Represents a midi output device. More...

#include <juce_MidiDevices.h>

Inheritance diagram for juce::MidiOutput:

Collaboration diagram for juce::MidiOutput:

[legend]

Classes
struct	PendingMessage

Public Member Functions
	~MidiOutput () override
	Destructor. More...

void	clearAllPendingMessages ()
	Gets rid of any midi messages that had been added by sendBlockOfMessages(). More...

MidiDeviceInfo	getDeviceInfo () const noexcept
	Returns the MidiDeviceInfo struct containing some information about this device. More...

String	getIdentifier () const noexcept
	Returns the identifier of this device. More...

String	getName () const noexcept
	Returns the name of this device. More...

bool	isBackgroundThreadRunning () const noexcept
	Returns true if the background thread used to send blocks of data is running. More...

void	sendBlockOfMessages (const MidiBuffer &buffer, double millisecondCounterToStartAt, double samplesPerSecondForBuffer)
	This lets you supply a block of messages that will be sent out at some point in the future. More...

void	sendBlockOfMessagesNow (const MidiBuffer &buffer)
	Sends out a sequence of MIDI messages immediately. More...

void	sendMessageNow (const MidiMessage &message)
	Sends out a MIDI message immediately. More...

void	setName (const String &newName) noexcept
	Sets a custom name for the device. More...

void	startBackgroundThread ()
	Starts up a background thread so that the device can send blocks of data. More...

void	stopBackgroundThread ()
	Stops the background thread, and clears any pending midi events. More...

Static Public Member Functions
static std::unique_ptr< MidiOutput >	createNewDevice (const String &deviceName)
	This will try to create a new midi output device (only available on Linux, macOS and iOS). More...

static Array< MidiDeviceInfo >	getAvailableDevices ()
	Returns a list of the available midi output devices. More...

static MidiDeviceInfo	getDefaultDevice ()
	Returns the MidiDeviceInfo of the default midi output device to use. More...

static std::unique_ptr< MidiOutput >	openDevice (const String &deviceIdentifier)
	Tries to open one of the midi output devices. More...

Private Types
enum	{ realtimeAudioPriority = -1 }
	Special realtime audio thread priority. More...

using	ThreadID = void *
	A value type used for thread IDs. More...

Private Member Functions
	MidiOutput (const String &, const String &)

void	addListener (Listener *)
	Add a listener to this thread which will receive a callback when signalThreadShouldExit was called on this thread. More...

void	closeThreadHandle ()

ThreadID	getThreadId () const noexcept
	Returns the ID of this thread. More...

const String &	getThreadName () const noexcept
	Returns the name of the thread. More...

bool	isThreadRunning () const
	Returns true if the thread is currently active. More...

void	killThread ()

void	launchThread ()

void	notify () const
	Wakes up the thread. More...

void	removeListener (Listener *)
	Removes a listener added with addListener. More...

void	run () override
	Must be implemented to perform the thread's actual code. More...

void	setAffinityMask (uint32 affinityMask)
	Sets the affinity mask for the thread. More...

bool	setPriority (int priority)
	Changes the thread's priority. More...

void	signalThreadShouldExit ()
	Sets a flag to tell the thread it should stop. More...

void	startThread ()
	Starts the thread running. More...

void	startThread (int priority)
	Starts the thread with a given priority. More...

bool	stopThread (int timeOutMilliseconds)
	Attempts to stop the thread running. More...

void	threadEntryPoint ()

bool	threadShouldExit () const
	Checks whether the thread has been told to stop running. More...

bool	wait (int timeOutMilliseconds) const
	Suspends the execution of this thread until either the specified timeout period has elapsed, or another thread calls the notify() method to wake it up. More...

bool	waitForThreadToExit (int timeOutMilliseconds) const
	Waits for the thread to stop. More...

