Feature: PianoRoll Knife (LMMS#5845)

* Initial PianoRoll razor feature

* Restore PianoRoll edit mode after focusOut and in razor mode.

* Show changes directly after cut.

* Fix hanging note after adjusting vol/pan with razor action.

* Extract the split action to a separate method

	This PR addresses some suggestions from a review, the most
important ones being:
	- Extracting the note split action to a separate method, called
Pattern::splitNotes
	- Removing getMouseTickPos method
	- Adding a variable that holds the current razor position and a
method to update it (quantizing if CTRL is not pressed)
	- Using [this] to capture "this" on the lambda function instead
of [=], since the latter doesn't work as intended from C++20 forward
	- Fixing some code style and adding comments

* Removes an extra call to noteUnderMouse

	By removing "&& noteUnderMouse()" from the mousePressEvent
conditional, we avoid an extra call to noteUnderMouse. The only
difference in the behavior of the tool is that now clicking on a place
that doesn't have a note will exit Razor mode.

* Style change suggested by @russiankumar

* Cancel razor action on SHIFT release.

* Make razor cut-line (color) themable.

* Add razor cut-line color to classic theme style.css

* Rename razor to knife.

* Change pixmap from razor to knife (from LMMS#5524)

* Remove SHIFT behavior.

* Change knife shortcut to SHIFT+K

Co-authored-by: CYBERDEViL <cyberdevil@notabug.org>
Co-authored-by: Ian Caio <iancaio_dev@hotmail.com>

data/themes/classic/style.css

@@ -155,6 +155,7 @@ PianoRoll {
 	qproperty-ghostNoteBorders: true;
 	qproperty-barColor: #4afd85;
 	qproperty-markedSemitoneColor: rgba( 0, 255, 200, 60 );
+	qproperty-knifeCutLine: rgba(255, 0, 0, 255);
 	/* Piano keys */
 	qproperty-whiteKeyWidth: 64;
 	qproperty-whiteKeyActiveTextColor: #000;

data/themes/default/style.css

@@ -187,6 +187,7 @@ PianoRoll {
 	qproperty-ghostNoteBorders: false;
 	qproperty-barColor: #078f3a;
 	qproperty-markedSemitoneColor: rgba(255, 255, 255, 30);
+	qproperty-knifeCutLine: rgba(255, 0, 0, 255);
 	/* Piano keys */
 	qproperty-whiteKeyWidth: 64;
 	qproperty-whiteKeyActiveTextColor: #000;

include/Pattern.h

@@ -76,6 +76,9 @@ class LMMS_EXPORT Pattern : public TrackContentObject
 	Note * addStepNote( int step );
 	void setStep( int step, bool enabled );
 
+	// Split the list of notes on the given position
+	void splitNotes(NoteVector notes, TimePos pos);
+
 	// pattern-type stuff
 	inline PatternTypes type() const
 	{

include/PianoRoll.h

@@ -70,6 +70,7 @@ class PianoRoll : public QWidget
 	Q_PROPERTY(QColor textColorLight MEMBER m_textColorLight)
 	Q_PROPERTY(QColor textShadow MEMBER m_textShadow)
 	Q_PROPERTY(QColor markedSemitoneColor MEMBER m_markedSemitoneColor)
+	Q_PROPERTY(QColor knifeCutLine MEMBER m_knifeCutLineColor)
 	Q_PROPERTY(int noteOpacity MEMBER m_noteOpacity)
 	Q_PROPERTY(bool noteBorders MEMBER m_noteBorders)
 	Q_PROPERTY(int ghostNoteOpacity MEMBER m_ghostNoteOpacity)
@@ -95,6 +96,7 @@ class PianoRoll : public QWidget
 		ModeErase,
 		ModeSelect,
 		ModeEditDetuning,
+		ModeEditKnife
 	};
 
 	/*! \brief Resets settings to default when e.g. creating a new project */
@@ -226,7 +228,8 @@ protected slots:
 		ActionResizeNote,
 		ActionSelectNotes,
 		ActionChangeNoteProperty,
-		ActionResizeNoteEditArea
+		ActionResizeNoteEditArea,
+		ActionKnife
 	};
 
 	enum NoteEditMode
@@ -282,6 +285,9 @@ protected slots:
 	void playChordNotes(int key, int velocity=-1);
 	void pauseChordNotes(int key);
 
