ceph/src/boost/tools/build/example/qt/qt4/hello/arrow.cpp

   1 // Copyright Vladimir Prus 2005.
   2 // Distributed under the Boost Software License, Version 1.0.
   3 // (See accompanying file LICENSE_1_0.txt
   4 // or copy at http://www.boost.org/LICENSE_1_0.txt)
   5
   6 #include "arrow.h"
   7
   8 #include <QtGui/qapplication.h>
   9
  10 #include <QtGui/qwidget.h>
  11 #include <QtGui/qpainter.h>
  12 #include <QtGui/qpainterpath.h>
  13
  14 #include <stdlib.h>
  15 #include <math.h>
  16
  17 Arrow_widget::Arrow_widget(QWidget* parent) : QWidget(parent), color_(0)
  18 {
  19     QPalette pal = palette();
  20     pal.setBrush(backgroundRole(), QBrush(Qt::white));
  21     setPalette(pal);
  22 }
  23
  24 void Arrow_widget::slotChangeColor()
  25 {
  26     color_ = (color_ + 1) % 3;
  27     update();
  28 }
  29
  30 void
  31 Arrow_widget::draw_arrow(int x1, int y1, int x2, int y2, QPainter& painter)
  32 {
  33     // The length of the from the tip of the arrow to the point
  34     // where line starts.
  35     const int arrowhead_length = 16;
  36
  37     QPainterPath arrow;
  38     arrow.moveTo(x1, y1);
  39
  40     // Determine the angle of the straight line.
  41     double a1 = (x2-x1);
  42     double a2 = (y2-y1);
  43     double b1 = 1;
  44     double b2 = 0;
  45
  46     double straight_length = sqrt(a1*a1 + a2*a2);
  47
  48     double dot_product = a1*b1 + a2*b2;
  49     double cosine = dot_product/
  50         (sqrt(pow(a1, 2) + pow(a2, 2))*sqrt(b1 + b2));
  51     double angle = acos(cosine);
  52     if (y1 < y2)
  53     {
  54         angle = -angle;
  55     }
  56     double straight_angle = angle*180/M_PI;
  57
  58     double limit = 10;
  59
  60     double angle_to_vertical;
  61     if (fabs(straight_angle) < 90)
  62         angle_to_vertical = fabs(straight_angle);
  63     else if (straight_angle > 0)
  64         angle_to_vertical = 180-straight_angle;
  65     else
  66         angle_to_vertical = 180-(-straight_angle);
  67
  68     double angle_delta = 0;
  69     if (angle_to_vertical > limit)
  70         angle_delta = 30 * (angle_to_vertical - limit)/90;
  71     double start_angle = straight_angle > 0
  72         ? straight_angle - angle_delta :
  73         straight_angle + angle_delta;
  74
  75
  76     QMatrix m1;
  77     m1.translate(x1, y1);
  78     m1.rotate(-start_angle);
  79
  80     double end_angle = straight_angle > 0
  81         ? (straight_angle + 180 + angle_delta) :
  82         (straight_angle + 180 - angle_delta);
  83
  84     QMatrix m2;
  85     m2.reset();
  86     m2.translate(x2, y2);
  87     m2.rotate(-end_angle);
  88
  89     arrow.cubicTo(m1.map(QPointF(straight_length/2, 0)),
  90                   m2.map(QPointF(straight_length/2, 0)),
  91                   m2.map(QPointF(arrowhead_length, 0)));
  92
  93     painter.save();
  94     painter.setBrush(Qt::NoBrush);
  95     painter.drawPath(arrow);
  96     painter.restore();
  97
  98     painter.save();
  99     painter.translate(x2, y2);
 100
 101     painter.rotate(-90);
 102     painter.rotate(-end_angle);
 103     painter.rotate(180);
 104
 105     QPolygon arrowhead(4);
 106     arrowhead.setPoint(0, 0, 0);
 107     arrowhead.setPoint(1, arrowhead_length/3, -arrowhead_length*5/4);
 108     arrowhead.setPoint(2, 0, -arrowhead_length);
 109     arrowhead.setPoint(3, -arrowhead_length/3, -arrowhead_length*5/4);
 110
 111     painter.drawPolygon(arrowhead);
 112
 113     painter.restore();
 114
 115 }
 116
 117
 118 void Arrow_widget::paintEvent(QPaintEvent*)
 119 {
 120     QPainter p(this);
 121
 122     p.setRenderHint(QPainter::Antialiasing);
 123
 124     int base_x = 550;
 125     int base_y = 200;
 126
 127     if (color_ == 0)
 128         p.setBrush(Qt::black);
 129     else if (color_ == 1)
 130         p.setBrush(Qt::green);
 131     else if (color_ == 2)
 132         p.setBrush(Qt::yellow);
 133     else
 134         p.setBrush(Qt::black);
 135
 136     for (int x_step = 0; x_step < 6; ++x_step)
 137     {
 138         for (int y_step = 1; y_step <= 3; ++y_step)
 139         {
 140             draw_arrow(base_x, base_y, base_x+x_step*100,
 141                        base_y - y_step*50, p);
 142
 143             draw_arrow(base_x, base_y, base_x+x_step*100,
 144                        base_y + y_step*50, p);
 145
 146             draw_arrow(base_x, base_y, base_x-x_step*100,
 147                        base_y + y_step*50, p);
 148
 149             draw_arrow(base_x, base_y, base_x-x_step*100,
 150                        base_y - y_step*50, p);
 151         }
 152     }
 153
 154     draw_arrow(50, 400, 1000, 450, p);
 155     draw_arrow(1000, 400, 50, 450, p);
 156
 157 }
 158