The first line proves that friday arvo drinks are fast approaching...
On Fri, Feb 25, 2011 at 3:20 PM, Jeremy North <jeremy.no...@gmail.com>wrote: > You asking me implementation details on code I just put together in 5 mins. > > OK... > > a) Keyboard - well that sucks. I blame MS. > 1) Initially was expecting scroll details to be handled by the record > structure. Trapping WMNotify instead of CNNotify doesn't work (just tried). > 2) I thought I searched the source and couldn't find it. Guess I searched > wrong (since I had LVM_??? in the comment). > > I guess the H and V scrolling thing is down to the implementor for why > they'd want to differentiate the two. You can get enough detail to > distinguish in the message received if needed. > > Also it will only work with ComCtrl version 6 and above (XP+). > > On Fri, Feb 25, 2011 at 2:55 PM, Jolyon Smith <jsm...@deltics.co.nz>wrote: > >> A good spot, but this code doesn’t solve it either. It provides a >> universal way of handling scrollbar or mousewheel scroll notifications, >> although a bit of extra work is then required to discriminate between H vs >> V scrolling, but when I added this to my listview class it didn’t get called >> as the result of keyboard scrolling either. >> >> >> >> Couple of supplementary questions: >> >> >> >> 1. Where do you get TWMNotifyLV from? Why not just use TWMNotify ? >> >> 2. Why not use the LVN_BEGINSCROLL/LVN_ENDSCROLL constants, rather >> than literals + comments ? >> >> >> >> >> >> *From:* delphi-boun...@delphi.org.nz [mailto:delphi-boun...@delphi.org.nz] >> *On Behalf Of *Jeremy North >> *Sent:* Friday, 25 February 2011 16:21 >> >> *To:* NZ Borland Developers Group - Delphi List >> *Subject:* Re: [DUG] Listview problem >> >> >> >> Don't forget "scrolling" also occurs when you use the arrow keys. >> >> >> >> My contribution (just made up then)... >> >> >> >> unit ScrollingListView; >> >> >> >> interface >> >> >> >> uses >> Windows, Messages, ComCtrls, CommCtrl, Controls; >> >> >> >> type >> TJSListView = class(TListView) >> private >> type >> TJSScrollEvent = procedure (Sender: TObject; const BeginScroll: >> Boolean) of object; >> var >> FOnEndScroll: TJSScrollEvent; >> FOnBeginScroll: TJSScrollEvent; >> protected >> procedure DoScroll(const AStart: Boolean); virtual; >> procedure CNNotify(var Message: TWMNotifyLV); message CN_NOTIFY; >> public >> property OnBeginScroll: TJSScrollEvent read FOnBeginScroll write >> FOnBeginScroll; >> property OnEndScroll: TJSScrollEvent read FOnEndScroll write >> FOnEndScroll; >> end; >> >> >> >> implementation >> >> >> >> { TJSListView } >> >> >> >> procedure TJSListView.CNNotify(var Message: TWMNotifyLV); >> begin >> if Message.NMHdr.code = -180 then // LVM_BEGINSCROLL >> begin >> DoScroll(True); >> end; >> if Message.NMHdr.code = -181 then // LVM_ENDSCROLL >> begin >> DoScroll(False); >> end; >> inherited; >> end; >> >> >> >> procedure TJSListView.DoScroll(const AStart: Boolean); >> var >> LEvent: TJSScrollEvent; >> begin >> if AStart then >> LEvent := OnBeginScroll >> else >> LEvent := OnEndScroll; >> if Assigned(LEvent) then >> LEvent(Self, AStart); >> end; >> >> >> >> end. >> >> >> >> >> >> >> >> On Fri, Feb 25, 2011 at 2:01 PM, David O'Brien <d...@iccs.co.nz> wrote: >> >> Sorted it thanks, had mixed versions of code in the component. The events >> do fire… >> >> >> >> *From:* delphi-boun...@delphi.org.nz [mailto:delphi-boun...