summaryrefslogtreecommitdiffstats
path: root/src/corelib/tools/qline.cpp
blob: bbedfa948e52252536e2681c3b3d349642c6f048 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
/****************************************************************************
**
** Copyright (C) 2020 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qline.h"

#include "qdebug.h"
#include "qdatastream.h"
#include "qmath.h"
#include <private/qnumeric_p.h>

QT_BEGIN_NAMESPACE

/*!
    \class QLine
    \inmodule QtCore
    \ingroup painting

    \brief The QLine class provides a two-dimensional vector using
    integer precision.

    A QLine describes a finite length line (or a line segment) on a
    two-dimensional surface. The start and end points of the line are
    specified using integer point accuracy for coordinates. Use the
    QLineF constructor to retrieve a floating point copy.

    \table
    \row
        \li \inlineimage qline-point.png
        \li \inlineimage qline-coordinates.png
    \endtable

    The positions of the line's start and end points can be retrieved
    using the p1(), x1(), y1(), p2(), x2(), and y2() functions. The
    dx() and dy() functions return the horizontal and vertical
    components of the line. Use isNull() to determine whether the
    QLine represents a valid line or a null line.

    Finally, the line can be translated a given offset using the
    translate() function.

    \sa QLineF, QPolygon, QRect
*/

/*!
    \fn QLine::QLine()

    Constructs a null line.
*/

/*!
    \fn QLine::QLine(const QPoint &p1, const QPoint &p2)

    Constructs a line object that represents the line between \a p1 and
    \a p2.
*/

/*!
    \fn QLine::QLine(int x1, int y1, int x2, int y2)

    Constructs a line object that represents the line between (\a x1, \a y1) and
    (\a x2, \a y2).
*/

/*!
    \fn bool QLine::isNull() const

    Returns \c true if the line does not have distinct start and end points;
    otherwise returns \c false.
*/

/*!
    \fn QPoint QLine::p1() const

    Returns the line's start point.

    \sa x1(), y1(), p2()
*/

/*!
    \fn QPoint QLine::p2() const

    Returns the line's end point.

    \sa x2(), y2(), p1()
*/

/*!
    \fn int QLine::x1() const

    Returns the x-coordinate of the line's start point.

    \sa p1()
*/

/*!
    \fn int QLine::y1() const

    Returns the y-coordinate of the line's start point.

    \sa p1()
*/

/*!
    \fn int QLine::x2() const

    Returns the x-coordinate of the line's end point.

    \sa p2()
*/

/*!
    \fn int QLine::y2() const

    Returns the y-coordinate of the line's end point.

    \sa p2()
*/

/*!
    \fn int QLine::dx() const

    Returns the horizontal component of the line's vector.

    \sa dy()
*/

/*!
    \fn int QLine::dy() const

    Returns the vertical component of the line's vector.

    \sa dx()
*/

/*!
    \fn bool QLine::operator!=(const QLine &line) const

    Returns \c true if the given \a line is not the same as \e this line.

    A line is different from another line if any of their start or
    end points differ, or the internal order of the points is different.
*/

/*!
    \fn bool QLine::operator==(const QLine &line) const

    Returns \c true if the given \a line is the same as \e this line.

    A line is identical to another line if the start and end points
    are identical, and the internal order of the points is the same.
*/

/*!
    \fn void QLine::translate(const QPoint &offset)

    Translates this line by the given \a offset.
*/

/*!
    \fn void QLine::translate(int dx, int dy)
    \overload

    Translates this line the distance specified by \a dx and \a dy.
*/

/*!
    \fn QLine QLine::translated(const QPoint &offset) const

    \since 4.4

    Returns this line translated by the given \a offset.
*/

/*!
    \fn QLine QLine::translated(int dx, int dy) const
    \overload
    \since 4.4

    Returns this line translated the distance specified by \a dx and \a dy.
*/

/*!
    \fn QPoint QLine::center() const

    \since 5.8

    Returns the center point of this line. This is equivalent to
    (p1() + p2()) / 2, except it will never overflow.
*/

/*!
    \fn void QLine::setP1(const QPoint &p1)
    \since 4.4

    Sets the starting point of this line to \a p1.