+	void setKnifeAction();
+	void cancelKnifeAction();
+
 	void updateScrollbars();
 	void updatePositionLineHeight();
 
@@ -304,6 +310,7 @@ protected slots:
 	static QPixmap * s_toolSelect;
 	static QPixmap * s_toolMove;
 	static QPixmap * s_toolOpen;
+	static QPixmap* s_toolKnife;
 
 	static PianoRollKeyTypes prKeyOrder[];
 
@@ -389,6 +396,7 @@ protected slots:
 
 	EditModes m_editMode;
 	EditModes m_ctrlMode; // mode they were in before they hit ctrl
+	EditModes m_knifeMode; // mode they where in before entering knife mode
 
 	bool m_mouseDownRight; //true if right click is being held down
 
@@ -408,6 +416,10 @@ protected slots:
 	// did we start a mouseclick with shift pressed
 	bool m_startedWithShift;
 
+	// Variable that holds the position in ticks for the knife action
+	int m_knifeTickPos;
+	void updateKnifePos(QMouseEvent* me);
+
 	friend class PianoRollWindow;
 
 	StepRecorderWidget m_stepRecorderWidget;
@@ -428,6 +440,7 @@ protected slots:
 	QColor m_textColorLight;
 	QColor m_textShadow;
 	QColor m_markedSemitoneColor;
+	QColor m_knifeCutLineColor;
 	int m_noteOpacity;
 	int m_ghostNoteOpacity;
 	bool m_noteBorders;

src/gui/editors/PianoRoll.cpp

@@ -115,6 +115,7 @@ QPixmap * PianoRoll::s_toolErase = NULL;
 QPixmap * PianoRoll::s_toolSelect = NULL;
 QPixmap * PianoRoll::s_toolMove = NULL;
 QPixmap * PianoRoll::s_toolOpen = NULL;
+QPixmap* PianoRoll::s_toolKnife = nullptr;
 
 TextFloat * PianoRoll::s_textFloat = NULL;
 
@@ -200,6 +201,7 @@ PianoRoll::PianoRoll() :
 	m_textColorLight( 0, 0, 0 ),
 	m_textShadow( 0, 0, 0 ),
 	m_markedSemitoneColor( 0, 0, 0 ),
+	m_knifeCutLineColor(0, 0, 0),
 	m_noteOpacity( 255 ),
 	m_ghostNoteOpacity( 255 ),
 	m_noteBorders( true ),
@@ -271,6 +273,10 @@ PianoRoll::PianoRoll() :
 	{
 		s_toolOpen = new QPixmap( embed::getIconPixmap( "automation" ) );
 	}
+	if (s_toolKnife == nullptr)
+	{
+		s_toolKnife = new QPixmap(embed::getIconPixmap("edit_knife"));
+	}
 
 	// init text-float
 	if( s_textFloat == NULL )
@@ -1268,8 +1274,16 @@ void PianoRoll::keyPressEvent(QKeyEvent* ke)
 			break;
 
 		case Qt::Key_Escape:
-			// Same as Ctrl + Shift + A
-			clearSelectedNotes();
+			// On the Knife mode, ESC cancels it
+			if (m_editMode == ModeEditKnife)
+			{
+				cancelKnifeAction();
+			}
+			else
+			{
+				// Same as Ctrl + Shift + A
+				clearSelectedNotes();
+			}
 			break;
 
 		case Qt::Key_Backspace:
@@ -1314,6 +1328,12 @@ void PianoRoll::keyPressEvent(QKeyEvent* ke)
 		}
 
 		case Qt::Key_Control:
+			// Ctrl will not enter selection mode if we are
+			// in Knife mode, but unquantize it
+			if (m_editMode == ModeEditKnife)
+			{
+				break;
+			}
 			// Enter selection mode if:
 			// -> this window is active
 			// -> shift is not pressed
@@ -1353,6 +1373,10 @@ void PianoRoll::keyReleaseEvent(QKeyEvent* ke )
 	switch( ke->key() )
 	{
 		case Qt::Key_Control:
+			if (m_editMode == ModeEditKnife)
+			{
+				break;
+			}
 			computeSelectedNotes( ke->modifiers() & Qt::ShiftModifier);
 			m_editMode = m_ctrlMode;
 			update();
@@ -1441,6 +1465,26 @@ void PianoRoll::mousePressEvent(QMouseEvent * me )
 		return;
 	}
 
