Adding a trail (gradient) behind the position bar (#5543)

* src/gui/editors/SongEditor.cpp

* Gradient can be toggled and color can be changed.

* Made playback line (and tail) transparent to mouse clicks

* Gradient disappears when paused/stopped; tail length depends on zoom

* Fixes bug where gradient appears when a pattern is played; style corrections

* Cleaned up code

* Rename m_zoomLevels to s_zoomLevels

* Finalising code

* Make positionLine class independent of parent zooming model

* Edit a bug fix to make it more efficient

* Rename m_x and finalise positionLine code

* Rename m_x and finalise positionLine changes

* Rename X to playHeadPos

data/themes/classic/style.css

@@ -118,6 +118,11 @@ QMenu::indicator:selected {
 	background-color: #747474;
 }
 
+positionLine {
+	qproperty-tailGradient: false;
+	qproperty-lineColor: rgb(255, 255, 255);
+}
+
 PianoRoll {
 	background-color: rgb(0, 0, 0);
 	qproperty-backgroundShade: rgba( 255, 255, 255, 10 );

data/themes/default/style.css

@@ -150,6 +150,11 @@ QMenu::indicator:selected {
 	background-color: #101213;
 }
 
+positionLine {
+	qproperty-tailGradient: true;
+	qproperty-lineColor: rgb(255, 255, 255);
+}
+
 PianoRoll {
 	background-color: #141616;
 	qproperty-backgroundShade: rgba(255, 255, 255, 10);

include/SongEditor.h

@@ -28,6 +28,7 @@
 #define SONG_EDITOR_H
 
 #include <QVector>
+#include <QLinearGradient>
 
 #include "ActionGroup.h"
 #include "Editor.h"
@@ -47,13 +48,28 @@ class TimeLineWidget;
 
 class positionLine : public QWidget
 {
+	Q_OBJECT
+	Q_PROPERTY ( bool tailGradient READ hasTailGradient WRITE setHasTailGradient )
+	Q_PROPERTY ( QColor lineColor READ lineColor WRITE setLineColor )
 public:
-	positionLine( QWidget * parent );
+	positionLine ( QWidget* parent );
+	
+	// qproperty access functions
+	bool hasTailGradient () const;
+	void setHasTailGradient ( const bool g );
+	QColor lineColor () const;
+	void setLineColor ( const QColor & c );
+
+public slots:
+	void zoomChange (double zoom);
 
 private:
-	void paintEvent( QPaintEvent * pe ) override;
+	void paintEvent( QPaintEvent* pe ) override;
+	
+	bool m_hasTailGradient;
+	QColor m_lineColor;
 
-} ;
+};
 
 
 class SongEditor : public TrackContainerView
@@ -164,6 +180,9 @@ private:
 	bool m_selectRegion;
 
 	friend class SongEditorWindow;
+
+signals:
+	void zoomingValueChanged( double );
 } ;
 
 

src/gui/editors/SongEditor.cpp

@@ -52,26 +52,89 @@
 #include "PianoRoll.h"
 #include "Track.h"
 
-positionLine::positionLine( QWidget * parent ) :
-	QWidget( parent )
+positionLine::positionLine( QWidget* parent ) :
+	QWidget( parent ),
+	m_hasTailGradient ( false ),
+	m_lineColor (0, 0, 0, 0)
 {
-	setFixedWidth( 1 );
+	resize( 8, height() );
+	
 	setAttribute( Qt::WA_NoSystemBackground, true );
+	setAttribute( Qt::WA_TransparentForMouseEvents );
 }
 
