 Although
VB provides a number of very flexible routines for identifying data on
the clipboard, the APIs provide a more extensive means to interrogate
the clipboard for the data types currently available.
EnumClipboardFormats can be used when identification of the current
clipboard data is required. Current clipboard data formats are stored in
an ordered list. To perform an enumeration of clipboard data formats, a
series of calls to EnumClipboardFormats is made; for each call, the
format parameter specifies an available clipboard format, and the
function returns the next available clipboard format.
Because EnumClipboardFormats enumerates formats in the order that they
were placed on the clipboard, a well behaved and well designed
application will add information to the clipboard in order from the most
descriptive clipboard format to the least descriptive format.
Similarly, a well designed application retrieves data for pasting using
the first clipboard format that can be handled, as that will be the most
descriptive clipboard format.
Windows performs automatic type conversions for certain clipboard
formats. In the case of such a format, EnumClipboardFormats enumerates
the specified format, then enumerates the formats to which it can be
converted. Because such conversion is a behind-the-scene operation,
there is no differentiation in the listings returned by
EnumClipboardFormats for a data format actually on the clipboard and one
that has been synthesised by Windows. With this conversion functionality
it is therefore possible, using the clipboard APIs, to request that
Windows provide data in a specific format (for example, when the data
format on the clipboard is CF_DIB you could request CF_PALETTE. If the
requested data is one of the supported Synthesized Clipboard Formats,
Windows will convert the data to the requested format if possible,
noting that some conversions are only available on later versions of
Windows). |
Option Explicit
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Copyright ©1996-2011 VBnet/Randy Birch, All Rights Reserved.
' Some pages may also contain other copyrights by the author.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Distribution: You can freely use this code in your own
' applications, but you may not reproduce
' or publish this code on any web site,
' online service, or distribute as source
' on any media without express permission.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'predefined clipboard formats
Private Const CF_TEXT As Long = 1
Private Const CF_BITMAP As Long = 2
Private Const CF_METAFILEPICT As Long = 3
Private Const CF_SYLK As Long = 4
Private Const CF_DIF As Long = 5
Private Const CF_TIFF As Long = 6
Private Const CF_OEMTEXT As Long = 7
Private Const CF_DIB As Long = 8
Private Const CF_PALETTE As Long = 9
Private Const CF_PENDATA As Long = 10
Private Const CF_RIFF As Long = 11
Private Const CF_WAVE As Long = 12
Private Const CF_UNICODETEXT As Long = 13
Private Const CF_ENHMETAFILE As Long = 14
Private Const CF_FILES As Long = 15
Private Const CF_HDROP As Long = CF_FILES
Private Const CF_LOCALE As Long = 16
Private Const CF_DIBV5 As Long = 17
Private Const CF_OWNERDISPLAY As Long = &H80
Private Const CF_DSPTEXT As Long = &H81
Private Const CF_DSPBITMAP As Long = &H82
Private Const CF_DSPMETAFILEPICT As Long = &H83
Private Const CF_DSPENHMETAFILE As Long = &H8E
Private Const ERROR_SUCCESS As Long = 0&
Private Const LB_SETTABSTOPS As Long = &H192
Private Declare Function OpenClipboard Lib "user32" _
(ByVal hwnd As Long) As Long
Private Declare Function EnumClipboardFormats Lib "user32" _
(ByVal wFormat As Long) 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 Declare Function CloseClipboard Lib "user32" () As Long
Private Declare Function lstrlenW Lib "kernel32" _
(ByVal lpString As Long) As Long
Private Declare Function SendMessage Lib "user32" _
Alias "SendMessageA" _
(ByVal hwnd As Long, _
ByVal wMsg As Long, _
ByVal wParam As Long, _
lParam As Any) As Long
Private Sub Form_Load()
ReDim TabStop(0) As Long
TabStop(0) = 90
With List1
.Move 200, 200, 7000, 2400
.Clear
Call SendMessage(.hwnd, LB_SETTABSTOPS, 0&, ByVal 0&)
Call SendMessage(.hwnd, LB_SETTABSTOPS, 1, TabStop(0))
.Refresh
End With
With Command1
.Move 200, List1.Top + List1.Height + 200, 2000, 345
.Caption = "EnumClipboardFormats"
End With
With Label1
.Move Command1.Left + Command1.Width + 200, Command1.Top + 50
.AutoSize = True
.Caption = ""
End With
End Sub
Private Sub Command1_Click()
Dim fmt As Long
List1.Clear
If OpenClipboard(0&) <> 0 Then
Do
'This may appear confusing. To start an
'enumeration of clipboard formats, set
'format to zero. When format is zero,
'EnumClipboardFormats retrieves the first
'available clipboard format. For subsequent
'calls during an enumeration the value from
'the result of the previous EnumClipboardFormats
'call is assigned to the format member.
fmt = EnumClipboardFormats(fmt)
If fmt > ERROR_SUCCESS Then
List1.AddItem GetCBTypeDesc(fmt)
End If
Loop Until fmt = ERROR_SUCCESS
Call CloseClipboard
End If 'OpenClipboard
Label1.Caption = List1.ListCount & " formats on clipboard."
