1// Copyright (C) 2016 The Qt Company Ltd.
2// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
3
4#include "qlayout.h"
5
6#include "qapplication.h"
7#include "qlayoutengine_p.h"
8#if QT_CONFIG(menubar)
9#include "qmenubar.h"
10#endif
11#if QT_CONFIG(toolbar)
12#include "qtoolbar.h"
13#endif
14#if QT_CONFIG(sizegrip)
15#include "qsizegrip.h"
16#endif
17#include "qevent.h"
18#include "qstyle.h"
19#include "qvariant.h"
20#include "qwidget_p.h"
21#include "qlayout_p.h"
22
23QT_BEGIN_NAMESPACE
24
25static int menuBarHeightForWidth(QWidget *menubar, int w)
26{
27 if (menubar && !menubar->isHidden() && !menubar->isWindow()) {
28 int result = menubar->heightForWidth(qMax(a: w, b: menubar->minimumWidth()));
29 if (result == -1)
30 result = menubar->sizeHint().height();
31 const int min = qSmartMinSize(w: menubar).height();
32 result = qBound(min, val: result, max: menubar->maximumSize().height());
33 if (result != -1)
34 return result;
35 }
36 return 0;
37}
38
39/*!
40 \class QLayout
41 \brief The QLayout class is the base class of geometry managers.
42
43 \ingroup geomanagement
44 \inmodule QtWidgets
45
46 This is an abstract base class inherited by the concrete classes
47 QBoxLayout, QGridLayout, QFormLayout, and QStackedLayout.
48
49 For users of QLayout subclasses or of QMainWindow there is seldom
50 any need to use the basic functions provided by QLayout, such as
51 setSizeConstraint() or setMenuBar(). See \l{Layout Management}
52 for more information.
53
54 To make your own layout manager, implement the functions
55 addItem(), sizeHint(), setGeometry(), itemAt() and takeAt(). You
56 should also implement minimumSize() to ensure your layout isn't
57 resized to zero size if there is too little space. To support
58 children whose heights depend on their widths, implement
59 hasHeightForWidth() and heightForWidth(). See the
60 \l{layouts/flowlayout}{Flow Layout} example for
61 more information about implementing custom layout managers.
62
63 Geometry management stops when the layout manager is deleted.
64
65 \sa QLayoutItem, {Layout Management}, {Basic Layouts Example},
66 {Flow Layout Example}
67*/
68
69
70/*!
71 Constructs a new top-level QLayout, with parent \a parent.
72
73 The layout is set directly as the top-level layout for
74 \a parent. There can be only one top-level layout for a
75 widget. It is returned by QWidget::layout().
76
77 If \a parent is \nullptr, then you must insert this layout
78 into another layout, or set it as a widget's layout using
79 QWidget::setLayout().
80
81 \sa QWidget::setLayout()
82*/
83QLayout::QLayout(QWidget *parent)
84 : QObject(*new QLayoutPrivate, parent)
85{
86 if (!parent)
87 return;
88 parent->setLayout(this);
89}
90
91/*! \internal
92 */
93QLayout::QLayout(QLayoutPrivate &dd, QLayout *lay, QWidget *w)
94 : QObject(dd, lay ? static_cast<QObject*>(lay) : static_cast<QObject*>(w))
95{
96 Q_D(QLayout);
97 if (lay) {
98 lay->addItem(this);
99 } else if (w) {
100 if (Q_UNLIKELY(w->layout())) {
101 qWarning(msg: "QLayout: Attempting to add QLayout \"%ls\" to %s \"%ls\", which"
102 " already has a layout",
103 qUtf16Printable(QObject::objectName()), w->metaObject()->className(),
104 qUtf16Printable(w->objectName()));
105 setParent(nullptr);
106 } else {
107 d->topLevel = true;
108 w->d_func()->layout = this;
109 QT_TRY {
110 invalidate();
111 } QT_CATCH(...) {
112 w->d_func()->layout = nullptr;
113 QT_RETHROW;
114 }
115 }
116 }
117}
118
119QLayoutPrivate::QLayoutPrivate()