Static Private Member Functions
static bool	currentThreadShouldExit ()
	Checks whether the current thread has been told to stop running. More...

static int	getAdjustedPriority (int)

static Thread *	getCurrentThread ()
	Finds the thread object that is currently running. More...

static ThreadID	getCurrentThreadId ()
	Returns an id that identifies the caller thread. More...

static void	initialiseJUCE (void jniEnv, void jContext)
	Initialises the JUCE subsystem for projects not created by the Projucer. More...

static void	launch (std::function< void()> functionToRun)
	Invokes a lambda or function on its own thread. More...

static void	setCurrentThreadAffinityMask (uint32 affinityMask)
	Changes the affinity mask for the caller thread. More...

static void	setCurrentThreadName (const String &newThreadName)
	Changes the name of the caller thread. More...

static bool	setCurrentThreadPriority (int priority)
	Changes the priority of the caller thread. More...

static bool	setThreadPriority (void *, int)

static void	sleep (int milliseconds)
	Suspends the execution of the current thread until the specified timeout period has elapsed (note that this may not be exact). More...

static void	yield ()
	Yields the current thread's CPU time-slot and allows a new thread to run. More...

Private Attributes
uint32	affinityMask = 0

WaitableEvent	defaultEvent

bool	deleteOnThreadEnd = false

MidiDeviceInfo	deviceInfo

PendingMessage *	firstMessage = nullptr

std::unique_ptr< Pimpl >	internal

bool	isAndroidRealtimeThread = false

ListenerList< Listener, Array< Listener *, CriticalSection > >	listeners

CriticalSection	lock

Atomic< int32 >	shouldExit { 0 }

CriticalSection	startStopLock

WaitableEvent	startSuspensionEvent

Atomic< void * >	threadHandle { nullptr }

Atomic< ThreadID >	threadId = {}

const String	threadName

int	threadPriority = 5

size_t	threadStackSize

Detailed Description

Represents a midi output device.

To create one of these, use the static getAvailableDevices() method to find out what outputs are available, and then use the openDevice() method to try to open one.

See also: MidiInput

@tags{Audio}

Member Typedef Documentation

◆ ThreadID

using juce::Thread::ThreadID = void*

inherited

A value type used for thread IDs.

See also: getCurrentThreadId(), getThreadId()

Member Enumeration Documentation

◆ anonymous enum

anonymous enum

inherited

Special realtime audio thread priority.

This priority will create a high-priority thread which is best suited for realtime audio processing.

Currently, this priority is identical to priority 9, except when building for Android with OpenSL/Oboe support.

In this case, JUCE will ask OpenSL/Oboe to construct a super high priority thread specifically for realtime audio processing.

Note that this priority can only be set before the thread has started. Switching to this priority, or from this priority to a different priority, is not supported under Android and will assert.

For best performance this thread should yield at regular intervals and not call any blocking APIs.

See also: startThread, setPriority, sleep, WaitableEvent

Enumerator
realtimeAudioPriority

Constructor & Destructor Documentation

◆ ~MidiOutput()

juce::MidiOutput::~MidiOutput ( )

override

Destructor.

◆ MidiOutput()

juce::MidiOutput::MidiOutput	(	const String &	,
		const String &
	)

explicitprivate

Member Function Documentation

◆ addListener()

void juce::Thread::addListener ( Listener * )

inherited

Add a listener to this thread which will receive a callback when signalThreadShouldExit was called on this thread.

See also: signalThreadShouldExit, removeListener

◆ clearAllPendingMessages()

void juce::MidiOutput::clearAllPendingMessages ( )

Gets rid of any midi messages that had been added by sendBlockOfMessages().

◆ closeThreadHandle()

void juce::Thread::closeThreadHandle ( )

privateinherited

References juce::Thread::threadHandle, and juce::Thread::threadId.

◆ createNewDevice()

static std::unique_ptr<MidiOutput> juce::MidiOutput::createNewDevice ( const String & deviceName )

static

This will try to create a new midi output device (only available on Linux, macOS and iOS).

This will attempt to create a new midi output device with the specified name that other apps can connect to and use as their midi input.

NB - if you are calling this method on iOS you must have enabled the "Audio Background Capability" setting in the iOS exporter otherwise this method will fail.

Returns an empty object if a device can't be created.

Parameters

deviceName the name of the device to create

◆ currentThreadShouldExit()

static bool juce::Thread::currentThreadShouldExit ( )

staticinherited

Checks whether the current thread has been told to stop running.

On the message thread, this will always return false, otherwise it will return threadShouldExit() called on the current thread.

See also: threadShouldExit

◆ getAdjustedPriority()

static int juce::Thread::getAdjustedPriority ( int )

staticprivateinherited

◆ getAvailableDevices()

static Array<MidiDeviceInfo> juce::MidiOutput::getAvailableDevices ( )

static

Returns a list of the available midi output devices.

