PythonからWindows APIを使ってウィンドウ表示

はじめに

ctypesパッケージを使ってWindows APIを呼び出すサンプルとしてウィンドウを表示してみた。

ソース

winapp.py

from ctypes import *
from ctypes.wintypes import *

gdi32 = windll.gdi32
kernel32 = windll.kernel32
user32 = windll.user32

CS_HREDRAW = 0x0002
CS_VREDRAW = 0x0001
IDC_ARROW = 32512
COLOR_WINDOW = 5
WS_OVERLAPPEDWINDOW = 0x00CF0000
CW_USEDEFAULT = 0x80000000
SW_SHOWDEFAULT = 10
WM_DESTROY = 0x0002
WM_PAINT = 0x000F
WNDPROC = WINFUNCTYPE(LONG, HWND, UINT, WPARAM, LPARAM)

class WNDCLASSEXW(Structure):
    _fields_ = [
        ("cbSize", UINT),
        ("style", UINT),
        ("lpfnWndProc", WNDPROC),
        ("cbClsExtra", c_int),
        ("cbWndExtra", c_int),
        ("hInstance", HINSTANCE),
        ("hIcon", HICON),
        ("hCursor", HANDLE),
        ("hbrBackground", HBRUSH),
        ("lpszMenuName", LPCWSTR),
        ("lpszClassName", LPCWSTR),
        ("hIconSm", HICON),
    ]

class PAINTSTRUCT(Structure):
    _fields_ = [
        ("hdc", HDC),
        ("fErase", BOOL),
        ("rcPaint", RECT),
        ("fRestore", BOOL),
        ("fIncUpdate", BOOL),
        ("rgbReserved", BYTE * 32),
    ]

def WinMain(hInstance, nShowCmd):

    wc = WNDCLASSEXW()
    wc.cbSize = sizeof(WNDCLASSEXW)
    wc.style = CS_HREDRAW | CS_VREDRAW
    wc.lpfnWndProc = WNDPROC(WndProc)
    wc.hInstance = hInstance
    wc.hCursor = user32.LoadCursorW(None, IDC_ARROW)
    wc.hbrBackground = HBRUSH(COLOR_WINDOW + 1)
    wc.lpszClassName = "winapp"

    ret = user32.RegisterClassExW(wc)

    hWnd = user32.CreateWindowExW(
        0, "winapp", "winapp",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, 0,
        CW_USEDEFAULT, 0,
        None, None, hInstance, None)
    user32.ShowWindow(hWnd, nShowCmd)
    user32.UpdateWindow(hWnd)

    msg = MSG()
    while user32.GetMessageW(byref(msg), None, 0, 0):
        user32.TranslateMessage(msg)
        user32.DispatchMessageW(msg)
    return msg.wParam

def WndProc(hWnd, uMsg, wParam, lParam):
    if uMsg == WM_DESTROY:
        user32.PostQuitMessage(0)
        return 0
    if uMsg == WM_PAINT:
        OnPaint(hWnd)
        return 0
    return user32.DefWindowProcW(hWnd, uMsg, WPARAM(wParam), LPARAM(lParam))

def OnPaint(hWnd):
    ps = PAINTSTRUCT()
    hdc = user32.BeginPaint(hWnd, byref(ps))
    txt = "hello, world"
    gdi32.TextOutW(hdc, 10, 10, txt, len(txt))
    user32.EndPaint(hWnd, ps)

hInstance = kernel32.GetModuleHandleW(None)
WinMain(hInstance, SW_SHOWDEFAULT)

実行

py winapp.py