120 : QObjectPrivate(), insideSpacing(-1), userLeftMargin(-1), userTopMargin(-1), userRightMargin(-1),
121 userBottomMargin(-1), topLevel(false), enabled(true), activated(true), autoNewChild(false),
122 constraint(QLayout::SetDefaultConstraint), menubar(nullptr)
123{
124}
125
126void QLayoutPrivate::getMargin(int *result, int userMargin, QStyle::PixelMetric pm) const
127{
128 if (!result)
129 return;
130
131 Q_Q(const QLayout);
132 if (userMargin >= 0) {
133 *result = userMargin;
134 } else if (!topLevel) {
135 *result = 0;
136 } else if (QWidget *pw = q->parentWidget()) {
137 *result = pw->style()->pixelMetric(metric: pm, option: nullptr, widget: pw);
138 } else {
139 *result = 0;
140 }
141}
142
143// Static item factory functions that allow for hooking things in Designer
144
145QLayoutPrivate::QWidgetItemFactoryMethod QLayoutPrivate::widgetItemFactoryMethod = nullptr;
146QLayoutPrivate::QSpacerItemFactoryMethod QLayoutPrivate::spacerItemFactoryMethod = nullptr;
147
148QWidgetItem *QLayoutPrivate::createWidgetItem(const QLayout *layout, QWidget *widget)
149{
150 if (widgetItemFactoryMethod)
151 if (QWidgetItem *wi = (*widgetItemFactoryMethod)(layout, widget))
152 return wi;
153 return new QWidgetItemV2(widget);
154}
155
156QSpacerItem *QLayoutPrivate::createSpacerItem(const QLayout *layout, int w, int h, QSizePolicy::Policy hPolicy, QSizePolicy::Policy vPolicy)
157{
158 if (spacerItemFactoryMethod)
159 if (QSpacerItem *si = (*spacerItemFactoryMethod)(layout, w, h, hPolicy, vPolicy))
160 return si;
161 return new QSpacerItem(w, h, hPolicy, vPolicy);
162}
163
164
165
166/*!
167 \fn void QLayout::addItem(QLayoutItem *item)
168
169 Implemented in subclasses to add an \a item. How it is added is
170 specific to each subclass.
171
172 This function is not usually called in application code. To add a widget
173 to a layout, use the addWidget() function; to add a child layout, use the
174 addLayout() function provided by the relevant QLayout subclass.
175
176 \b{Note:} The ownership of \a item is transferred to the layout, and it's
177 the layout's responsibility to delete it.
178
179 \sa addWidget(), QBoxLayout::addLayout(), QGridLayout::addLayout()
180*/
181
182/*!
183 Adds widget \a w to this layout in a manner specific to the
184 layout. This function uses addItem().
185*/
186void QLayout::addWidget(QWidget *w)
187{
188 addChildWidget(w);
189 addItem(QLayoutPrivate::createWidgetItem(layout: this, widget: w));
190}
191
192
193
194/*!
195 Sets the alignment for widget \a w to \a alignment and returns
196 true if \a w is found in this layout (not including child
197 layouts); otherwise returns \c false.
198*/
199bool QLayout::setAlignment(QWidget *w, Qt::Alignment alignment)
200{
201 int i = 0;
202 QLayoutItem *item = itemAt(index: i);
203 while (item) {
204 if (item->widget() == w) {
205 item->setAlignment(alignment);
206 invalidate();
207 return true;
208 }
209 ++i;
210 item = itemAt(index: i);
211 }
212 return false;
213}
214
215/*!
216 \overload
217
218 Sets the alignment for the layout \a l to \a alignment and
219 returns \c true if \a l is found in this layout (not including child
220 layouts); otherwise returns \c false.
221*/
222bool QLayout::setAlignment(QLayout *l, Qt::Alignment alignment)
223{
224 int i = 0;
225 QLayoutItem *item = itemAt(index: i);
226 while (item) {
227 if (item->layout() == l) {
228 item->setAlignment(alignment);
229 invalidate();
230 return true;
231 }
232 ++i;
233 item = itemAt(index: i);
234 }
235 return false;
236}
237
238/*!
