juce::MidiKeyboardState Class Reference

Represents a piano keyboard, keeping track of which keys are currently pressed. More...

#include <juce_MidiKeyboardState.h>

Collaboration diagram for juce::MidiKeyboardState:

Classes
class	Listener
	Receives events from a MidiKeyboardState object. More...

Public Member Functions
	MidiKeyboardState ()
void	addListener (Listener *listener)
	Registers a listener for callbacks when keys go up or down. More...
void	allNotesOff (int midiChannel)
	This will turn off any currently-down notes for the given midi channel. More...
bool	isNoteOn (int midiChannel, int midiNoteNumber) const noexcept
	Returns true if the given midi key is currently held down for the given midi channel. More...
bool	isNoteOnForChannels (int midiChannelMask, int midiNoteNumber) const noexcept
	Returns true if the given midi key is currently held down on any of a set of midi channels. More...
void	noteOff (int midiChannel, int midiNoteNumber, float velocity)
	Turns a specified note off. More...
void	noteOn (int midiChannel, int midiNoteNumber, float velocity)
	Turns a specified note on. More...
void	processNextMidiBuffer (MidiBuffer &buffer, int startSample, int numSamples, bool injectIndirectEvents)
	Scans a midi stream for up/down events and adds its own events to it. More...
void	processNextMidiEvent (const MidiMessage &message)
	Looks at a key-up/down event and uses it to update the state of this object. More...
void	removeListener (Listener *listener)
	Deregisters a listener. More...
void	reset ()
	Resets the state of the object. More...

Private Member Functions
void	noteOffInternal (int midiChannel, int midiNoteNumber, float velocity)
void	noteOnInternal (int midiChannel, int midiNoteNumber, float velocity)

Private Attributes
MidiBuffer	eventsToAdd
ListenerList< Listener >	listeners
CriticalSection	lock
std::atomic< uint16 >	noteStates [128]

Detailed Description

Represents a piano keyboard, keeping track of which keys are currently pressed.

This object can parse a stream of midi events, using them to update its idea of which keys are pressed for each individual midi channel.

When keys go up or down, it can broadcast these events to listener objects.

It also allows key up/down events to be triggered with its noteOn() and noteOff() methods, and midi messages for these events will be merged into the midi stream that gets processed by processNextMidiBuffer().

@tags{Audio}

Constructor & Destructor Documentation

MidiKeyboardState()

juce::MidiKeyboardState::MidiKeyboardState

(

)

Member Function Documentation

addListener()

void juce::MidiKeyboardState::addListener

(

Listener *

listener

)

Registers a listener for callbacks when keys go up or down.

See also

removeListener

allNotesOff()

void juce::MidiKeyboardState::allNotesOff

(

int

midiChannel

)

This will turn off any currently-down notes for the given midi channel.

If you pass 0 for the midi channel, it will in fact turn off all notes on all channels.

Calling this method will make calls to noteOff(), so can trigger synchronous callbacks and events being added to the midi stream.

isNoteOn()

bool juce::MidiKeyboardState::isNoteOn ( int  midiChannel, int  midiNoteNumber  ) const

noexcept

Returns true if the given midi key is currently held down for the given midi channel.

The channel number must be between 1 and 16. If you want to see if any notes are on for a range of channels, use the isNoteOnForChannels() method.

isNoteOnForChannels()

bool juce::MidiKeyboardState::isNoteOnForChannels ( int  midiChannelMask, int  midiNoteNumber  ) const

noexcept

Returns true if the given midi key is currently held down on any of a set of midi channels.

The channel mask has a bit set for each midi channel you want to test for - bit 0 = midi channel 1, bit 1 = midi channel 2, etc.

If a note is on for at least one of the specified channels, this returns true.

noteOff()

void juce::MidiKeyboardState::noteOff	(	int	midiChannel,
		int	midiNoteNumber,
		float	velocity
	)

Turns a specified note off.

This will cause a suitable midi note-off event to be injected into the midi buffer during the next call to processNextMidiBuffer().

It will also trigger a synchronous callback to the listeners to tell them that the key has gone up.

But if the note isn't actually down for the given channel, this method will in fact do nothing.

noteOffInternal()

void juce::MidiKeyboardState::noteOffInternal ( int  midiChannel, int  midiNoteNumber, float  velocity  )

private

noteOn()

void juce::MidiKeyboardState::noteOn	(	int	midiChannel,
		int	midiNoteNumber,
		float	velocity
	)

Turns a specified note on.

This will cause a suitable midi note-on event to be injected into the midi buffer during the next call to processNextMidiBuffer().

It will also trigger a synchronous callback to the listeners to tell them that the key has gone down.

noteOnInternal()

void juce::MidiKeyboardState::noteOnInternal ( int  midiChannel, int  midiNoteNumber, float  velocity  )

private

processNextMidiBuffer()

void juce::MidiKeyboardState::processNextMidiBuffer	(	MidiBuffer &	buffer,
		int	startSample,
		int	numSamples,
		bool	injectIndirectEvents
	)

Scans a midi stream for up/down events and adds its own events to it.

This will look for any up/down events and use them to update the internal state, synchronously making suitable callbacks to the listeners.

If injectIndirectEvents is true, then midi events to produce the recent noteOn() and noteOff() calls will be added into the buffer.

Only the section of the buffer whose timestamps are between startSample and (startSample + numSamples) will be affected, and any events added will be placed between these times.

If you're going to use this method, you'll need to keep calling it regularly for it to work satisfactorily.

To process a single midi event at a time, use the processNextMidiEvent() method instead.

processNextMidiEvent()

void juce::MidiKeyboardState::processNextMidiEvent

(

const MidiMessage &

message

)

Looks at a key-up/down event and uses it to update the state of this object.

To process a buffer full of midi messages, use the processNextMidiBuffer() method instead.

removeListener()

void juce::MidiKeyboardState::removeListener

(

Listener *

listener

)

Deregisters a listener.

See also

addListener

reset()

void juce::MidiKeyboardState::reset

(

)

Resets the state of the object.

All internal data for all the channels is reset, but no events are sent as a result.

If you want to release any keys that are currently down, and to send out note-up midi messages for this, use the allNotesOff() method instead.

Member Data Documentation

eventsToAdd

MidiBuffer juce::MidiKeyboardState::eventsToAdd

private

listeners

ListenerList<Listener> juce::MidiKeyboardState::listeners

private

lock

CriticalSection juce::MidiKeyboardState::lock

private

noteStates

std::atomic<uint16> juce::MidiKeyboardState::noteStates[128]

private

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

• juce_MidiKeyboardState.h