Radio Button Control Example

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#include <windows.h>

#define ID_BLUE   1
#define ID_GREEN  2
#define ID_RED    3

int red = 0;
int green = 0;
int blue = 0;

COLORREF bk_color;

LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);

int WINAPI WinMain(HINSTANCE hInstance,
                   HINSTANCE hPrevInstance,
                   LPSTR lpCmdLine,
                   int nCmdShow)
{
    WNDCLASSEX wc;
    MSG msg;

    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = 0;
    wc.lpfnWndProc = WndProc;
    wc.cbClsExtra = 0;
    wc.cbWndExtra = 0;
    wc.hInstance = hInstance;
    wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
    wc.lpszMenuName = NULL;
    wc.lpszClassName = TEXT("MyWindowClass");
    wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION);

    RegisterClassEx(&wc);

    CreateWindowEx(
        WS_EX_CLIENTEDGE,
        TEXT("MyWindowClass"),
        TEXT("Check Box Demo"),
        WS_OVERLAPPEDWINDOW | WS_VISIBLE,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        700,
        350,
        NULL,
        NULL,
        hInstance,
        NULL);

    while (GetMessage(&msg, NULL, 0, 0) > 0)
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return (int)msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd,
                         UINT msg,
                         WPARAM wParam,
                         LPARAM lParam)
{
    HDC hdc;
    PAINTSTRUCT ps;
    HBRUSH hBrush;
    RECT rect;
    int checked;

    switch (msg)
    {
        case WM_CREATE:

            CreateWindow(
                TEXT("BUTTON"),
                TEXT("Blue"),
                WS_CHILD | WS_VISIBLE | BS_AUTOCHECKBOX,
                200, 60, 70, 30,
                hwnd,
                (HMENU)ID_BLUE,
                NULL,
                NULL);

            CreateWindow(
                TEXT("BUTTON"),
                TEXT("Green"),
                WS_CHILD | WS_VISIBLE | BS_AUTOCHECKBOX,
                280, 60, 70, 30,
                hwnd,
                (HMENU)ID_GREEN,
                NULL,
                NULL);

            CreateWindow(
                TEXT("BUTTON"),
                TEXT("Red"),
                WS_CHILD | WS_VISIBLE | BS_AUTOCHECKBOX,
                360, 60, 70, 30,
                hwnd,
                (HMENU)ID_RED,
                NULL,
                NULL);

            return 0;

        case WM_COMMAND:

            if (HIWORD(wParam) == BN_CLICKED)
            {
                switch (LOWORD(wParam))
                {
                    case ID_BLUE:

                        checked = IsDlgButtonChecked(hwnd, ID_BLUE);
                        blue = checked * 255;
                        break;

                    case ID_GREEN:

                        checked = IsDlgButtonChecked(hwnd, ID_GREEN);
                        green = checked * 255;
                        break;

                    case ID_RED:

                        checked = IsDlgButtonChecked(hwnd, ID_RED);
                        red = checked * 255;
                        break;
                }

                InvalidateRect(hwnd, NULL, TRUE);
            }

            return 0;

        case WM_PAINT:

            hdc = BeginPaint(hwnd, &ps);

            bk_color = RGB(red, green, blue);

            hBrush = CreateSolidBrush(bk_color);

            GetClientRect(hwnd, &rect);

            FillRect(hdc, &rect, hBrush);

            DeleteObject(hBrush);

            EndPaint(hwnd, &ps);

            return 0;

        case WM_DESTROY:

            PostQuitMessage(0);
            return 0;
    }

    return DefWindowProc(hwnd, msg, wParam, lParam);
}