程式語言 - Netwide Assembler (NASM) - Win32 API - Painting - Create Pen

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

Pen可以想像成是一支畫筆，粗細、顏色都可以設定，DC(Device Context)可以透過SelectObject()選擇畫筆

main.asm

    %include "head.asm" 

    segment .text
WndProc:
    push ebp
    mov ebp, esp
         
    cmp dword [ebp + ARG2], WM_PAINT
    je .handle_paint
    cmp dword [ebp + ARG2], WM_CLOSE
    je .handle_close
    cmp dword [ebp + ARG2], WM_DESTROY
    je .handle_destroy
    jmp .handle_default
    
.handle_paint:
    push ps
    push dword [ebp + ARG1]
    call BeginPaint
    mov [hDC], eax
  
    push 0ffh
    push 10
    push PS_SOLID
    call CreatePen
    mov [hPen], eax
 
    push dword [hPen]
    push dword [hDC]
    call SelectObject
 
    push 0
    push 0
    push 0
    push dword [hDC]
    call MoveToEx
 
    push 100
    push 100
    push dword [hDC]
    call LineTo
  
    push ps
    push dword [ebp + ARG1]
    call EndPaint
  
    push dword [hPen]
    call DeleteObject
    xor eax, eax
    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
    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
      
.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 22~26：創造一支Pen，粗細是10，顏色則是紅色
Line 28~30：選擇要使用的Pen
Line 32~41：畫一條線
Line 47~48：刪除資源

完成