SendMessage to Speedup ListView

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Abhay Sobti - 27 Oct 2006 12:24 GMT

Hello Everyone,

I know this is a VB forum, but my question pertains to VFP. I am trying to
stop a ListView from redrawing itself as I am inserting 3000 ListItems.
However, the following code does not prevent it from redrawing. Can you
Help?

Abhay Sobti

#DEFINE WM_SETREDRAW 11

DECLARE INTEGER SendMessage IN user32 INTEGER hWnd,;
INTEGER Msg,;
INTEGER wParam,;
INTEGER lParam

=SendMessage(THIS.Lv.hWnd, WM_SETREDRAW ,.T.,0)

** Now I populate the ListBox

=SendMessage(THIS.Lv.hWnd, WM_SETREDRAW ,.F.,0)

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AA - 27 Oct 2006 13:15 GMT

Try
Thisform.LockScreen=.T.

-Anders

> Hello Everyone,
>
[quoted text clipped - 17 lines]
>
> =SendMessage(THIS.Lv.hWnd, WM_SETREDRAW ,.F.,0)

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Abhay Sobti - 28 Oct 2006 06:34 GMT

Tried Visible=.F. , and also LockScreen.
Not much affect

Abhay

> Try
> Thisform.LockScreen=.T.
[quoted text clipped - 22 lines]
>>
>> =SendMessage(THIS.Lv.hWnd, WM_SETREDRAW ,.F.,0)

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AA - 29 Oct 2006 17:25 GMT

If you're working in VFP you can fill a ListBox control with 3000 AddItem or
AddListItem calls in a loop, times the number of columns, or with a single
line setting RecordSource to a multidimensionsl array or to a cursor.
-Anders

> Tried Visible=.F. , and also LockScreen.
> Not much affect
[quoted text clipped - 27 lines]
>>>
>>> =SendMessage(THIS.Lv.hWnd, WM_SETREDRAW ,.F.,0)

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Samir Ibrahim - 02 Nov 2006 08:51 GMT

I have tried this

thisform.listview.visible = .F.
thisform.listview.enable = .F.
* then populate the list view with 100 recoreds * 114 field
thisform.listview.visible = .T.
thisform.listview.enable = .T.

the speed was 2 min 42 sec and after it was 5 sec

Samir ibrahim

> Tried Visible=.F. , and also LockScreen.
> Not much affect
[quoted text clipped - 27 lines]
>>>
>>> =SendMessage(THIS.Lv.hWnd, WM_SETREDRAW ,.F.,0)

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Abhay Sobti - 03 Nov 2006 13:12 GMT

Thanks Samir,

Yes ! There is a difference in speed. But my listview has only 3 columns
with 2000 rows. The difference is not really substantial.

thanks anyway

>I have tried this
>
[quoted text clipped - 39 lines]
>>>>
>>>> =SendMessage(THIS.Lv.hWnd, WM_SETREDRAW ,.F.,0)

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Jack Jackson - 27 Oct 2006 15:16 GMT

>Hello Everyone,
>
[quoted text clipped - 17 lines]
>
>=SendMessage(THIS.Lv.hWnd, WM_SETREDRAW ,.F.,0)

I don't know about the Listiviw, but with the TreeView setting its
Visible property to .F. speeds it up considerably.

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Alex.K - 27 Nov 2006 02:00 GMT

Samir,

Try this:

Add a BeginUpdate and a EndUpdate Method to the ListView..
Add new properties WasSorted and ViewStyle

in the PROCEDURE BeginUpdate:
WITH THIS
** To try and speed up the loading process:
** 1) Turn off sorting
** 2) Disable the control
** 3) Change the View style to 3 - List
.Visible = .F.
.WasSorted = .Sorted
.Object.Sorted = .F.
.Object.Enabled = .F.
.ViewStyle = .Object.View
.Object.View = lvwList
SendMessage(.hWnd, WM_SETREDRAW, 0, 0)
LockWindowUpdate(.hWnd)
ENDWITH

in the PROCEDURE EndUpdate:
WITH THIS
.Object.Sorted = .WasSorted
.Object.Enabled = .T.
.Object.View = .ViewStyle
SendMessage(.hWnd, WM_SETREDRAW, 1, 0)
LockWindowUpdate(0)
.Visible = .T.
ENDWITH

The issue the following on loading:

Thisform.yourListView.BeginUpdate

-- Load all your items...

Thisform.yourListView.EndUpdate

FYI: In your SendMessage use integer values for boolean

Hope this helps.

- Alex

----- Original Message -----
From: Abhay Sobti
Newsgroups: microsoft.public.fox.vfp.lck-api
Sent: Friday, November 03, 2006 5:12 AM
Subject: Re: SendMessage to Speedup ListView

Thanks Samir,

Yes ! There is a difference in speed. But my listview has only 3 columns
with 2000 rows. The difference is not really substantial.

thanks anyway

>I have tried this
>
[quoted text clipped - 41 lines]
>>>>
>>>> =SendMessage(THIS.Lv.hWnd, WM_SETREDRAW ,.F.,0)

Reply to this Message