QArrow.cpp

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#include "QArrow.h"
 
#include <math.h>
 
#include <QPainter>
 
QArrow::QArrow(qreal l, qreal a, qreal hl, qreal hw, QPen& pen,
               QGraphicsItem* parent)
    : QGraphicsItem(parent)
{
    _arrowLength = l;
    _arrowAngle = a;
    _headLength = hl;
    _headWidth = hw;
    _arrowPen = pen;
}
 
QArrow::QArrow(qreal l, qreal a, QPen& pen, QGraphicsItem* parent)
    : QGraphicsItem(parent)
{
    _arrowLength = l;
    _arrowAngle = a;
    _headLength = 8;  // default headlength
    _headWidth = 5;   // default headwidth
    _arrowPen = pen;
}
 
QArrow::~QArrow() = default;
 
double QArrow::calcCos(double angle)
{
    return cos(angle * PI / 180);
}
 
double QArrow::calcSin(double angle)
{
    return sin(angle * PI / 180);
}
 
QRectF QArrow::boundingRect() const
{
    double deltaX = cos(_arrowAngle) * _arrowLength;
    double deltaY = sin(_arrowAngle) * _arrowLength;
 
    return QRectF(0, 0, deltaX, deltaY);
}
 
double QArrow::getLength()
{
    return _arrowLength;
}
 
double QArrow::getAngle()
{
    return _arrowAngle;
}
 
void QArrow::paint(QPainter* painter, const QStyleOptionGraphicsItem* option,
                   QWidget* widget)
{
    Q_UNUSED(option)
    Q_UNUSED(widget)
 
    double ddeltaX = calcCos(_arrowAngle) * _arrowLength;
    double ddeltaY = calcSin(_arrowAngle) * _arrowLength;
    double theta = atan(ddeltaY / ddeltaX);
    double theta2 = (ddeltaX < 0.0) ? (theta + PI) : theta;
    int lengthdeltaX = -static_cast<int>(cos(theta2) * _headLength);
    int lengthdeltaY = -static_cast<int>(sin(theta2) * _headLength);
    auto widthdeltaX = static_cast<int>(sin(theta2) * _headWidth);
    auto widthdeltaY = static_cast<int>(cos(theta2) * _headWidth);
    auto deltaX = static_cast<int>(ddeltaX);
    auto deltaY = static_cast<int>(ddeltaY);
    painter->setPen(_arrowPen);
    painter->drawLine(0, 0, deltaX, deltaY);
    painter->drawLine(deltaX,
                      deltaY,
                      deltaX + lengthdeltaX + widthdeltaX,
                      deltaY + lengthdeltaY - widthdeltaY);
    painter->drawLine(deltaX,
                      deltaY,
                      deltaX + lengthdeltaX - widthdeltaX,
                      deltaY + lengthdeltaY + widthdeltaY);
}
 
void QArrow::setAngle(qreal a)
{
    _arrowAngle = a;
}
 
void QArrow::setLength(qreal l)
{
    _arrowLength = l;
}