SOLAR OS - API - GUI - Create Window

Solar OS API - GUI - Functions

Do not call us... We will call-back.

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PROC API_Window_Set_Callback  STDCALL
	USES	ecx,ebx,esi,edi
	ARG	wnd_handle, call_type, lp_callback

This function setups the window's user mode callback.

Arguments

Argument	Type	Description
wnd_handle	dword	HANDLE of the window who's callback to setup.
call_type	dword	What callback to execute Usually OS_CALL_AFTER is used to define user code and actions.
lp_callback	dword	Offset to user defined callback function. 0xffffffffh (-1) Means no function.

Returns

EAX = 0 (API_OK) if sucessfull
EAX = 8000_0001h (ERR_INVALID_PARAMS) if error

Possible errors

Unknown callback type
wrong wnd_handle

Remarks:

BEFORE callback is used to take over default OS draw or actions like supercalssing a controll or user defined draw/skin done before OS.
OS DEFAULT callback implements standard controls behaviour like: draw, move, resize, click, etc.
AFTER callback is used to define user mode code and actions like ::On_Click or ::On_Paint actions
Only the DEFAULT callback is required for a window to function properly. And this is auto setup for every window at creation time.
Non defined Callback is -1 in respective field.

Callback execution order

OS executes window callbacks in this order:

1) BEFORE callack IF defined. IF this callback returns -1 THEN OS will not call DEFAULT callback anymore
2) OS DEFAULT callback
3) AFTER callback IF defined
OS_CALL_NOTIFY is executed out of order once every OS frame

Typical Callback prototype:

Below is a sample callback suitable to be used as a template in your code.

PROC My_App_Callback STDCALL
	USES	ebx,ecx,edx,esi,edi
	ARG	wnd_handle, wnd_action, wnd_param1, wnd_param2

	;--------------------------------------
	; a case based on message/event value
	;--------------------------------------
	.IF [wnd_action] == ACT_PAINT_CHILD
		;-----------------------------
		; Wnd::On_Paint
		; todo: add paint code here
		;-----------------------------
		
		
	.ELSEIF [wnd_action] == ACT_LEFT_UP_CHILD
		;-----------------------------------
		; Wnd::ON_Mouse_Left_Down :)
		; todo: add click code here
		;-----------------------------------

	.ELSEIF [wnd_action] == ACT_KEY_CHILD
		;-----------------------------------
		; Wnd::ON_Key :)
		; todo: add keyboard code here
		;-----------------------------------

		
	.ELSEIF [wnd_action] == ACT_CLOSE_CHILD
		;---------------------------
		;Wnd::Destructor
		;todo:add release code here
		;---------------------------

	.ENDIF

	;-------------------------------------
	; by convention you should return zero 
	;-------------------------------------
	xor	eax,eax
	ret
ENDP

About calback parameters:

Please note that wnd_param1 and wnd_param2 depend on message/event type. For example:

On mouse events they hold mouse_x,mouse_y locations for the event.
On key events they hold KEY_EX code and hardware scancode
On paint they hold parnet_x,parent_y on screen
On some events they can be bogus/useless

However the wnd_handle and wnd_action parameters always exist and they always mean the same.

Available callback types:

Theoretically you should not use OS_CALL_DEFAULT unless you really know what you are doing. Also OS_CALL_BEFORE is safe to use but was not troughly tested. OS_CALL_AFTER is pretty safe and tested a lot.

;----------------------------------
; OS Known callbacks
;----------------------------------
OS_CALL_BEFORE		EQU	1
OS_CALL_DEFAULT		EQU	2
OS_CALL_AFTER		EQU	3
OS_CALL_NOTIFY		EQU	4