summaryrefslogtreecommitdiffstats
path: root/src/gui/graphicsview/qgraphicsanchorlayout.cpp
blob: e21cd999c706048f4e860b34cb64fcd4dc7980f8 (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
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtGui module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/

/*!
    \class QGraphicsAnchorLayout
    \brief The QGraphicsAnchorLayout class provides a layout where one can anchor widgets
    together in Graphics View.
    \since 4.6
    \ingroup appearance
    \ingroup geomanagement
    \ingroup graphicsview-api

    The anchor layout allows developers to specify how widgets should be placed relative to
    each other, and to the layout itself. The specification is made by adding anchors to the
    layout by calling addAnchor(), addAnchors() or addCornerAnchors().

    Existing anchors in the layout can be accessed with the anchor() function.
    Items that are anchored are automatically added to the layout, and if items
    are removed, all their anchors will be automatically removed.

    \beginfloatleft
    \inlineimage simpleanchorlayout-example.png Using an anchor layout to align simple colored widgets.
    \endfloat

    Anchors are always set up between edges of an item, where the "center" is also considered to
    be an edge. Consider the following example:

    \snippet examples/graphicsview/simpleanchorlayout/main.cpp adding anchors

    Here, the right edge of item \c a is anchored to the left edge of item \c b and the bottom
    edge of item \c a is anchored to the top edge of item \c b, with the result that
    item \c b will be placed diagonally to the right and below item \c b.

    The addCornerAnchors() function provides a simpler way of anchoring the corners
    of two widgets than the two individual calls to addAnchor() shown in the code
    above. Here, we see how a widget can be anchored to the top-left corner of the enclosing
    layout:

    \snippet examples/graphicsview/simpleanchorlayout/main.cpp adding a corner anchor

    In cases where anchors are used to match the widths or heights of widgets, it is
    convenient to use the addAnchors() function. As with the other functions for specifying
    anchors, it can also be used to anchor a widget to a layout.

    \clearfloat
    \section1 Size Hints and Size Policies in an Anchor Layout

    QGraphicsAnchorLayout respects each item's size hints and size policies. However it does
    not currently respect their stretch factors. This might change in the future, so avoid
    using stretch factors in anchor layouts if you want to avoid any future regressions in
    behavior.

    \section1 Spacing within an Anchor Layout

    The layout may distribute some space between the items. If the spacing has not been
    explicitly specified, the actual amount of space will usually be 0.

    However, if the first edge is the \e opposite of the second edge (e.g., the right edge
    of the first widget is anchored to the left edge of the second widget), the size of the
    anchor will be queried from the style through a pixel metric:
    \l{QStyle::}{PM_LayoutHorizontalSpacing} for horizontal anchors and
    \l{QStyle::}{PM_LayoutVerticalSpacing} for vertical anchors.

    If the spacing is negative, the items will overlap to some extent.

    \sa QGraphicsLinearLayout, QGraphicsGridLayout, QGraphicsLayout
*/

/*!
    \class QGraphicsAnchor
    \brief The QGraphicsAnchor class represents an anchor between two items in a
           QGraphicsAnchorLayout.
    \since 4.6
    \ingroup appearance
    \ingroup geomanagement
    \ingroup graphicsview-api

    The graphics anchor provides an API that enables you to query and manipulate the
    properties an anchor has. When an anchor is added to the layout with
    QGraphicsAnchorLayout::addAnchor(), a QGraphicsAnchor instance is returned where the properties
    are initialized to their default values. The properties can then be further changed, and they
    will be picked up the next time the layout is activated.

    \sa QGraphicsAnchorLayout::anchor()

*/
#include "qgraphicsanchorlayout_p.h"

QT_BEGIN_NAMESPACE

QGraphicsAnchor::QGraphicsAnchor(QGraphicsAnchorLayout *parentLayout)
    : QObject(*(new QGraphicsAnchorPrivate))
{
    Q_D(QGraphicsAnchor);
    Q_ASSERT(parentLayout);
    d->layoutPrivate = parentLayout->d_func();
}

/*!
    Removes the QGraphicsAnchor object from the layout and destroys it.
*/
QGraphicsAnchor::~QGraphicsAnchor()
{
}

/*!
    \property QGraphicsAnchor::sizePolicy
    \brief the size policy for the QGraphicsAnchor.

    By setting the size policy on an anchor you can configure how the item can resize itself
    from its preferred spacing. For instance, if the anchor has the size policy
    QSizePolicy::Minimum, the spacing is the minimum size of the anchor. However, its size
    can grow up to the anchors maximum size. If the default size policy is QSizePolicy::Fixed,
    the anchor can neither grow or shrink, which means that the only size the anchor can have
    is the spacing. QSizePolicy::Fixed is the default size policy.
    QGraphicsAnchor always has a minimum spacing of 0 and a very large maximum spacing.

