AudioProcessorValueTreeState Class Reference

This class contains a ValueTree that is used to manage an AudioProcessor's entire state. More...

#include <juce_AudioProcessorValueTreeState.h>

Inheritance diagram for AudioProcessorValueTreeState:

Classes
class	ButtonAttachment
	An object of this class maintains a connection between a Button and a parameter in an AudioProcessorValueTreeState. More...
class	ComboBoxAttachment
	An object of this class maintains a connection between a ComboBox and a parameter in an AudioProcessorValueTreeState. More...
struct	Listener
	A listener class that can be attached to an AudioProcessorValueTreeState. More...
class	Parameter
	A parameter class that maintains backwards compatibility with deprecated AudioProcessorValueTreeState functionality. More...
class	ParameterLayout
	A class to contain a set of RangedAudioParameters and AudioProcessorParameterGroups containing RangedAudioParameters. More...
class	SliderAttachment
	An object of this class maintains a connection between a Slider and a parameter in an AudioProcessorValueTreeState. More...

Public Member Functions
	AudioProcessorValueTreeState (AudioProcessor &processorToConnectTo, UndoManager *undoManagerToUse, const Identifier &valueTreeType, ParameterLayout parameterLayout)
	Creates a state object for a given processor, and sets up all the parameters that will control that processor. More...
	AudioProcessorValueTreeState (AudioProcessor &processorToConnectTo, UndoManager *undoManagerToUse)
	This constructor is discouraged and will be deprecated in a future version of JUCE! Use the other constructor instead. More...
	~AudioProcessorValueTreeState () override
	Destructor. More...
RangedAudioParameter *	createAndAddParameter (std::unique_ptr< RangedAudioParameter > parameter)
	This function adds a parameter to the attached AudioProcessor and that parameter will be managed by this AudioProcessorValueTreeState object. More...
RangedAudioParameter *	getParameter (StringRef parameterID) const noexcept
	Returns a parameter by its ID string. More...
std::atomic< float > *	getRawParameterValue (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. More...
void	addParameterListener (StringRef parameterID, Listener *listener)
	Attaches a callback to one of the parameters, which will be called when the parameter changes. More...
void	removeParameterListener (StringRef parameterID, Listener *listener)
	Removes a callback that was previously added with addParameterCallback(). More...
Value	getParameterAsValue (StringRef parameterID) const
	Returns a Value object that can be used to control a particular parameter. More...
NormalisableRange< float >	getParameterRange (StringRef parameterID) const noexcept
	Returns the range that was set when the given parameter was created. More...
ValueTree	copyState ()
	Returns a copy of the state value tree. More...
void	replaceState (const ValueTree &newState)
	Replaces the state value tree. More...

Public Attributes
AudioProcessor &	processor
	A reference to the processor with which this state is associated. More...
ValueTree	state
	The state of the whole processor. More...
UndoManager *const	undoManager
	Provides access to the undo manager that this object is using. More...

Detailed Description

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

It has its own internal class of parameter object that is 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.

The favoured constructor of this class takes a collection of RangedAudioParameters or AudioProcessorParameterGroups of RangedAudioParameters and adds them to the attached AudioProcessor directly.

The deprecated way of using this class is as follows:

1) Create an AudioProcessorValueTreeState, and give it some parameters using createAndAddParameter(). 2) Initialise the state member variable with a type name.

The deprecated constructor will be removed from the API in a future version of JUCE!

Constructor & Destructor Documentation

AudioProcessorValueTreeState() [1/2]

AudioProcessorValueTreeState::AudioProcessorValueTreeState	(	AudioProcessor &	processorToConnectTo,
		UndoManager *	undoManagerToUse,
		const Identifier &	valueTreeType,
		ParameterLayout	parameterLayout
	)

Creates a state object for a given processor, and sets up all the parameters that will control that processor.

You should not assign a new ValueTree to the state, or call createAndAddParameter, after using this constructor.

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.

The ParameterLayout parameter has a set of constructors that allow you to add multiple RangedAudioParameters and AudioProcessorParameterGroups containing RangedAudioParameters to the AudioProcessorValueTreeState inside this constructor.

