程式語言 - MASM32 - Set Scrollbar

參考資訊：
http://www.winprog.org/tutorial/
http://winapi.freetechsecrets.com/win32/
https://github.com/gammasoft71/Examples_Win32

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.asm

    .386
    .model flat,stdcall
    option casemap:none
      
include c:\masm32\include\msvcrt.inc
include c:\masm32\include\windows.inc
include c:\masm32\include\kernel32.inc
include c:\masm32\include\user32.inc
      
includelib c:\masm32\lib\msvcrt.lib
includelib c:\masm32\lib\user32.lib
includelib c:\masm32\lib\kernel32.lib
      
    .data
szCaption   db "main",0
hWin        dd 0
hInstance   dd 0
CommandLine dd 0
defWndProc  dd 0
SLUP        db "LINE++",0
SLDN        db "LINE--",0
SPUP        db "PAGE++",0
SPDN        db "PAGE--",0
      
    .code
WndProc proc hWnd:HWND, uMsg:UINT, wParam:WPARAM, lParam:LPARAM
    .if uMsg == WM_VSCROLL
        mov eax, wParam
        and eax, 0fffh
        .if eax == SB_LINEUP
            invoke SetWindowText, hWnd, offset SLUP
        .elseif eax == SB_LINEDOWN
            invoke SetWindowText, hWnd, offset SLDN
        .elseif eax == SB_PAGEUP
            invoke SetWindowText, hWnd, offset SPUP
        .elseif eax == SB_PAGEDOWN
            invoke SetWindowText, hWnd, offset SPDN
        .endif
        xor eax, eax
        ret
    .elseif uMsg == WM_CLOSE
        invoke DestroyWindow, hWnd
        xor eax, eax
        ret
    .elseif uMsg == WM_DESTROY
        invoke PostQuitMessage, 0
        xor eax, eax
        ret
    .endif
    
    invoke CallWindowProc, defWndProc, hWnd, uMsg, wParam, lParam
    ret
WndProc endp
     
WinMain proc hInst:DWORD, hPrevInst:DWORD, CmdLine:DWORD, CmdShow:DWORD
    local msg:MSG
      
    invoke CreateWindowEx, WS_EX_LEFT, WC_DIALOG, offset szCaption, 
        WS_OVERLAPPEDWINDOW or WS_VISIBLE or WS_VSCROLL, 0, 0, 300, 300, NULL, NULL, NULL, NULL
    mov hWin, eax
     
    invoke SetWindowLong, hWin, GWL_WNDPROC, WndProc
    mov defWndProc, eax
 
    invoke SetScrollRange, hWin, SB_VERT, 0, 100, FALSE
    invoke SetScrollPos, hWin, SB_VERT, 50, TRUE
@@:
    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 27~40：處理Scrollbar訊息並且顯示在視窗標題
Line 59：WS_VSCROLL是垂直的Scrollbar，WS_HSCROLL則是水平的Scrollbar
Line 65：設定Scrollbar最大的範圍
Line 66：設定Scrollbar目前的位置

完成