FASM >> Assembly (x86) >> Win32 API >> Painting

Set Pixel

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參考資訊：
1. fasm

屏幕的最小顯示單位是像素，像素由紅色(Red)、綠色(Green)、藍色(Blue)、Alpha等四個顏色組成，因此，在呼叫CreateWindow()時，傳入的解析度，如：300x300，代表該視窗(有效區域)的X軸有300個像素，而Y軸則是有300個像素，這個300x300像素的區域是可以用來繪製任何東西，WM_PAINT是處理視窗重新繪畫的事件，繪畫的相關處理都需要在這個事件完成，比較特別的是，Windows視窗將繪圖的許多東西抽象化，最基本的需求是：一個DC(Device Context)和一個BITMAP，DC可以想像成是一個畫台，而BITMAP則是一片畫布(Buffer)，DC有了Buffer就可以畫上任何東西並將其顯示在視窗上

main.asm

    format PE GUI 4.0
    entry start
      
    include "c:\fasm\include\win32a.inc"
     
    section ".idata" import data readable writeable
library user, "user32.dll", kernel, "kernel32.dll", gdi, "gdi32.dll"

import gdi,                              \
    SetPixel,        "SetPixel"

import user,                             \
    EndPaint,        "EndPaint",         \
    SetTimer,        "SetTimer",         \
    wsprintf,        "wsprintfA",        \
    KillTimer,       "KillTimer",        \
    BeginPaint,      "BeginPaint",       \
    MessageBox,      "MessageBoxA",      \
    GetMessage,      "GetMessageA",      \
    SetScrollPos,    "SetScrollPos",     \
    DestroyWindow,   "DestroyWindow",    \
    SetWindowText,   "SetWindowTextA",   \
    SetWindowLong,   "SetWindowLongA",   \
    SetScrollRange,  "SetScrollRange",   \
    CreateWindowEx,  "CreateWindowExA",  \
    CallWindowProc,  "CallWindowProcA",  \
    DispatchMessage, "DispatchMessageA", \
    PostQuitMessage, "PostQuitMessage"
     
import kernel,                           \
    ExitProcess,     "ExitProcess",      \
    GetCommandLine,  "GetCommandLineA",  \
    GetModuleHandle, "GetModuleHandleA"
      
    section ".data" data readable writeable
hWin        dd 0
szCaption   db "main",0
hInstance   dd 0
CommandLine dd 0
defWndProc  dd 0
 
    section ".text" code readable executable
proc WndProc hWnd, uMsg, wParam, lParam
    local x:DWORD
    local y:DWORD
    local hdc:DWORD
    local ps:PAINTSTRUCT

    mov eax, [uMsg]
    cmp eax, WM_PAINT
    je .handle_paint
    cmp eax, WM_CLOSE
    je .handle_close
    cmp eax, WM_DESTROY
    je .handle_destroy
    invoke CallWindowProc, [defWndProc], [hWnd], [uMsg], [wParam], [lParam]
    jmp .finish
 
.handle_paint:
    lea eax, [ps]
    invoke BeginPaint, [hWnd], eax
    mov [hdc], eax

    xor eax, eax
    mov [y], eax
.ylp:
    xor eax, eax
    mov [x], eax
.xlp:
    invoke SetPixel, [hdc], [x], [y], 0ffh
    inc dword [x]
    cmp dword [x], 100
    jb .xlp
    inc dword [y]
    cmp dword [y], 100
    jb .ylp

    lea eax, [ps]
    invoke EndPaint, [hWnd], eax
    xor eax, eax
    jmp .finish
 
.handle_close:
    invoke DestroyWindow, [hWnd]
    xor eax, eax
    jmp .finish
     
.handle_destroy:
    invoke PostQuitMessage, 0
    xor eax, eax
    jmp .finish
      
.finish:
    ret
endp
     
proc WinMain hInst, hPrevInst, CmdLine, CmdShow
    local msg:MSG
     
    invoke CreateWindowEx, WS_EX_LEFT, WC_DIALOG, szCaption, \
        WS_OVERLAPPEDWINDOW or WS_VISIBLE, 0, 0, 300, 300, NULL, NULL, NULL, NULL
    mov [hWin], eax
     
    invoke SetWindowLong, [hWin], GWL_WNDPROC, WndProc
    mov [defWndProc], eax
  
@@:
    lea eax, [msg]
    invoke GetMessage, eax, NULL, 0, 0
    cmp eax, 0
    je @f
    lea eax, [msg]
    invoke DispatchMessage, eax
    jmp @b
@@:
    mov eax, [msg.wParam]
    ret
endp
     
start:
    invoke GetModuleHandle, NULL
    mov [hInstance], eax
      
    invoke GetCommandLine
    mov [CommandLine], eax
      
    stdcall WinMain, [hInstance], NULL, [CommandLine], SW_SHOWNORMAL
    invoke ExitProcess, eax

Line 59~81：處理繪畫事件
Line 60~62：取得視窗的DC，該DC已經有Buffer可以使用，因此，可以直接在上面繪製任何東西
Line 64~76：透過SetPixel()畫出一個正方形，顏色是紅色
Line 78~79：結束繪製

Makefile

export WINEPREFIX=/home/user/.wine_amd64

TARGET=main
MYWINE=box86 wine
FASM32=/home/user/.wine_amd64/drive_c/fasm

all:
	${MYWINE} ${FASM32}/fasm.exe ${TARGET}.asm

run:
	${MYWINE} ${TARGET}.exe

clean:
	rm -rf ${TARGET}.exe

編譯、執行

$ make
$ make run

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