End Sub
Private Function TrimNull(startstr As String) As String
TrimNull = Left$(startstr, lstrlenW(StrPtr(startstr)))
End Function
Private Function GetCBTypeDesc(ByVal nFormat As Long) As String
Dim cbBuff As Long
Dim buff As String
'descriptions of various clipboard formats
Select Case nFormat
Case CF_TEXT
buff = "CF_TEXT" & vbTab & "Null-terminated plain ANSI text in global memory block"
Case CF_BITMAP
buff = "CF_BITMAP" & vbTab & "A bitmap compatible with Windows 2.x"
Case CF_METAFILEPICT
buff = "CF_METAFILEPICT" & vbTab & "Windows metafile w/additional info " & _
"re how the metafile should be displayed"
Case CF_SYLK
buff = "CF_SYLK" & vbTab & "Symbolic Link (SYLK) - ASCII text format " & _
"used by older MS products)"
Case CF_DIF
buff = "CF_DIF" & vbTab & "Software Art's data interchange format " & _
"(DIF - ASCII text format)"
Case CF_TIFF
buff = "CF_TIFF" & vbTab & "Tagged Interchange File Format (TIF) data " & _
"in a global memory block"
Case CF_OEMTEXT
buff = "CF_OEMTEXT" & vbTab & "Similar to CF_TEXT but using the OEM " & _
"character set"
Case CF_DIB
buff = "CF_DIB" & vbTab & "Global memory block containing a Windows " & _
"device-independent bitmap (DIB) as a BITMAPINFO " & _
"structure followed by the bitmap bits"
Case CF_PALETTE
buff = "CF_PALETTE" & vbTab & "Color-palette handle (used in conjunction " & _
"with CF_DIB)"
Case CF_PENDATA
buff = "CF_PENDATA" & vbTab & "Data for the pen extensions to Windows"
Case CF_RIFF
buff = "CF_RIFF" & vbTab & "Resource interchange file format (RIFF) " & _
"data as a global memory block"
Case CF_WAVE
buff = "CF_WAVE" & vbTab & "Specific case of RIFF in which the contained " & _
"data is a waveform (sampled sound)"
Case CF_UNICODETEXT
buff = "CF_UNICODETEXT" & vbTab & "Unicode text format, available only " & _
"under Windows NT 4.0 or later"
Case CF_ENHMETAFILE
buff = "CF_ENHMETAFILE" & vbTab & "Handle to an enhanced metafile (HENHMETAFILE)"
Case CF_FILES, CF_HDROP
buff = "CF_FILES/CF_HDROP" & vbTab & "Handle that identifies a list " & _
"of files, such as a set of files dragged from " & _
"the Windows Explorer"
Case CF_LOCALE
buff = "CF_LOCALE" & vbTab & "Handle to the locale identifier associated " & _
"with text in the clipboard"
Case CF_DIBV5
buff = "CF_DIBV5" & vbTab & "Memory object containing BITMAPV5HEADER " & _
"structure followed by the bitmap color space " & _
"information and the bitmap bits (2000/XP only)"
Case CF_OWNERDISPLAY
buff = "CF_OWNERDISPLAY" & vbTab & "Owner-display format. The clipboard " & _
"owner must display and update the clipboard viewer"
Case CF_DSPTEXT
buff = "CF_DSPTEXT" & vbTab & "Text display format associated with a " & _
"private format"
Case CF_DSPBITMAP
buff = "CF_DSPBITMAP" & vbTab & "Bitmap display format associated with " & _
"a private format"
Case CF_DSPMETAFILEPICT
buff = "CF_DSPMETAFILEPICT" & vbTab & "Metafile-picture display format " & _
"associated with a private format"
Case CF_DSPENHMETAFILE
buff = "CF_DSPENHMETAFILE" & vbTab & "Enhanced metafile display format " & _
"associated with a private format"
Case Else
'try to get the data type as
'used by the clipboard
buff = Space$(256)
cbBuff = Len(buff)
If GetClipboardFormatName(nFormat, buff, cbBuff) = 0 Then
buff = "Unknown" & vbTab & CStr(nFormat)
Else
buff = "PRIVATE" & vbTab & TrimNull(buff)
End If
End Select
GetCBTypeDesc = buff
End Function
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