    \sa QGraphicsAnchor::spacing
*/

void QGraphicsAnchor::setSizePolicy(QSizePolicy::Policy policy)
{
    Q_D(QGraphicsAnchor);
    d->setSizePolicy(policy);
}

QSizePolicy::Policy QGraphicsAnchor::sizePolicy() const
{
    Q_D(const QGraphicsAnchor);
    return d->sizePolicy;
}

/*!
    \property QGraphicsAnchor::spacing
    \brief the preferred space between items in the QGraphicsAnchorLayout.

    Depending on the anchor type, the default spacing is either
    0 or a value returned from the style.

    \sa QGraphicsAnchorLayout::addAnchor()
*/
void QGraphicsAnchor::setSpacing(qreal spacing)
{
    Q_D(QGraphicsAnchor);
    d->setSpacing(spacing);
}

qreal QGraphicsAnchor::spacing() const
{
    Q_D(const QGraphicsAnchor);
    return d->spacing();
}

void QGraphicsAnchor::unsetSpacing()
{
    Q_D(QGraphicsAnchor);
    d->unsetSpacing();
}

/*!
    Constructs a QGraphicsAnchorLayout instance.  \a parent is passed to
    QGraphicsLayout's constructor.
  */
QGraphicsAnchorLayout::QGraphicsAnchorLayout(QGraphicsLayoutItem *parent)
    : QGraphicsLayout(*new QGraphicsAnchorLayoutPrivate(), parent)
{
    Q_D(QGraphicsAnchorLayout);
    d->createLayoutEdges();
}

/*!
    Destroys the QGraphicsAnchorLayout object.
*/
QGraphicsAnchorLayout::~QGraphicsAnchorLayout()
{
    Q_D(QGraphicsAnchorLayout);

    for (int i = count() - 1; i >= 0; --i) {
        QGraphicsLayoutItem *item = d->items.at(i);
        removeAt(i);
        if (item) {
            if (item->ownedByLayout())
                delete item;
        }
    }

    d->removeCenterConstraints(this, QGraphicsAnchorLayoutPrivate::Horizontal);
    d->removeCenterConstraints(this, QGraphicsAnchorLayoutPrivate::Vertical);
    d->deleteLayoutEdges();

    Q_ASSERT(d->itemCenterConstraints[0].isEmpty());
    Q_ASSERT(d->itemCenterConstraints[1].isEmpty());
    Q_ASSERT(d->items.isEmpty());
    Q_ASSERT(d->m_vertexList.isEmpty());
}

/*!
    Creates an anchor between the edge \a firstEdge of item \a firstItem and the edge \a secondEdge
    of item \a secondItem. The magnitude of the anchor is picked up from the style. Anchors
    between a layout edge and an item edge will have a size of 0.
    If there is already an anchor between the edges, the the new anchor will replace the old one.

    \a firstItem and \a secondItem are automatically added to the layout if they are not part
    of the layout. This means that count() can increase by up to 2.

    The spacing an anchor will get depends on the type of anchor. For instance, anchors from the
    Right edge of one item to the Left edge of another (or vice versa) will use the default
    horizontal spacing. The same behaviour applies to Bottom to Top anchors, (but they will use
    the default vertical spacing). For all other anchor combinations, the spacing will be 0.
    All anchoring functions will follow this rule.

    The spacing can also be set manually by using QGraphicsAnchor::setSpacing() method.

    Calling this function where \a firstItem or \a secondItem are ancestors of the layout have
    undefined behaviour.

    \sa addAnchors(), addCornerAnchors()
 */
QGraphicsAnchor *
QGraphicsAnchorLayout::addAnchor(QGraphicsLayoutItem *firstItem, Qt::AnchorPoint firstEdge,
                                 QGraphicsLayoutItem *secondItem, Qt::AnchorPoint secondEdge)
{
    Q_D(QGraphicsAnchorLayout);
    QGraphicsAnchor *a = d->addAnchor(firstItem, firstEdge, secondItem, secondEdge);
    invalidate();
    return a;
}

/*!
    Returns the anchor between the anchor points defined by \a firstItem and \a firstEdge and
    \a secondItem and \a secondEdge. If there is no such anchor, the function will return 0.
*/
QGraphicsAnchor *
QGraphicsAnchorLayout::anchor(QGraphicsLayoutItem *firstItem, Qt::AnchorPoint firstEdge,
                              QGraphicsLayoutItem *secondItem, Qt::AnchorPoint secondEdge)
{
    Q_D(QGraphicsAnchorLayout);
    return d->getAnchor(firstItem, firstEdge, secondItem, secondEdge);
}

/*!
    Creates two anchors between \a firstItem and \a secondItem specified by the corners,
    \a firstCorner and \a secondCorner, where one is for the horizontal edge and another
    one for the vertical edge.

