程式語言 - MASM32 - Single Document Interface (SDI) - Handle Event



參考資訊:
http://winapi.freetechsecrets.com/win32/
https://github.com/gammasoft71/Examples_Win32
http://masm32.com/board/index.php?topic=3584.0

當視窗有事件需要被處理時,系統會透過呼叫註冊的Callback副程式來處理,而這個Callback副程式就是在註冊Class時,設定給lpfnWndProc的事件處理副程式,因此,當這個事件處理副程式被呼叫時,可以處理自己感興趣的事件,而其餘事件則交給系統處理(透過呼叫DefWindowProc()),需要注意的是,例如:WM_CLOSE,就必須由該視窗自己處理,因為系統無法知道還有哪些額外的資源需要被釋放掉

main.asm

    .386
    .model flat,stdcall
    option casemap:none
   
include c:\masm32\include\windows.inc
include c:\masm32\include\kernel32.inc
include c:\masm32\include\user32.inc
   
includelib c:\masm32\lib\user32.lib
includelib c:\masm32\lib\kernel32.lib
   
    .data
szName      db "main",0
hWin        dd 0
hInstance   dd 0
CommandLine dd 0
wndClass    WNDCLASS <0>
   
    .code
WndProc proc hWnd:HWND, uMsg:UINT, wParam:WPARAM, lParam:LPARAM
    .if uMsg == WM_CLOSE
        invoke DestroyWindow, hWnd
        xor eax, eax
        ret
    .elseif uMsg == WM_DESTROY
        invoke PostQuitMessage, 0
        xor eax, eax
        ret
    .endif
 
    invoke DefWindowProc, hWnd, uMsg, wParam, lParam
    ret
WndProc endp

WinMain proc hInst:DWORD, hPrevInst:DWORD, CmdLine:DWORD, CmdShow:DWORD
    local msg:MSG

    mov wndClass.lpfnWndProc, WndProc
    mov wndClass.lpszClassName, offset szName
    invoke RegisterClass, offset wndClass

    invoke CreateWindowEx, WS_EX_LEFT, offset szName, offset szName, 
        WS_OVERLAPPEDWINDOW or WS_VISIBLE, 0, 0, 300, 300, NULL, NULL, NULL, NULL
    mov hWin, eax
  
@@:
    invoke GetMessage, addr msg, NULL, 0, 0
    cmp eax, 0
    je @f
    invoke DispatchMessage, addr msg
    jmp @b
@@:
    mov eax, msg.wParam
    ret
WinMain endp
 
start:
    invoke GetModuleHandle, NULL
    mov hInstance, eax
   
    invoke GetCommandLine
    mov CommandLine, eax
   
    invoke WinMain, hInstance, NULL, CommandLine, SW_SHOWDEFAULT
    invoke ExitProcess, eax
end start

Line 21~29:關閉視窗的順序為:主視窗收到WM_CLOSE事件時,呼叫DestroyWindow(),DestroyWindow()會自動將子視窗的相關資源也一併釋放掉(包含Resource描述的資源),系統接著會發送WM_DESTROY事件給主視窗,待主視窗收到WM_DESTROY事件時,呼叫PostQuitMessage()結束視窗,值得注意的地方是,SendMessage()是屬於Block方式呼叫(必須等待動作執行完畢才返回),而PostQuitMessage()則是Non-block方式呼叫
Line 31:其餘事件由系統代為處理

完成