程式語言 - Netwide Assembler (NASM) - Win32 API - Set Scrollbar

參考資訊：
https://masm32.com/board/index.php
https://www.nasm.us/xdoc/2.13rc9/html/nasmdoc0.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.asm

    %include "head.asm" 

    segment .text
WndProc:
    push ebp
    mov ebp, esp
     
    cmp dword [ebp + ARG2], WM_VSCROLL
    je .handle_vscroll
    cmp dword [ebp + ARG2], WM_CLOSE
    je .handle_close
    cmp dword [ebp + ARG2], WM_DESTROY
    je .handle_destroy
    jmp .handle_default
 
.handle_vscroll:
    cmp word [ebp + ARG3], SB_LINEUP
    je .handle_sb_line_up
    cmp word [ebp + ARG3], SB_LINEDOWN
    je .handle_sb_line_down
    cmp word [ebp + ARG3], SB_PAGEUP
    je .handle_sb_page_up
    cmp word [ebp + ARG3], SB_PAGEDOWN
    je .handle_sb_page_down
    jmp .finish
 
.handle_sb_line_up:
    push SLUP
    push dword [ebp + ARG1]
    call SetWindowText
    jmp .finish
 
.handle_sb_line_down:
    push SLDN
    push dword [ebp + ARG1]
    call SetWindowText
    jmp .finish
 
.handle_sb_page_up:
    push SPUP
    push dword [ebp + ARG1]
    call SetWindowText
    jmp .finish
 
.handle_sb_page_down:
    push SPDN
    push dword [ebp + ARG1]
    call SetWindowText
    jmp .finish
 
.handle_close:
    push dword [ebp + ARG1]
    call DestroyWindow
    xor eax, eax
    jmp .finish
     
.handle_destroy:
    push 0
    call PostQuitMessage
    xor eax, eax
    jmp .finish
     
.handle_default:
    push dword [ebp + ARG4]
    push dword [ebp + ARG3]
    push dword [ebp + ARG2]
    push dword [ebp + ARG1]
    push dword [pDefWndProc]
    call CallWindowProc
     
.finish:
    leave
    ret 16
     
WinMain:
    push ebp
    mov ebp, esp
      
    push 0
    push 0
    push 0
    push 0
    push 300
    push 300
    push 0
    push 0
    push WS_OVERLAPPEDWINDOW | WS_VISIBLE | WS_VSCROLL
    push szAppName
    push WC_DIALOG
    push WS_EX_LEFT
    call CreateWindowEx
    mov [hWin], eax
     
    push WndProc
    push GWL_WNDPROC
    push dword [hWin]
    call SetWindowLong
    mov [pDefWndProc], eax
  
    push 0
    push 100
    push 0
    push SB_VERT
    push dword [hWin]
    call SetScrollRange
 
    push 1
    push 50
    push SB_VERT
    push dword [hWin]
    call SetScrollPos
.loop:
    push 0
    push 0
    push 0
    push msg
    call GetMessage
    cmp eax, 0
    je .exit
      
    push msg
    call DispatchMessage
    jmp .loop
      
.exit:
    mov eax, [msg + MSG.wParam]
    leave
    ret 16
      
_start:
    push 0
    call GetModuleHandle
    mov [hInstance], eax
      
    call GetCommandLine
    mov [pCommand], eax
      
    push SW_SHOWNORMAL
    push dword [pCommand]
    push 0
    push dword [hInstance]
    call WinMain
      
    push eax
    call ExitProcess

Line 27~55：處理Scrollbar訊息並且顯示在視窗標題
Line 87：WS_VSCROLL是垂直的Scrollbar，WS_HSCROLL則是水平的Scrollbar
Line 100~105：設定Scrollbar最大的範圍
Line 107~111：設定Scrollbar目前的位置

完成