Ruler: Factor out the calculation of the tick spacing

[pulseview.git] / pv / view / ruler.hpp

/*
 * This file is part of the PulseView project.
 *
 * Copyright (C) 2012 Joel Holdsworth <joel@airwebreathe.org.uk>
 *
 * 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; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 */

#ifndef PULSEVIEW_PV_VIEW_RULER_HPP
#define PULSEVIEW_PV_VIEW_RULER_HPP

#include <functional>
#include <memory>

#include <boost/optional.hpp>

#include "marginwidget.hpp"
#include <pv/util.hpp>

namespace pv {
namespace view {

class TimeItem;
class ViewItem;

class Ruler : public MarginWidget
{
	Q_OBJECT

private:

	/// Height of the ruler in multipes of the text height
	static const float RulerHeight;

	static const int MinorTickSubdivision;

	/// Height of the hover arrow in multiples of the text height
	static const float HoverArrowSize;

public:
	Ruler(View &parent);

public:
	QSize sizeHint() const;

	/**
	 * The extended area that the header widget would like to be sized to.
	 * @remarks This area is the area specified by sizeHint, extended by
	 * the area to overlap the viewport.
	 */
	QSize extended_size_hint() const;

private:
	/**
	 * Gets the time items.
	 */
	std::vector< std::shared_ptr<pv::view::ViewItem> > items();

	/**
	 * Gets the first view item which has a label that contains @c pt .
	 * @param pt the point to search with.
	 * @return the view item that has been found, or and empty
	 *   @c shared_ptr if no item was found.
	 */
	std::shared_ptr<pv::view::ViewItem> get_mouse_over_item(
		const QPoint &pt);

private:
	void paintEvent(QPaintEvent *event);

	void mouseDoubleClickEvent(QMouseEvent *e);

	/**
	 * Draw a hover arrow under the cursor position.
	 * @param p The painter to draw into.
	 * @param text_height The height of a single text ascent.
	 */
	void draw_hover_mark(QPainter &p, int text_height);

	int calculate_text_height() const;

	struct TickPositions
	{
		std::vector<std::pair<double, QString>> major;
		std::vector<double> minor;
	};

	/**
	 * Holds the tick positions so that they don't have to be recalculated on
	 * every redraw. Set by 'paintEvent()' when needed.
	 */
	boost::optional<TickPositions> tick_position_cache_;

	/**
	 * Calculates the major and minor tick positions.
	 *
	 * @param major_period The period between the major ticks.
	 * @param offset The time at the left border of the ruler.
	 * @param scale The scale in seconds per pixel.
	 * @param width the Width of the ruler.
	 * @param format_function A function used to format the major tick times.
	 * @return An object of type 'TickPositions' that contains the major tick
	 *         positions together with the labels at that ticks, and the minor
	 *         tick positions.
	 */
	static TickPositions calculate_tick_positions(
		const double major_period,
		const pv::util::Timestamp& offset,
		const double scale,
		const int width,
		std::function<QString(const pv::util::Timestamp&)> format_function);

protected:
	void resizeEvent(QResizeEvent*) override;

private Q_SLOTS:
	void hover_point_changed();

	// Resets the 'tick_position_cache_'.
	void invalidate_tick_position_cache();
};

} // namespace view
} // namespace pv

#endif // PULSEVIEW_PV_VIEW_RULER_HPP