JUCE/modules/juce_gui_basics/keyboard/juce_KeyboardFocusTraverser.cpp

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

   This file is part of the JUCE 6 technical preview.
   Copyright (c) 2020 - Raw Material Software Limited

   You may use this code under the terms of the GPL v3
   (see www.gnu.org/licenses).

   For this technical preview, this file is not subject to commercial licensing.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

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

namespace juce
{

namespace KeyboardFocusHelpers
{
    static int getOrder (const Component* c)
    {
        auto order = c->getExplicitFocusOrder();
        return order > 0 ? order : (std::numeric_limits<int>::max() / 2);
    }

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

            for (auto* c : parent->getChildren())
                if (c->isVisible() && c->isEnabled())
                    localComps.add (c);

            // This will sort so that they are ordered in terms of left-to-right
            // and then top-to-bottom.
            std::stable_sort (localComps.begin(), localComps.end(),
                              [] (const Component* a, const Component* b)
            {
                auto explicitOrder1 = getOrder (a);
                auto explicitOrder2 = getOrder (b);

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

                if (a->getY() != b->getY())
                    return a->getY() < b->getY();

                return a->getX() < b->getX();
            });

            for (auto* c : localComps)
            {
                if (c->getWantsKeyboardFocus())
                    comps.add (c);

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

    static Component* findFocusContainer (Component* c)
    {
        c = c->getParentComponent();

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

        return c;
    }

    static Component* getIncrementedComponent (Component* current, int delta)
    {
        if (auto* focusContainer = findFocusContainer (current))
        {
            Array<Component*> comps;
            KeyboardFocusHelpers::findAllFocusableComponents (focusContainer, comps);

            if (! comps.isEmpty())
            {
                auto index = comps.indexOf (current);
                return comps [(index + comps.size() + delta) % comps.size()];
            }
        }

        return nullptr;
    }
}

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

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

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

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

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

    return comps.getFirst();
}

} // namespace juce