> Greetings,
> I am a newbie who made a little program that whenever I get new text
> into my clipboard it pastes that text into a listbox.  I did this by
> checking the clipboard by a timer set to 1 second.  I was told that
> there was a better way to do this than the timer.  I was told about
> subclassing the form to recieve a message that the clipboard has
> changed.  For the last several days I have been reading about
> subclassing, and SendMessage, etc. and am now more confused than
> ever:).  Not sure of which functions to use or how to access the
> cliboard data once I am informed of a change. Does anyone have any
> leads about how to do this?  What api functions I might need?  ANd
> basically a description in simple english of how it is done so that I
> might read the right references to figure it out.  Maybe a good site
> with a good description of how to subclass.  Any takers?
> Mark

> Greetings,
> I am a newbie who made a little program that whenever I get new text
> into my clipboard it pastes that text into a listbox.  I did this by
> checking the clipboard by a timer set to 1 second.  I was told that
> there was a better way to do this than the timer.  I was told about
> subclassing the form to recieve a message that the clipboard has
> changed.  For the last several days I have been reading about
> subclassing, and SendMessage, etc. and am now more confused than
> ever:).  Not sure of which functions to use or how to access the
> cliboard data once I am informed of a change. Does anyone have any
> leads about how to do this?  What api functions I might need?  ANd
> basically a description in simple english of how it is done so that I
> might read the right references to figure it out.  Maybe a good site
> with a good description of how to subclass.  Any takers?
> Mark
>=20

>This is a multi-part message in MIME format.

>------=_NextPart_000_00D7_01BF48DF.9C2D8900
>Content-Type: text/plain;
>    charset="iso-8859-1"
>Content-Transfer-Encoding: quoted-printable

>Subclassing is a very touchy subject and it is not a good idea for =
>somebody new to programming to jump right into such a topic without =
>first becoming familiar with the language. For example, when =
>subclassing, you cannot use the Stop button or the End statement and it =
>is very difficult to debug the application. If there is a bug in your =
>application, your program will probably crash taking the IDE with it. =
>Sticking with the one second timer really isn't such a bad idea, unless =
>you are working with large amounts of text. But I will still give you a =
>pointer to checking the clipboard. Add the following code to a module:
>Public Declare Function SetClipboardViewer Lib "user32.dll" (ByVal hWnd =
>As Long) As Long
>Public Declare Function ChangeClipboardChain Lib "user32.dll" (ByVal =
>hWndRemove As Long, ByVal hWndNext As Long) As Long
>Public Declare Function SendMessageA Lib "user32.dll" (ByVal hWnd As =
>Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As =
>Long
>Public Declare Function SetWindowLongA Lib "user32.dll" (ByVal hWnd As =
>Long, ByVal nIndex As Integer, ByVal dwNewValue As Long) As Long
>Public Declare Function CallWindowProcA Lib "user32.dll" (ByVal =
>lpfnWndProc As Long, ByVal hWnd As Long, ByVal uMsg As Long, ByVal =
>wParam As Long, ByVal lParam As Long) As Long

>Public Const WM_CHANGECBCHAIN =3D &H30D
>Public Const WM_DRAWCLIPBOARD =3D &H308
>Public Const GWL_WNDPROC =3D -4

>Public hWndNext As Long
>Public lpfnWndProc As Long
>Public Function WndProc(ByVal hWnd As Long, ByVal uMsg As Long, ByVal =
>wParam As Long, ByVal lParam As Long) As Long
>    Select Case uMsg
>            Case WM_DRAWCLIPBOARD
>                    If Clipboard.GetFormat(vbCFText) Then
>                            frmMain.lstList.AddItem Clipboard.GetText(vbCFText)
>                    End If
>                    SendMessageA hWndNext, uMsg, wParam, lParam
>                    WndProc =3D 0
>                    Exit Function
>            Case WM_CHANGECBCHAIN
>                    If wParam =3D hWndNext Then=20
>                            lParam =3D hWndNext
>                    End If
>                    SendMessageA hWndNext, uMsg, wParam, lParam
>                    WndProc =3D 0
>                    Exit Function
>            Case Else
>                    WndProc =3D CallWindowProcA(lpfnWndProc, hWnd, uMsg, wParam, lParam)
>                    Exit Function
>    End Select
>End Function
>And add the following code to a form named frmMain with a list box =
>control called lstList on it:

