JUCE
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JUCEApplicationBase Class Referenceabstract

Abstract base class for application classes. More...

Inherited by JUCEApplication.

Public Member Functions

virtual ~JUCEApplicationBase ()
 Destructor.
 
virtual const String getApplicationName ()=0
 Returns the application's name.
 
virtual const String getApplicationVersion ()=0
 Returns the application's version number.
 
virtual bool moreThanOneInstanceAllowed ()=0
 Checks whether multiple instances of the app are allowed.
 
virtual void initialise (const String &commandLineParameters)=0
 Called when the application starts.
 
virtual void shutdown ()=0
 
virtual void anotherInstanceStarted (const String &commandLine)=0
 Indicates that the user has tried to start up another instance of the app.
 
virtual void systemRequestedQuit ()=0
 Called when the operating system is trying to close the application.
 
virtual void suspended ()=0
 This method is called when the application is being put into background mode by the operating system.
 
virtual void resumed ()=0
 This method is called when the application is being woken from background mode by the operating system.
 
virtual void unhandledException (const std::exception *, const String &sourceFilename, int lineNumber)=0
 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.
 
void setApplicationReturnValue (int newReturnValue) noexcept
 Sets the value that should be returned as the application's exit code when the app quits.
 
int getApplicationReturnValue () const noexcept
 Returns the value that has been set as the application's exit code.
 
bool isInitialising () const noexcept
 Returns true if the application hasn't yet completed its initialise() method and entered the main event loop.
 

Static Public Member Functions

static JUCEApplicationBasegetInstance () noexcept
 Returns the global instance of the application object that's running.
 
static void quit ()
 Signals that the main message loop should stop and the application should terminate.
 
static StringArray JUCE_CALLTYPE getCommandLineParameterArray ()
 Returns the application's command line parameters as a set of strings.
 
static String JUCE_CALLTYPE getCommandLineParameters ()
 Returns the application's command line parameters as a single string.
 
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.
 

Protected Member Functions

 JUCEApplicationBase ()
 

Detailed Description

Abstract base class for application classes.

Note that in the juce_gui_basics module, there's a utility class JUCEApplication which derives from JUCEApplicationBase, and takes care of a few chores. Most of the time you'll want to derive your class from JUCEApplication rather than using JUCEApplicationBase directly, but if you're not using the juce_gui_basics module then you might need to go straight to this base class.

Any application that wants to run an event loop must declare a subclass of JUCEApplicationBase, 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.

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
JUCEApplication, START_JUCE_APPLICATION

Constructor & Destructor Documentation

JUCEApplicationBase::JUCEApplicationBase ( )
protected
virtual JUCEApplicationBase::~JUCEApplicationBase ( )
virtual

Destructor.

Member Function Documentation

static JUCEApplicationBase* JUCEApplicationBase::getInstance ( )
staticnoexcept

Returns the global instance of the application object that's running.

virtual const String JUCEApplicationBase::getApplicationName ( )
pure virtual

Returns the application's name.

Implemented in JUCEApplication.

virtual const String JUCEApplicationBase::getApplicationVersion ( )
pure virtual

Returns the application's version number.

Implemented in JUCEApplication.

virtual bool JUCEApplicationBase::moreThanOneInstanceAllowed ( )
pure virtual

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 the Mac where this isn't possible).

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.

Implemented in JUCEApplication.

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

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
virtual void JUCEApplicationBase::shutdown ( )
pure virtual
virtual void JUCEApplicationBase::anotherInstanceStarted ( const String commandLine)
pure virtual

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

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

Implemented in JUCEApplication.

virtual void JUCEApplicationBase::systemRequestedQuit ( )
pure virtual

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.

Implemented in JUCEApplication.

virtual void JUCEApplicationBase::suspended ( )
pure virtual

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

Implemented in JUCEApplication.

virtual void JUCEApplicationBase::resumed ( )
pure virtual

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

Implemented in JUCEApplication.

virtual void JUCEApplicationBase::unhandledException ( const std::exception *  ,
const String sourceFilename,
int  lineNumber 
)
pure virtual

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.

Implemented in JUCEApplication.

static void JUCEApplicationBase::quit ( )
static

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().

static StringArray JUCE_CALLTYPE JUCEApplicationBase::getCommandLineParameterArray ( )
static

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

See Also
getCommandLineParameters
static String JUCE_CALLTYPE JUCEApplicationBase::getCommandLineParameters ( )
static

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

See Also
getCommandLineParameterArray
void JUCEApplicationBase::setApplicationReturnValue ( int  newReturnValue)
noexcept

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
int JUCEApplicationBase::getApplicationReturnValue ( ) const
noexcept

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

See Also
setApplicationReturnValue
static bool JUCEApplicationBase::isStandaloneApp ( )
staticnoexcept

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

bool JUCEApplicationBase::isInitialising ( ) const
noexcept

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.


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