239 \property QLayout::spacing
240 \brief the spacing between widgets inside the layout
241
242 If no value is explicitly set, the layout's spacing is inherited
243 from the parent layout, or from the style settings for the parent
244 widget.
245
246 For QGridLayout and QFormLayout, it is possible to set different horizontal and
247 vertical spacings using \l{QGridLayout::}{setHorizontalSpacing()}
248 and \l{QGridLayout::}{setVerticalSpacing()}. In that case,
249 spacing() returns -1.
250
251 \sa contentsRect(), getContentsMargins(), QStyle::layoutSpacing(),
252 QStyle::pixelMetric()
253*/
254
255int QLayout::spacing() const
256{
257 Q_D(const QLayout);
258 if (d->insideSpacing >=0) {
259 return d->insideSpacing;
260 } else {
261 // arbitrarily prefer horizontal spacing to vertical spacing
262 return qSmartSpacing(layout: this, pm: QStyle::PM_LayoutHorizontalSpacing);
263 }
264}
265
266void QLayout::setSpacing(int spacing)
267{
268 Q_D(QLayout);
269 d->insideSpacing = spacing;
270 invalidate();
271}
272
273/*!
274 \since 4.3
275
276 Sets the \a left, \a top, \a right, and \a bottom margins to use
277 around the layout.
278
279 By default, QLayout uses the values provided by the style. On
280 most platforms, the margin is 11 pixels in all directions.
281
282 \sa getContentsMargins(), QStyle::pixelMetric(),
283 {QStyle::}{PM_LayoutLeftMargin},
284 {QStyle::}{PM_LayoutTopMargin},
285 {QStyle::}{PM_LayoutRightMargin},
286 {QStyle::}{PM_LayoutBottomMargin}
287*/
288void QLayout::setContentsMargins(int left, int top, int right, int bottom)
289{
290 Q_D(QLayout);
291
292 if (d->userLeftMargin == left && d->userTopMargin == top &&
293 d->userRightMargin == right && d->userBottomMargin == bottom)
294 return;
295
296 d->userLeftMargin = left;
297 d->userTopMargin = top;
298 d->userRightMargin = right;
299 d->userBottomMargin = bottom;
300 invalidate();
301}
302
303/*!
304 \since 4.6
305
306 Sets the \a margins to use around the layout.
307
308 By default, QLayout uses the values provided by the style. On
309 most platforms, the margin is 11 pixels in all directions.
310
311 \sa contentsMargins()
312*/
313void QLayout::setContentsMargins(const QMargins &margins)
314{
315 setContentsMargins(left: margins.left(), top: margins.top(), right: margins.right(), bottom: margins.bottom());
316}
317
318/*!
319 \since 6.1
320
321 Unsets any user-defined margins around the layout. The layout will
322 use the default values provided by the style.
323
324 \sa setContentsMargins()
325*/
326void QLayout::unsetContentsMargins()
327{
328 setContentsMargins(left: -1, top: -1, right: -1, bottom: -1);
329}
330
331/*!
332 \since 4.3
333
334 For each of \a left, \a top, \a right and \a bottom that is not
335 \nullptr, stores the size of the margin named in the location the
336 pointer refers to.
337
338 By default, QLayout uses the values provided by the style. On
339 most platforms, the margin is 11 pixels in all directions.
340
341 \sa setContentsMargins(), QStyle::pixelMetric(),
342 {QStyle::}{PM_LayoutLeftMargin},
343 {QStyle::}{PM_LayoutTopMargin},
344 {QStyle::}{PM_LayoutRightMargin},
345 {QStyle::}{PM_LayoutBottomMargin}
346*/
347void QLayout::getContentsMargins(int *left, int *top, int *right, int *bottom) const
348{
349 Q_D(const QLayout);
350 d->getMargin(result: left, userMargin: d->userLeftMargin, pm: QStyle::PM_LayoutLeftMargin);
351 d->getMargin(result: top, userMargin: d->userTopMargin, pm: QStyle::PM_LayoutTopMargin);
352 d->getMargin(result: right, userMargin: d->userRightMargin, pm: QStyle::PM_LayoutRightMargin);
353 d->getMargin(result: bottom, userMargin: d->userBottomMargin, pm: QStyle::PM_LayoutBottomMargin);
354}
355
356/*!
