[win32] - how can i call the WM_DRAWITEM message?

[Cambalinho]

i'm trying call the wm_drawitem message without sucess

if(KeyPressed(VK_MENU)==true) SendMessage(hButton,WM_DRAWITEM,NULL,NULL);

what i'm doing wrong?

[2kaud]

See http://msdn.microsoft.com/en-us/libr...=vs.85%29.aspx

wParam Specifies the identifier of the control that sent the WM_DRAWITEM message. If the message was sent by a menu, this parameter is zero.

lParam Pointer to a DRAWITEMSTRUCT structure containing information about the item to be drawn and the type of drawing required.

You need to pass a pointer to a DRAWITEMSTRUCT structure that contains the required info.

[Cambalinho]

"wParam Specifies the identifier of the control that sent the WM_DRAWITEM message. If the message was sent by a menu, this parameter is zero."
i belive you mean the ID... but how i get the ID?

"lParam Pointer to a DRAWITEMSTRUCT structure containing information about the item to be drawn and the type of drawing required.


You need to pass a pointer to a DRAWITEMSTRUCT structure that contains the required info."
how can i get the DRAWITEMSTRUCT from actual state?

[Cambalinho]

heres what i did:

if(KeyPressed(VK_MENU)==true) SendMessage(hButton,WM_DRAWITEM,GetDlgCtrlID(hButton),MAKEWPARAM(GetDlgCtrlID(hButton),BN_PUSHED));

but isn't working
please tell me more

[VictorN]

heres what i did:

if(KeyPressed(VK_MENU)==true) SendMessage(hButton,WM_DRAWITEM,GetDlgCtrlID(hButton),MAKEWPARAM(GetDlgCtrlID(hButton),BN_PUSHED));

but isn't working
please tell me more

First do NOT place more than one statement in one line. Do it like

if(KeyPressed(VK_MENU))
     SendMessage(hButton,WM_DRAWITEM,GetDlgCtrlID(hButton),MAKEWPARAM(GetDlgCtrlID(hButton),BN_PUSHED));

Second, never compare something returning BOOL with TRUE nor with true. The return value of the Win API may be either 0 (FALSE) or any other non-zero integer that is interpreted as TRUE.
After that you could debug your code and what goes wrong and why...

[2kaud]

The lparam needs to be a pointer to a DRAWITEMSTRUCT as I indicated in my post #2. What you have shown in post #4 isn't a pointer for the lparam parameter. You need to initialise a struct and then pass its memory address. The format of the structure is here http://msdn.microsoft.com/en-us/libr...=vs.85%29.aspx

So you need something like this

DRAWITEMSTRUCT dis = {0};
//Initialise the fields for dis
if (KeyPressed(VK_MENU))
    SendMessage(hButton, WM_DRAWITEM, (WPARAM)GetDlgCtrlID(hButton), (LPARAM)&dis);

Are you sure you need to send this message? What are you trying to accomplish? There may be better ways of achieving it.

[ovidiucucu]

WM_DRAWITEM message is...

[ MSDN ]
...sent to the parent window of an owner-drawn button, combo box, list box, or menu when a visual aspect of the button, combo box, list box, or menu has changed.

It is sent by the system when needed, and it has no sense to be directly sent from your application.