added instrument::applyRelease(...)

git-svn-id: https://lmms.svn.sf.net/svnroot/lmms/trunk/lmms@519 0778d3d1-df1d-0410-868b-ea421aaaa00d

include/instrument.h

@@ -49,6 +49,7 @@
 
 
 #include "plugin.h"
+#include "mixer.h"
 
 
 // forward-declarations
@@ -131,6 +132,11 @@ class instrument : public QWidget, public plugin
 		return( m_instrumentTrack );
 	}
 
+	// instruments may use this to apply a soft fade out at the end of
+	// notes - method does this only if really less or equal
+	// desiredReleaseFrames() frames are left
+	void applyRelease( sampleFrame * buf, const notePlayHandle * _n );
+
 
 private:
 	instrumentTrack * m_instrumentTrack;

src/core/instrument.cpp

@@ -28,6 +28,7 @@
 #include "instrument.h"
 #include "instrument_track.h"
 #include "dummy_instrument.h"
+#include "note_play_handle.h"
 
 
 instrument::instrument( instrumentTrack * _instrument_track,
@@ -105,5 +106,25 @@ bool instrument::isFromTrack( const track * _track ) const
 
 
 
+void instrument::applyRelease( sampleFrame * buf, const notePlayHandle * _n )
+{
+	const fpp_t frames = _n->framesLeftForCurrentPeriod();
+	const fpp_t fpp = engine::getMixer()->framesPerPeriod();
+	const f_cnt_t fl = _n->framesLeft();
+	if( fl <= desiredReleaseFrames()+fpp )
+	{
+		for( fpp_t f = fl > desiredReleaseFrames() ?
+				( tMax( fpp - desiredReleaseFrames(), 0 ) +
+					fl % fpp ) : 0; f < frames; ++f )
+		{
+			const float fac = (float)( fl-f-1 ) /
+							desiredReleaseFrames();
+			for( ch_cnt_t ch = 0; ch < DEFAULT_CHANNELS; ++ch )
+			{
+				buf[f][ch] *= fac;
+			}
+		}
+	}
+}
 
 #endif