程式語言 - High Level Assembly (HLA) - Win32 API (HLA v1.x) - Single Document Interface (SDI) - Handle Event



參考網站:
http://winapi.freetechsecrets.com/win32/
http://masm32.com/board/index.php?topic=3584.0
https://www.plantation-productions.com/Webster/
https://www.plantation-productions.com/Webster/Win32Asm/win32API.html

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.hla

program main;
 
#include("w.hhf")
#include("args.hhf")
#include("memory.hhf")
#include("strings.hhf")
 
static
    hInstance:   dword;
    CommandLine: string;
    wndClass:    w.WNDCLASS;
 
readonly
    szName: string:= "main";

procedure WndProc(hWnd:dword; uMsg:uns32; wParam:dword; lParam:dword); @stdcall;
begin WndProc;
    if (uMsg == w.WM_CLOSE) then
        w.DestroyWindow(hWnd);
        xor(eax, eax);
        exit WndProc;
    elseif (uMsg == w.WM_DESTROY) then
        w.PostQuitMessage(0);
        xor(eax, eax);
        exit WndProc;
    endif;

    w.DefWindowProc(hWnd, uMsg, wParam, lParam);
end WndProc;

procedure WinMain(hInst:dword; hPrevInst:dword; CmdLine:string; CmdShow:dword);
var
    msg: w.MSG;
 
begin WinMain;
    mov(&WndProc, wndClass.lpfnWndProc);
    mov(szName, wndClass.lpszClassName);
    w.RegisterClass(wndClass);

    w.CreateWindowEx(w.WS_EX_LEFT, szName, szName,
        w.WS_OVERLAPPEDWINDOW | w.WS_VISIBLE, 0, 0, 300, 300, 0, 0, NULL, NULL);
     
    forever
        w.GetMessage(msg, NULL, 0, 0);
        breakif(!eax);
 
        w.DispatchMessage(msg);
    endfor;
    mov(msg.wParam, eax);
end WinMain;
 
begin main;
    w.GetModuleHandle(NULL);
    mov(eax, hInstance);
    mov(arg.cmdLn(), CommandLine);
 
    WinMain(hInstance, NULL, CommandLine, w.SW_SHOWNORMAL);
 
    w.ExitProcess(eax);
end main;

Line 18~26: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 28:其餘事件由系統代為處理

完成