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
Arrow_widget(QWidget * parent)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
slotChangeColor()24 void Arrow_widget::slotChangeColor()
25 {
26 color_ = (color_ + 1) % 3;
27 update();
28 }
29
30 void
draw_arrow(int x1,int y1,int x2,int y2,QPainter & painter)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
paintEvent(QPaintEvent *)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
159