    \sa setP2(), p1()
*/


/*!
    \fn void QLine::setP2(const QPoint &p2)
    \since 4.4

    Sets the end point of this line to \a p2.

    \sa setP1(), p2()
*/


/*!
    \fn void QLine::setPoints(const QPoint &p1, const QPoint &p2)
    \since 4.4

    Sets the start point of this line to \a p1 and the end point of this line to \a p2.

    \sa setP1(), setP2(), p1(), p2()
*/


/*!
    \fn void QLine::setLine(int x1, int y1, int x2, int y2)
    \since 4.4

    Sets this line to the start in \a x1, \a y1 and end in \a x2, \a y2.

    \sa setP1(), setP2(), p1(), p2()
*/



#ifndef QT_NO_DEBUG_STREAM
QDebug operator<<(QDebug dbg, const QLine &p)
{
    QDebugStateSaver saver(dbg);
    dbg.nospace() << "QLine(" << p.p1() << ',' << p.p2() << ')';
    return dbg;
}
#endif

#ifndef QT_NO_DATASTREAM
/*!
    \relates QLine

    Writes the given \a line to the given \a stream and returns a
    reference to the stream.

    \sa {Serializing Qt Data Types}
*/

QDataStream &operator<<(QDataStream &stream, const QLine &line)
{
    stream << line.p1() << line.p2();
    return stream;
}

/*!
    \relates QLine

    Reads a line from the given \a stream into the given \a line and
    returns a reference to the stream.

    \sa {Serializing Qt Data Types}
*/

QDataStream &operator>>(QDataStream &stream, QLine &line)
{
    QPoint p1, p2;
    stream >> p1;
    stream >> p2;
    line = QLine(p1, p2);

    return stream;
}

#endif // QT_NO_DATASTREAM

/*!
    \class QLineF
    \inmodule QtCore
    \ingroup painting

    \brief The QLineF class provides a two-dimensional vector using
    floating point precision.

    A QLineF describes a finite length line (or line segment) on a
    two-dimensional surface. QLineF defines the start and end points
    of the line using floating point accuracy for coordinates.  Use
    the toLine() function to retrieve an integer-based copy of this
    line.

    \table
    \row
        \li \inlineimage qline-point.png
        \li \inlineimage qline-coordinates.png
    \endtable

    The positions of the line's start and end points can be retrieved
    using the p1(), x1(), y1(), p2(), x2(), and y2() functions. The
    dx() and dy() functions return the horizontal and vertical
    components of the line, respectively.

    The line's length can be retrieved using the length() function,
    and altered using the setLength() function.  Similarly, angle()
    and setAngle() are respectively used for retrieving and altering
    the angle of the line. Use the isNull()
    function to determine whether the QLineF represents a valid line
    or a null line.

    The intersects() function determines the IntersectionType for this
    line and a given line, while the angleTo() function returns the
    angle between the lines. In addition, the unitVector() function
    returns a line that has the same starting point as this line, but
    with a length of only 1, while the normalVector() function returns
    a line that is perpendicular to this line with the same starting
    point and length.

    Finally, the line can be translated a given offset using the
    translate() function, and can be traversed using the pointAt()
    function.

    \section1 Constraints

    QLine is limited to the minimum and maximum values for the
    \c int type. Operations on a QLine that could potentially result
    in values outside this range will result in undefined behavior.

    \sa QLine, QPolygonF, QRectF
*/

/*!
    \typealias QLineF::IntersectType
    \deprecated Use QLineF::IntersectionType instead.
*/

/*!
    \enum QLineF::IntersectionType

    Describes the intersection between two lines.