>Private Sub Form_Load()
>    lpfnWndProc =3D SetWindowLongA(hWnd, GWL_WNDPROC, AddressOf WndProc)
>    hWndNext =3D SetClipboardViewer(hWnd)
>End Sub
>Now, subclassing is when you handle the work that VB does behind the =
>scenes. When Windows wants to let your program know that an event has =
>occured, it sends your window a message. This message is sent to the =
>window procedure of your window, which is basically a function. =
>Normally, VisualBasic provides a window procedure and when it is sent a =
>message, like WM_SIZE, it causes the form to trigger a Form_Resize =
>event. But sometimes you need to listen for messages that VisualBasic =
>does not automatically send to the form. For example, the WM_MOVE =
>message is sent to the window procedure when the window is being moved, =
>but you will notice that there is no VB event triggered for this =
>message, so if you want to check when the form is being moved, you have =
>to subclass the form and listen for a WM_MOVE message. In the above =
>example, the window listens for two different messages, =
>WM_CHANGECBCHAIN, and WM_DRAWCLIPBOARD these messages aren't usually =
>sent to the window unless you have set it up as a clipboard listener, as =
>is done in the second line of the Form_Load event. The first line of =
>this procedure is to actually do the subclassing of the form. It sets =
>the window procedure to the function WndProc and stores the last =
>function in a variable called lpfnWndProc. The function listens for =
>certain messages, such as WM_CHANGECBCHAIN, and takes appropriate =
>action. If a message is sent to it that it does not want any special =
>action taken for, such as WM_SIZE, the default action should be taken. =
>This is done by sending the message to the old window procedure, which =
>has been stored in the variable lpfnWndProc. The WM_DRAWCLIPBOARD =
>message is sent to the window when the clipboard contents have changed, =
>so the new text is added to the list box. The WM_CHANGECBCHAIN also has =
>to be processed because your window has been registered in a list of =
>windows that watch the clipboard. You have to pass the message to the =
>next window in the chain when the clipboard is updated, so you have to =
>process the WM_CHANGECBCHAIN when a window is removed from the chain. If =
>the window is the one after yours, you have to pass the message to a =
>different window because the one you normally send it to is gone. You =
>can pick through this code and see what you make of it, but this should, =
>by no means, be used as a complete guide to subclassing. This might, =
>perhaps give you a better understanding of subclassing, or it may just =
>confuse you even more.

>--=20
>Hope this helps,
>Jason Bouzane

>> Greetings,
>> I am a newbie who made a little program that whenever I get new text
>> into my clipboard it pastes that text into a listbox.  I did this by
>> checking the clipboard by a timer set to 1 second.  I was told that
>> there was a better way to do this than the timer.  I was told about
>> subclassing the form to recieve a message that the clipboard has
>> changed.  For the last several days I have been reading about
>> subclassing, and SendMessage, etc. and am now more confused than
>> ever:).  Not sure of which functions to use or how to access the
>> cliboard data once I am informed of a change. Does anyone have any
>> leads about how to do this?  What api functions I might need?  ANd
>> basically a description in simple english of how it is done so that I
>> might read the right references to figure it out.  Maybe a good site
>> with a good description of how to subclass.  Any takers?
>> Mark
>>=20

>------=_NextPart_000_00D7_01BF48DF.9C2D8900
>Content-Type: text/html;
>    charset="iso-8859-1"
>Content-Transfer-Encoding: quoted-printable