You can open one of the devices by passing its identifier into the openDevice() method.

See also: MidiDeviceInfo, getDevices, getDefaultDeviceIndex, openDevice

◆ getCurrentThread()

static Thread* juce::Thread::getCurrentThread ( )

staticinherited

Finds the thread object that is currently running.

Note that the main UI thread (or other non-JUCE threads) don't have a Thread object associated with them, so this will return nullptr.

◆ getCurrentThreadId()

Thread::ThreadID juce::Thread::getCurrentThreadId ( )

staticinherited

Returns an id that identifies the caller thread.

To find the ID of a particular thread object, use getThreadId().

Returns: a unique identifier that identifies the calling thread.

See also: getThreadId

Referenced by juce::ThreadLocalValue< Type >::get(), and juce::ThreadLocalValue< Type >::releaseCurrentThreadStorage().

◆ getDefaultDevice()

static MidiDeviceInfo juce::MidiOutput::getDefaultDevice ( )

static

Returns the MidiDeviceInfo of the default midi output device to use.

◆ getDeviceInfo()

MidiDeviceInfo juce::MidiOutput::getDeviceInfo ( ) const

inlinenoexcept

Returns the MidiDeviceInfo struct containing some information about this device.

◆ getIdentifier()

String juce::MidiOutput::getIdentifier ( ) const

inlinenoexcept

Returns the identifier of this device.

◆ getName()

String juce::MidiOutput::getName ( ) const

inlinenoexcept

Returns the name of this device.

◆ getThreadId()

ThreadID juce::Thread::getThreadId ( ) const

noexceptinherited

Returns the ID of this thread.

That means the ID of this thread object - not of the thread that's calling the method. This can change when the thread is started and stopped, and will be invalid if the thread's not actually running.

See also: getCurrentThreadId

◆ getThreadName()

const String& juce::Thread::getThreadName ( ) const

inlinenoexceptinherited

Returns the name of the thread.

This is the name that gets set in the constructor.

◆ initialiseJUCE()

static void juce::Thread::initialiseJUCE	(	void *	jniEnv,
		void *	jContext
	)

staticinherited

Initialises the JUCE subsystem for projects not created by the Projucer.

On Android, JUCE needs to be initialised once before it is used. The Projucer will automatically generate the necessary java code to do this. However, if you are using JUCE without the Projucer or are creating a library made with JUCE intended for use in non-JUCE apks, then you must call this method manually once on apk startup.

You can call this method from C++ or directly from java by calling the following java method:

com.rmsl.juce.Java.initialiseJUCE (myContext);

Note that the above java method is only available in Android Studio projects created by the Projucer. If you need to call this from another type of project then you need to add the following java file to your project:

package com.rmsl.juce;
 
public class Java
{
    static { System.loadLibrary ("juce_jni"); }
    public native static void initialiseJUCE (Context context);
}

Parameters

jniEnv	this is a pointer to JNI's JNIEnv variable. Any callback from Java into C++ will have this passed in as it's first parameter.
jContext	this is a jobject referring to your app/service/receiver/ provider's Context. JUCE needs this for many of it's internal functions.

◆ isBackgroundThreadRunning()

bool juce::MidiOutput::isBackgroundThreadRunning ( ) const

inlinenoexcept

Returns true if the background thread used to send blocks of data is running.

See also: startBackgroundThread, stopBackgroundThread

◆ isThreadRunning()

bool juce::Thread::isThreadRunning ( ) const

inherited

Returns true if the thread is currently active.

◆ killThread()

void juce::Thread::killThread ( )

privateinherited

References juce::Atomic< Type >::get(), jassertfalse, and juce::Thread::threadHandle.

◆ launch()

static void juce::Thread::launch ( std::function< void()> functionToRun )

staticinherited

Invokes a lambda or function on its own thread.

This will spin up a Thread object which calls the function and then exits. Bear in mind that starting and stopping a thread can be a fairly heavyweight operation, so you might prefer to use a ThreadPool if you're kicking off a lot of short background tasks.

Also note that using an anonymous thread makes it very difficult to interrupt the function when you need to stop it, e.g. when your app quits. So it's up to you to deal with situations where the function may fail to stop in time.

