JUCE/modules/juce_gui_basics/keyboard/juce_KeyboardFocusTraverser.cpp

/*
  ==============================================================================

   This file is part of the JUCE library - "Jules' Utility Class Extensions"
   Copyright 2004-11 by Raw Material Software Ltd.

  ------------------------------------------------------------------------------

   JUCE can be redistributed and/or modified under the terms of the GNU General
   Public License (Version 2), as published by the Free Software Foundation.
   A copy of the license is included in the JUCE distribution, or can be found
   online at www.gnu.org/licenses.

   JUCE is distributed in the hope that it will be useful, but WITHOUT ANY
   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
   A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

  ------------------------------------------------------------------------------

   To release a closed-source product which uses JUCE, commercial licenses are
   available: visit www.rawmaterialsoftware.com/juce for more information.

  ==============================================================================
*/

BEGIN_JUCE_NAMESPACE

//==============================================================================
KeyboardFocusTraverser::KeyboardFocusTraverser()
{
}

KeyboardFocusTraverser::~KeyboardFocusTraverser()
{
}

//==============================================================================
namespace KeyboardFocusHelpers
{
    // This will sort a set of components, so that they are ordered in terms of
    // left-to-right and then top-to-bottom.
    class ScreenPositionComparator
    {
    public:
        ScreenPositionComparator() {}

        static int compareElements (const Component* const first, const Component* const second)
        {
            int explicitOrder1 = first->getExplicitFocusOrder();
            if (explicitOrder1 <= 0)
                explicitOrder1 = std::numeric_limits<int>::max() / 2;

            int explicitOrder2 = second->getExplicitFocusOrder();
            if (explicitOrder2 <= 0)
                explicitOrder2 = std::numeric_limits<int>::max() / 2;

            if (explicitOrder1 != explicitOrder2)
                return explicitOrder1 - explicitOrder2;

            const int diff = first->getY() - second->getY();

            return (diff == 0) ? first->getX() - second->getX()
                               : diff;
        }
    };

    static void findAllFocusableComponents (Component* const parent, Array <Component*>& comps)
    {
        if (parent->getNumChildComponents() > 0)
        {
            Array <Component*> localComps;
            ScreenPositionComparator comparator;

            int i;
            for (i = parent->getNumChildComponents(); --i >= 0;)
            {
                Component* const c = parent->getChildComponent (i);

                if (c->isVisible() && c->isEnabled())
                    localComps.addSorted (comparator, c);
            }

            for (i = 0; i < localComps.size(); ++i)
            {
                Component* const c = localComps.getUnchecked (i);

                if (c->getWantsKeyboardFocus())
                    comps.add (c);

                if (! c->isFocusContainer())
                    findAllFocusableComponents (c, comps);
            }
        }
    }
}

namespace KeyboardFocusHelpers
{
    Component* getIncrementedComponent (Component* const current, const int delta)
    {
        Component* focusContainer = current->getParentComponent();

        if (focusContainer != nullptr)
        {
            while (focusContainer->getParentComponent() != nullptr && ! focusContainer->isFocusContainer())
                focusContainer = focusContainer->getParentComponent();

            if (focusContainer != nullptr)
            {
                Array <Component*> comps;
                KeyboardFocusHelpers::findAllFocusableComponents (focusContainer, comps);

                if (comps.size() > 0)
                {
                    const int index = comps.indexOf (current);
                    return comps [(index + comps.size() + delta) % comps.size()];
                }
            }
        }

        return nullptr;
    }
}

Component* KeyboardFocusTraverser::getNextComponent (Component* current)
{
    return KeyboardFocusHelpers::getIncrementedComponent (current, 1);
}

Component* KeyboardFocusTraverser::getPreviousComponent (Component* current)
{
    return KeyboardFocusHelpers::getIncrementedComponent (current, -1);
}

Component* KeyboardFocusTraverser::getDefaultComponent (Component* parentComponent)
{
    Array <Component*> comps;

    if (parentComponent != nullptr)
        KeyboardFocusHelpers::findAllFocusableComponents (parentComponent, comps);

    return comps.getFirst();
}


END_JUCE_NAMESPACE