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Topic: List view: detecting columnclick (Read 806 times) |
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Hans
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List view: detecting columnclick
« Thread started on: Jul 8th, 2016, 1:29pm » |
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Does anybody has experience in detecting clicking the header in a List View using WN_COLUMNCLICK?
My list view works excelent, but detecting the columnclick doesn't work so far.
Hans
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Richard Russell
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Re: List view: detecting columnclick
« Reply #1 on: Jul 8th, 2016, 3:51pm » |
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on Jul 8th, 2016, 1:29pm, Hans wrote:| My list view works excelent, but detecting the columnclick doesn't work so far. |
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Unfortunately the LVN_COLUMNCLICK notification arrives in a WM_NOTIFY message. Although you can intercept WM_NOTIFY messages using WMLiberty.DLL there are typically so many of them that they are likely to flood the handler and crash your program. 
Ideally what you want is a version of WMLiberty.dll that provides more detailed filtering, so that rather than intercepting every WM_NOTIFY message it intercepts only those containing (say) a LVN_COLUMNCLICK notification. Unfortunately I'm not aware that such a DLL exists.
What have you tried so far? If you are lucky you may get away with using WMLiberty.dll to intercept all WM_NOTIFY messages, but it is risky.
Richard.
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Hans
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Re: List view: detecting columnclick
« Reply #2 on: Jul 15th, 2016, 7:39pm » |
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I use msghook.dll. The central part in my code is:
Code:'prepare callbacks
hMsgProc = hwnd(#view.GetMsgHookCallback)
calldll #MsgHook, "TrapMsgFor",hLV as ulong, r as boolean
calldll #MsgHook, "TrapMsgFor",hSlide as ulong, r as boolean
calldll #MsgHook, "WatchMsg", hLV as ulong, _WM_LBUTTONDBLCLK as long, r as boolean
calldll #MsgHook, "WatchMsg", hLV as ulong, _WM_LBUTTONUP as long, r as boolean
calldll #MsgHook, "WatchMsg", hLV as ulong, _WM_RBUTTONUP as long, r as boolean
calldll #MsgHook, "WatchMsg", hLV as ulong, LVM.COLUMNCLICK as long, r as boolean
calldll #MsgHook, "WatchMsg", hSlide as ulong, _WM_LBUTTONUP as long, r as boolean
calldll #MsgHook, "WatchMsg", hParent as ulong, _WM_NOTIFY as long, r as boolean
calldll #user32, "GetWindowLongA",hMsgProc as ulong,_GWL_ID as short,callbackID as long
calldll #MsgHook, "CreateGetMsgProcHook", hParent as ulong, callbackID as long, hMsgProc as ulong, hHook as ulong
The callback part is:
Code:[view.callback]
calldll #MsgHook, "GetMsg", msg as struct, ret as void
mesg=msg.message.struct
select case mesg
case _WM_LBUTTONDBLCLK
if fname$<>"" then Notice "test" : goto [content.edit]
case _WM_LBUTTONUP
if msg.hndl.struct=hSlide then goto [navigate.scroll]
rec=LVGETSINGSEL(hLV)
r=DBVIEWNEXTLOAD(hLV,hSlide,rec,record,first,last,"edit")
case _WM_RBUTTONUP
if fname$<>"" then
rec=LVGETSINGSEL(hLV) : record=first+rec-1
goto [content.edit]
end if
case _WM_NOTIFY
if msg.hndl.struct=hParent then print "x"
case LVM.COLUMNCLICK
test=test
end select
goto [view.scanloop]
"[view.scanloop]" is in stead of "wait". Here I catch some keystrokes.
I hope someone has some experience with msghook.
Hans
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Hans
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Re: List view: detecting columnclick
« Reply #3 on: Jul 15th, 2016, 7:43pm » |
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I never meet crashes using this code.
_WM_LBUTTONDBLCLK works as expected, so does _WM_LBUTTONUP and _WM_RBUTTONUP.
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Richard Russell
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Re: List view: detecting columnclick
« Reply #4 on: Jul 15th, 2016, 10:48pm » |
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on Jul 15th, 2016, 7:43pm, Hans wrote:
I'm not familiar with msghook.dll. I would be very interested to know how it compares with WMLiberty.dll; perhaps it has some advantages. Because I've not met it before msghook.dll is not on the list of DLLs (known to be) compatible with LBB. If you have ascertained that it is compatible I will update the list.