+	// -- Knife
+	if (m_editMode == ModeEditKnife && me->button() == Qt::LeftButton)
+	{
+		NoteVector n;
+		Note* note = noteUnderMouse();
+
+		if (note)
+		{
+			n.append(note);
+
+			updateKnifePos(me);
+
+			// Call splitNotes for the note
+			m_pattern->splitNotes(n, TimePos(m_knifeTickPos));
+		}
+
+		update();
+		return;
+	}
+
 	if( m_editMode == ModeEditDetuning && noteUnderMouse() )
 	{
 		static QPointer<AutomationPattern> detuningPattern = nullptr;
@@ -1946,6 +1990,24 @@ void PianoRoll::pauseChordNotes(int key)
 	}
 }
 
+void PianoRoll::setKnifeAction()
+{
+	if (m_editMode != ModeEditKnife)
+	{
+		m_knifeMode = m_editMode;
+		m_editMode = ModeEditKnife;
+		m_action = ActionKnife;
+		setCursor(Qt::ArrowCursor);
+		update();
+	}
+}
+
+void PianoRoll::cancelKnifeAction()
+{
+	m_editMode = m_knifeMode;
+	m_action = ActionNone;
+	update();
+}
 
 
 
@@ -2047,6 +2109,12 @@ void PianoRoll::mouseReleaseEvent( QMouseEvent * me )
 
 	s_textFloat->hide();
 
+	// Quit knife mode if we pressed and released the right mouse button
+	if (m_editMode == ModeEditKnife && me->button() == Qt::RightButton)
+	{
+		cancelKnifeAction();
+	}
+
 	if( me->button() & Qt::LeftButton )
 	{
 		mustRepaint = true;
@@ -2105,7 +2173,11 @@ void PianoRoll::mouseReleaseEvent( QMouseEvent * me )
 	}
 
 	m_currentNote = NULL;
-	m_action = ActionNone;
+
+	if (m_action != ActionKnife)
+	{
+		m_action = ActionNone;
+	}
 
 	if( m_editMode == ModeDraw )
 	{
@@ -2131,6 +2203,8 @@ void PianoRoll::mouseMoveEvent( QMouseEvent * me )
 
 	if( m_action == ActionNone && me->buttons() == 0 )
 	{
+		// When cursor is between note editing area and volume/panning
+		// area show vertical size cursor.
 		if( me->y() > keyAreaBottom() && me->y() < noteEditTop() )
 		{
 			setCursor( Qt::SizeVerCursor );
@@ -2160,6 +2234,12 @@ void PianoRoll::mouseMoveEvent( QMouseEvent * me )
 		return;
 	}
 
+	// Update Knife position if we are on knife mode
+	if (m_editMode == ModeEditKnife)
+	{
+		updateKnifePos(me);
+	}
+
 	if( me->y() > PR_TOP_MARGIN || m_action != ActionNone )
 	{
 		bool edit_note = ( me->y() > noteEditTop() )
@@ -2439,7 +2519,7 @@ void PianoRoll::mouseMoveEvent( QMouseEvent * me )
 				}
 			}
 		}
-		else if (me->buttons() == Qt::NoButton && m_editMode != ModeDraw)
+		else if (me->buttons() == Qt::NoButton && m_editMode != ModeDraw && m_editMode != ModeEditKnife)
 		{
 			// Is needed to restore cursor when it previously was set to
 			// Qt::SizeVerCursor (between keyAreaBottom and noteEditTop)
@@ -2535,6 +2615,24 @@ void PianoRoll::mouseMoveEvent( QMouseEvent * me )
 
