JUCE  v5.1.1-3-g1a0b28c73
JUCE API
JUCEApplication Class Referenceabstract

An instance of this class is used to specify initialisation and shutdown code for the application. More...

#include <juce_Application.h>

Inheritance diagram for JUCEApplication:
Collaboration diagram for JUCEApplication:

Public Member Functions

 JUCEApplication ()
 Constructs a JUCE app object. More...
 
 ~JUCEApplication ()
 Destructor. More...
 
void anotherInstanceStarted (const String &commandLine) override
 Indicates that the user has tried to start up another instance of the app. More...
 
virtual void backButtonPressed ()
 Override this method to be informed when the back button is pressed on a device. More...
 
ApplicationCommandTargetfindFirstTargetParentComponent ()
 If this object is a Component, this method will search upwards in its current UI hierarchy for the next parent component that implements the ApplicationCommandTarget class. More...
 
void getAllCommands (Array< CommandID > &) override
 
virtual const String getApplicationName ()=0
 Returns the application's name. More...
 
int getApplicationReturnValue () const noexcept
 Returns the value that has been set as the application's exit code. More...
 
virtual const String getApplicationVersion ()=0
 Returns the application's version number. More...
 
void getCommandInfo (CommandID, ApplicationCommandInfo &) override
 
ApplicationCommandTargetgetNextCommandTarget () override
 
ApplicationCommandTargetgetTargetForCommand (const CommandID commandID)
 Searches this target and all subsequent ones for the first one that can handle the specified command. More...
 
virtual void initialise (const String &commandLineParameters)=0
 Called when the application starts. More...
 
bool invoke (const InvocationInfo &invocationInfo, const bool asynchronously)
 Makes this target invoke a command. More...
 
bool invokeDirectly (const CommandID commandID, const bool asynchronously)
 Invokes a given command directly on this target. More...
 
bool isCommandActive (const CommandID commandID)
 Checks whether this command can currently be performed by this target. More...
 
bool isInitialising () const noexcept
 Returns true if the application hasn't yet completed its initialise() method and entered the main event loop. More...
 
bool moreThanOneInstanceAllowed () override
 Checks whether multiple instances of the app are allowed. More...
 
bool perform (const InvocationInfo &) override
 
void resumed () override
 This method is called when the application is being woken from background mode by the operating system. More...
 
void setApplicationReturnValue (int newReturnValue) noexcept
 Sets the value that should be returned as the application's exit code when the app quits. More...
 
virtual void shutdown ()=0
 
void suspended () override
 This method is called when the application is being put into background mode by the operating system. More...
 
void systemRequestedQuit () override
 Called when the operating system is trying to close the application. More...
 
void unhandledException (const std::exception *e, const String &sourceFilename, int lineNumber) override
 If any unhandled exceptions make it through to the message dispatch loop, this callback will be triggered, in case you want to log them or do some other type of error-handling. More...
 

Static Public Member Functions

static StringArray getCommandLineParameterArray ()
 Returns the application's command line parameters as a set of strings. More...
 
static String getCommandLineParameters ()
 Returns the application's command line parameters as a single string. More...
 
static JUCEApplicationgetInstance () noexcept
 Returns the global instance of the application object being run. More...
 
static bool isStandaloneApp () noexcept
 Returns true if this executable is running as an app (as opposed to being a plugin or other kind of shared library. More...
 
static void quit ()
 Signals that the main message loop should stop and the application should terminate. More...
 

Private Member Functions

bool initialiseApp () override
 

Detailed Description

An instance of this class is used to specify initialisation and shutdown code for the application.

Any application that wants to run an event loop must declare a subclass of JUCEApplicationBase or JUCEApplication, and implement its various pure virtual methods.

It then needs to use the START_JUCE_APPLICATION macro somewhere in a CPP file to declare an instance of this class and generate suitable platform-specific boilerplate code to launch the app.

Note that this class is derived from JUCEApplicationBase, which contains most of the useful methods and functionality. This derived class is here simply as a convenient way to also inherit from an ApplicationCommandTarget, and to implement default versions of some of the pure virtual base class methods. But you can derive your app object directly from JUCEApplicationBase if you want to, and by doing so can avoid having a dependency on the juce_gui_basics module.

e.g.

class MyJUCEApp : public JUCEApplication
{
public:
MyJUCEApp() {}
~MyJUCEApp() {}
void initialise (const String& commandLine) override
{
myMainWindow = new MyApplicationWindow();
myMainWindow->setBounds (100, 100, 400, 500);
myMainWindow->setVisible (true);
}
void shutdown() override
{
myMainWindow = nullptr;
}
const String getApplicationName() override
{
return "Super JUCE-o-matic";
}
const String getApplicationVersion() override
{
return "1.0";
}
private:
};
// this generates boilerplate code to launch our app class:
See also
JUCEApplicationBase, START_JUCE_APPLICATION

Constructor & Destructor Documentation

◆ JUCEApplication()

JUCEApplication::JUCEApplication ( )

Constructs a JUCE app object.

