C++20&Win API&WIL IUIAutomationElementを列挙する

COMとWILを使ってIUIAutomationElementを列挙するコードです。

実行例（ExplorerPatcher起動中）

Source.cpp

#include <format>
#include <iostream>
#include "string_util.hpp"

#define STRICT
#define NOMINMAX
#include <Windows.h>
#include <UIAutomation.h>
#include "stl_win.hpp"

#include "wil/com.h"

int main()
{
    std::wcout.imbue(std::locale("", std::locale::ctype));

    auto coinit = wil::CoInitializeEx(COINIT_APARTMENTTHREADED);
    auto uiAutomation = wil::CoCreateInstance<CUIAutomation, IUIAutomation>(CLSCTX_INPROC_SERVER);

    auto hwnds = GetWindowHandles();
    std::wcout << L"WindowHandle, ClassName, WindowText, UIAutomation ElementName, ClassName" << std::endl;
    for (auto hwnd : hwnds)
    {
        wil::com_ptr<IUIAutomationElement> uiAutoElem;
        if (FAILED(uiAutomation->ElementFromHandle(hwnd, uiAutoElem.put())))
            continue;

        wil::unique_bstr name, className;
        uiAutoElem->get_CurrentName(name.put());
        uiAutoElem->get_CurrentClassName(className.put());

        std::wcout
            << std::format(L"{}, {}, {}, {}, {}",
                pad_start(to_wstring_hex_uc(std::bit_cast<size_t>(hwnd)), MAX_SIZE_T_HEX_LENGTH, L'0'),
                GetClassNameW(hwnd),
                GetWindowTextW(hwnd),
                wil::string_get_not_null(name),
                wil::string_get_not_null(className))
            << std::endl;
    }

    return 0;
}

string_util.hpp

#pragma once

#include <string>

const size_t MAX_SIZE_T_HEX_LENGTH = sizeof(size_t) * 2;

constexpr std::wstring to_wstring_hex_uc(size_t x)
{
    std::wstring s;
    for (; x != 0; x /= 16)
    {
        auto m = x % 16;
        s.push_back(static_cast<wchar_t>((m < 10 ? L'0' : L'A' - 10) + m));
    }
    return s;
}

constexpr std::wstring pad_start(std::wstring_view source, size_t length, wchar_t fill)
{
    if (source.size() >= length)
        return std::wstring(source.cbegin(), source.cend());
    std::wstring s;
    s.reserve(length);
    s.append(length - source.size(), fill);
    s.append(source);
    return s;
}

stl_win.hpp

#pragma once

#include <bit>
#include <string>
#include <vector>

BOOL CALLBACK GetWindowHandlesWorker(HWND hwnd, LPARAM lParam)
{
    auto& v = *std::bit_cast<std::vector<HWND>*>(lParam);
    v.emplace_back(hwnd);
    EnumChildWindows(hwnd, GetWindowHandlesWorker, lParam);
    return TRUE;
}

std::vector<HWND> GetWindowHandles()
{
    std::vector<HWND> v;
    EnumWindows(GetWindowHandlesWorker, std::bit_cast<LPARAM>(std::addressof(v)));
    return v;
}

std::wstring GetClassNameW(HWND hwnd)
{
    std::wstring s;
    for (int size = 0xff; ; size += 0xff)
    {
        s.resize(size);
        auto copied = ::GetClassNameW(hwnd, s.data(), size + 1);
        if (copied != 0)
        {
            s.resize(copied);
            s.shrink_to_fit();
            break;
        }
        else if (GetLastError() != ERROR_INSUFFICIENT_BUFFER)
        {
            return {};
        }
    }
    return s;
}

std::wstring GetWindowTextW(HWND hwnd)
{
    auto len = GetWindowTextLengthW(hwnd);
    if (len == 0)
        return {};

    std::wstring s(len, L'\0');
    if (GetWindowTextW(hwnd, s.data(), len + 1) == 0)
        return {};
    return s;
}