DoubleBuffer - WndProc

gistfile1.asm

WndProc PROC hWin:DWORD, uMsg:DWORD, wParam:DWORD, lParam:DWORD

        ; determine which message we need to process

	cmp uMsg, WM_CREATE
	je	CreateMessage

	cmp uMsg, WM_DESTROY
	je	DestroyMessage

	cmp uMsg, WM_ERASEBKGND
	je  EraseBackgroundMessage

	cmp uMsg, WM_CLOSE
	je	CloseMessage

	cmp uMsg, WM_SIZE
	je	SizeMessage

	cmp uMsg, WM_PAINT
	je	PaintMessage
	
	jmp DefaultWindowHandler

CreateMessage:

        ; on creation, we want to create an initial back-buffer	
	invoke RecreateBackBuffer, hWin
	jmp DefaultWindowHandler

DestroyMessage:
	
        ; on destruction, we just want to kill the back buffer
	invoke DestroyBackBuffer, hWin
	invoke PostQuitMessage, 0
	xor eax, eax
	ret

EraseBackgroundMessage:

        ; we want to tell windows that we've handled the background
        ; being erased by ourselves so it doesn't try to and end up
        ; making our application flicker - poor form!
	mov eax, 1
	ret

CloseMessage:

        ; closing the application just flips our message pump control
        ; variable so that we can break out
	mov bRunning, 0
	jmp DefaultWindowHandler

SizeMessage:

        ; when the window changes size, we re-create the buffer
	invoke RecreateBackBuffer, hWin
	jmp DefaultWindowHandler

PaintMessage:

        ; painting is just flicking that back buffer onto the 
        ; viewable video memory
	invoke FlipBackBuffer, hWin
	mov eax, 1
	ret

DefaultWindowHandler:
	invoke DefWindowProc,hWin,uMsg,wParam,lParam
	ret

WndProc ENDP