    \table
    \row
    \li \inlineimage qlinef-unbounded.png
    \li \inlineimage qlinef-bounded.png
    \row
    \li QLineF::UnboundedIntersection
    \li QLineF::BoundedIntersection
    \endtable

    \value NoIntersection Indicates that the lines do not intersect;
    i.e. they are parallel.

    \value UnboundedIntersection The two lines intersect, but not
    within the range defined by their lengths. This will be the case
    if the lines are not parallel. intersect() will also return this
    value if the intersect point is within the start and end point of
    only one of the lines.

    \value BoundedIntersection The two lines intersect with each other
    within the start and end points of each line.

    \sa intersects()
*/

/*!
    \fn QLineF::QLineF()

    Constructs a null line.
*/

/*!
    \fn QLineF::QLineF(const QPointF &p1, const QPointF &p2)

    Constructs a line object that represents the line between \a p1 and
    \a p2.
*/

/*!
    \fn QLineF::QLineF(qreal x1, qreal y1, qreal x2, qreal y2)

    Constructs a line object that represents the line between (\a x1, \a y1) and
    (\a x2, \a y2).
*/

/*!
    \fn QLineF::QLineF(const QLine &line)

    Construct a QLineF object from the given integer-based \a line.

    \sa toLine()
*/

/*!
    \fn bool QLineF::isNull() const

    Returns \c true if the line does not have distinct start and end points;
    otherwise returns \c false. The start and end points are considered distinct
    if qFuzzyCompare() can distinguish them in at least one coordinate.

    \note Due to the use of fuzzy comparison, isNull() may return \c true for
    lines whose length() is not zero.

    \sa qFuzzyCompare(), length()
*/

/*!
    \fn QPointF QLineF::p1() const

    Returns the line's start point.

    \sa x1(), y1(), p2()
*/

/*!
    \fn QPointF QLineF::p2() const

    Returns the line's end point.

    \sa x2(), y2(), p1()
*/

/*!
    \fn QLine QLineF::toLine() const

    Returns an integer-based copy of this line.

    Note that the returned line's start and end points are rounded to
    the nearest integer.

    \sa QLineF()
*/
/*!
    \fn qreal QLineF::x1() const

    Returns the x-coordinate of the line's start point.

    \sa p1()
*/

/*!
    \fn qreal QLineF::y1() const

    Returns the y-coordinate of the line's start point.

    \sa p1()
*/

/*!
    \fn qreal QLineF::x2() const

    Returns the x-coordinate of the line's end point.

    \sa p2()
*/

/*!
    \fn qreal QLineF::y2() const

    Returns the y-coordinate of the line's end point.

    \sa p2()
*/

/*!
    \fn qreal QLineF::dx() const

    Returns the horizontal component of the line's vector.

    \sa dy(), pointAt()
*/

/*!
    \fn qreal QLineF::dy() const

    Returns the vertical component of the line's vector.

    \sa dx(), pointAt()
*/

/*!
    \fn void QLineF::setLength(qreal length)

    Sets the length of the line to the given finite \a length. QLineF will move
    the end point - p2() - of the line to give the line its new length, unless
    length() was previously zero, in which case no scaling is attempted.

    \sa length(), unitVector()
*/

/*!
    \fn QLineF QLineF::normalVector() const

    Returns a line that is perpendicular to this line with the same starting
    point and length.

    \image qlinef-normalvector.png

    \sa unitVector()
*/

/*!
    \fn bool QLineF::operator!=(const QLineF &line) const

    Returns \c true if the given \a line is not the same as \e this line.

    A line is different from another line if their start or end points
    differ, or the internal order of the points is different.
*/

/*!
    \fn bool QLineF::operator==(const QLineF &line) const

    Returns \c true if the given \a line is the same as this line.

    A line is identical to another line if the start and end points
    are identical, and the internal order of the points is the same.
*/

/*!
  \fn qreal QLineF::pointAt(qreal t) const

  Returns the point at the position specified by finite parameter \a t. The
  function returns the line's start point if t = 0, and its end point if t = 1.