357 \since 4.6
358
359 Returns the margins used around the layout.
360
361 By default, QLayout uses the values provided by the style. On
362 most platforms, the margin is 11 pixels in all directions.
363
364 \sa setContentsMargins()
365*/
366QMargins QLayout::contentsMargins() const
367{
368 int left, top, right, bottom;
369 getContentsMargins(left: &left, top: &top, right: &right, bottom: &bottom);
370 return QMargins(left, top, right, bottom);
371}
372
373/*!
374 \since 4.3
375
376 Returns the layout's geometry() rectangle, but taking into account the
377 contents margins.
378
379 \sa setContentsMargins(), getContentsMargins()
380*/
381QRect QLayout::contentsRect() const
382{
383 Q_D(const QLayout);
384 int left, top, right, bottom;
385 getContentsMargins(left: &left, top: &top, right: &right, bottom: &bottom);
386 return d->rect.adjusted(xp1: +left, yp1: +top, xp2: -right, yp2: -bottom);
387}
388
389
390/*!
391 Returns the parent widget of this layout, or \nullptr if this
392 layout is not installed on any widget.
393
394 If the layout is a sub-layout, this function returns the parent
395 widget of the parent layout.
396
397 \sa parent()
398*/
399QWidget *QLayout::parentWidget() const
400{
401 Q_D(const QLayout);
402 if (!d->topLevel) {
403 if (parent()) {
404 QLayout *parentLayout = qobject_cast<QLayout*>(object: parent());
405 if (Q_UNLIKELY(!parentLayout)) {
406 qWarning(msg: "QLayout::parentWidget: A layout can only have another layout as a parent.");
407 return nullptr;
408 }
409 return parentLayout->parentWidget();
410 } else {
411 return nullptr;
412 }
413 } else {
414 Q_ASSERT(parent() && parent()->isWidgetType());
415 return static_cast<QWidget *>(parent());
416 }
417}
418
419/*!
420 \reimp
421*/
422bool QLayout::isEmpty() const
423{
424 int i = 0;
425 QLayoutItem *item = itemAt(index: i);
426 while (item) {
427 if (!item->isEmpty())
428 return false;
429 ++i;
430 item = itemAt(index: i);
431 }
432 return true;
433}
434
435/*!
436 \reimp
437*/
438QSizePolicy::ControlTypes QLayout::controlTypes() const
439{
440 if (count() == 0)
441 return QSizePolicy::DefaultType;
442 QSizePolicy::ControlTypes types;
443 for (int i = count() - 1; i >= 0; --i)
444 types |= itemAt(index: i)->controlTypes();
445 return types;
446}
447
448/*!
449 \reimp
450*/
451void QLayout::setGeometry(const QRect &r)
452{
453 Q_D(QLayout);
454 d->rect = r;
455}
456
457/*!
458 \reimp
459*/
460QRect QLayout::geometry() const
461{
462 Q_D(const QLayout);
463 return d->rect;
464}
465
466/*!
