程式語言 - High Level Assembly (HLA) - Win32 API (HLA v1.x) - Set Scrollbar


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

當視窗的可視區域(如：300x300像素)小於顯示圖片大小(如：640x480像素)時，這時可以使用Windows視窗元件Scrollbar，用來做顯示位置調整的動作，Scrollbar元件有垂直和水平兩種方向並且提供視窗事件回報機制(WM_VSCROLL、WM_HSCROLL)，因此，這裡的Scrollbar元件並不能夠自動幫忙做顯示位置調整的動作，取而代之的是，在收到WM_VSCROLL、WM_HSCROLL事件時，使用者必須自己決定哪些東西要顯示在視窗的可視區域上

main.hla

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program main;
      
#include("w.hhf")
#include("args.hhf")
#include("memory.hhf")
#include("strings.hhf")
      
static
    hWin:        dword;
    hInstance:   dword;
    CommandLine: string;
    defWndProc:  dword;
    
readonly
    SLUP:      string:= "LINE++";
    SLDN:      string:= "LINE--";
    SPUP:      string:= "PAGE++";
    SPDN:      string:= "PAGE--";
    szCaption: string:= "main";
     
procedure WndProc(hWnd:dword; uMsg:uns32; wParam:dword; lParam:dword); @stdcall;
begin WndProc;
    if (uMsg == w.WM_VSCROLL) then
        mov(wParam, eax);
        and($ffff, eax);
        if (eax == w.SB_LINEUP) then
            w.SetWindowText(hWnd, SLUP);
        elseif (eax == w.SB_LINEDOWN) then
            w.SetWindowText(hWnd, SLDN);
        elseif (eax == w.SB_PAGEUP) then
            w.SetWindowText(hWnd, SPUP);
        elseif (eax == w.SB_PAGEDOWN) then
            w.SetWindowText(hWnd, SPDN);
        endif;
        xor(eax, eax);
    elseif (uMsg == w.WM_CLOSE) then
        w.DestroyWindow(hWnd);
        xor(eax, eax);
    elseif (uMsg == w.WM_DESTROY) then
        w.PostQuitMessage(0);
        xor(eax, eax);
    else
        w.CallWindowProc(defWndProc, hWnd, uMsg, wParam, lParam);
    endif;
end WndProc;
     
procedure WinMain(hInst:dword; hPrevInst:dword; CmdLine:string; CmdShow:dword);
var
    msg: w.MSG;
      
begin WinMain;
    w.CreateWindowEx(w.WS_EX_LEFT, w.WC_DIALOG, szCaption,
        w.WS_OVERLAPPEDWINDOW | w.WS_VISIBLE | w.WS_VSCROLL, 0, 0, 300, 300, 0, 0, NULL, NULL);
    mov(eax, hWin);
     
    w.SetWindowLong(hWin, w.GWL_WNDPROC, &WndProc);
    mov(eax, defWndProc);
 
    w.SetScrollRange(hWin, w.SB_VERT, 0, 100, false);
    w.SetScrollPos(hWin, w.SB_VERT, 50, true);
    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 23~35：處理Scrollbar訊息並且顯示在視窗標題
Line 53：WS_VSCROLL是垂直的Scrollbar，WS_HSCROLL則是水平的Scrollbar
Line 59：設定Scrollbar最大的範圍
Line 60：設定Scrollbar目前的位置

完成