D2D1 Overlay

#include <windows.h>
#include <d2d1.h>
#include <dwmapi.h>

LRESULT CALLBACK WindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    switch (uMsg)
    {
        case WM_DESTROY:
        {
            PostQuitMessage(0);
            return 0;
        }
    }
    return DefWindowProc(hWnd, uMsg, wParam, lParam);
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd)
{
    WNDCLASSEX wndClass;
    ZeroMemory(&wndClass, sizeof(WNDCLASSEX));

    wndClass.cbSize = sizeof(WNDCLASSEX);
    wndClass.hbrBackground = (HBRUSH)CreateSolidBrush(RGB(0, 0, 0));
    wndClass.hInstance = hInstance;
    wndClass.lpfnWndProc = WindowProc;
    wndClass.lpszClassName = "Overlay";
    wndClass.style = CS_HREDRAW | CS_VREDRAW;

    RegisterClassEx(&wndClass);

    RECT rc = {0, 0, 1440, 900};
    AdjustWindowRectEx(&rc, WS_OVERLAPPEDWINDOW, false, WS_EX_OVERLAPPEDWINDOW);

    HWND hWnd = CreateWindowEx(WS_EX_LAYERED, "Overlay", "OverlayWindow", WS_EX_TOPMOST | WS_POPUP,
        0, 0, rc.right - rc.left, rc.bottom - rc.top, NULL, NULL, hInstance, NULL);

    ID2D1Factory *factory = NULL;
    ID2D1HwndRenderTarget *renderTarget = NULL;
    ID2D1SolidColorBrush *brush = NULL;

    HRESULT hResult = D2D1CreateFactory(D2D1_FACTORY_TYPE_SINGLE_THREADED, &factory);

    RECT rc2;
    GetClientRect(hWnd, &rc2);

    factory->CreateHwndRenderTarget(
        D2D1::RenderTargetProperties(D2D1_RENDER_TARGET_TYPE_DEFAULT, D2D1::PixelFormat(DXGI_FORMAT_UNKNOWN, D2D1_ALPHA_MODE_PREMULTIPLIED)),
        D2D1::HwndRenderTargetProperties(hWnd, D2D1::SizeU(rc2.right, rc2.bottom), D2D1_PRESENT_OPTIONS_IMMEDIATELY),
        &renderTarget);

    renderTarget->CreateSolidColorBrush(D2D1::ColorF(0, 0, 0, 0), &brush);

    const MARGINS margin = {-1};
    SetLayeredWindowAttributes(hWnd, RGB(0, 0, 0), 255, ULW_COLORKEY | LWA_ALPHA);
    DwmExtendFrameIntoClientArea(hWnd, &margin);

    ShowWindow(hWnd, nShowCmd);
    MSG messages = {0};

    while (messages.message != WM_QUIT)
    {
        if (PeekMessage(&messages, NULL, 0, 0, PM_REMOVE))
        {
            TranslateMessage(&messages);
            DispatchMessage(&messages);
        }
        else
        {
            renderTarget->BeginDraw();
            renderTarget->Clear(D2D1::ColorF(0.0f, 0.0f, 0.0f, 0.0f));
            brush->SetColor(D2D1::ColorF(1.0f, 0.0f, 0.0f, 1.0f));
            renderTarget->DrawEllipse(D2D1::Ellipse(D2D1::Point2F(100, 100), 50, 50), brush, 3.0f);
            renderTarget->EndDraw();
        }
    }

}