467 \reimp
468*/
469void QLayout::invalidate()
470{
471 Q_D(QLayout);
472 d->rect = QRect();
473 update();
474}
475
476static bool removeWidgetRecursively(QLayoutItem *li, QObject *w)
477{
478 QLayout *lay = li->layout();
479 if (!lay)
480 return false;
481 int i = 0;
482 QLayoutItem *child;
483 while ((child = lay->itemAt(index: i))) {
484 if (child->widget() == w) {
485 delete lay->takeAt(index: i);
486 lay->invalidate();
487 return true;
488 } else if (removeWidgetRecursively(li: child, w)) {
489 return true;
490 } else {
491 ++i;
492 }
493 }
494 return false;
495}
496
497
498void QLayoutPrivate::doResize()
499{
500 Q_Q(QLayout);
501 QWidget *mw = q->parentWidget();
502 QRect rect = mw->testAttribute(attribute: Qt::WA_LayoutOnEntireRect) ? mw->rect() : mw->contentsRect();
503 const int mbh = menuBarHeightForWidth(menubar, w: rect.width());
504 const int mbTop = rect.top();
505 rect.setTop(mbTop + mbh);
506 q->setGeometry(rect);
507#if QT_CONFIG(menubar)
508 if (menubar)
509 menubar->setGeometry(ax: rect.left(), ay: mbTop, aw: rect.width(), ah: mbh);
510#endif
511}
512
513
514/*!
515 \internal
516 Performs child widget layout when the parent widget is
517 resized. Also handles removal of widgets. \a e is the
518 event
519*/
520void QLayout::widgetEvent(QEvent *e)
521{
522 Q_D(QLayout);
523 const QEvent::Type type = e->type();
524 if (!d->enabled && type != QEvent::ChildRemoved)
525 return;
526
527 switch (type) {
528 case QEvent::Resize:
529 if (d->activated)
530 d->doResize();
531 else
532 activate();
533 break;
534 case QEvent::ChildRemoved:
535 {
536 QChildEvent *c = (QChildEvent *)e;
537 QObject *child = c->child();
538 QObjectPrivate *op = QObjectPrivate::get(o: child);
539 if (op->wasWidget) {
540#if QT_CONFIG(menubar)
541 if (child == d->menubar)
542 d->menubar = nullptr;
543#endif
544 removeWidgetRecursively(li: this, w: child);
545 }
546 }
547 break;
548 case QEvent::LayoutRequest:
549 if (static_cast<QWidget *>(parent())->isVisible())
550 activate();
551 break;
552 default:
553 break;
554 }
555}
556
557/*!
558 \reimp
559*/
560void QLayout::childEvent(QChildEvent *e)
561{
562 Q_D(QLayout);
563 if (!d->enabled)
564 return;
565
566 if (e->type() != QEvent::ChildRemoved)
567 return;
568
569 if (QLayout *childLayout = qobject_cast<QLayout *>(object: e->child()))
570 removeItem(childLayout);
571}
572
573/*!
574 \internal
575 Also takes contentsMargins and menu bar into account.
576*/
577int QLayout::totalMinimumHeightForWidth(int w) const
578{
579 Q_D(const QLayout);
580 int side=0, top=0;
581 if (d->topLevel) {
582 QWidget *parent = parentWidget();
583 parent->ensurePolished();
584 QWidgetPrivate *wd = parent->d_func();
585 side += wd->leftmargin + wd->rightmargin;
586 top += wd->topmargin + wd->bottommargin;
587 }
588 int h = minimumHeightForWidth(w - side) + top;
589#if QT_CONFIG(menubar)
590 h += menuBarHeightForWidth(menubar: d->menubar, w);
591#endif
592 return h;
593}
594
595/*!
596 \internal
597 Also takes contentsMargins and menu bar into account.
598*/
599int QLayout::totalHeightForWidth(int w) const
600{
601 Q_D(const QLayout);
602 int side=0, top=0;
603 if (d->topLevel) {
604 QWidget *parent = parentWidget();
605 parent->ensurePolished();
606 QWidgetPrivate *wd = parent->d_func();
607 side += wd->leftmargin + wd->rightmargin;
608 top += wd->topmargin + wd->bottommargin;
609 }
610 int h = heightForWidth(w - side) + top;
611#if QT_CONFIG(menubar)
612 h += menuBarHeightForWidth(menubar: d->menubar, w);
613#endif
614 return h;
615}
616
617/*!
