UpdateDisplay/Main.cpp

#include <Windows.h>
#include <io.h>
#include <fcntl.h>

#include <iostream>
#include <string>
#include <exception>


#include "Display.h"


void print_help()
{
    std::cout
        << "UpdateDisplay" << std::endl
        << "=============" << std::endl
        << std::endl
        << "Usage: UpdateDisplay.exe <options...>" << std::endl
        << std::endl
        << "By default the program will refresh display settings." << std::endl
        << std::endl
        << "Possible options:" << std::endl
        << std::endl
        << "--rotate" << "\t - Rotates Display" << std::endl
        << "\t0"      << "\t - Landscape" << std::endl
        << "\t90"     << "\t - Prtrait" << std::endl
        << "\t180"    << "\t - Flippd Landscape" << std::endl
        << "\t270"    << "\t - Flippd Prtrait" << std::endl
        << std::endl;
}


void main(int argc, char** argv)
{
    if (argc == 1)
        return print_help();

    Display dis;

    char** arg = argv;
    arg++;
    for (int i = 1; i < argc; i++, arg++)
    {
        std::string a(*arg);

        if (a == "--help")
            print_help();

        else if (a == "--rotate")
        {
            i++;
            arg++;
            if (i == argc)
                throw std::exception("Argumment to --rotate not specified");
            a = std::string(*arg);

            if (a == "0")
                dis.rotate(Display::Rotation::ROTATE_0);
            else if (a == "90")
                dis.rotate(Display::Rotation::ROTATE_90);
            else if (a == "180")
                dis.rotate(Display::Rotation::ROTATE_180);
            else if (a == "270")
                dis.rotate(Display::Rotation::ROTATE_270);
            else
                throw std::exception(("Unknown rotation: "+a).c_str());
        }
    }

    dis.apply();
}


// Taken from https://stackoverflow.com/a/74999569
static void get_command_line_args(int* argc, char*** argv)
{
    // Get the command line arguments as wchar_t strings
    wchar_t** wargv = CommandLineToArgvW(GetCommandLineW(), argc);
    if (!wargv) { *argc = 0; *argv = NULL; return; }

    // Count the number of bytes necessary to store the UTF-8 versions of those strings
    int n = 0;
    for (int i = 0; i < *argc; i++)
        n += WideCharToMultiByte(CP_UTF8, 0, wargv[i], -1, NULL, 0, NULL, NULL) + 1;

    // Allocate the argv[] array + all the UTF-8 strings
    *argv = (char**)malloc((*argc + 1) * sizeof(char*) + n);
    if (!*argv) { *argc = 0; return; }

    // Convert all wargv[] --> argv[]
    char* arg = (char*)&((*argv)[*argc + 1]);
    for (int i = 0; i < *argc; i++)
    {
        (*argv)[i] = arg;
        arg += WideCharToMultiByte(CP_UTF8, 0, wargv[i], -1, arg, n, NULL, NULL) + 1;
    }
    (*argv)[*argc] = NULL;
}


// Source - https://stackoverflow.com/a
// Posted by Roger Sanders, modified by community. See post 'Timeline' for change history
// Retrieved 2025-12-13, License - CC BY-SA 3.0
void BindCrtHandlesToStdHandles(bool bindStdIn, bool bindStdOut, bool bindStdErr)
{
    // Re-initialize the C runtime "FILE" handles with clean handles bound to "nul". We do this because it has been
    // observed that the file number of our standard handle file objects can be assigned internally to a value of -2
    // when not bound to a valid target, which represents some kind of unknown internal invalid state. In this state our
    // call to "_dup2" fails, as it specifically tests to ensure that the target file number isn't equal to this value
    // before allowing the operation to continue. We can resolve this issue by first "re-opening" the target files to
    // use the "nul" device, which will place them into a valid state, after which we can redirect them to our target
    // using the "_dup2" function.
    if (bindStdIn)
    {
        FILE* dummyFile;
        freopen_s(&dummyFile, "nul", "r", stdin);
    }
    if (bindStdOut)
    {
        FILE* dummyFile;
        freopen_s(&dummyFile, "nul", "w", stdout);
    }
    if (bindStdErr)
    {
        FILE* dummyFile;
        freopen_s(&dummyFile, "nul", "w", stderr);
    }

