Focus on MouseOver in Windows with Ogre3D

Question

I have an application using the Ogre3D to create multiple render windows, and I'm using the solution posted here to support non-exclusive mouse input to these windows. However, I find that I have to physically click on a render window before it regains focus, whereas I'd really like the render windows to gain focus on a mouseover event. Is it possible to capture a mouseover event on an unfocused render window in Ogre3D/OIS and then subsequently set the focus for the render window?

Answer 1

To support this kind of functionality using Ogre3D in Windows, I had to implement a singleton object that kept a collection of all of the instantiated displays.

class InputProcessor
{
    /// @name Types
    /// @{
public:
    /// @}

    /// @name InputProcessor implementation
    /// @{
public:
    void addDisplay(Display* _pDisplay);

    bool processMouseMoved(int _x, int _y, int _z, int _keyModifier);
    bool processMousePressed(int _keyModifier, int _id);
    bool processMouseReleased(int _keyModifier, int _id);

    static InputProcessor& getSingleton();
    /// @}

    /// @name 'Structors
    /// @{
private:
     InputProcessor();
    ~InputProcessor();
    /// @}

    /// @name Member Variables
    /// @{
private:
    typedef std::set<Display*>     Displays_type;
    Displays_type                  m_displays;
    /// @}

};  // class InputProcessor

Then, in my UIFrameListener (which derives from Ogre3D's ExampleFrameListener), I transform the mouse window coordinates to global screen coordinates. If the mouse happens to reside outside of the window region, I apply the relative mouse movement to the last recorded mouse position; otherwise, I simply apply the absolute mouse position within the window:

bool
UIFrameListener::mouseMoved(const OIS::MouseEvent& e)
{
    int keyModifierState = GetKeyModifierState();
    int windowLeft = m_display.getLeft();
    int windowTop = m_display.getTop();
    int windowWidth = m_display.m_pWindow->getWidth();
    int windowHeight = m_display.m_pWindow->getHeight();

    if (e.state.X.abs != 0 && e.state.X.abs != windowWidth)
    {
        m_lastX = e.state.X.abs;
    }
    else
    {
        m_lastX += e.state.X.rel;
    }
    int x = windowLeft + (m_display.m_width * m_lastX) / windowWidth;

    if (e.state.Y.abs != 0 && e.state.Y.abs != windowHeight)
    {
        m_lastY = e.state.Y.abs;
    }
    else
    {
        m_lastY += e.state.Y.rel;
    }
    int y = windowTop + (m_display.m_height * m_lastY) / windowHeight;

    int z = 0;
    if (e.state.Z.rel != 0)
    {
        z = e.state.Z.rel / -120;
    }

    return InputProcessor::getSingleton().processMouseMoved(x, y, z, keyModifierState);
}

And in InputProcessor::processMouseMoved(), I determine which window the mouse cursor is in (if any), and then set the focus appropriately, i.e.

bool
InputProcessor::processMouseMoved(int _x,
                                  int _y,
                                  int _z,
                                  int _keyModifier)
{
    bool found = false;

    Displays_type::iterator iter = m_displays.begin();
    while (iter != m_displays.end() && !found)
    {
        int left = (*iter)->getLeft();
        int top = (*iter)->getTop();
        int width = (*iter)->m_pWindow->getWidth();
        int height = (*iter)->m_pWindow->getHeight();

        if (left <= _x && left + width  > _x &&
            top  <= _y && top  + height > _y)
        {
            found = true;
        }
        else
        {
            iter++;
        }
    }

    if (iter != m_displays.end())
    {
        int left = (*iter)->getLeft();
        int top = (*iter)->getTop();

        (*iter)->m_pContext->ProcessMouseMove(
            _x - left, _y - top, _keyModifier
        );

        (*iter)->m_pContext->ProcessMouseWheel(_z, _keyModifier);

        if (!(*iter)->hasFocus())
        {
            (*iter)->setFocus(true);
        }
    }

    return true;
}

And in the implementation of Display, I have a method Display::setFocus() that sets the focus on the appropriate window:

void
Display::setFocus(bool _hasFocus)
{
    if (m_handle != NULL && _hasFocus)
    {
        SetFocus(m_handle);
    }
}