/libs/JUCE/modules/juce_events/messages/juce_ApplicationBase.h

/*

  ==============================================================================



   This file is part of the JUCE library.

   Copyright (c) 2015 - ROLI Ltd.



   Permission is granted to use this software under the terms of either:

   a) the GPL v2 (or any later version)

   b) the Affero GPL v3



   Details of these licenses can be found at: www.gnu.org/licenses



   JUCE is distributed in the hope that it will be useful, but WITHOUT ANY

   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR

   A PARTICULAR PURPOSE.  See the GNU General Public License for more details.



   ------------------------------------------------------------------------------



   To release a closed-source product which uses JUCE, commercial licenses are

   available: visit www.juce.com for more information.



  ==============================================================================

*/



#ifndef JUCE_APPLICATIONBASE_H_INCLUDED

#define JUCE_APPLICATIONBASE_H_INCLUDED





//==============================================================================

/**

    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. @code

        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:

            ScopedPointer<MyApplicationWindow> myMainWindow;

        };



        // this generates boilerplate code to launch our app class:

        START_JUCE_APPLICATION (MyJUCEApp)

    @endcode



    @see JUCEApplication, START_JUCE_APPLICATION

*/

class JUCE_API  JUCEApplicationBase

{

protected:

    //==============================================================================

    JUCEApplicationBase();



public:

    /** Destructor. */

    virtual ~JUCEApplicationBase();



    //==============================================================================

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

    static JUCEApplicationBase* getInstance() noexcept          { return appInstance; }



    //==============================================================================

    /** Returns the application's name. */

    virtual const String getApplicationName() = 0;



    /** Returns the application's version number. */

    virtual const String getApplicationVersion() = 0;



    /** 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.

    */

    virtual bool moreThanOneInstanceAllowed() = 0;



    /** 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.



        @param commandLineParameters    the 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 shutdown, quit

    */

    virtual void initialise (const String& commandLineParameters) = 0;



    /* Called to allow the application to clear up before exiting.



       After JUCEApplication::quit() has been called, the event-dispatch loop will

       terminate, and this method will get called to allow the app to sort itself

       out.



       Be careful that nothing happens in this method that might rely on messages

       being sent, or any kind of window activity, because the message loop is no

       longer running at this point.



        @see DeletedAtShutdown

    */

    virtual void shutdown() = 0;



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



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

    */

    virtual void anotherInstanceStarted (const String& commandLine) = 0;



    /** 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.

    */

    virtual void systemRequestedQuit() = 0;



    /** This method is called when the application is being put into background mode

        by the operating system.

    */

    virtual void suspended() = 0;



    /** This method is called when the application is being woken from background mode

        by the operating system.

    */

    virtual void resumed() = 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.



        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.

    */

    virtual void unhandledException (const std::exception*,

                                     const String& sourceFilename,

                                     int lineNumber) = 0;



    //==============================================================================

    /** 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 MessageManager

    */

    static void quit();



    //==============================================================================

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

        @see getCommandLineParameters

    */

    static StringArray JUCE_CALLTYPE getCommandLineParameterArray();



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

        @see getCommandLineParameterArray

    */

    static String JUCE_CALLTYPE getCommandLineParameters();



    //==============================================================================

    /** 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 getApplicationReturnValue

    */

    void setApplicationReturnValue (int newReturnValue) noexcept;



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

        @see setApplicationReturnValue

    */

    int getApplicationReturnValue() const noexcept              { return appReturnValue; }



    //==============================================================================

    /** Returns true if this executable is running as an app (as opposed to being a plugin

        or other kind of shared library. */

    static bool isStandaloneApp() noexcept                      { return createInstance != nullptr; }



    /** 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.

    */

    bool isInitialising() const noexcept                        { return stillInitialising; }





    //==============================================================================

   #ifndef DOXYGEN

    // The following methods are for internal use only...

    static int main();

    static int main (int argc, const char* argv[]);



    static void appWillTerminateByForce();

    typedef JUCEApplicationBase* (*CreateInstanceFunction)();

    static CreateInstanceFunction createInstance;



    virtual bool initialiseApp();

    int shutdownApp();

    static void JUCE_CALLTYPE sendUnhandledException (const std::exception*, const char* sourceFile, int lineNumber);

    bool sendCommandLineToPreexistingInstance();

   #endif



private:

    //==============================================================================

    static JUCEApplicationBase* appInstance;

    int appReturnValue;

    bool stillInitialising;



    struct MultipleInstanceHandler;

    friend struct MultipleInstanceHandler;

    friend struct ContainerDeletePolicy<MultipleInstanceHandler>;

    ScopedPointer<MultipleInstanceHandler> multipleInstanceHandler;



    JUCE_DECLARE_NON_COPYABLE (JUCEApplicationBase)

};





#endif   // JUCE_APPLICATIONBASE_H_INCLUDED