Quote:I never meet crashes using this code.
_WM_LBUTTONDBLCLK works as expected, so does _WM_LBUTTONUP and _WM_RBUTTONUP. |
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That you don't have crashes, even when you intercept WM_NOTIFY messages (which you do in the code you listed) is encouraging and may suggest that you will be able to make it work, despite the probable high volume of messages.
The code you would need is something like this:
Initialisation Code: LVN.COLUMNCLICK = -108
struct nmhdr, hwndFrom as ulong, idFrom as long, code as long
Intercept Code: case _WM_NOTIFY
nmhdr.struct = msg.lparam.struct
if nmhdr.code.struct = LVN.COLUMNCLICK then
' handle columnclick here
end if
Richard.
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Hans
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Re: List view: detecting columnclick
« Reply #5 on: Jul 18th, 2016, 3:01pm » |
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The original site of msghook does not exist anymore. But still it can be downloaded at: http://vb.mvps.org/tools/MsgHook/.
So far I don't have succes. I inserted the pieces of code you offered. The program never gets within de part of "case _WM_NOTIFY", which makes all the rest useless.
I added Code:calldll #MsgHook, "WatchMsg", hLV as ulong, _WM_NOTIFY as long, r as boolean
in the part "prepare callbacks", that did not help either.
Hans
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Richard Russell
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Re: List view: detecting columnclick
« Reply #6 on: Jul 18th, 2016, 9:26pm » |
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on Jul 18th, 2016, 3:01pm, Hans wrote:| So far I don't have success. |
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I know it can be made to work because I've done it successfully in BBC BASIC. In that case I used the embedded assembler to write my own custom message filter, to avoid overloading BASIC with the high volume of WM_NOTIFY messages.
So, as a last resort, my code could be ported to LBB using the 'BBC BASIC escape' feature (starting a line with an exclamation mark). Obviously the end result would be completely incompatible with LB 4, but at least you would end up with a working solution. Whether you want to go down that route is another matter!
Richard.
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Hans
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Re: List view: detecting columnclick
« Reply #7 on: Jul 19th, 2016, 09:27am » |
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After repeated searching I found a piece of code on the LB forum that does the trick with WMLiberty. After my vacation I'll study it. Maybe I can find what I am doing wrong, maybe WMLiberty is just better for this.
Have a good summer
Hans
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SarmedNafi
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Re: List view: detecting columnclick
« Reply #8 on: Jul 19th, 2016, 11:57am » |
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I will remain Waiting you Hans.
We got a red summer here.
Sarmed
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| « Last Edit: Jul 19th, 2016, 11:58am by SarmedNafi » |
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Hans
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Re: List view: detecting columnclick
« Reply #9 on: Aug 30th, 2016, 1:20pm » |
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Using WMLiberty has serious drawbacks. On punishment of crashes, you can not use Wait, Confirm, Notice, Prompt, PopupMenu, Input and Input$(1) in your code. And who knows what else. On a crash you don't get a clou what happend. My code is quit large, so I don't want to get lost.
Maybe I'll try something with a translucent graphicbox placed over the header. Then I can track clicks on that graphicbox and translate that to which header is clicked.
Hans
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Richard Russell
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Re: List view: detecting columnclick
« Reply #10 on: Aug 30th, 2016, 3:00pm » |
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on Aug 30th, 2016, 1:20pm, Hans wrote:| Using WMLiberty has serious drawbacks. On punishment of crashes, you can not use Wait, Confirm, Notice, Prompt, PopupMenu, Input and Input$(1) in your code. |
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My understanding is that most, if not all, of these limitations are specific to LB 4 and don't apply to LBB. For example I'm certain that it's OK to use WAIT with WMLiberty in LBB, and my expectation would be that the rest are OK too.
Do you have evidence that any of those statements cause problems when using WMLiberty with LBB? If so I would be interested to see examples that demonstrate the problem.
The one thing I do know is bad, when using WMLiberty, is calling the Sleep API for a lengthy period (e.g. for more than a couple of milliseconds) because that will introduce an undesirable latency in handling the trapped message. This is particularly an issue if trying to intercept WM_NOTIFY messages.
Richard.
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