◆ launchThread()

void juce::Thread::launchThread ( )

privateinherited

References juce::Atomic< Type >::get(), juce::gl::handle, juce::Thread::isAndroidRealtimeThread, jassertfalse, juce::threadEntryProc(), juce::Thread::threadHandle, juce::Thread::threadId, and juce::Thread::threadStackSize.

◆ notify()

void juce::Thread::notify ( ) const

inherited

Wakes up the thread.

If the thread has called the wait() method, this will wake it up.

See also: wait

◆ openDevice()

static std::unique_ptr<MidiOutput> juce::MidiOutput::openDevice ( const String & deviceIdentifier )

static

Tries to open one of the midi output devices.

This will return a MidiOutput object if it manages to open it, you can then send messages to this device.

If the device can't be opened, this will return an empty object.

Parameters

deviceIdentifier the ID of the device to open - use the getAvailableDevices() method to find the available devices that can be opened

See also: getDevices

◆ removeListener()

void juce::Thread::removeListener ( Listener * )

inherited

Removes a listener added with addListener.

◆ run()

void juce::MidiOutput::run ( )

overrideprivatevirtual

Must be implemented to perform the thread's actual code.

Remember that the thread must regularly check the threadShouldExit() method whilst running, and if this returns true it should return from the run() method as soon as possible to avoid being forcibly killed.

See also: threadShouldExit, startThread

Implements juce::Thread.

◆ sendBlockOfMessages()

void juce::MidiOutput::sendBlockOfMessages	(	const MidiBuffer &	buffer,
		double	millisecondCounterToStartAt,
		double	samplesPerSecondForBuffer
	)

This lets you supply a block of messages that will be sent out at some point in the future.

The MidiOutput class has an internal thread that can send out timestamped messages - this appends a set of messages to its internal buffer, ready for sending.

This will only work if you've already started the thread with startBackgroundThread().

A time is specified, at which the block of messages should be sent. This time uses the same time base as Time::getMillisecondCounter(), and must be in the future.

The samplesPerSecondForBuffer parameter indicates the number of samples per second used by the MidiBuffer. Each event in a MidiBuffer has a sample position, and the samplesPerSecondForBuffer value is needed to convert this sample position to a real time.

◆ sendBlockOfMessagesNow()

void juce::MidiOutput::sendBlockOfMessagesNow ( const MidiBuffer & buffer )

Sends out a sequence of MIDI messages immediately.

◆ sendMessageNow()

void juce::MidiOutput::sendMessageNow ( const MidiMessage & message )

Sends out a MIDI message immediately.

◆ setAffinityMask()

void juce::Thread::setAffinityMask ( uint32 affinityMask )

inherited

Sets the affinity mask for the thread.

This will only have an effect next time the thread is started - i.e. if the thread is already running when called, it'll have no effect.

See also: setCurrentThreadAffinityMask

◆ setCurrentThreadAffinityMask()

void juce::Thread::setCurrentThreadAffinityMask ( uint32 affinityMask )

staticinherited

Changes the affinity mask for the caller thread.

This will change the affinity mask for the thread that calls this static method.

See also: setAffinityMask

References juce::Thread::affinityMask, juce::ignoreUnused(), and jassertfalse.

◆ setCurrentThreadName()

void juce::Thread::setCurrentThreadName ( const String & newThreadName )

staticinherited

Changes the name of the caller thread.

Different OSes may place different length or content limits on this name.

References JUCE_AUTORELEASEPOOL, juce::juceStringToNS(), and juce::gl::name.

Referenced by juce::MessageThread::start().

◆ setCurrentThreadPriority()

static bool juce::Thread::setCurrentThreadPriority ( int priority )

staticinherited

Changes the priority of the caller thread.

Similar to setPriority(), but this static method acts on the caller thread. May return false if for some reason the priority can't be changed.

See also: setPriority

Referenced by juce::MessageThread::start().

◆ setName()

void juce::MidiOutput::setName ( const String & newName )

inlinenoexcept

Sets a custom name for the device.

◆ setPriority()

bool juce::Thread::setPriority ( int priority )

inherited

Changes the thread's priority.

May return false if for some reason the priority can't be changed.

Parameters

priority the new priority, in the range 0 (lowest) to 10 (highest). A priority of 5 is normal.