YourAudioProcessor()
    : apvts (*this, &undoManager, "PARAMETERS",
             { std::make_unique<AudioParameterFloat> ("a", "Parameter A", NormalisableRange<float> (-100.0f, 100.0f), 0),
               std::make_unique<AudioParameterInt> ("b", "Parameter B", 0, 5, 2) })

To add parameters programatically you can call add repeatedly on a ParameterLayout instance:

AudioProcessorValueTreeState::ParameterLayout createParameterLayout()
{
    AudioProcessorValueTreeState::ParameterLayout layout;
 
    for (int i = 1; i < 9; ++i)
        layout.add (std::make_unique<AudioParameterInt> (String (i), String (i), 0, i, 0));
 
    return layout;
}
 
YourAudioProcessor()
    : apvts (*this, &undoManager, "PARAMETERS", createParameterLayout())
{
}

Parameters

processorToConnectTo	The Processor that will be managed by this object
undoManagerToUse	An optional UndoManager to use; pass nullptr if no UndoManager is required
valueTreeType	The identifier used to initialise the internal ValueTree
parameterLayout	An object that holds all parameters and parameter groups that the AudioProcessor should use.

AudioProcessorValueTreeState() [2/2]

AudioProcessorValueTreeState::AudioProcessorValueTreeState	(	AudioProcessor &	processorToConnectTo,
		UndoManager *	undoManagerToUse
	)

This constructor is discouraged and will be deprecated in a future version of JUCE! Use the other constructor instead.

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()

AudioProcessorValueTreeState::~AudioProcessorValueTreeState ( )

override

Destructor.

Member Function Documentation

createAndAddParameter()

RangedAudioParameter * AudioProcessorValueTreeState::createAndAddParameter

(

std::unique_ptr< RangedAudioParameter >

parameter

)

This function adds a parameter to the attached AudioProcessor and that parameter will be managed by this AudioProcessorValueTreeState object.

getParameter()

RangedAudioParameter * AudioProcessorValueTreeState::getParameter ( StringRef  parameterID ) const

noexcept

Returns a parameter by its ID string.

getRawParameterValue()

std::atomic< float > * AudioProcessorValueTreeState::getRawParameterValue ( 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.

Note that calling this method from within AudioProcessorValueTreeState::Listener::parameterChanged() is not guaranteed to return an up-to-date value for the parameter.

addParameterListener()

void AudioProcessorValueTreeState::addParameterListener	(	StringRef	parameterID,
		Listener *	listener
	)

Attaches a callback to one of the parameters, which will be called when the parameter changes.

removeParameterListener()

void AudioProcessorValueTreeState::removeParameterListener	(	StringRef	parameterID,
		Listener *	listener
	)

Removes a callback that was previously added with addParameterCallback().

getParameterAsValue()

Value AudioProcessorValueTreeState::getParameterAsValue

(

StringRef

parameterID

)

const

Returns a Value object that can be used to control a particular parameter.

getParameterRange()

NormalisableRange< float > AudioProcessorValueTreeState::getParameterRange ( StringRef  parameterID ) const

noexcept

Returns the range that was set when the given parameter was created.

copyState()

ValueTree AudioProcessorValueTreeState::copyState

(

)

Returns a copy of the state value tree.

The AudioProcessorValueTreeState's ValueTree is updated internally on the message thread, but there may be cases when you may want to access the state from a different thread (getStateInformation is a good example). This method flushes all pending audio parameter value updates and returns a copy of the state in a thread safe way.

Note: This method uses locks to synchronise thread access, so whilst it is thread-safe, it is not realtime-safe. Do not call this method from within your audio processing code!

replaceState()

void AudioProcessorValueTreeState::replaceState

(

const ValueTree &

newState

)

Replaces the state value tree.

The AudioProcessorValueTreeState's ValueTree is updated internally on the message thread, but there may be cases when you may want to modify the state from a different thread (setStateInformation is a good example). This method allows you to replace the state in a thread safe way.

Note: This method uses locks to synchronise thread access, so whilst it is thread-safe, it is not realtime-safe. Do not call this method from within your audio processing code!

Member Data Documentation

processor

AudioProcessor& AudioProcessorValueTreeState::processor

A reference to the processor with which this state is associated.

state

ValueTree AudioProcessorValueTreeState::state

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 createAndAddParameter().

undoManager

UndoManager* const AudioProcessorValueTreeState::undoManager

Provides access to the undo manager that this object is using.

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The documentation for this class was generated from the following file:

• juce_AudioProcessorValueTreeState.h