ListBox Owner Draw Flicker on Resize

  • Thread starter Thread starter nak
  • Start date Start date
N

nak

Hi there,

I have an owner drawn listbox that works fine and without flicker except
when it is resized. The only examples I've come across for double buffering
require painting the entire control within the OnPaint event, of course this
isn't how I would like to draw the control as it negates the purpose of it
being owner drawn and I may as well just create the control from scratch.

I've also seen potential fixes involving the EnableVisualStyles property
but this does not work for me. Has anyone got any wizzy tips for curing
this resize flicker? Thanks a million in advance.

Nick.
 
nak said:
Hi there,

I have an owner drawn listbox that works fine and without flicker
except when it is resized. The only examples I've come across for double
buffering require painting the entire control within the OnPaint event, of
course this isn't how I would like to draw the control as it negates the
purpose of it being owner drawn and I may as well just create the control
from scratch.

I've also seen potential fixes involving the EnableVisualStyles
property but this does not work for me. Has anyone got any wizzy tips for
curing this resize flicker? Thanks a million in advance.

Nick.
Click to expand...

Hi!
You can use SendMessage and a constant for Autoredraw.
First false. Then true. Then refresh.

Earlybite
 
Hi Earlybite,
Hi!
You can use SendMessage and a constant for Autoredraw.
Click to expand...

Would this be the same as the ResizeRedraw property? If so I have tried
using that and it still does not work.

Nick.
 
nak said:
Hi Earlybite,


Would this be the same as the ResizeRedraw property? If so I have
tried using that and it still does not work.

Nick.
Click to expand...

Hi!
?ResizeRedraw? Don't know!
SendMessage is a API-Call and with autoredraw to false it stops every
redraw,
so you have to refresh form and so on.

Private Const WM_SETREDRAW = &HB
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA"
(ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As
Any) As Long

Call SendMessage(hWnd, WM_SETREDRAW, 0&, 0&) ' Set to false
Resize or replace with your code
Call SendMessage(hWnd, WM_SETREDRAW, 1&, 0&) ' Set to true
Refresh ' You have to try. [It can be you have to refresh all controls :-( ]

This will work (also with very big sized controls)
greetings
Earlybite
 
Hi Earlybite,
Hi!
?ResizeRedraw? Don't know!
SendMessage is a API-Call and with autoredraw to false it stops every
redraw,
so you have to refresh form and so on.

Private Const WM_SETREDRAW = &HB
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA"
(ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As
Any) As Long

Call SendMessage(hWnd, WM_SETREDRAW, 0&, 0&) ' Set to false
Resize or replace with your code
Call SendMessage(hWnd, WM_SETREDRAW, 1&, 0&) ' Set to true
Refresh ' You have to try. [It can be you have to refresh all controls
:-( ]

This will work (also with very big sized controls)
greetings
Earlybite
Click to expand...

I'm not convinced that this is going to help me to be honest, I don't
want to prevent redraws, I want to prevent a flicker during resize, stopping
it from redrawing completely will just mean that the control will look very
bad while resizing. I just tried it and it stops redraw completely until
enabled again, definitely not what I want to do.

I think the problem is caused by the underlying listbox itself clearing
the buffering during a resize, if it is actually double buffered, it's very
poorly double buffered, I have controls that I double buffer myself and get
no flicker at all so not quite sure what's going on underneath. It would be
cool if I could handle the double buffering myself along with Owner Drawn
but I can't see any examples of doing so.

Nick.
 
Earlybite said:
Private Const WM_SETREDRAW = &HB
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA"
(ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As
Any) As Long
Click to expand...

If you want it platform independent:

Private Declare Function SendMessage Lib "user32" Alias "SendMessageA"
(ByVal hWnd As intptr, ByVal wMsg As uinteger, ByVal wParam As intptr,
byval lParam As intptr) As intptr


Armin
 
Armin said:
If you want it platform independent:

Private Declare Function SendMessage Lib "user32" Alias "SendMessageA"
(ByVal hWnd As intptr, ByVal wMsg As uinteger, ByVal wParam As intptr,
byval lParam As intptr) As intptr
Click to expand...

or better

Private Declare AUTO Function SendMessage Lib "user32" (...)


Armin
 
If you want it platform independent:

Private Declare Function SendMessage Lib "user32" Alias "SendMessageA"
(ByVal hWnd As intptr, ByVal wMsg As uinteger, ByVal wParam As intptr,
byval lParam As intptr) As intptr


Armin
Click to expand...

The use of Long as a type was wrong anyway :) Long is a 64-bit integer...
 
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