axmol/CocosDenshion/emscripten/SimpleAudioEngine.cpp

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// XXX: This is all just a bit of a hack. SDL uses channels as its underlying
// abstraction, whilst CocosDenshion deals in individual effects. Consequently
// we can't set start/stop, because to SDL, effects (chunks) are just opaque
// blocks of data that get scheduled on channels. To workaround this, we assign
// each sound to a channel, but since there are only 32 channels, we use the
// modulus of the sound's address (which on Emscripten is just an incrementing
// integer) to decide which channel.
//
// A more rigorous implementation would have logic to store the state of
// channels and restore it as necessary. This should probably just be
// considered a toy for now, but it will probably prove sufficient for many
// use-cases. Recall also that Emscripten undoes this abstraction on the other
// side because it is using HTML5 audio objects as its underlying primitive!

#include <map>
#include <string>
#include <stdio.h>
#include <unistd.h>

#include "SimpleAudioEngine.h"
#include "cocos2d.h"

#include <SDL/SDL.h>
#include <SDL/SDL_mixer.h>

USING_NS_CC;

using namespace std;

namespace CocosDenshion
{
	struct soundData {
        Mix_Chunk *chunk;
		bool   isLooped;
	};

	typedef map<string, soundData *> EffectsMap;
	EffectsMap s_effects;
    float s_effectsVolume = 1.0;

	typedef enum {
		PLAYING,
		STOPPED,
		PAUSED,
	} playStatus;

	struct backgroundMusicData {
		Mix_Music *music;
	};
	typedef map<string, backgroundMusicData *> BackgroundMusicsMap;
	BackgroundMusicsMap s_backgroundMusics;
    float s_backgroundVolume = 1.0;

	static SimpleAudioEngine  *s_engine = 0;

    // Unfortunately this is just hard-coded in Emscripten's SDL
    // implementation.
    static const int NR_CHANNELS = 32;
    static void stopBackground(bool bReleaseData)
    {
        SimpleAudioEngine *engine = SimpleAudioEngine::sharedEngine();
        engine->stopBackgroundMusic();
    }

	SimpleAudioEngine::SimpleAudioEngine()
	{
	}

	SimpleAudioEngine::~SimpleAudioEngine()
	{
	}

	SimpleAudioEngine* SimpleAudioEngine::sharedEngine()
	{
		if (!s_engine)
			s_engine = new SimpleAudioEngine();
        
		return s_engine;
	}

	void SimpleAudioEngine::end()
	{
		// clear all the sounds
	    EffectsMap::const_iterator end = s_effects.end();
	    for (EffectsMap::iterator it = s_effects.begin(); it != end; it++)
	    {
            Mix_FreeChunk(it->second->chunk);
			delete it->second;
	    }
	    s_effects.clear();

		// and the background too
		stopBackground(true);

		for (BackgroundMusicsMap::iterator it = s_backgroundMusics.begin(); it != s_backgroundMusics.end(); ++it)
		{
            Mix_FreeMusic(it->second->music);
			delete it->second;
		}
		s_backgroundMusics.clear();
	}

	//
	// background audio
	//
    void SimpleAudioEngine::preloadBackgroundMusic(const char* pszFilePath)
	{
	}

	void SimpleAudioEngine::playBackgroundMusic(const char* pszFilePath, bool bLoop)
	{
        std::string key = std::string(pszFilePath);
        struct backgroundMusicData *musicData;
        if(!s_backgroundMusics.count(key))
        {
            musicData = new struct backgroundMusicData();
            musicData->music = Mix_LoadMUS(pszFilePath);
            s_backgroundMusics[key] = musicData;
        }
        else
        {
            musicData = s_backgroundMusics[key];
        }