 
 
+void PianoRoll::updateKnifePos(QMouseEvent* me)
+{
+	// Calculate the TimePos from the mouse
+	int mouseViewportPos = me->x() - m_whiteKeyWidth;
+	int mouseTickPos = mouseViewportPos / (m_ppb / TimePos::ticksPerBar()) + m_currentPosition;
+
+	// If ctrl is not pressed, quantize the position
+	if (!(me->modifiers() & Qt::ControlModifier))
+	{
+		mouseTickPos = floor(mouseTickPos / quantization()) * quantization();
+	}
+
+	m_knifeTickPos = mouseTickPos;
+}
+
+
+
+
 void PianoRoll::dragNotes( int x, int y, bool alt, bool shift, bool ctrl )
 {
 	// dragging one or more notes around
@@ -3232,6 +3330,41 @@ void PianoRoll::paintEvent(QPaintEvent * pe )
 			}
 		}
 
+		// -- Knife tool (draw cut line)
+		if (m_action == ActionKnife)
+		{
+			auto xCoordOfTick = [this](int tick) {
+				return m_whiteKeyWidth + (
+					(tick - m_currentPosition) * m_ppb / TimePos::ticksPerBar());
+			};
+			Note* n = noteUnderMouse();
+			if (n)
+			{
+				const int key = n->key() - m_startKey + 1;
+				int y = y_base - key * m_keyLineHeight;
+
+				int x = xCoordOfTick(m_knifeTickPos);
+
+				if (x > xCoordOfTick(n->pos()) &&
+					x < xCoordOfTick(n->pos() + n->length()))
+				{
+					p.setPen(QPen(m_knifeCutLineColor, 1));
+					p.drawLine(x, y, x, y + m_keyLineHeight);
+
+					setCursor(Qt::BlankCursor);
+				}
+				else
+				{
+					setCursor(Qt::ArrowCursor);
+				}
+			}
+			else
+			{
+				setCursor(Qt::ArrowCursor);
+			}
+		}
+		// -- End knife tool
+
 		//draw current step recording notes
 		for( const Note *note : m_stepRecorder.getCurStepNotes() )
 		{
@@ -3353,6 +3486,7 @@ void PianoRoll::paintEvent(QPaintEvent * pe )
 			case ModeErase: cursor = s_toolErase; break;
 			case ModeSelect: cursor = s_toolSelect; break;
 			case ModeEditDetuning: cursor = s_toolOpen; break;
+			case ModeEditKnife: cursor = s_toolKnife; break;
 		}
 		QPoint mousePosition = mapFromGlobal( QCursor::pos() );
 		if( cursor != NULL && mousePosition.y() > keyAreaTop() && mousePosition.x() > noteEditLeft())
@@ -3560,7 +3694,12 @@ void PianoRoll::focusOutEvent( QFocusEvent * )
 			m_pattern->instrumentTrack()->pianoModel()->setKeyState( i, false );
 		}
 	}
-	m_editMode = m_ctrlMode;
+	if (m_editMode == ModeEditKnife) {
+		m_editMode = m_knifeMode;
+		m_action = ActionNone;
+	} else {
+		m_editMode = m_ctrlMode;
+	}
 	update();
 }
 
@@ -4443,7 +4582,14 @@ PianoRollWindow::PianoRollWindow() :
 	connect(glueAction, SIGNAL(triggered()), m_editor, SLOT(glueNotes()));
 	glueAction->setShortcut( Qt::SHIFT | Qt::Key_G );
 
+	// Knife
+	QAction * knifeAction = new QAction(embed::getIconPixmap("edit_knife"),
+				tr("Knife"), noteToolsButton);
+	connect(knifeAction, &QAction::triggered, m_editor, &PianoRoll::setKnifeAction);
+	knifeAction->setShortcut( Qt::SHIFT | Qt::Key_K );
+
 	noteToolsButton->addAction(glueAction);
+	noteToolsButton->addAction(knifeAction);
 
 	notesActionsToolBar->addWidget(noteToolsButton);