Step Recording feature (#4544)

(Addresses #1421)

**Behaviour description:**

* Toggle step-recording mode using the dedicated icon.
* This mode is mutually exclusive with other recoding modes (record/record
  accompany).
* Step-Recording while song is playing is allowed (and fun! :) ).
* When start recording, the start recording-position will be set where the
  timeline curser points (quantized backwards using PianoRoll's current
  quantization). If step-recording is started while the pattern is playing the
  start recording-position is set to the beginning of the pattern.
* Step length is determined by the Piano Roll's current note-length (can be
  changed dynamically during step-recording).
* The record-position can be moved forward/backward using the right/left keys.
* When notes are pressed on keyboard/midi-device, they will be added
  temporarily ("recorded") with a length of a step. while still pressed, user
  can adjust the length by steps resolution using the arrow keys (e.g. moving
  right once will make the note's length 2-steps, another right press will make
  the length 3-steps etc.).
* When all pressed-keys are released, the actual recording happen and the
  notes are added.
* If the user press multiple notes, and release some of them for some time
  which indicates it is intentional i.e. he didn't want to do a full release
  to record the step but rather just change what will be recorded (I set the
  "intentional release threshold" to 70 milliseconds) - these note will be
  removed from current step-recording. e.g.
* Added notes are not quantized, making the addition simpler and WYSIWYG
* Similiarly to adding notes using mouse clicks, an undo-checkpoint is added
  per added step and not for the whole recording as in other record modes.

include/Editor.h

@@ -51,6 +51,7 @@ protected slots:
 	virtual void play() {}
 	virtual void record() {}
 	virtual void recordAccompany() {}
+	virtual void toggleStepRecording() {}
 	virtual void stop() {}
 
 private slots:
@@ -64,7 +65,7 @@ private slots:
 	///
 	/// \param	record	If set true, the editor's toolbar will contain record
 	///					buttons in addition to the play and stop buttons.
-	Editor(bool record = false);
+	Editor(bool record = false, bool record_step = false);
 	virtual ~Editor();
 
 
@@ -73,6 +74,7 @@ private slots:
 	QAction* m_playAction;
 	QAction* m_recordAction;
 	QAction* m_recordAccompanyAction;
+	QAction* m_toggleStepRecordingAction;
 	QAction* m_stopAction;
 };
 

include/PianoRoll.h

@@ -38,6 +38,8 @@
 #include "lmms_basics.h"
 #include "Song.h"
 #include "ToolTip.h"
+#include "StepRecorder.h"
+#include "StepRecorderWidget.h"
 
 class QPainter;
 class QPixmap;
@@ -104,6 +106,11 @@ class PianoRoll : public QWidget
 		return m_recording;
 	}
 
+	inline bool isStepRecording() const
+	{
+		return m_stepRecorder.isRecording();
+	}
+
 	const Pattern* currentPattern() const
 	{
 		return m_pattern;
@@ -189,6 +196,7 @@ protected slots:
 	void play();
 	void record();
 	void recordAccompany();
+	bool toggleStepRecording();
 	void stop();
 
 	void startRecordNote( const Note & n );
@@ -206,9 +214,11 @@ protected slots:
 
 	void updatePosition(const MidiTime & t );
 	void updatePositionAccompany(const MidiTime & t );
+	void updatePositionStepRecording(const MidiTime & t );
 
 	void zoomingChanged();
 	void quantizeChanged();
+	void noteLengthChanged();
 	void quantizeNotes();
 
 	void updateSemiToneMarkerMenu();
@@ -405,6 +415,9 @@ protected slots:
 
 	friend class PianoRollWindow;
 
+	StepRecorderWidget m_stepRecorderWidget;
+	StepRecorder m_stepRecorder;
+
 	// qproperty fields
 	QColor m_barLineColor;
 	QColor m_beatLineColor;
@@ -449,6 +462,7 @@ class PianoRollWindow : public Editor, SerializingObject
 	void stop();
 	void record();
 	void recordAccompany();
+	void toggleStepRecording();
 	void stopRecording();
 
 	bool isRecording() const;
@@ -473,11 +487,14 @@ class PianoRollWindow : public Editor, SerializingObject
 
 
 private slots:
-	void patternRenamed();
+	void updateAfterPatternChange();
 	void ghostPatternSet( bool state );
 
 private:
+	void patternRenamed();
 	void focusInEvent(QFocusEvent * event);
+	void stopStepRecording();
+	void updateStepRecordingIcon();
 