@delphi.org.nz] >> *On Behalf Of *Jolyon Smith >> *Sent:* Friday, 25 February 2011 3:43 p.m. >> >> >> *To:* 'NZ Borland Developers Group - Delphi List' >> >> *Subject:* Re: [DUG] Listview problem >> >> >> >> A WM_VSCROLL message handler works perfectly for me. >> >> >> >> However, this will only be sent for scrollbar directed scrolling. To also >> handle mousewheel scrolling you will have to implement a WM_MOUSEWHEEL >> message handler (and WM_HMOUSEWHEEL if appropriate to your needs). Could >> it be mouse scrolling that you are missing ? >> >> >> >> I would also note that you will almost certainly want to distinguish >> between H and V scrolling, rather than have a “universal” “some sort of >> scrolling has occurred” notification. You may also wish to be able to >> respond both before and after scrolling has occurred. >> >> >> >> >> >> In my list view class I have: >> >> >> >> TScrollNotification = ( >> >> snBeforeHScroll, >> >> snBeforeHWheel, >> >> snBeforeVScroll, >> >> snBeforeWheel, >> >> snHScroll, >> >> snHWheel, >> >> snVScroll, >> >> snWheel >> >> ); >> >> >> >> >> >> procedure TXListview.WMVScroll(var aMessage: TWMVScroll); >> >> begin >> >> DoScroll(snBeforeVScroll); >> >> inherited; >> >> DoScroll(snVScroll); >> >> end; >> >> >> >> procedure TXListview.WMHScroll(var aMessage: TWMHScroll); >> >> begin >> >> DoScroll(snBeforeHScroll); >> >> inherited; >> >> DoScroll(snHScroll); >> >> end; >> >> >> >> >> >> >> >> and similar for mousewheel messages of course, where DoScroll: >> >> >> >> >> >> procedure TXListview.DoScroll(const aNotification: TScrollNotification); >> >> begin >> >> if (aNotification in [snBeforeHScroll, snBeforeVScroll, >> snBeforeHWheel, snBeforeWheel]) then >> >> CancelEdit; >> >> >> >> if Assigned(fOnScroll) then >> >> fOnScroll(self, aNotification); >> >> end; >> >> >> >> >> >> i.e. my listview also provides a facility for sub-item editing and when >> scrolling occurs, the first thing I do before doing the actual scrolling is >> dismiss any sub-item editor that may be active, before then firing the >> OnScroll event to allow my application code to respond as it may require. >> >> >> >> hth >> >> >> >> >> >> *From:* delphi-boun...@delphi.org.nz [mailto:delphi-boun...@delphi.org.nz] >> *On Behalf Of *David O'Brien >> *Sent:* Friday, 25 February 2011 15:09 >> *To:* NZ Borland Developers Group - Delphi List >> *Subject:* [DUG] Listview problem >> >> >> >> I am working on an application (D2009) where I need to know when a >> TListView is Scrolled. >> >> I have used Application.OnMessage to look for WM_VScroll messages, but >> they do not happen, also have tried creating the below which I thought >> should work: >> >> >> >> TLVScrollEvent = procedure(Sender: TObject) of object; >> >> >> >> TICListView = class(TListView) >> >> private >> >> FOnScroll: TLVScrollEvent; >> >> protected >> >> Procedure WMVScroll( Var Msg: TMessage ); message WM_VSCROLL; >> >> Procedure WMHScroll( Var Msg: TMessage ); message WM_HSCROLL; >> >> property OnScroll: TLVScrollEvent read FOnScroll write FOnscroll ; >> >> end; >> >> >> >> procedure Register ; >> >> >> >> implementation >> >> >> >> procedure Register; >> >> begin >> >> RegisterComponents('Dave', [TICListView]); >> >> end; >> >> >> >> procedure TICListView.WMHScroll(var Msg: TMessage); >> >> begin >> >> OnScroll ; >> >> inherited; >> >> end; >> >> >> >> procedure TICListView.WMVScroll(var Msg: TMessage); >> >> begin >> >> OnScroll ; >> >> inherited; >> >> end; >> >> >> >> which also doesn’t fire. I have written a list of all messages fired when >> the scrollbar is moved, but there doesn’t seem to be anything useful… >> >> >> >> Anyone have a solution? >> >> >> >> Regards, >> >> Dave. >> >> >> _______________________________________________ >> NZ Borland Developers Group - Delphi mailing list >> Post: delphi@delphi.org.nz >> Admin: http://delphi.org.nz/mailman/listinfo/delphi >> Unsubscribe: send an email to delphi-requ...@delphi.org.nz with Subject: >> unsubscribe >> >> >> >> _______________________________________________ >> NZ Borland Developers Group - Delphi mailing list >> Post: delphi@delphi.org.nz >> Admin: http://delphi.org.nz/mailman/listinfo/delphi >> Unsubscribe: send an email to delphi-requ...@delphi.org.nz with Subject: >> unsubscribe >> > >
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