See also: realtimeAudioPriority

◆ setThreadPriority()

bool juce::Thread::setThreadPriority	(	void *	handle,
		int	priority
	)

staticprivateinherited

References juce::gl::handle, juce::jmap(), and juce::gl::param.

◆ signalThreadShouldExit()

void juce::Thread::signalThreadShouldExit ( )

inherited

Sets a flag to tell the thread it should stop.

Calling this means that the threadShouldExit() method will then return true. The thread should be regularly checking this to see whether it should exit.

If your thread makes use of wait(), you might want to call notify() after calling this method, to interrupt any waits that might be in progress, and allow it to reach a point where it can exit.

See also: threadShouldExit, waitForThreadToExit

◆ sleep()

void juce::Thread::sleep ( int milliseconds )

staticinherited

Suspends the execution of the current thread until the specified timeout period has elapsed (note that this may not be exact).

The timeout period must not be negative and whilst sleeping the thread cannot be woken up so it should only be used for short periods of time and when other methods such as using a WaitableEvent or CriticalSection are not possible.

References juce::UnitTestCategories::time.

Referenced by juce::OpenGLContext::NativeContext::initialiseOnRenderThread(), juce::MessageThread::start(), and juce::OpenGLContext::NativeContext::swapBuffers().

◆ startBackgroundThread()

void juce::MidiOutput::startBackgroundThread ( )

Starts up a background thread so that the device can send blocks of data.

Call this to get the device ready, before using sendBlockOfMessages().

◆ startThread() [1/2]

void juce::Thread::startThread ( )

inherited

Starts the thread running.

This will cause the thread's run() method to be called by a new thread. If this thread is already running, startThread() won't do anything.

See also: stopThread

◆ startThread() [2/2]

void juce::Thread::startThread ( int priority )

inherited

Starts the thread with a given priority.

Launches the thread with a given priority, where 0 = lowest, 10 = highest. If the thread is already running, its priority will be changed.

See also: startThread, setPriority, realtimeAudioPriority

◆ stopBackgroundThread()

void juce::MidiOutput::stopBackgroundThread ( )

Stops the background thread, and clears any pending midi events.

See also: startBackgroundThread

◆ stopThread()

bool juce::Thread::stopThread ( int timeOutMilliseconds )

inherited

Attempts to stop the thread running.

This method will cause the threadShouldExit() method to return true and call notify() in case the thread is currently waiting.

Hopefully the thread will then respond to this by exiting cleanly, and the stopThread method will wait for a given time-period for this to happen.

If the thread is stuck and fails to respond after the timeout, it gets forcibly killed, which is a very bad thing to happen, as it could still be holding locks, etc. which are needed by other parts of your program.

Parameters

timeOutMilliseconds The number of milliseconds to wait for the thread to finish before killing it by force. A negative value in here will wait forever.

Returns: true if the thread was cleanly stopped before the timeout, or false if it had to be killed by force.

See also: signalThreadShouldExit, threadShouldExit, waitForThreadToExit, isThreadRunning

◆ threadEntryPoint()

void juce::Thread::threadEntryPoint ( )

privateinherited

◆ threadShouldExit()

bool juce::Thread::threadShouldExit ( ) const

inherited

Checks whether the thread has been told to stop running.

Threads need to check this regularly, and if it returns true, they should return from their run() method at the first possible opportunity.

See also: signalThreadShouldExit, currentThreadShouldExit

◆ wait()

bool juce::Thread::wait ( int timeOutMilliseconds ) const

inherited

Suspends the execution of this thread until either the specified timeout period has elapsed, or another thread calls the notify() method to wake it up.

A negative timeout value means that the method will wait indefinitely.

Returns: true if the event has been signalled, false if the timeout expires.

◆ waitForThreadToExit()

bool juce::Thread::waitForThreadToExit ( int timeOutMilliseconds ) const

inherited

Waits for the thread to stop.

This will wait until isThreadRunning() is false or until a timeout expires.

Parameters

timeOutMilliseconds the time to wait, in milliseconds. If this value is less than zero, it will wait forever.

Returns: true if the thread exits, or false if the timeout expires first.

◆ yield()

void juce::Thread::yield ( )

staticinherited

Yields the current thread's CPU time-slot and allows a new thread to run.

