Set 32 for buffersize min value in gui (LMMS#4336)

This is a bit too low resolution as some values cannot be reached by dragging the slider so we also reduce the maximum buffer size to 4096.

src/gui/SetupDialog.cpp

@@ -66,6 +66,8 @@
 #include "MidiApple.h"
 #include "MidiDummy.h"
 
+constexpr int BUFFERSIZE_RESOLUTION = 32;
+
 inline void labelWidget( QWidget * _w, const QString & _txt )
 {
 	QLabel * title = new QLabel( _txt, _w );
@@ -176,12 +178,12 @@ SetupDialog::SetupDialog( ConfigTabs _tab_to_open ) :
 	bufsize_tw->setFixedHeight( 80 );
 
 	m_bufSizeSlider = new QSlider( Qt::Horizontal, bufsize_tw );
-	m_bufSizeSlider->setRange( 1, 256 );
+	m_bufSizeSlider->setRange( 1, 128 );
 	m_bufSizeSlider->setTickPosition( QSlider::TicksBelow );
 	m_bufSizeSlider->setPageStep( 8 );
 	m_bufSizeSlider->setTickInterval( 8 );
 	m_bufSizeSlider->setGeometry( 10, 16, 340, 18 );
-	m_bufSizeSlider->setValue( m_bufferSize / 64 );
+	m_bufSizeSlider->setValue( m_bufferSize / BUFFERSIZE_RESOLUTION );
 
 	connect( m_bufSizeSlider, SIGNAL( valueChanged( int ) ), this,
 						SLOT( setBufferSize( int ) ) );
@@ -877,7 +879,7 @@ void SetupDialog::accept()
 
 void SetupDialog::setBufferSize( int _value )
 {
-	const int step = DEFAULT_BUFFER_SIZE / 64;
+	const int step = DEFAULT_BUFFER_SIZE / BUFFERSIZE_RESOLUTION;
 	if( _value > step && _value % step )
 	{
 		int mod_value = _value % step;
@@ -897,7 +899,7 @@ void SetupDialog::setBufferSize( int _value )
 		m_bufSizeSlider->setValue( _value );
 	}
 
-	m_bufferSize = _value * 64;
+	m_bufferSize = _value * BUFFERSIZE_RESOLUTION;
 	m_bufSizeLbl->setText( tr( "Frames: %1\nLatency: %2 ms" ).arg(
 					m_bufferSize ).arg(
 						1000.0f * m_bufferSize /
@@ -910,7 +912,7 @@ void SetupDialog::setBufferSize( int _value )
 
 void SetupDialog::resetBufSize()
 {
-	setBufferSize( DEFAULT_BUFFER_SIZE / 64 );
+	setBufferSize( DEFAULT_BUFFER_SIZE / BUFFERSIZE_RESOLUTION );
 }