    This is a convenience function, since anchoring corners can be expressed as anchoring
    two edges. For instance:

    \snippet examples/graphicsview/simpleanchorlayout/main.cpp adding a corner anchor in two steps

    This can also be achieved with the following line of code:

    \snippet examples/graphicsview/simpleanchorlayout/main.cpp adding a corner anchor

    If there is already an anchor between the edge pairs, it will be replaced by the anchors that
    this function specifies.

    \a firstItem and \a secondItem are automatically added to the layout if they are not part of the
    layout. This means that count() can increase by up to 2.

    \sa addAnchor(), addAnchors()
*/
void QGraphicsAnchorLayout::addCornerAnchors(QGraphicsLayoutItem *firstItem,
                                             Qt::Corner firstCorner,
                                             QGraphicsLayoutItem *secondItem,
                                             Qt::Corner secondCorner)
{
    Q_D(QGraphicsAnchorLayout);

    // Horizontal anchor
    Qt::AnchorPoint firstEdge = (firstCorner & 1 ? Qt::AnchorRight: Qt::AnchorLeft);
    Qt::AnchorPoint secondEdge = (secondCorner & 1 ? Qt::AnchorRight: Qt::AnchorLeft);
    d->addAnchor(firstItem, firstEdge, secondItem, secondEdge);

    // Vertical anchor
    firstEdge = (firstCorner & 2 ? Qt::AnchorBottom: Qt::AnchorTop);
    secondEdge = (secondCorner & 2 ? Qt::AnchorBottom: Qt::AnchorTop);
    d->addAnchor(firstItem, firstEdge, secondItem, secondEdge);

    invalidate();
}

/*!
    Anchors two or four edges of \a firstItem with the corresponding
    edges of \a secondItem, so that \a firstItem has the same size as
    \a secondItem in the dimensions specified by \a orientations.

    For example, the following example anchors the left and right edges of two items
    to match their widths:

    \snippet examples/graphicsview/simpleanchorlayout/main.cpp adding anchors to match sizes in two steps

    This can also be achieved using the following line of code:

    \snippet examples/graphicsview/simpleanchorlayout/main.cpp adding anchors to match sizes

    \sa addAnchor(), addCornerAnchors()
*/
void QGraphicsAnchorLayout::addAnchors(QGraphicsLayoutItem *firstItem,
                                       QGraphicsLayoutItem *secondItem,
                                       Qt::Orientations orientations)
{
    if (orientations & Qt::Horizontal) {
        addAnchor(secondItem, Qt::AnchorLeft, firstItem, Qt::AnchorLeft);
        addAnchor(firstItem, Qt::AnchorRight, secondItem, Qt::AnchorRight);
    }
    if (orientations & Qt::Vertical) {
        addAnchor(secondItem, Qt::AnchorTop, firstItem, Qt::AnchorTop);
        addAnchor(firstItem, Qt::AnchorBottom, secondItem, Qt::AnchorBottom);
    }
}

/*!
    Sets the default horizontal spacing for the anchor layout to \a spacing.

    \sa horizontalSpacing(), setVerticalSpacing(), setSpacing()
*/
void QGraphicsAnchorLayout::setHorizontalSpacing(qreal spacing)
{
    Q_D(QGraphicsAnchorLayout);

    // ### We don't support negative spacing yet
    if (spacing < 0) {
        spacing = 0;
        qWarning() << "QGraphicsAnchorLayout does not support negative spacing.";
    }

    d->spacings[0] = spacing;
    invalidate();
}

/*!
    Sets the default vertical spacing for the anchor layout to \a spacing.

    \sa verticalSpacing(), setHorizontalSpacing(), setSpacing()
*/
void QGraphicsAnchorLayout::setVerticalSpacing(qreal spacing)
{
    Q_D(QGraphicsAnchorLayout);

    // ### We don't support negative spacing yet
    if (spacing < 0) {
        spacing = 0;
        qWarning() << "QGraphicsAnchorLayout does not support negative spacing.";
    }

    d->spacings[1] = spacing;
    invalidate();
}

/*!
    Sets the default horizontal and the default vertical spacing for the anchor layout to \a spacing.

    If an item is anchored with no spacing associated with the anchor, it will use the default
    spacing.