If there are no other threads of equal or higher priority currently running then this will return immediately and the current thread will continue to run.

Member Data Documentation

◆ affinityMask

uint32 juce::Thread::affinityMask = 0

privateinherited

Referenced by juce::Thread::setCurrentThreadAffinityMask().

◆ defaultEvent

WaitableEvent juce::Thread::defaultEvent

privateinherited

◆ deleteOnThreadEnd

bool juce::Thread::deleteOnThreadEnd = false

privateinherited

◆ deviceInfo

MidiDeviceInfo juce::MidiOutput::deviceInfo

private

◆ firstMessage

PendingMessage* juce::MidiOutput::firstMessage = nullptr

private

◆ internal

std::unique_ptr<Pimpl> juce::MidiOutput::internal

private

◆ isAndroidRealtimeThread

bool juce::Thread::isAndroidRealtimeThread = false

privateinherited

Referenced by juce::Thread::launchThread().

◆ listeners

ListenerList<Listener, Array<Listener*, CriticalSection> > juce::Thread::listeners

privateinherited

◆ lock

CriticalSection juce::MidiOutput::lock

private

◆ shouldExit

Atomic<int32> juce::Thread::shouldExit { 0 }

privateinherited

◆ startStopLock

CriticalSection juce::Thread::startStopLock

privateinherited

◆ startSuspensionEvent

WaitableEvent juce::Thread::startSuspensionEvent

privateinherited

◆ threadHandle

Atomic<void*> juce::Thread::threadHandle { nullptr }

privateinherited

Referenced by juce::Thread::closeThreadHandle(), juce::Thread::killThread(), and juce::Thread::launchThread().

◆ threadId

Atomic<ThreadID> juce::Thread::threadId = {}

privateinherited

Referenced by juce::Thread::closeThreadHandle(), and juce::Thread::launchThread().

◆ threadName

const String juce::Thread::threadName

privateinherited

◆ threadPriority

int juce::Thread::threadPriority = 5

privateinherited

◆ threadStackSize

size_t juce::Thread::threadStackSize

privateinherited

Referenced by juce::Thread::launchThread().

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

juce_MidiDevices.h

Classes

Public Member Functions

Static Public Member Functions

Private Types

Private Member Functions

Static Private Member Functions

Private Attributes

Detailed Description

Member Typedef Documentation

◆ ThreadID

Member Enumeration Documentation

◆ anonymous enum

Constructor & Destructor Documentation

◆ ~MidiOutput()

◆ MidiOutput()

Member Function Documentation

◆ addListener()

◆ clearAllPendingMessages()

◆ closeThreadHandle()

◆ createNewDevice()

◆ currentThreadShouldExit()

◆ getAdjustedPriority()

◆ getAvailableDevices()

◆ getCurrentThread()

◆ getCurrentThreadId()

◆ getDefaultDevice()

◆ getDeviceInfo()

◆ getIdentifier()

◆ getName()

◆ getThreadId()

◆ getThreadName()

◆ initialiseJUCE()

◆ isBackgroundThreadRunning()

◆ isThreadRunning()

◆ killThread()

◆ launch()

◆ launchThread()

◆ notify()

◆ openDevice()

◆ removeListener()

◆ run()

◆ sendBlockOfMessages()

◆ sendBlockOfMessagesNow()

◆ sendMessageNow()

◆ setAffinityMask()

◆ setCurrentThreadAffinityMask()

◆ setCurrentThreadName()

◆ setCurrentThreadPriority()

◆ setName()

◆ setPriority()

◆ setThreadPriority()

◆ signalThreadShouldExit()

◆ sleep()

◆ startBackgroundThread()

◆ startThread() [1/2]

◆ startThread() [2/2]

◆ stopBackgroundThread()

◆ stopThread()

◆ threadEntryPoint()

◆ threadShouldExit()

◆ wait()

◆ waitForThreadToExit()

◆ yield()

Member Data Documentation

◆ affinityMask

◆ defaultEvent

◆ deleteOnThreadEnd

◆ deviceInfo

◆ firstMessage

◆ internal

◆ isAndroidRealtimeThread

◆ listeners

◆ lock

◆ shouldExit

◆ startStopLock

◆ startSuspensionEvent

◆ threadHandle

◆ threadId

◆ threadName

◆ threadPriority