><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
><HTML><HEAD>
><META http-equiv=3DContent-Type content=3D"text/html; =
>charset=3Diso-8859-1">
><META content=3D"MSHTML 5.50.3825.1300" name=3DGENERATOR>
><STYLE></STYLE>
></HEAD>
><BODY>
><DIV><FONT face=3DArial size=3D2>Subclassing is a very touchy subject =
>and it is not=20
>a good idea for somebody new to programming to jump right into such a =
>topic=20
>without first becoming familiar with the language. For example, when=20
>subclassing, you cannot use the Stop button or the End statement and it =
>is very=20
>difficult to debug the application. If there is a bug in your =
>application, your=20
>program will probably crash taking the IDE with it. Sticking with the =
>one second=20
>timer really isn't such a bad idea, unless you are working with large =
>amounts of=20
>text. But I will still give you a pointer to checking the clipboard. Add =
>the=20
>following code to a module:</FONT></DIV><PRE>Public Declare Function =
>SetClipboardViewer Lib "user32.dll" (ByVal hWnd As Long) As Long
>Public Declare Function ChangeClipboardChain Lib "user32.dll" (ByVal =
>hWndRemove As Long, ByVal hWndNext As Long) As Long
>Public Declare Function SendMessageA Lib "user32.dll" (ByVal hWnd As =
>Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As =
>Long
>Public Declare Function SetWindowLongA Lib "user32.dll" (ByVal hWnd As =
>Long, ByVal nIndex As Integer, ByVal dwNewValue As Long) As Long
>Public Declare Function CallWindowProcA Lib "user32.dll" (ByVal =
>lpfnWndProc As Long, ByVal hWnd As Long, ByVal uMsg As Long, ByVal =
>wParam As Long, ByVal lParam As Long) As Long

>Public Const WM_CHANGECBCHAIN =3D &H30D
>Public Const WM_DRAWCLIPBOARD =3D &H308
>Public Const GWL_WNDPROC =3D -4

>Public hWndNext As Long
>Public lpfnWndProc As Long
>Public Function WndProc(ByVal hWnd As Long, ByVal uMsg As Long, ByVal =
>wParam As Long, ByVal lParam As Long) As Long
>    Select Case uMsg
>            Case WM_DRAWCLIPBOARD
>                    If Clipboard.GetFormat(vbCFText) Then
>                            frmMain.lstList.AddItem Clipboard.GetText(vbCFText)
>                    End If
>                    SendMessageA hWndNext, uMsg, wParam, lParam
>                    WndProc =3D 0
>                    Exit Function
>            Case WM_CHANGECBCHAIN
>                    If wParam =3D hWndNext Then=20
>                            lParam =3D hWndNext
>                    End If
>                    SendMessageA hWndNext, uMsg, wParam, lParam
>                    WndProc =3D 0
>                    Exit Function
>            Case Else
>                    WndProc =3D CallWindowProcA(lpfnWndProc, hWnd, uMsg, wParam, lParam)
>                    Exit Function
>    End Select
>End Function</PRE>
><DIV><FONT face=3DArial size=3D2>And add the following code to a form =
>named frmMain=20
>with a list box control called lstList on it:</FONT></DIV>
><DIV><FONT face=3DArial size=3D2></FONT>?</DIV><PRE>Private Sub =
>Form_Load()
>    lpfnWndProc =3D SetWindowLongA(hWnd, GWL_WNDPROC, AddressOf WndProc)
>    hWndNext =3D SetClipboardViewer(hWnd)
>End Sub</PRE>
><DIV><FONT face=3DArial size=3D2>Now, subclassing is when you handle the =
>work that=20
>VB does behind the scenes. When Windows wants to let your program know =
>that an=20
>event has occured, it sends your window a message. This message is sent =
>to the=20
>window procedure of your window, which is basically a function. =
>Normally,=20
>VisualBasic provides a window procedure and when it is

>This is a multi-part message in MIME format.

>------=_NextPart_000_00D7_01BF48DF.9C2D8900
>Content-Type: text/plain;
>       charset="iso-8859-1"
>Content-Transfer-Encoding: quoted-printable

>Subclassing is a very touchy subject and it is not a good idea for =
>somebody new to programming to jump right into such a topic without =
>first becoming familiar with the language. For example, when =
>subclassing, you cannot use the Stop button or the End statement and it =
>is very difficult to debug the application. If there is a bug in your =
>application, your program will probably crash taking the IDE with it. =
>Sticking with the one second timer really isn't such a bad idea, unless =
>you are working with large amounts of text. But I will still give you a =
>pointer to checking the clipboard. Add the following code to a module:
>Public Declare Function SetClipboardViewer Lib "user32.dll" (ByVal hWnd =
>As Long) As Long
>Public Declare Function ChangeClipboardChain Lib "user32.dll" (ByVal =
>hWndRemove As Long, ByVal hWndNext As Long) As Long
>Public Declare Function SendMessageA Lib "user32.dll" (ByVal hWnd As =
>Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As =
>Long
>Public Declare Function SetWindowLongA Lib "user32.dll" (ByVal hWnd As =
>Long, ByVal nIndex As Integer, ByVal dwNewValue As Long) As Long
>Public Declare Function CallWindowProcA Lib "user32.dll" (ByVal =
>lpfnWndProc As Long, ByVal hWnd As Long, ByVal uMsg As Long, ByVal =
>wParam As Long, ByVal lParam As Long) As Long

