JUCE/modules/juce_audio_processors/utilities/juce_AudioProcessorValueTreeState.h

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

   This file is part of the JUCE library.
   Copyright (c) 2015 - ROLI Ltd.

   Permission is granted to use this software under the terms of either:
   a) the GPL v2 (or any later version)
   b) the Affero GPL v3

   Details of these licenses can be found 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.juce.com for more information.

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

#pragma once

#if JUCE_COMPILER_SUPPORTS_LAMBDAS

/**
    This class contains a ValueTree which is used to manage an AudioProcessor's entire state.

    It has its own internal class of parameter object which are linked to values
    within its ValueTree, and which are each identified by a string ID.

    You can get access to the underlying ValueTree object via the state member variable,
    so you can add extra properties to it as necessary.

    It also provides some utility child classes for connecting parameters directly to
    GUI controls like sliders.

    To use:
    1) Create an AudioProcessorValueTreeState, and give it some parameters using createParameter().
    2) Initialise the state member variable with a type name.
*/
class JUCE_API  AudioProcessorValueTreeState  : private Timer,
                                                private ValueTree::Listener
{
public:
    /** Creates a state object for a given processor.

        The UndoManager is optional and can be a nullptr.
        After creating your state object, you should add parameters with the
        createAndAddParameter() method. Note that each AudioProcessorValueTreeState
        should be attached to only one processor, and must have the same lifetime as the
        processor, as they will have dependencies on each other.
    */
    AudioProcessorValueTreeState (AudioProcessor& processorToConnectTo,
                                  UndoManager* undoManagerToUse);

    /** Destructor. */
    ~AudioProcessorValueTreeState();

    /** Creates and returns a new parameter object for controlling a parameter
        with the given ID.

        Calling this will create and add a special type of AudioProcessorParameter to the
        AudioProcessor to which this state is attached.

        @param parameterID          A unique string ID for the new parameter
        @param parameterName        The name that the parameter will return from AudioProcessorParameter::getName()
        @param labelText            The label that the parameter will return from AudioProcessorParameter::getLabel()
        @param valueRange           A mapping that will be used to determine the value range which this parameter uses
        @param defaultValue         A default value for the parameter (in non-normalised units)
        @param valueToTextFunction  A function that will convert a non-normalised value to a string for the
                                    AudioProcessorParameter::getText() method. This can be nullptr to use the
                                    default implementation
        @param textToValueFunction  The inverse of valueToTextFunction
        @returns the parameter object that was created
    */
    AudioProcessorParameterWithID* createAndAddParameter (const String& parameterID,
                                                          const String& parameterName,
                                                          const String& labelText,
                                                          NormalisableRange<float> valueRange,
                                                          float defaultValue,
                                                          std::function<String (float)> valueToTextFunction,
                                                          std::function<float (const String&)> textToValueFunction);

    /** Returns a parameter by its ID string. */
    AudioProcessorParameterWithID* getParameter (StringRef parameterID) const noexcept;

    /** Returns a pointer to a floating point representation of a particular
        parameter which a realtime process can read to find out its current value.
    */
    float* getRawParameterValue (StringRef parameterID) const noexcept;

    /** A listener class that can be attached to an AudioProcessorValueTreeState.
        Use AudioProcessorValueTreeState::addParameterListener() to register a callback.
    */
    struct JUCE_API  Listener
    {
        Listener();
        virtual ~Listener();

        /** This callback method is called by the AudioProcessorValueTreeState when a parameter changes. */
        virtual void parameterChanged (const String& parameterID, float newValue) = 0;
    };

    /** Attaches a callback to one of the parameters, which will be called when the parameter changes. */
    void addParameterListener (StringRef parameterID, Listener* listener);

    /** Removes a callback that was previously added with addParameterCallback(). */
    void removeParameterListener (StringRef parameterID, Listener* listener);

    /** Returns a Value object that can be used to control a particular parameter. */
    Value getParameterAsValue (StringRef parameterID) const;

    /** Returns the range that was set when the given parameter was created. */
    NormalisableRange<float> getParameterRange (StringRef parameterID) const noexcept;

    /** A reference to the processor with which this state is associated. */
    AudioProcessor& processor;

    /** The state of the whole processor.

