lmms/include/Knob.h

/*
 * Knob.h - powerful knob-widget
 *
 * Copyright (c) 2004-2008 Tobias Doerffel <tobydox/at/users.sourceforge.net>
 *
 * 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 LMMS_GUI_KNOB_H
#define LMMS_GUI_KNOB_H

#include <memory>

#include "FloatModelEditorBase.h"



namespace lmms::gui
{


enum class KnobType
{
	Dark28, Bright26, Small17, Vintage32, Styled
} ;


void convertPixmapToGrayScale(QPixmap &pixMap);

class LMMS_EXPORT Knob : public FloatModelEditorBase
{
	Q_OBJECT
	Q_ENUMS( KnobType )

	Q_PROPERTY(float innerRadius READ innerRadius WRITE setInnerRadius)
	Q_PROPERTY(float outerRadius READ outerRadius WRITE setOuterRadius)

	Q_PROPERTY(float centerPointX READ centerPointX WRITE setCenterPointX)
	Q_PROPERTY(float centerPointY READ centerPointY WRITE setCenterPointY)

	Q_PROPERTY(float lineWidth READ lineWidth WRITE setLineWidth)

	// Unfortunately, the gradient syntax doesn't create our gradient
	// correctly so we need to do this:
	Q_PROPERTY(QColor outerColor READ outerColor WRITE setOuterColor)

	Q_PROPERTY(QColor lineActiveColor MEMBER m_lineActiveColor)
	Q_PROPERTY(QColor lineInactiveColor MEMBER m_lineInactiveColor)
	Q_PROPERTY(QColor arcActiveColor MEMBER m_arcActiveColor)
	Q_PROPERTY(QColor arcInactiveColor MEMBER m_arcInactiveColor)

	Q_PROPERTY(KnobType knobNum READ knobNum WRITE setknobNum)
	
	Q_PROPERTY(QColor textColor READ textColor WRITE setTextColor)

	void initUi( const QString & _name ); //!< to be called by ctors
	void onKnobNumUpdated(); //!< to be called when you updated @a m_knobNum

public:
	/**
	 * @brief Determines how the label of the knob is rendered.
	 * 
	 * Labels can be rendered using the font that is set for the knob or using a
	 * font with a fixed size which is determined by SMALL_FONT_SIZE.
	 */
	enum class LabelRendering
	{
		/**
		 * @brief Renders the label using the font that is set for the widget.
		 * 
		 * The space that's needed for the label is determined using the font metrics of the knob's font.
		 */
		WidgetFont,

		/**
		 * @brief Renders the labels in legacy mode. This uses a fixed font size and does not adhere
		 * to the font size that's set for the widget's font.
		 * 
		 * @deprecated Do not use this mode in new code as it is considered deprecated and might be removed in the future.
		 */
		LegacyFixedFontSize
	};

	/**
	 * @brief Construct a Knob with the given style and no label.
	 * 
	 * @param _knob_num Style of the knob
	 * @param _parent Parent widget
	 * @param _name Object name of the widget
	 */
	Knob( KnobType _knob_num, QWidget * _parent = nullptr, const QString & _name = QString() );

	/**
	 * @brief Construct a Knob with the given style and label text.
	 * 
	 * @param knobNum Style of the knob
	 * @param labelText Text for the label
	 * @param parent Parent widget
	 * @param labelRendering Determines if the label uses the widget font or a font with a fixed size of 12 pixels (LegacyFixedFontSize). The default is to use the widget font.
	 * @param name Object name of the widget
	 */
	Knob(KnobType knobNum, const QString& labelText, QWidget* parent = nullptr, LabelRendering labelRendering = LabelRendering::WidgetFont, const QString& name = QString());

	/**
	 * @brief Constructs a knob with a label font in the pixel size.
	 * 
	 * @param knobNum Style of the knob
	 * @param labelText Text for the label
	 * @param labelPixelSize Pixel size for the label
	 * @param parent Parent widget
	 * @param name Object name of the widget
	 */
	Knob(KnobType knobNum, const QString& labelText, int labelPixelSize, QWidget* parent, const QString& name = QString());

	Knob( QWidget * _parent = nullptr, const QString & _name = QString() ); //!< default ctor
	
	Knob( const Knob& other ) = delete;

	const QString& getLabel() const;
	void setLabel(const QString& txt);

	void setTotalAngle( float angle );

	// Begin styled knob accessors
	float innerRadius() const;
	void setInnerRadius( float r );

	float outerRadius() const;
	void setOuterRadius( float r );

	KnobType knobNum() const;
	void setknobNum( KnobType k );

	QPointF centerPoint() const;
	float centerPointX() const;
	void setCenterPointX( float c );
	float centerPointY() const;
	void setCenterPointY( float c );

	float lineWidth() const;
	void setLineWidth( float w );

	QColor outerColor() const;
	void setOuterColor( const QColor & c );
	
	QColor textColor() const;
	void setTextColor( const QColor & c );


protected:
	void paintEvent(QPaintEvent*) override;

	void changeEvent(QEvent * ev) override;

	/*!
	 * Affects how the label of the knob is rendered.
	 *
	 * The default mode returns false. The height of the label text is taken into account when a new fixed
	 * size is computed for the Knob. When the label text is painted the descent of the font is used to
	 * compute the base line. The default mode returns false.
	 * 
	 * Enabling fixed font size rendering mode leads to the following behavior:
	 * * The height of the label is not taken into account when the new fixed height of the Knob is computed.
	 *   Instead a fixed size of 10 is added for the label.
	 * * When the knob is painted the baseline of the font is always set to 2 pixels away from the lower side
	 *   of the Knob's rectangle.
	 * * The label is always rendered with a size of SMALL_FONT_SIZE.
	 */
	bool fixedFontSizeLabelRendering() const { return m_fixedFontSizeLabelRendering; }

	/*!
	 * Set the button to legacy rendering mode which uses a fixed font size and that does not take the size
	 * of the widget's font into account.
	 * 
	 * This can be thought of as a legacy mode which reinstates the old behavior of the knob.
	 *
	 * @see fixedFontSizeLabelRendering().
	 */
	void setFixedFontSizeLabelRendering();

private:
	QLineF calculateLine( const QPointF & _mid, float _radius,
						float _innerRadius = 1) const;

	void drawKnob( QPainter * _p );
	void drawLabel(QPainter& p);
	bool updateAngle();

	int angleFromValue( float value, float minValue, float maxValue, float totalAngle ) const
	{
		return static_cast<int>( ( value - 0.5 * ( minValue + maxValue ) ) / ( maxValue - minValue ) * m_totalAngle ) % 360;
	}

	void updateFixedSize();

	QString m_label;
	bool m_fixedFontSizeLabelRendering = false;

	std::unique_ptr<QPixmap> m_knobPixmap;

	float m_totalAngle;
	int m_angle;
	QImage m_cache;

	// Styled knob stuff, could break out
	QPointF m_centerPoint;
	float m_innerRadius;
	float m_outerRadius;
	float m_lineWidth;
	QColor m_outerColor;

	QColor m_lineActiveColor;
	QColor m_lineInactiveColor;
	QColor m_arcActiveColor;
	QColor m_arcInactiveColor;
	
	QColor m_textColor;

	KnobType m_knobNum;
};

} // namespace lmms::gui

#endif // LMMS_GUI_KNOB_H