    Currently QGraphicsAnchorLayout does not support negative default spacings.

    \sa setHorizontalSpacing(), setVerticalSpacing()
*/
void QGraphicsAnchorLayout::setSpacing(qreal spacing)
{
    Q_D(QGraphicsAnchorLayout);

    // ### Currently we do not support negative anchors inside the graph.
    // To avoid those being created by a negative spacing, we must
    // make this test.
    if (spacing < 0) {
        spacing = 0;
        qWarning() << "QGraphicsAnchorLayout does not support negative spacing.";
    }

    d->spacings[0] = d->spacings[1] = spacing;
    invalidate();
}

/*!
    Returns the default horizontal spacing for the anchor layout.

    \sa verticalSpacing(), setHorizontalSpacing()
*/
qreal QGraphicsAnchorLayout::horizontalSpacing() const
{
    Q_D(const QGraphicsAnchorLayout);
    return d->effectiveSpacing(QGraphicsAnchorLayoutPrivate::Horizontal);
}

/*!
    Returns the default vertical spacing for the anchor layout.

    \sa horizontalSpacing(), setVerticalSpacing()
*/
qreal QGraphicsAnchorLayout::verticalSpacing() const
{
    Q_D(const QGraphicsAnchorLayout);
    return d->effectiveSpacing(QGraphicsAnchorLayoutPrivate::Vertical);
}

/*!
    \reimp
*/
void QGraphicsAnchorLayout::setGeometry(const QRectF &geom)
{
    Q_D(QGraphicsAnchorLayout);

    QGraphicsLayout::setGeometry(geom);
    d->calculateVertexPositions(QGraphicsAnchorLayoutPrivate::Horizontal);
    d->calculateVertexPositions(QGraphicsAnchorLayoutPrivate::Vertical);
    d->setItemsGeometries(geom);
}

/*!
    Removes the layout item at \a index without destroying it. Ownership of
    the item is transferred to the caller.

    Removing an item will also remove any of the anchors associated with it.

    \sa itemAt(), count()
*/
void QGraphicsAnchorLayout::removeAt(int index)
{
    Q_D(QGraphicsAnchorLayout);
    QGraphicsLayoutItem *item = d->items.value(index);

    if (!item)
        return;

    // Removing an item affects both horizontal and vertical graphs
    d->restoreSimplifiedGraph(QGraphicsAnchorLayoutPrivate::Horizontal);
    d->restoreSimplifiedGraph(QGraphicsAnchorLayoutPrivate::Vertical);

    d->removeCenterConstraints(item, QGraphicsAnchorLayoutPrivate::Horizontal);
    d->removeCenterConstraints(item, QGraphicsAnchorLayoutPrivate::Vertical);
    d->removeAnchors(item);
    d->items.remove(index);

    item->setParentLayoutItem(0);
    invalidate();
}

/*!
    \reimp
*/
int QGraphicsAnchorLayout::count() const
{
    Q_D(const QGraphicsAnchorLayout);
    return d->items.size();
}

/*!
    \reimp
*/
QGraphicsLayoutItem *QGraphicsAnchorLayout::itemAt(int index) const
{
    Q_D(const QGraphicsAnchorLayout);
    return d->items.value(index);
}

/*!
    \reimp
*/
void QGraphicsAnchorLayout::invalidate()
{
    Q_D(QGraphicsAnchorLayout);
    QGraphicsLayout::invalidate();
    d->calculateGraphCacheDirty = 1;
}

/*!
    \reimp
*/
QSizeF QGraphicsAnchorLayout::sizeHint(Qt::SizeHint which, const QSizeF &constraint) const
{
    Q_UNUSED(constraint);
    Q_D(const QGraphicsAnchorLayout);

    // Some setup calculations are delayed until the information is
    // actually needed, avoiding unnecessary recalculations when
    // adding multiple anchors.

    // sizeHint() / effectiveSizeHint() already have a cache
    // mechanism, using invalidate() to force recalculation. However
    // sizeHint() is called three times after invalidation (for max,
    // min and pref), but we just need do our setup once.

    const_cast<QGraphicsAnchorLayoutPrivate *>(d)->calculateGraphs();

    // ### apply constraint!
    QSizeF engineSizeHint(
        d->sizeHints[QGraphicsAnchorLayoutPrivate::Horizontal][which],
        d->sizeHints[QGraphicsAnchorLayoutPrivate::Vertical][which]);

    qreal left, top, right, bottom;
    getContentsMargins(&left, &top, &right, &bottom);

    return engineSizeHint + QSizeF(left + right, top + bottom);
}

QT_END_NAMESPACE