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// Copyright Vladimir Prus 2005.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt
// or copy at http://www.boost.org/LICENSE_1_0.txt)
#include "arrow.h"
#include <QtGui/qapplication.h>
#include <QtGui/qwidget.h>
#include <QtGui/qpainter.h>
#include <QtGui/qpainterpath.h>
#include <stdlib.h>
#include <math.h>
Arrow_widget::Arrow_widget(QWidget* parent) : QWidget(parent), color_(0)
{
QPalette pal = palette();
pal.setBrush(backgroundRole(), QBrush(Qt::white));
setPalette(pal);
}
void Arrow_widget::slotChangeColor()
{
color_ = (color_ + 1) % 3;
update();
}
void
Arrow_widget::draw_arrow(int x1, int y1, int x2, int y2, QPainter& painter)
{
// The length of the from the tip of the arrow to the point
// where line starts.
const int arrowhead_length = 16;
QPainterPath arrow;
arrow.moveTo(x1, y1);
// Determine the angle of the straight line.
double a1 = (x2-x1);
double a2 = (y2-y1);
double b1 = 1;
double b2 = 0;
double straight_length = sqrt(a1*a1 + a2*a2);
double dot_product = a1*b1 + a2*b2;
double cosine = dot_product/
(sqrt(pow(a1, 2) + pow(a2, 2))*sqrt(b1 + b2));
double angle = acos(cosine);
if (y1 < y2)
{
angle = -angle;
}
double straight_angle = angle*180/M_PI;
double limit = 10;
double angle_to_vertical;
if (fabs(straight_angle) < 90)
angle_to_vertical = fabs(straight_angle);
else if (straight_angle > 0)
angle_to_vertical = 180-straight_angle;
else
angle_to_vertical = 180-(-straight_angle);
double angle_delta = 0;
if (angle_to_vertical > limit)
angle_delta = 30 * (angle_to_vertical - limit)/90;
double start_angle = straight_angle > 0
? straight_angle - angle_delta :
straight_angle + angle_delta;
QMatrix m1;
m1.translate(x1, y1);
m1.rotate(-start_angle);
double end_angle = straight_angle > 0
? (straight_angle + 180 + angle_delta) :
(straight_angle + 180 - angle_delta);
QMatrix m2;
m2.reset();
m2.translate(x2, y2);
m2.rotate(-end_angle);
arrow.cubicTo(m1.map(QPointF(straight_length/2, 0)),
m2.map(QPointF(straight_length/2, 0)),
m2.map(QPointF(arrowhead_length, 0)));
painter.save();
painter.setBrush(Qt::NoBrush);
painter.drawPath(arrow);
painter.restore();
painter.save();
painter.translate(x2, y2);
painter.rotate(-90);
painter.rotate(-end_angle);
painter.rotate(180);
QPolygon arrowhead(4);
arrowhead.setPoint(0, 0, 0);
arrowhead.setPoint(1, arrowhead_length/3, -arrowhead_length*5/4);
arrowhead.setPoint(2, 0, -arrowhead_length);
arrowhead.setPoint(3, -arrowhead_length/3, -arrowhead_length*5/4);
painter.drawPolygon(arrowhead);
painter.restore();
}
void Arrow_widget::paintEvent(QPaintEvent*)
{
QPainter p(this);
p.setRenderHint(QPainter::Antialiasing);
int base_x = 550;
int base_y = 200;
if (color_ == 0)
p.setBrush(Qt::black);
else if (color_ == 1)
p.setBrush(Qt::green);
else if (color_ == 2)
p.setBrush(Qt::yellow);
else
p.setBrush(Qt::black);
for (int x_step = 0; x_step < 6; ++x_step)
{
for (int y_step = 1; y_step <= 3; ++y_step)
{
draw_arrow(base_x, base_y, base_x+x_step*100,
base_y - y_step*50, p);
draw_arrow(base_x, base_y, base_x+x_step*100,
base_y + y_step*50, p);
draw_arrow(base_x, base_y, base_x-x_step*100,
base_y + y_step*50, p);
draw_arrow(base_x, base_y, base_x-x_step*100,
base_y - y_step*50, p);
}
}
draw_arrow(50, 400, 1000, 450, p);
draw_arrow(1000, 400, 50, 450, p);
}
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