  \sa dx(), dy()
*/

/*!
    Returns the length of the line.

    \sa setLength(), isNull()
*/
qreal QLineF::length() const
{
    return qHypot(dx(), dy());
}

/*!
    \since 4.4

    Returns the angle of the line in degrees.

    The return value will be in the range of values from 0.0 up to but not
    including 360.0. The angles are measured counter-clockwise from a point
    on the x-axis to the right of the origin (x > 0).

    \sa setAngle()
*/
qreal QLineF::angle() const
{
    const qreal dx = pt2.x() - pt1.x();
    const qreal dy = pt2.y() - pt1.y();

    const qreal theta = qRadiansToDegrees(qAtan2(-dy, dx));

    const qreal theta_normalized = theta < 0 ? theta + 360 : theta;

    if (qFuzzyCompare(theta_normalized, qreal(360)))
        return qreal(0);
    else
        return theta_normalized;
}

/*!
    \since 4.4

    Sets the angle of the line to the given \a angle (in degrees).
    This will change the position of the second point of the line such that
    the line has the given angle.

    Positive values for the angles mean counter-clockwise while negative values
    mean the clockwise direction. Zero degrees is at the 3 o'clock position.

    \sa angle()
*/
void QLineF::setAngle(qreal angle)
{
    const qreal angleR = qDegreesToRadians(angle);
    const qreal l = length();

    const qreal dx = qCos(angleR) * l;
    const qreal dy = -qSin(angleR) * l;

    pt2.rx() = pt1.x() + dx;
    pt2.ry() = pt1.y() + dy;
}

/*!
    \since 4.4

    Returns a QLineF with the given \a length and \a angle.

    The first point of the line will be on the origin.

    Positive values for the angles mean counter-clockwise while negative values
    mean the clockwise direction. Zero degrees is at the 3 o'clock position.
*/
QLineF QLineF::fromPolar(qreal length, qreal angle)
{
    const qreal angleR = qDegreesToRadians(angle);
    return QLineF(0, 0, qCos(angleR) * length, -qSin(angleR) * length);
}

/*!
    Returns the unit vector for this line, i.e a line starting at the
    same point as \e this line with a length of 1.0, provided the line
    is non-null.

    \sa normalVector(), setLength()
*/
QLineF QLineF::unitVector() const
{
    const qreal x = dx();
    const qreal y = dy();

    const qreal len = qHypot(x, y);
    QLineF f(p1(), QPointF(pt1.x() + x / len, pt1.y() + y / len));

#ifndef QT_NO_DEBUG
    if (qAbs(f.length() - 1) >= 0.001)
        qWarning("QLine::unitVector: New line does not have unit length");
#endif

    return f;
}

/*!
    \fn QLineF::IntersectionType QLineF::intersects(const QLineF &line, QPointF *intersectionPoint) const
    \since 5.14

    Returns a value indicating whether or not \e this line intersects
    with the given \a line.

    The actual intersection point is extracted to \a intersectionPoint
    (if the pointer is valid). If the lines are parallel, the
    intersection point is undefined.
*/
QLineF::IntersectionType QLineF::intersects(const QLineF &l, QPointF *intersectionPoint) const
{
    // ipmlementation is based on Graphics Gems III's "Faster Line Segment Intersection"
    const QPointF a = pt2 - pt1;
    const QPointF b = l.pt1 - l.pt2;
    const QPointF c = pt1 - l.pt1;

    const qreal denominator = a.y() * b.x() - a.x() * b.y();
    if (denominator == 0 || !qt_is_finite(denominator))
        return NoIntersection;

    const qreal reciprocal = 1 / denominator;
    const qreal na = (b.y() * c.x() - b.x() * c.y()) * reciprocal;
    if (intersectionPoint)
        *intersectionPoint = pt1 + a * na;

    if (na < 0 || na > 1)
        return UnboundedIntersection;

    const qreal nb = (a.x() * c.y() - a.y() * c.x()) * reciprocal;
    if (nb < 0 || nb > 1)
        return UnboundedIntersection;

    return BoundedIntersection;
}

/*!
    \fn void QLineF::translate(const QPointF &offset)