>Public Const WM_CHANGECBCHAIN =3D &H30D
>Public Const WM_DRAWCLIPBOARD =3D &H308
>Public Const GWL_WNDPROC =3D -4

>Public hWndNext As Long
>Public lpfnWndProc As Long
>Public Function WndProc(ByVal hWnd As Long, ByVal uMsg As Long, ByVal =
>wParam As Long, ByVal lParam As Long) As Long
>       Select Case uMsg
>               Case WM_DRAWCLIPBOARD
>                       If Clipboard.GetFormat(vbCFText) Then
>                               frmMain.lstList.AddItem

>                       End If
>                       SendMessageA hWndNext, uMsg, wParam, lParam
>                       WndProc =3D 0
>                       Exit Function
>               Case WM_CHANGECBCHAIN
>                       If wParam =3D hWndNext Then=20
>                               lParam =3D hWndNext
>                       End If
>                       SendMessageA hWndNext, uMsg, wParam, lParam
>                       WndProc =3D 0
>                       Exit Function
>               Case Else
>                       WndProc =3D CallWindowProcA(lpfnWndProc, hWnd, uMsg,
wParam, lParam)
>                       Exit Function
>       End Select
>End Function
>And add the following code to a form named frmMain with a list box =
>control called lstList on it:

>Private Sub Form_Load()
>       lpfnWndProc =3D SetWindowLongA(hWnd, GWL_WNDPROC, AddressOf WndProc)
>       hWndNext =3D SetClipboardViewer(hWnd)
>End Sub
>Now, subclassing is when you handle the work that VB does behind the =
>scenes. When Windows wants to let your program know that an event has =
>occured, it sends your window a message. This message is sent to the =
>window procedure of your window, which is basically a function. =
>Normally, VisualBasic provides a window procedure and when it is sent a =
>message, like WM_SIZE, it causes the form to trigger a Form_Resize =
>event. But sometimes you need to listen for messages that VisualBasic =
>does not automatically send to the form. For example, the WM_MOVE =
>message is sent to the window procedure when the window is being moved, =
>but you will notice that there is no VB event triggered for this =
>message, so if you want to check when the form is being moved, you have =
>to subclass the form and listen for a WM_MOVE message. In the above =
>example, the window listens for two different messages, =
>WM_CHANGECBCHAIN, and WM_DRAWCLIPBOARD these messages aren't usually =
>sent to the window unless you have set it up as a clipboard listener, as =
>is done in the second line of the Form_Load event. The first line of =
>this procedure is to actually do the subclassing of the form. It sets =
>the window procedure to the function WndProc and stores the last =
>function in a variable called lpfnWndProc. The function listens for =
>certain messages, such as WM_CHANGECBCHAIN, and takes appropriate =
>action. If a message is sent to it that it does not want any special =
>action taken for, such as WM_SIZE, the default action should be taken. =
>This is done by sending the message to the old window procedure, which =
>has been stored in the variable lpfnWndProc. The WM_DRAWCLIPBOARD =
>message is sent to the window when the clipboard contents have changed, =
>so the new text is added to the list box. The WM_CHANGECBCHAIN also has =
>to be processed because your window has been registered in a list of =
>windows that watch the clipboard. You have to pass the message to the =
>next window in the chain when the clipboard is updated, so you have to =
>process the WM_CHANGECBCHAIN when a window is removed from the chain. If =
>the window is the one after yours, you have to pass the message to a =
>different window because the one you normally send it to is gone. You =
>can pick through this code and see what you make of it, but this should, =
>by no means, be used as a complete guide to subclassing. This might, =
>perhaps give you a better understanding of subclassing, or it may just =
>confuse you even more.

