GPXSee/src/axisitem.cpp

#include <cmath>
#include <QPainter>
#include "axisitem.h"

#include <QDebug>

#define TICK        6
#define PADDING     6
#define XTICKS      15
#define YTICKS      10
#define FONT_FAMILY "Arial"
#define FONT_SIZE   12


struct Label {
	double min;
	double max;
	double d;
};

static double niceNum(double x, int round)
{
	int expv;
	double f;
	double nf;

	expv = floor(log10(x));
	f = x / pow(10.0, expv);

	if (round) {
		if (f < 1.5)
			nf = 1.0;
		else if (f < 3.0)
			nf = 2.0;
		else if (f < 7.0)
			nf = 5.0;
		else
			nf = 10.0;
	} else {
		if (f <= 1.0)
			nf = 1.;
		else if (f <= 2.0)
			nf = 2.0;
		else if (f <= 5.0)
			nf = 5.0;
		else
			nf = 10.0;
	}

	return nf * pow(10.0, expv);
}

static struct Label label(double min, double max, int ticks)
{
	double range;
	struct Label l;

	range = niceNum(max - min, 0);
	l.d = niceNum(range / ticks, 1);
	l.min = ceil(min / l.d) * l.d;
	l.max = floor(max / l.d) * l.d;

	return l;
}


AxisItem::AxisItem(Type type)
{
	_type = type;
	_size = 0;
}

void AxisItem::setRange(const QPointF &range)
{
	_range = range;
	updateBoundingRect();
	prepareGeometryChange();
}

void AxisItem::setSize(qreal size)
{
	_size = size;
	updateBoundingRect();
	prepareGeometryChange();
}

void AxisItem::setLabel(const QString& label)
{
	_label = label;
	updateBoundingRect();
	prepareGeometryChange();
}

void AxisItem::updateBoundingRect()
{
	QFont font;
	font.setPixelSize(FONT_SIZE);
	font.setFamily(FONT_FAMILY);
	QFontMetrics fm(font);
	QRect ss, es, ls;
	struct Label l;


	l = label(_range.x(), _range.y(), (_type == X) ? XTICKS : YTICKS);
	es = fm.tightBoundingRect(QString::number(l.max));
	ss = fm.tightBoundingRect(QString::number(l.min));
	ls = fm.tightBoundingRect(_label);

	if (_type == X) {
		_boundingRect = QRectF(-ss.width()/2, -TICK/2,
		_size + es.width()/2 + ss.width()/2,
		ls.height() + es.height() - fm.descent() + TICK + 2*PADDING);
	} else {
		_boundingRect = QRectF(-(ls.height() + es.width() + 2*PADDING
		  - fm.descent() + TICK/2), -(_size + es.height()/2
		  + fm.descent()), ls.height() -fm.descent() + es.width() + 2*PADDING
		  + TICK, _size + es.height()/2 + fm.descent() + ss.height()/2);
	}
}

void AxisItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
	  QWidget *widget)
{
	Q_UNUSED(option);
	Q_UNUSED(widget);
	QFont font;
	font.setPixelSize(FONT_SIZE);
	font.setFamily(FONT_FAMILY);
	painter->setFont(font);
	QFontMetrics fm(font);
	QRect ts, ls;
	struct Label l;
	qreal range = _range.y() - _range.x();
	qreal val;


	ls = fm.tightBoundingRect(_label);

	if (_type == X) {
		painter->drawLine(0, 0, _size, 0);

		l = label(_range.x(), _range.y(), XTICKS);
		for (int i = 0; i < ((l.max - l.min) / l.d) + 1; i++) {
			val = l.min + i * l.d;
			QString str = QString::number(val);

			painter->drawLine((_size/range) * (val - _range.x()), TICK/2,
			  (_size/range) * (val - _range.x()), -TICK/2);
			ts = fm.tightBoundingRect(str);
			painter->drawText(((_size/range) * (val - _range.x()))
			  - (ts.width()/2), ts.height() + TICK/2 + PADDING, str);
		}

		painter->drawText(_size/2 - ls.width()/2, ls.height() + ts.height()
		  - 2*fm.descent() + TICK/2 + 2*PADDING, _label);
	} else {
		painter->drawLine(0, 0, 0, -_size);

		l = label(_range.x(), _range.y(), YTICKS);
		for (int i = 0; i < ((l.max - l.min) / l.d) + 1; i++) {
			val = l.min + i * l.d;
			QString str = QString::number(val);

			painter->drawLine(TICK/2, -((_size/range) * (val - _range.x())),
			  -TICK/2, -((_size/range) * (val - _range.x())));
			ts = fm.tightBoundingRect(str);
			painter->drawText(-(ts.width() + PADDING + TICK/2), -((_size/range)
			  * (val - _range.x())) + (ts.height()/2), str);
		}

		painter->rotate(-90);
		painter->drawText(_size/2 - ls.width()/2, -(ts.width()
		  + 2*PADDING + TICK/2), _label);
		painter->rotate(90);
	}

/*
	painter->setPen(Qt::red);
	painter->drawRect(boundingRect());
*/
}

QSizeF AxisItem::margin()
{
	QFont font;
	font.setPixelSize(FONT_SIZE);
	QFontMetrics fm(font);
	QRect ss, es, ls;
	struct Label l;


	l = label(_range.x(), _range.y(), (_type == X) ? XTICKS : YTICKS);
	es = fm.tightBoundingRect(QString::number(l.max));
	ss = fm.tightBoundingRect(QString::number(l.min));
	ls = fm.tightBoundingRect(_label);

	if (_type == X) {
		return QSizeF(es.width()/2,
		  ls.height() + es.height() - fm.descent() + TICK/2 + 2*PADDING);
	} else {
		return QSizeF(ls.height() -fm.descent() + es.width() + 2*PADDING
		  + TICK/2, es.height()/2 + fm.descent());
	}
}