    Translates this line by the given \a offset.
*/

/*!
    \fn void QLineF::translate(qreal dx, qreal dy)
    \overload

    Translates this line the distance specified by \a dx and \a dy.
*/

/*!
    \fn QLineF QLineF::translated(const QPointF &offset) const

    \since 4.4

    Returns this line translated by the given \a offset.
*/

/*!
    \fn QLineF QLineF::translated(qreal dx, qreal dy) const
    \overload
    \since 4.4

    Returns this line translated the distance specified by \a dx and \a dy.
*/

/*!
    \fn QPointF QLineF::center() const

    \since 5.8

    Returns the center point of this line. This is equivalent to
    0.5 * p1() + 0.5 * p2().
*/

/*!
    \fn void QLineF::setP1(const QPointF &p1)
    \since 4.4

    Sets the starting point of this line to \a p1.

    \sa setP2(), p1()
*/


/*!
    \fn void QLineF::setP2(const QPointF &p2)
    \since 4.4

    Sets the end point of this line to \a p2.

    \sa setP1(), p2()
*/


/*!
    \fn void QLineF::setPoints(const QPointF &p1, const QPointF &p2)
    \since 4.4

    Sets the start point of this line to \a p1 and the end point of this line to \a p2.

    \sa setP1(), setP2(), p1(), p2()
*/


/*!
    \fn void QLineF::setLine(qreal x1, qreal y1, qreal x2, qreal y2)
    \since 4.4

    Sets this line to the start in \a x1, \a y1 and end in \a x2, \a y2.

    \sa setP1(), setP2(), p1(), p2()
*/

/*!
  \fn qreal QLineF::angleTo(const QLineF &line) const

  \since 4.4

  Returns the angle (in degrees) from this line to the given \a
  line, taking the direction of the lines into account. If the lines
  do not \l{intersects()}{intersect} within their range, it is the
  intersection point of the extended lines that serves as origin (see
  QLineF::UnboundedIntersection).

  The returned value represents the number of degrees you need to add
  to this line to make it have the same angle as the given \a line,
  going counter-clockwise.

  \sa intersects()
*/
qreal QLineF::angleTo(const QLineF &l) const
{
    if (isNull() || l.isNull())
        return 0;

    const qreal a1 = angle();
    const qreal a2 = l.angle();

    const qreal delta = a2 - a1;
    const qreal delta_normalized = delta < 0 ? delta + 360 : delta;

    if (qFuzzyCompare(delta, qreal(360)))
        return 0;
    else
        return delta_normalized;
}

#ifndef QT_NO_DEBUG_STREAM
QDebug operator<<(QDebug dbg, const QLineF &p)
{
    QDebugStateSaver saver(dbg);
    dbg.nospace() << "QLineF(" << p.p1() << ',' << p.p2() << ')';
    return dbg;
}
#endif

#ifndef QT_NO_DATASTREAM
/*!
    \relates QLineF

    Writes the given \a line to the given \a stream and returns a
    reference to the stream.

    \sa {Serializing Qt Data Types}
*/

QDataStream &operator<<(QDataStream &stream, const QLineF &line)
{
    stream << line.p1() << line.p2();
    return stream;
}

/*!
    \relates QLineF

    Reads a line from the given \a stream into the given \a line and
    returns a reference to the stream.

    \sa {Serializing Qt Data Types}
*/

QDataStream &operator>>(QDataStream &stream, QLineF &line)
{
    QPointF start, end;
    stream >> start;
    stream >> end;
    line = QLineF(start, end);

    return stream;
}

#endif // QT_NO_DATASTREAM

QT_END_NAMESPACE