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Using a WndProc overriderespond to scrolling events (to keep 2 listviews scrolling in sync). My user control includes an Overrides of WndProc (I've attached the code at the end of this mail). Is it possible to 'disable' this override until I need it - it's just when I populate the ListViews this sub is called repeatadly. What I'd like to do is populate the listviews and then 'enable' this override to catch and trigger a scrolling event. tia Rob Protected Overrides Sub WndProc(ByRef m As Message) MyBase.WndProc(m) If m.Msg = WM_VSCROLL OrElse m.Msg = WM_MOUSEWHEEL Then RaiseEvent VerticalScroll(Nothing, Nothing) ElseIf m.Msg = WM_NOTIFY Then Dim lParam As NMHDR = CType(m.GetLParam(GetType(NMHDR)), NMHDR) If lParam.code = NM_HOVER Then OnMouseHover(EventArgs.Empty) End If ElseIf m.Msg = LVM_ENSUREVISIBLE Then RaiseEvent VerticalScroll(Nothing, Nothing) End If End Sub Use a boolean variable or property.
Private MyBool as boolean = false Protected Overrides Sub WndProc(ByRef m As Message) MyBase.WndProc(m) if MyBool = true then If m.Msg = WM_VSCROLL OrElse m.Msg = WM_MOUSEWHEEL Then RaiseEvent VerticalScroll(Nothing, Nothing) ElseIf m.Msg = WM_NOTIFY Then Dim lParam As NMHDR = CType(m.GetLParam(GetType(NMHDR)), NMHDR) If lParam.code = NM_HOVER Then OnMouseHover(EventArgs.Empty) End If ElseIf m.Msg = LVM_ENSUREVISIBLE Then RaiseEvent VerticalScroll(Nothing, Nothing) End If end if End Sub Rob wrote: Show quoteHide quote > I've constructed a user control inherited from ListView so I can handle and > respond to scrolling events (to keep 2 listviews scrolling in sync). > > My user control includes an Overrides of WndProc (I've attached the code at > the end of this mail). Is it possible to 'disable' this override until I need > it - it's just when I populate the ListViews this sub is called repeatadly. > What I'd like to do is populate the listviews and then 'enable' this override > to catch and trigger a scrolling event. > > tia > > Rob > > Protected Overrides Sub WndProc(ByRef m As Message) > MyBase.WndProc(m) > If m.Msg = WM_VSCROLL OrElse m.Msg = WM_MOUSEWHEEL Then > RaiseEvent VerticalScroll(Nothing, Nothing) > ElseIf m.Msg = WM_NOTIFY Then > Dim lParam As NMHDR = CType(m.GetLParam(GetType(NMHDR)), NMHDR) > If lParam.code = NM_HOVER Then > OnMouseHover(EventArgs.Empty) > End If > ElseIf m.Msg = LVM_ENSUREVISIBLE Then > RaiseEvent VerticalScroll(Nothing, Nothing) > End If > End Sub Thanks - I was really wondering if there was an equivalent to the
Addhandler/Removehandler event approach to bypass the call to the sub completely (until I was ready). r Show quoteHide quote "rowe_newsgroups" wrote: > Use a boolean variable or property. > > Private MyBool as boolean = false > > Protected Overrides Sub WndProc(ByRef m As Message) > MyBase.WndProc(m) > if MyBool = true then > If m.Msg = WM_VSCROLL OrElse m.Msg = WM_MOUSEWHEEL Then > RaiseEvent VerticalScroll(Nothing, Nothing) > ElseIf m.Msg = WM_NOTIFY Then > Dim lParam As NMHDR = CType(m.GetLParam(GetType(NMHDR)), > NMHDR) > If lParam.code = NM_HOVER Then > OnMouseHover(EventArgs.Empty) > End If > ElseIf m.Msg = LVM_ENSUREVISIBLE Then > RaiseEvent VerticalScroll(Nothing, Nothing) > End If > end if > End Sub > > > Rob wrote: > > I've constructed a user control inherited from ListView so I can handle and > > respond to scrolling events (to keep 2 listviews scrolling in sync). > > > > My user control includes an Overrides of WndProc (I've attached the code at > > the end of this mail). Is it possible to 'disable' this override until I need > > it - it's just when I populate the ListViews this sub is called repeatadly. > > What I'd like to do is populate the listviews and then 'enable' this override > > to catch and trigger a scrolling event. > > > > tia > > > > Rob > > > > Protected Overrides Sub WndProc(ByRef m As Message) > > MyBase.WndProc(m) > > If m.Msg = WM_VSCROLL OrElse m.Msg = WM_MOUSEWHEEL Then > > RaiseEvent VerticalScroll(Nothing, Nothing) > > ElseIf m.Msg = WM_NOTIFY Then > > Dim lParam As NMHDR = CType(m.GetLParam(GetType(NMHDR)), NMHDR) > > If lParam.code = NM_HOVER Then > > OnMouseHover(EventArgs.Empty) > > End If > > ElseIf m.Msg = LVM_ENSUREVISIBLE Then > > RaiseEvent VerticalScroll(Nothing, Nothing) > > End If > > End Sub > > Rob,
