Merge pull request #39 from vitorbaraujo/master

Implementation of sound effects and volume

include/engine.h

@@ -40,6 +40,12 @@ namespace ijengine {
         void set_audio_dir(const string& dir_path);
         void play_audio_from_path(const string& path);
         void stop_audio();
+
+        void play_sound_effect(const string &path);
+
+        int set_audio_volume(double percentage);
+        int set_sound_effect_volume(double percentage);
+
     }
 
     namespace event {

include/kernel.h

@@ -32,6 +32,10 @@ namespace ijengine {
         virtual void set_audio_dir(const string& dir_path) = 0;
         virtual void play_audio_from_path(const string& title) = 0;
         virtual void stop_audio() = 0;
+        virtual void play_sound_effect(const string& path) = 0;
+
+        virtual int set_audio_volume(double percentage) = 0;
+        virtual int set_sound_effect_volume(double percentage) = 0;
 
 	virtual list<MouseEvent> pending_mouse_events(unsigned now) = 0;
 	virtual list<SystemEvent> pending_system_events(unsigned now) = 0;

kernel/sdl2/sdl2kernel.cpp

@@ -276,7 +276,7 @@ SDL2Kernel::play_audio_from_path(const string& path)
             // printf("error: %s\n", Mix_GetError());
         }
 
-        Mix_PlayMusic(audio, -1);
+        Mix_FadeInMusic(audio, -1, 2000);
     }
 }
 
@@ -286,6 +286,41 @@ SDL2Kernel::stop_audio()
     Mix_HaltMusic();
 }
 
+void
+SDL2Kernel::play_sound_effect(const string& path)
+{
+    Mix_Chunk *effect = Mix_LoadWAV(path.c_str());
+
+    if(not effect){
+        printf("Failed to load sound effect\n");
+    }
+
+    Mix_PlayChannel(-1, effect, 0);
+}
+
+int
+SDL2Kernel::set_audio_volume(double percentage)
+{
+    double new_volume = (MIX_MAX_VOLUME * percentage);
+
+    // Mix_VolumeMusic(int volume)
+    // if volume is -1, returns current volume
+    int d = Mix_VolumeMusic(new_volume);
+
+    return d;
+}
+
+int
+SDL2Kernel::set_sound_effect_volume(double percentage){
+    double new_volume = (MIX_MAX_VOLUME * percentage);
+
+    // Mix_Volume(channel, volume)
+    // if channel is -1, set volume to all channels
+    int d = Mix_Volume(-1, new_volume);
+
+    return d;
+}
+
 void
 SDL2Kernel::update_pending_events(unsigned now)
 {

kernel/sdl2/sdl2kernel.h

@@ -22,6 +22,9 @@ class SDL2Kernel : public Kernel {
     void set_audio_dir(const string& dir_path);
     void play_audio_from_path(const string& title);
     void stop_audio();
+    void play_sound_effect(const string& path);
+    int set_audio_volume(double percentage);
+    int set_sound_effect_volume(double percentage);
 
     list<MouseEvent> pending_mouse_events(unsigned now);
     list<SystemEvent> pending_system_events(unsigned now);

src/engine.cpp

@@ -105,7 +105,25 @@ namespace ijengine
         void
         stop_audio()
         {
-           kernel->stop_audio();
+            kernel->stop_audio();
+        }
+
+        void
+        play_sound_effect(const string &path)
+        {
+            kernel->play_sound_effect(path);
+        }
+
+        int
+        set_audio_volume(double percentage)
+        {
+            return kernel->set_audio_volume(percentage);
+        }
+
+        int
+        set_sound_effect_volume(double percentage)
+        {
+            return kernel->set_sound_effect_volume(percentage);
         }
     }