Method DoDragDrop

Source/Engine/Platform/Windows/WindowsWindow.DragDrop.cpp:571–615

WindowsGuiData GuiDragDropData;

DragDropEffect Window::DoDragDrop(const StringView& data)
{
    // Create background worker that will keep updating GUI (perform rendering)
    const auto task = New<DoDragDropJob>();
    Task::StartNew(task);
    while (task->GetState() == TaskState::Queued)
        Platform::Sleep(1);

    // Create descriptors
    FORMATETC fmtetc = { CF_TEXT, nullptr, DVASPECT_CONTENT, -1, TYMED_HGLOBAL };
    STGMEDIUM stgmed = { TYMED_HGLOBAL, { nullptr }, nullptr };

    // Create a HGLOBAL inside the storage medium
    stgmed.hGlobal = StringToHandle(data);

    // Create drop source
    auto dropSource = new WindowsDragSource(&fmtetc, &stgmed, 1);

    // Do the drag drop operation
    DWORD dwEffect;
    HRESULT result = ::DoDragDrop(dropSource, dropSource, DROPEFFECT_COPY | DROPEFFECT_MOVE | DROPEFFECT_LINK | DROPEFFECT_SCROLL, &dwEffect);

    // Wait for job end
    Platform::AtomicStore(&task->ExitFlag, 1);
    task->Wait();

    // Release allocated data
    dropSource->Release();
    ReleaseStgMedium(&stgmed);

    // Fix hanging mouse state (Windows doesn't send WM_LBUTTONUP when we end the drag and drop)
    if (Input::GetMouseButton(MouseButton::Left))
    {
        ::POINT point;
        ::GetCursorPos(&point);
#if PLATFORM_SDL
        // Reset the internal button state in SDL
        SendMessageA((HWND)_handle, WM_LBUTTONUP, 0, MAKELPARAM(point.x, point.y));
#else
        Input::Mouse->OnMouseUp(Float2((float)point.x, (float)point.y), MouseButton::Left, this);
#endif
    }

    return SUCCEEDED(result) ? dropEffectFromOleEnum(dwEffect) : DragDropEffect::None;
}

HRESULT Window::DragEnter(Windows::IDataObject* pDataObj, Windows::DWORD grfKeyState, Windows::POINTL pt, Windows::DWORD* pdwEffect)
{