JUCE/modules/juce_blocks_basics/blocks/juce_TouchList.h

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

   This file is part of the JUCE library.
   Copyright (c) 2016 - ROLI Ltd.

   Permission is granted to use this software under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license/

   Permission to use, copy, modify, and/or distribute this software for any
   purpose with or without fee is hereby granted, provided that the above
   copyright notice and this permission notice appear in all copies.

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   TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
   FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT,
   OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
   USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
   TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
   OF THIS SOFTWARE.

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

   To release a closed-source product which uses other parts of JUCE not
   licensed under the ISC terms, commercial licenses are available: visit
   www.juce.com for more information.

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


/**
    Utility class to hold a list of TouchSurface::Touch objects with different
    indices and blockUIDs, where each touch has a mapping to some kind of
    user-supplied data value.

    The Type template is a user-defined type of object that will be stored for
    each touch element. The type must be default-constructable and copyable.
*/
template <typename Type>
class TouchList
{
public:
    /** Creates an empty touch list. */
    TouchList() {}

    /** Destructor. */
    ~TouchList() {}

    /** Returns the number of entries in the touch list. */
    int size() const noexcept { return touches.size(); }

    /** Returns the user data object that corresponds to the given touch.
        This will also update the stored state of the TouchEntry::touch value
        for this touch index.
    */
    Type& getValue (const TouchSurface::Touch& touch)
    {
        auto* t = find (touch);

        if (t == nullptr)
        {
            touches.add ({ touch, {} });
            return touches.getReference (touches.size() - 1).value;
        }
        else
        {
            t->touch = touch;
            return t->value;
        }
    }

    /** Returns true if a touch is already in the list. */
    bool contains (const TouchSurface::Touch& touch) const noexcept
    {
        return find (touch) != nullptr;
    }

    /** Updates the entry for the given touch, copying in the new state.
        If no entry with the same index and blockUID exists then a new entry is
        created. If given a touch which is a touch-end, this will *remove* any
        corresponding entries from the list.
    */
    void updateTouch (const TouchSurface::Touch& touch)
    {
        if (touch.isTouchEnd)
        {
            for (int i = touches.size(); --i >= 0;)
                if (matches (touches.getReference(i).touch, touch))
                    touches.remove (i);

            jassert (! contains (touch));
        }
        else
        {
            auto t = find (touch);

            if (t == nullptr)
                touches.add ({ touch, {} });
            else
                t->touch = touch;
        }
    }

    /** Holds the current state of a touch, along with the user-data associated with it. */
    struct TouchEntry
    {
        TouchSurface::Touch touch;
        Type value;
    };

    /** If a touch is in the list, returns a pointer to the TouchEntry.
        Otherwise, returns nullptr.
    */
    TouchEntry* find (const TouchSurface::Touch& touch) const noexcept
    {
        for (auto& t : touches)
            if (matches (t.touch, touch))
                return &t;

        return nullptr;
    }

    /** Allows iterator access to the list of touch entries. */
    TouchEntry* begin() const noexcept      { return touches.begin(); }

    /** Allows iterator access to the list of touch entries. */
    TouchEntry* end() const noexcept        { return touches.end(); }

    /** Retrieve a reference to particular item in the list of touch entires. */
    TouchEntry& operator[] (const int index) { return touches.getReference (index); }

    /** Resets all contents, doest not generate any call-backs. */
    void clear() noexcept                   { touches.clear(); }

private:
    //==========================================================================
    static bool matches (const TouchSurface::Touch& t1,
                         const TouchSurface::Touch& t2) noexcept
    {
        return t1.index == t2.index && t1.blockUID == t2.blockUID;
    }

    juce::Array<TouchEntry> touches;

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (TouchList)
};