    // Redirect unbuffered stdin from the current standard input handle
    if (bindStdIn)
    {
        HANDLE stdHandle = GetStdHandle(STD_INPUT_HANDLE);
        if (stdHandle != INVALID_HANDLE_VALUE)
        {
            int fileDescriptor = _open_osfhandle((intptr_t)stdHandle, _O_TEXT);
            if (fileDescriptor != -1)
            {
                FILE* file = _fdopen(fileDescriptor, "r");
                if (file != NULL)
                {
                    int dup2Result = _dup2(_fileno(file), _fileno(stdin));
                    if (dup2Result == 0)
                    {
                        setvbuf(stdin, NULL, _IONBF, 0);
                    }
                }
            }
        }
    }

    // Redirect unbuffered stdout to the current standard output handle
    if (bindStdOut)
    {
        HANDLE stdHandle = GetStdHandle(STD_OUTPUT_HANDLE);
        if (stdHandle != INVALID_HANDLE_VALUE)
        {
            int fileDescriptor = _open_osfhandle((intptr_t)stdHandle, _O_TEXT);
            if (fileDescriptor != -1)
            {
                FILE* file = _fdopen(fileDescriptor, "w");
                if (file != NULL)
                {
                    int dup2Result = _dup2(_fileno(file), _fileno(stdout));
                    if (dup2Result == 0)
                    {
                        setvbuf(stdout, NULL, _IONBF, 0);
                    }
                }
            }
        }
    }

    // Redirect unbuffered stderr to the current standard error handle
    if (bindStdErr)
    {
        HANDLE stdHandle = GetStdHandle(STD_ERROR_HANDLE);
        if (stdHandle != INVALID_HANDLE_VALUE)
        {
            int fileDescriptor = _open_osfhandle((intptr_t)stdHandle, _O_TEXT);
            if (fileDescriptor != -1)
            {
                FILE* file = _fdopen(fileDescriptor, "w");
                if (file != NULL)
                {
                    int dup2Result = _dup2(_fileno(file), _fileno(stderr));
                    if (dup2Result == 0)
                    {
                        setvbuf(stderr, NULL, _IONBF, 0);
                    }
                }
            }
        }
    }

    // Clear the error state for each of the C++ standard stream objects. We need to do this, as attempts to access the
    // standard streams before they refer to a valid target will cause the iostream objects to enter an error state. In
    // versions of Visual Studio after 2005, this seems to always occur during startup regardless of whether anything
    // has been read from or written to the targets or not.
    if (bindStdIn)
    {
        std::wcin.clear();
        std::cin.clear();
    }
    if (bindStdOut)
    {
        std::wcout.clear();
        std::cout.clear();
    }
    if (bindStdErr)
    {
        std::wcerr.clear();
        std::cerr.clear();
    }
}



int APIENTRY WinMain(HINSTANCE hInst, HINSTANCE hInstPrev, PSTR cmdline, int cmdshow)
{
    if (AttachConsole(ATTACH_PARENT_PROCESS))
        BindCrtHandlesToStdHandles(true, true, true);

    int argc = 0;
    char** argv = nullptr;
    try
    {
        get_command_line_args(&argc, &argv);

        main(argc, argv);

        if (argv)
            free(argv);

        return EXIT_SUCCESS;
    }
    catch (std::exception& ex)
    {
        if (argv)
            free(argv);

        MessageBoxA(nullptr, ex.what(), "UpdateDisplay error", MB_ICONERROR);

        return EXIT_FAILURE;
    }
}