If subclasses implement a constructor or destructor, they shouldn't call any JUCE code in there - put your startup/shutdown code in initialise() and shutdown() instead.

◆ ~JUCEApplication()

JUCEApplication::~JUCEApplication ( )

Destructor.

If subclasses implement a constructor or destructor, they shouldn't call any JUCE code in there - put your startup/shutdown code in initialise() and shutdown() instead.

Member Function Documentation

◆ anotherInstanceStarted()

void JUCEApplication::anotherInstanceStarted ( const String commandLine)
overridevirtual

Indicates that the user has tried to start up another instance of the app.

This will get called even if moreThanOneInstanceAllowed() is false.

Implements JUCEApplicationBase.

◆ backButtonPressed()

virtual void JUCEApplicationBase::backButtonPressed ( )
inlinevirtualinherited

Override this method to be informed when the back button is pressed on a device.

This is currently only implemented on Android devices.

References JUCE_CALLTYPE, and StandardApplicationCommandIDs::quit.

◆ findFirstTargetParentComponent()

ApplicationCommandTarget* ApplicationCommandTarget::findFirstTargetParentComponent ( )
inherited

If this object is a Component, this method will search upwards in its current UI hierarchy for the next parent component that implements the ApplicationCommandTarget class.

If your target is a Component, this is a very handy method to use in your getNextCommandTarget() implementation.

◆ getAllCommands()

void JUCEApplication::getAllCommands ( Array< CommandID > &  )
overridevirtual

◆ getApplicationName()

virtual const String JUCEApplication::getApplicationName ( )
pure virtual

Returns the application's name.

Implements JUCEApplicationBase.

◆ getApplicationReturnValue()

int JUCEApplicationBase::getApplicationReturnValue ( ) const
inlinenoexceptinherited

Returns the value that has been set as the application's exit code.

See also
setApplicationReturnValue

◆ getApplicationVersion()

virtual const String JUCEApplication::getApplicationVersion ( )
pure virtual

Returns the application's version number.

Implements JUCEApplicationBase.

◆ getCommandInfo()

void JUCEApplication::getCommandInfo ( CommandID  ,
ApplicationCommandInfo  
)
overridevirtual

◆ getCommandLineParameterArray()

static StringArray JUCEApplicationBase::getCommandLineParameterArray ( )
staticinherited

Returns the application's command line parameters as a set of strings.

See also
getCommandLineParameters

◆ getCommandLineParameters()

static String JUCEApplicationBase::getCommandLineParameters ( )
staticinherited

Returns the application's command line parameters as a single string.

See also
getCommandLineParameterArray

◆ getInstance()

static JUCEApplication* JUCEApplication::getInstance ( )
staticnoexcept

Returns the global instance of the application object being run.

◆ getNextCommandTarget()

ApplicationCommandTarget* JUCEApplication::getNextCommandTarget ( )
overridevirtual

◆ getTargetForCommand()

ApplicationCommandTarget* ApplicationCommandTarget::getTargetForCommand ( const CommandID  commandID)
inherited

Searches this target and all subsequent ones for the first one that can handle the specified command.

This will use getNextCommandTarget() to determine the chain of targets to try after this one.

◆ initialise()

virtual void JUCEApplicationBase::initialise ( const String commandLineParameters)
pure virtualinherited

Called when the application starts.

This will be called once to let the application do whatever initialisation it needs, create its windows, etc.

After the method returns, the normal event-dispatch loop will be run, until the quit() method is called, at which point the shutdown() method will be called to let the application clear up anything it needs to delete.

If during the initialise() method, the application decides not to start-up after all, it can just call the quit() method and the event loop won't be run.

Parameters
commandLineParametersthe line passed in does not include the name of the executable, just the parameter list. To get the parameters as an array, you can call JUCEApplication::getCommandLineParameters()
See also
shutdown, quit

◆ initialiseApp()

bool JUCEApplication::initialiseApp ( )
overrideprivate

◆ invoke()

bool ApplicationCommandTarget::invoke ( const InvocationInfo invocationInfo,
const bool  asynchronously 
)
inherited

Makes this target invoke a command.