        Mix_PlayMusic(musicData->music, bLoop ? -1 : 0);
	}

	void SimpleAudioEngine::stopBackgroundMusic(bool bReleaseData)
	{
        Mix_HaltMusic();
	}

	void SimpleAudioEngine::pauseBackgroundMusic()
	{
        Mix_PauseMusic();
	}

	void SimpleAudioEngine::resumeBackgroundMusic()
	{
        Mix_ResumeMusic();
	} 

	void SimpleAudioEngine::rewindBackgroundMusic()
	{
        CCLOGWARN("Cannot rewind background in Emscripten");
	}

	bool SimpleAudioEngine::willPlayBackgroundMusic()
	{
		return true;
	}

	bool SimpleAudioEngine::isBackgroundMusicPlaying()
	{
        return Mix_PlayingMusic();
	}

	float SimpleAudioEngine::getBackgroundMusicVolume()
	{
        return s_backgroundVolume;
	}

	void SimpleAudioEngine::setBackgroundMusicVolume(float volume)
	{
        // Ensure volume is between 0.0 and 1.0.
        volume = volume > 1.0 ? 1.0 : volume;
        volume = volume < 0.0 ? 0.0 : volume;

        Mix_VolumeMusic(volume * MIX_MAX_VOLUME);
        s_backgroundVolume = volume;
	}

	float SimpleAudioEngine::getEffectsVolume()
	{
		return s_effectsVolume;
	}

	void SimpleAudioEngine::setEffectsVolume(float volume)
	{
        volume = volume > 1.0 ? 1.0 : volume;
        volume = volume < 0.0 ? 0.0 : volume;

        // Need to set volume on every channel. SDL will then read this volume
        // level and apply it back to the individual sample.
        for(int i = 0; i < NR_CHANNELS; i++)
        {
            Mix_Volume(i, volume * MIX_MAX_VOLUME);
        }

        s_effectsVolume = volume;
	}

	unsigned int SimpleAudioEngine::playEffect(const char* pszFilePath, bool bLoop,
                                               float pitch, float pan, float gain)
	{
        std::string key = std::string(pszFilePath);
        struct soundData *sound;
        if(!s_effects.count(key))
        {
            sound = new struct soundData();
            sound->chunk = Mix_LoadWAV(pszFilePath);
            sound->isLooped = bLoop;
            s_effects[key] = sound;
        }
        else
        {
            sound = s_effects[key];
        }
        // This is safe here since Emscripten is just passing back an
        // incrementing integer each time you use the Mix_LoadWAV method.
        unsigned int result = (unsigned int) sound->chunk;

        // XXX: This is a bit of a hack, but... Choose a channel based on the
        // modulo of the # of channels. This allows us to set the volume
        // without passing around both chunk address and channel.
        Mix_PlayChannel(result % NR_CHANNELS, sound->chunk, bLoop ? -1 : 0);

        return result;
	}

	void SimpleAudioEngine::stopEffect(unsigned int nSoundId)
	{
        Mix_HaltChannel(nSoundId % NR_CHANNELS);
	}

	void SimpleAudioEngine::preloadEffect(const char* pszFilePath)
	{
	}

	void SimpleAudioEngine::unloadEffect(const char* pszFilePath)
	{
        std::string key = std::string(pszFilePath);
        if(!s_effects.count(key))
        {
            return;
        }

        struct soundData *sound = s_effects[key];

        Mix_FreeChunk(sound->chunk);
        delete sound;
        s_effects.erase(key);
	}

	void SimpleAudioEngine::pauseEffect(unsigned int nSoundId)
	{
        Mix_Pause(nSoundId % NR_CHANNELS);
	}

	void SimpleAudioEngine::pauseAllEffects()
	{
        for(int i = 0; i < NR_CHANNELS; i++)
        {
            Mix_Pause(i);
        }
	}

	void SimpleAudioEngine::resumeEffect(unsigned int nSoundId)
	{
        Mix_Resume(nSoundId % NR_CHANNELS);
	}

	void SimpleAudioEngine::resumeAllEffects()
	{
        for(int i = 0; i < NR_CHANNELS; i++)
        {
            Mix_Resume(i);
        }
	}

    void SimpleAudioEngine::stopAllEffects()
    {
        for(int i = 0; i < NR_CHANNELS; i++)
        {
            Mix_HaltChannel(i);
        }
    }

}