>--=20
>Hope this helps,
>Jason Bouzane

>> Greetings,
>> I am a newbie who made a little program that whenever I get new text
>> into my clipboard it pastes that text into a listbox.  I did this by
>> checking the clipboard by a timer set to 1 second.  I was told that
>> there was a better way to do this than the timer.  I was told about
>> subclassing the form to recieve a message that the clipboard has
>> changed.  For the last several days I have been reading about
>> subclassing, and SendMessage, etc. and am now more confused than
>> ever:).  Not sure of which functions to use or how to access the
>> cliboard data once I am informed of a change. Does anyone have any
>> leads about how to do this?  What api functions I might need?  ANd
>> basically a description in simple english of how it is done so that I
>> might read the right references to figure it out.  Maybe a good site
>> with a good description of how to subclass.  Any takers?
>> Mark
>>=20

>------=_NextPart_000_00D7_01BF48DF.9C2D8900
>Content-Type: text/html;
>       charset="iso-8859-1"
>Content-Transfer-Encoding: quoted-printable

><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
><HTML><HEAD>
><META http-equiv=3DContent-Type content=3D"text/html; =
>charset=3Diso-8859-1">
><META content=3D"MSHTML 5.50.3825.1300" name=3DGENERATOR>
><STYLE></STYLE>
></HEAD>
><BODY>
><DIV><FONT face=3DArial size=3D2>Subclassing is a very touchy subject =
>and it is not=20
>a good idea for somebody new to programming to jump right into such a =
>topic=20
>without first becoming familiar with the language. For example, when=20
>subclassing, you cannot use the Stop button or the End statement and it =
>is very=20
>difficult to debug the application. If there is a bug in your =
>application, your=20
>program will probably crash taking the IDE with it. Sticking with the =
>one second=20
>timer really isn't such a bad idea, unless you are working with large =
>amounts of=20
>text. But I will still give you a pointer to checking the clipboard. Add =
>the=20
>following code to a module:</FONT></DIV><PRE>Public Declare Function =
>SetClipboardViewer Lib "user32.dll" (ByVal hWnd As Long) As Long
>Public Declare Function ChangeClipboardChain Lib "user32.dll" (ByVal =
>hWndRemove As Long, ByVal hWndNext As Long) As Long
>Public Declare Function SendMessageA Lib "user32.dll" (ByVal hWnd As =
>Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As =
>Long
>Public Declare Function SetWindowLongA Lib "user32.dll" (ByVal hWnd As =
>Long, ByVal nIndex As Integer, ByVal dwNewValue As Long) As Long
>Public Declare Function CallWindowProcA Lib "user32.dll" (ByVal =
>lpfnWndProc As Long, ByVal hWnd As Long, ByVal uMsg As Long, ByVal =
>wParam As Long, ByVal lParam As Long) As Long

>Public Const WM_CHANGECBCHAIN =3D &amp;H30D
>Public Const WM_DRAWCLIPBOARD =3D &amp;H308
>Public Const GWL_WNDPROC =3D -4

>Public hWndNext As Long
>Public lpfnWndProc As Long
>Public Function WndProc(ByVal hWnd As Long, ByVal uMsg As Long, ByVal =
>wParam As Long, ByVal lParam As Long) As Long
>       Select Case uMsg
>               Case WM_DRAWCLIPBOARD
>                       If Clipboard.GetFormat(vbCFText) Then
>                               frmMain.lstList.AddItem

>                       End If
>                       SendMessageA hWndNext, uMsg, wParam, lParam
>                       WndProc =3D 0
>                       Exit Function
>               Case WM_CHANGECBCHAIN
>                       If wParam =3D hWndNext Then=20
>                               lParam =3D hWndNext
>                       End If
>                       SendMessageA hWndNext, uMsg, wParam, lParam
>                       WndProc =3D 0
>                       Exit Function
>               Case Else
>                       WndProc =3D CallWindowProcA(lpfnWndProc, hWnd, uMsg,
wParam, lParam)
>                       Exit Function
>       End Select
>End Function</PRE>
><DIV><FONT face=3DArial