[_Last]) Then ''''对于预先定义的已知格式，我们自己给出格式名： Select Case lFormatId Case CF_TEXT FormatName = "Text" Case CF_BITMAP FormatName = "Bitmap Picture" Case CF_METAFILEPICT FormatName = "Meta-File Picture" Case CF_SYLK FormatName = "Microsoft Symbolic Link (SYLK) data." Case CF_DIF FormatName = "Software Arts'''' Data Interchange information." Case CF_TIFF = 6 FormatName = "Tagged Image File Format (TIFF) Picture" Case CF_OEMTEXT FormatName = "Text (OEM)" Case CF_DIB FormatName = "DIB Bitmap Picture" Case CF_PALETTE FormatName = "Colour Palette" Case CF_PENDATA FormatName = "Pen Data" Case CF_RIFF FormatName = "RIFF Audio data" Case CF_WAVE FormatName = "Wave File" Case CF_UNICODETEXT FormatName = "Text (Unicode)" Case CF_ENHMETAFILE FormatName = "Enhanced Meta-File Picture" Case CF_HDROP FormatName = "File List" Case CF_LOCALE FormatName = "Text Locale Identifier" End Select Else ''''对于自定义格式，我们可以向剪贴板要注册过的名字： lSize = 255 sBuf = String$(lSize, 0) lR = GetClipboardFormatName(lFormatId, sBuf, lSize) If (lR <> 0) Then FormatName = Left$(sBuf, lR) End If End If End Property
Private Sub Command1_Click() Dim lR As Long Dim iCount As Long
List1.Clear If (OpenClipboard(Me.hWnd)) Then lR = EnumClipboardFormats(0) If (lR <> 0) Then Do iCount = iCount + 1 List1.AddItem FormatName(lR) List1.ItemData(List1.NewIndex) = lR lR = EnumClipboardFormats(lR) Loop While lR <> 0 End If End If CloseClipboard End Sub
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