Your code can call this method to invoke a command on this target, but normally you'd call it indirectly via ApplicationCommandManager::invoke() or ApplicationCommandManager::invokeDirectly().

If this target can perform the given command, it will call its perform() method to do so. If not, then getNextCommandTarget() will be used to determine the next target to try, and the command will be passed along to it.

Parameters
invocationInfothis must be correctly filled-in, describing the context for the invocation.
asynchronouslyif false, the command will be performed before this method returns. If true, a message will be posted so that the command will be performed later on the message thread, and this method will return immediately.
See also
perform, ApplicationCommandManager::invoke

◆ invokeDirectly()

bool ApplicationCommandTarget::invokeDirectly ( const CommandID  commandID,
const bool  asynchronously 
)
inherited

Invokes a given command directly on this target.

This is just an easy way to call invoke() without having to fill out the InvocationInfo structure.

◆ isCommandActive()

bool ApplicationCommandTarget::isCommandActive ( const CommandID  commandID)
inherited

Checks whether this command can currently be performed by this target.

This will return true only if a call to getCommandInfo() doesn't set the isDisabled flag to indicate that the command is inactive.

◆ isInitialising()

bool JUCEApplicationBase::isInitialising ( ) const
inlinenoexceptinherited

Returns true if the application hasn't yet completed its initialise() method and entered the main event loop.

This is handy for things like splash screens to know when the app's up-and-running properly.

References JUCE_CALLTYPE.

◆ isStandaloneApp()

static bool JUCEApplicationBase::isStandaloneApp ( )
inlinestaticnoexceptinherited

Returns true if this executable is running as an app (as opposed to being a plugin or other kind of shared library.

◆ moreThanOneInstanceAllowed()

bool JUCEApplication::moreThanOneInstanceAllowed ( )
overridevirtual

Checks whether multiple instances of the app are allowed.

If you application class returns true for this, more than one instance is permitted to run (except on OSX where the OS automatically stops you launching a second instance of an app without explicitly starting it from the command-line).

If it's false, the second instance won't start, but it you will still get a callback to anotherInstanceStarted() to tell you about this - which gives you a chance to react to what the user was trying to do.

Implements JUCEApplicationBase.

◆ perform()

bool JUCEApplication::perform ( const InvocationInfo )
overridevirtual

◆ quit()

static void JUCEApplicationBase::quit ( )
staticinherited

Signals that the main message loop should stop and the application should terminate.

This isn't synchronous, it just posts a quit message to the main queue, and when this message arrives, the message loop will stop, the shutdown() method will be called, and the app will exit.

Note that this will cause an unconditional quit to happen, so if you need an extra level before this, e.g. to give the user the chance to save their work and maybe cancel the quit, you'll need to handle this in the systemRequestedQuit() method - see that method's help for more info.

See also
MessageManager

Referenced by StandaloneFilterWindow::closeButtonPressed().

◆ resumed()

void JUCEApplication::resumed ( )
overridevirtual

This method is called when the application is being woken from background mode by the operating system.

Implements JUCEApplicationBase.

◆ setApplicationReturnValue()

void JUCEApplicationBase::setApplicationReturnValue ( int  newReturnValue)
noexceptinherited

Sets the value that should be returned as the application's exit code when the app quits.

This is the value that's returned by the main() function. Normally you'd leave this as 0 unless you want to indicate an error code.

See also
getApplicationReturnValue

◆ shutdown()

virtual void JUCEApplicationBase::shutdown ( )
pure virtualinherited

◆ suspended()

void JUCEApplication::suspended ( )
overridevirtual

This method is called when the application is being put into background mode by the operating system.

Implements JUCEApplicationBase.

◆ systemRequestedQuit()

void JUCEApplication::systemRequestedQuit ( )
overridevirtual

Called when the operating system is trying to close the application.

The default implementation of this method is to call quit(), but it may be overloaded to ignore the request or do some other special behaviour instead. For example, you might want to offer the user the chance to save their changes before quitting, and give them the chance to cancel.

If you want to send a quit signal to your app, this is the correct method to call, because it means that requests that come from the system get handled in the same way as those from your own application code. So e.g. you'd call this method from a "quit" item on a menu bar.

Implements JUCEApplicationBase.

◆ unhandledException()

void JUCEApplication::unhandledException ( const std::exception *  e,
const String sourceFilename,
int  lineNumber 
)
overridevirtual

If any unhandled exceptions make it through to the message dispatch loop, this callback will be triggered, in case you want to log them or do some other type of error-handling.

If the type of exception is derived from the std::exception class, the pointer passed-in will be valid. If the exception is of unknown type, this pointer will be null.

Implements JUCEApplicationBase.


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