The listview has a property used to disable scrolling or whatever during looding, because that can take a lot of time. It is one of the few controls which has that. https://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemwindowsformslistviewclassbeginupdatetopic.asp Is it not better to use that, than an Win32 method from which you don't know if it will be in future or other OS versions? Cor Show quoteHide quote "Rob" <R**@discussions.microsoft.com> schreef in bericht news:FDF7D785-FCA6-480F-905F-590F3B3BFDF2@microsoft.com... > I've constructed a user control inherited from ListView so I can handle > and > respond to scrolling events (to keep 2 listviews scrolling in sync). > > My user control includes an Overrides of WndProc (I've attached the code > at > the end of this mail). Is it possible to 'disable' this override until I > need > it - it's just when I populate the ListViews this sub is called > repeatadly. > What I'd like to do is populate the listviews and then 'enable' this > override > to catch and trigger a scrolling event. > > tia > > Rob > > Protected Overrides Sub WndProc(ByRef m As Message) > MyBase.WndProc(m) > If m.Msg = WM_VSCROLL OrElse m.Msg = WM_MOUSEWHEEL Then > RaiseEvent VerticalScroll(Nothing, Nothing) > ElseIf m.Msg = WM_NOTIFY Then > Dim lParam As NMHDR = CType(m.GetLParam(GetType(NMHDR)), NMHDR) > If lParam.code = NM_HOVER Then > OnMouseHover(EventArgs.Empty) > End If > ElseIf m.Msg = LVM_ENSUREVISIBLE Then > RaiseEvent VerticalScroll(Nothing, Nothing) > End If > End Sub Thanks
I need the user control and use of wndproc to support the lack of a scrolling event for the listview (after population). With the wndproc override I'm trapping most of the user scroll actions and raising an event which allows me to synchronise the scrolling between this listview and another listview (using topitem) - to give me 'compare side by side' ala Excel/Word type functionality. It's not a big deal but whenever I do something (like add an item) to either listivew then the wndproc override is triggered. I would like to surpress the override until I need it (ie after I've populated both views). I've got a beginupdate and endupdate settings around the population. thanks again Rob Show quoteHide quote "Cor Ligthert [MVP]" wrote: > Rob, > > The listview has a property used to disable scrolling or whatever during > looding, because that can take a lot of time. It is one of the few controls > which has that. > > https://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemwindowsformslistviewclassbeginupdatetopic.asp > > Is it not better to use that, than an Win32 method from which you don't know > if it will be in future or other OS versions? > > Cor > > > "Rob" <R**@discussions.microsoft.com> schreef in bericht > news:FDF7D785-FCA6-480F-905F-590F3B3BFDF2@microsoft.com... > > I've constructed a user control inherited from ListView so I can handle > > and > > respond to scrolling events (to keep 2 listviews scrolling in sync). > > > > My user control includes an Overrides of WndProc (I've attached the code > > at > > the end of this mail). Is it possible to 'disable' this override until I > > need > > it - it's just when I populate the ListViews this sub is called > > repeatadly. > > What I'd like to do is populate the listviews and then 'enable' this > > override > > to catch and trigger a scrolling event. > > > > tia > > > > Rob > > > > Protected Overrides Sub WndProc(ByRef m As Message) > > MyBase.WndProc(m) > > If m.Msg = WM_VSCROLL OrElse m.Msg = WM_MOUSEWHEEL Then > > RaiseEvent VerticalScroll(Nothing, Nothing) > > ElseIf m.Msg = WM_NOTIFY Then > > Dim lParam As NMHDR = CType(m.GetLParam(GetType(NMHDR)), NMHDR) > > If lParam.code = NM_HOVER Then > > OnMouseHover(EventArgs.Empty) > > End If > > ElseIf m.Msg = LVM_ENSUREVISIBLE Then > > RaiseEvent VerticalScroll(Nothing, Nothing) > > End If > > End Sub > > > 
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