 	PianoRoll* m_editor;
 

include/StepRecorder.h

@@ -0,0 +1,143 @@
+/*
+ * This file is part of LMMS - https://lmms.io
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+
+#ifndef STEP_RECORDER_H
+#define STEP_RECORDER_H
+
+#include <QTime>
+#include <QTimer>
+#include <QObject>
+#include <QKeyEvent>
+
+#include "Note.h"
+#include "lmms_basics.h"
+#include "Pattern.h"
+
+class PianoRoll;
+class StepRecorderWidget;
+
+class StepRecorder : public QObject
+{
+	Q_OBJECT
+
+	public:
+	StepRecorder(PianoRoll& pianoRoll, StepRecorderWidget& stepRecorderWidget);
+
+	void initialize();
+	void start(const MidiTime& currentPosition,const MidiTime& stepLength);
+	void stop();
+	void notePressed(const Note & n);
+	void noteReleased(const Note & n);
+	bool keyPressEvent(QKeyEvent* ke);
+	bool mousePressEvent(QMouseEvent* ke);
+	void setCurrentPattern(Pattern* newPattern);
+	void setStepsLength(const MidiTime& newLength);
+
+	QVector<Note*> getCurStepNotes();
+
+	bool isRecording() const
+	{
+		return m_isRecording;
+	}
+
+	QColor curStepNoteColor() const
+	{
+		return QColor(245,3,139); // radiant pink
+	}
+
+	private slots:
+	void removeNotesReleasedForTooLong();
+
+	private:
+	void stepForwards();
+	void stepBackwards();
+
+	void applyStep();
+	void dismissStep();
+	void prepareNewStep();
+
+	MidiTime getCurStepEndPos();
+
+	void updateCurStepNotes();
+	void updateWidget();
+
+	bool allCurStepNotesReleased();
+
+	PianoRoll& m_pianoRoll;
+	StepRecorderWidget& m_stepRecorderWidget;
+
+	bool m_isRecording = false;
+	MidiTime m_curStepStartPos = 0;
+	MidiTime m_curStepEndPos = 0;
+
+	MidiTime m_stepsLength;
+	MidiTime m_curStepLength; // current step length refers to the step currently recorded. it may defer from m_stepsLength
+							  // since the user can make current step larger
+
+	QTimer m_updateReleasedTimer;
+
+	Pattern* m_pattern;
+
+	class StepNote
+	{
+		public:
+		StepNote(const Note & note) : m_note(note), m_pressed(true) {};
+
+		void setPressed()
+		{
+			m_pressed = true;
+		}
+
+		void setReleased()
+		{
+			m_pressed = false;
+			releasedTimer.start();
+		}
+
+		int timeSinceReleased()
+		{
+			return releasedTimer.elapsed();
+		}
+
+		bool isPressed() const
+		{
+			return m_pressed;
+		}
+
+		bool isReleased() const
+		{
+			return !m_pressed;
+		}
+
+		Note m_note;
+
+		private:
+		bool m_pressed;
+		QTime releasedTimer;
+	} ;
+
+	QVector<StepNote*> m_curStepNotes; // contains the current recorded step notes (i.e. while user still press the notes; before they are applied to the pattern)
+
+	StepNote* findCurStepNote(const int key);
+
+	bool m_isStepInProgress = false;
+};
+
+#endif //STEP_RECORDER_H

include/StepRecorderWidget.h

@@ -0,0 +1,92 @@
+/*
+ * StepRecorderWidget.h - widget that provide gui markers for step recording
+ *
+ * This file is part of LMMS - https://lmms.io
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of"the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+#ifndef STEP_RECOREDER_WIDGET_H
+#define STEP_RECOREDER_WIDGET_H
+
+#include "lmms_basics.h"
+#include "Note.h"
+
+#include <QWidget>
+#include <QColor>
+#include <QPainter>
+
+class StepRecorderWidget : public QWidget
+{
+	Q_OBJECT
+
+public:
+	StepRecorderWidget(
+		QWidget * parent,
+		const int ppt,
+		const int marginTop,
+		const int marginBottom,
+		const int marginLeft,
+		const int marginRight);
+
+	//API used by PianoRoll
+	void setPixelsPerTact(int ppt);
+	void setCurrentPosition(MidiTime currentPosition);
+	void setBottomMargin(const int marginBottom);
+
+	//API used by StepRecorder
+	void setStepsLength(MidiTime stepsLength);
+	void setStartPosition(MidiTime pos);
+	void setEndPosition(MidiTime pos);
+
+	void showHint();
+
+private:
+	virtual void paintEvent(QPaintEvent * pe);
+
+	int xCoordOfTick(int tick);
+
+	void drawVerLine(QPainter* painter, int x, const QColor& color, int top, int bottom);
+	void drawVerLine(QPainter* painter, const MidiTime& pos, const QColor& color, int top, int bottom);
+
+	void updateBoundaries();
+
+	MidiTime m_stepsLength;
+	MidiTime m_curStepStartPos;
+	MidiTime m_curStepEndPos;
+
+	int m_ppt; // pixels per tact
+	MidiTime m_currentPosition; // current position showed by on PianoRoll
+
+	QColor m_colorLineStart;
+	QColor m_colorLineEnd;
+
+	// boundaries within piano roll window
+	int m_top;
+	int m_bottom;
+	int m_left;
+	int m_right;
+
+	const int m_marginTop;
+	int m_marginBottom; // not const since can change on resize of edit-note area
+	const int m_marginLeft;
+	const int m_marginRight;
+
+signals:
+	void positionChanged(const MidiTime & t);
+} ;
+
+#endif //STEP_RECOREDER_WIDGET_H

src/core/CMakeLists.txt

@@ -67,6 +67,7 @@ set(LMMS_SRCS
 	core/TrackContainer.cpp
 	core/ValueBuffer.cpp
 	core/VstSyncController.cpp
+	core/StepRecorder.cpp
 
 	core/audio/AudioAlsa.cpp
 	core/audio/AudioDevice.cpp