-
-
-
-void positionLine::paintEvent( QPaintEvent * pe )
+void positionLine::paintEvent( QPaintEvent* pe )
 {
 	QPainter p( this );
-	p.fillRect( rect(), QColor( 255, 255, 255, 153 ) );
+	
+	// If width is 1, we don't need a gradient
+	if (width() == 1)
+	{
+		p.fillRect( rect(),
+			QColor( m_lineColor.red(), m_lineColor.green(), m_lineColor.blue(), 153) );
+	}
+	
+	// If width > 1, we need the gradient
+	else
+	{
+		// Create the gradient trail behind the line
+		QLinearGradient gradient( rect().bottomLeft(), rect().bottomRight() );
+		
+		// If gradient is enabled, we're in focus and we're playing, enable gradient
+		if (Engine::getSong()->isPlaying() && m_hasTailGradient && 
+			Engine::getSong()->playMode() == Song::Mode_PlaySong)
+		{
+			gradient.setColorAt(( ( width() - 1.0 )/width() ),
+				QColor( m_lineColor.red(), m_lineColor.green(), m_lineColor.blue(), 60) );
+		}
+		else
+		{
+			gradient.setColorAt(( ( width() - 1.0 )/width() ),
+				QColor( m_lineColor.red(), m_lineColor.green(), m_lineColor.blue(), 0) );
+		}
+		
+		// Fill in the remaining parts
+		gradient.setColorAt(0,
+			QColor( m_lineColor.red(), m_lineColor.green(), m_lineColor.blue(), 0) );
+		gradient.setColorAt(1,
+			QColor( m_lineColor.red(), m_lineColor.green(), m_lineColor.blue(), 153) );
+		
+		// Fill line
+		p.fillRect( rect(), gradient );
+	}
 }
 
+// QProperty handles
+bool positionLine::hasTailGradient() const
+{ return m_hasTailGradient; }
+
+void positionLine::setHasTailGradient( const bool g )
+{ m_hasTailGradient = g; }
+
+QColor positionLine::lineColor() const
+{ return m_lineColor; }
+
+void positionLine::setLineColor( const QColor & c )
+{ m_lineColor = c; }
+
+// NOTE: the move() implementation fixes a bug where the position line would appear
+// in an unexpected location when positioned at the start of the track
+void positionLine::zoomChange( double zoom )
+{
+	int playHeadPos = x() + width() - 1;
+	
+	resize( 8.0 * zoom, height() );
+	move( playHeadPos - width() + 1, y() );
+	
+	update();
+}
+
+
+
+
 const QVector<double> SongEditor::m_zoomLevels =
 		{ 0.125f, 0.25f, 0.5f, 1.0f, 2.0f, 4.0f, 8.0f, 16.0f };
 
-
 SongEditor::SongEditor( Song * song ) :
 	TrackContainerView( song ),
 	m_song( song ),
@@ -111,6 +174,11 @@ SongEditor::SongEditor( Song * song ) :
 
 	m_positionLine = new positionLine( this );
 	static_cast<QVBoxLayout *>( layout() )->insertWidget( 1, m_timeLine );
+	
+	connect( m_song, SIGNAL( playbackStateChanged() ),
+			 m_positionLine, SLOT( update() ) );
+	connect( this, SIGNAL( zoomingValueChanged( double ) ),
+			 m_positionLine, SLOT( zoomChange( double ) ) );
 
 
 	// add some essential widgets to global tool-bar
@@ -250,6 +318,8 @@ SongEditor::SongEditor( Song * song ) :
 			m_zoomingModel->findText( "100%" ) );
 	connect( m_zoomingModel, SIGNAL( dataChanged() ),
 					this, SLOT( zoomingChanged() ) );
+	connect( m_zoomingModel, SIGNAL( dataChanged() ),
+					m_positionLine, SLOT( update() ) );
 
 	//Set up snapping model, 2^i
 	for ( int i = 3; i >= -4; i-- )
@@ -808,7 +878,7 @@ void SongEditor::updatePosition( const MidiTime & t )
 	if( x >= trackOpWidth + widgetWidth -1 )
 	{
 		m_positionLine->show();
-		m_positionLine->move( x, m_timeLine->height() );
+		m_positionLine->move( x-( m_positionLine->width() - 1 ), m_timeLine->height() );
 	}
 	else
 	{
@@ -837,11 +907,11 @@ void SongEditor::zoomingChanged()
 					setPixelsPerBar( pixelsPerBar() );
 	realignTracks();
 	updateRubberband();
+	
+	emit zoomingValueChanged( m_zoomLevels[m_zoomingModel->value()] );
 }
 
 
-
-
 void SongEditor::selectAllTcos( bool select )
 {
 	QVector<selectableObject *> so = select ? rubberBand()->selectableObjects() : rubberBand()->selectedObjects();