        This must be initialised after all calls to createAndAddParameter().
        You can replace this with your own ValueTree object, and can add properties and
        children to the tree. This class will automatically add children for each of the
        parameter objects that are created by createParameter().
    */
    ValueTree state;

    /** Provides access to the undo manager that this object is using. */
    UndoManager* const undoManager;

    //==============================================================================
    /** An object of this class maintains a connection between a Slider and a parameter
        in an AudioProcessorValueTreeState.

        During the lifetime of this SliderAttachment object, it keeps the two things in
        sync, making it easy to connect a slider to a parameter. When this object is
        deleted, the connection is broken. Make sure that your AudioProcessorValueTreeState
        and Slider aren't deleted before this object!
    */
    class JUCE_API  SliderAttachment
    {
    public:
        SliderAttachment (AudioProcessorValueTreeState& stateToControl,
                          const String& parameterID,
                          Slider& sliderToControl);
        ~SliderAttachment();

    private:
        struct Pimpl;
        friend struct ContainerDeletePolicy<Pimpl>;
        ScopedPointer<Pimpl> pimpl;
        JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (SliderAttachment)
    };

    //==============================================================================
    /** An object of this class maintains a connection between a ComboBox and a parameter
        in an AudioProcessorValueTreeState.

        During the lifetime of this ComboBoxAttachment object, it keeps the two things in
        sync, making it easy to connect a combo box to a parameter. When this object is
        deleted, the connection is broken. Make sure that your AudioProcessorValueTreeState
        and ComboBox aren't deleted before this object!
    */
    class JUCE_API  ComboBoxAttachment
    {
    public:
        ComboBoxAttachment (AudioProcessorValueTreeState& stateToControl,
                            const String& parameterID,
                            ComboBox& comboBoxToControl);
        ~ComboBoxAttachment();

    private:
        struct Pimpl;
        friend struct ContainerDeletePolicy<Pimpl>;
        ScopedPointer<Pimpl> pimpl;
        JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (ComboBoxAttachment)
    };

    //==============================================================================
    /** An object of this class maintains a connection between a Button and a parameter
        in an AudioProcessorValueTreeState.

        During the lifetime of this ButtonAttachment object, it keeps the two things in
        sync, making it easy to connect a button to a parameter. When this object is
        deleted, the connection is broken. Make sure that your AudioProcessorValueTreeState
        and Button aren't deleted before this object!
    */
    class JUCE_API  ButtonAttachment
    {
    public:
        ButtonAttachment (AudioProcessorValueTreeState& stateToControl,
                          const String& parameterID,
                          Button& buttonToControl);
        ~ButtonAttachment();

    private:
        struct Pimpl;
        friend struct ContainerDeletePolicy<Pimpl>;
        ScopedPointer<Pimpl> pimpl;
        JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (ButtonAttachment)
    };

private:
    //==============================================================================
    struct Parameter;
    friend struct Parameter;

    ValueTree getOrCreateChildValueTree (const String&);
    void timerCallback() override;

    void valueTreePropertyChanged (ValueTree&, const Identifier&) override;
    void valueTreeChildAdded (ValueTree&, ValueTree&) override;
    void valueTreeChildRemoved (ValueTree&, ValueTree&, int) override;
    void valueTreeChildOrderChanged (ValueTree&, int, int) override;
    void valueTreeParentChanged (ValueTree&) override;
    void valueTreeRedirected (ValueTree&) override;
    void updateParameterConnectionsToChildTrees();

    Identifier valueType, valuePropertyID, idPropertyID;
    bool updatingConnections;

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (AudioProcessorValueTreeState)
};

#endif