618 \internal
619 Also takes contentsMargins and menu bar into account.
620*/
621QSize QLayout::totalMinimumSize() const
622{
623 Q_D(const QLayout);
624 int side=0, top=0;
625 if (d->topLevel) {
626 QWidget *pw = parentWidget();
627 pw->ensurePolished();
628 QWidgetPrivate *wd = pw->d_func();
629 side += wd->leftmargin + wd->rightmargin;
630 top += wd->topmargin + wd->bottommargin;
631 }
632
633 QSize s = minimumSize();
634#if QT_CONFIG(menubar)
635 top += menuBarHeightForWidth(menubar: d->menubar, w: s.width() + side);
636#endif
637 return s + QSize(side, top);
638}
639
640/*!
641 \internal
642 Also takes contentsMargins and menu bar into account.
643*/
644QSize QLayout::totalSizeHint() const
645{
646 Q_D(const QLayout);
647 int side=0, top=0;
648 if (d->topLevel) {
649 QWidget *pw = parentWidget();
650 pw->ensurePolished();
651 QWidgetPrivate *wd = pw->d_func();
652 side += wd->leftmargin + wd->rightmargin;
653 top += wd->topmargin + wd->bottommargin;
654 }
655
656 QSize s = sizeHint();
657 if (hasHeightForWidth())
658 s.setHeight(heightForWidth(s.width() + side));
659#if QT_CONFIG(menubar)
660 top += menuBarHeightForWidth(menubar: d->menubar, w: s.width());
661#endif
662 return s + QSize(side, top);
663}
664
665/*!
666 \internal
667 Also takes contentsMargins and menu bar into account.
668*/
669QSize QLayout::totalMaximumSize() const
670{
671 Q_D(const QLayout);
672 int side=0, top=0;
673 if (d->topLevel) {
674 QWidget *pw = parentWidget();
675 pw->ensurePolished();
676 QWidgetPrivate *wd = pw->d_func();
677 side += wd->leftmargin + wd->rightmargin;
678 top += wd->topmargin + wd->bottommargin;
679 }
680
681 QSize s = maximumSize();
682#if QT_CONFIG(menubar)
683 top += menuBarHeightForWidth(menubar: d->menubar, w: s.width());
684#endif
685
686 if (d->topLevel)
687 s = QSize(qMin(a: s.width() + side, b: QLAYOUTSIZE_MAX),
688 qMin(a: s.height() + top, b: QLAYOUTSIZE_MAX));
689 return s;
690}
691
692/*!
693 \internal
694 Destroys the layout, deleting all child layouts.
695 Geometry management stops when a top-level layout is deleted.
696
697 The layout classes will probably be fatally confused if you delete
698 a sublayout.
699*/
700QLayout::~QLayout()
701{
702 Q_D(QLayout);
703 if (d->topLevel && parent() && parent()->isWidgetType() && parentWidget()->layout() == this)
704 parentWidget()->d_func()->layout = nullptr;
705 else if (QLayout *parentLayout = qobject_cast<QLayout *>(object: parent()))
706 parentLayout->removeItem(this);
707}
708
709
710/*!
711 This function is called from \c addLayout() or \c insertLayout() functions in
712 subclasses to add layout \a childLayout as a sub-layout.
713
714 The only scenario in which you need to call it directly is if you
715 implement a custom layout that supports nested layouts.
716
717 \sa QBoxLayout::addLayout(), QBoxLayout::insertLayout(), QGridLayout::addLayout()
718*/
719void QLayout::addChildLayout(QLayout *childLayout)
720{
721 if (Q_UNLIKELY(childLayout->parent())) {
722 qWarning(msg: "QLayout::addChildLayout: layout %s \"%ls\" already has a parent",
723 childLayout->metaObject()->className(), qUtf16Printable(childLayout->objectName()));
724 return;
725 }
726 childLayout->setParent(this);
727
728 if (QWidget *mw = parentWidget()) {
729 childLayout->d_func()->reparentChildWidgets(mw);
730 }
731
732}
733
734/*!
735 \internal
736 */
737bool QLayout::adoptLayout(QLayout *layout)
738{
739 const bool ok = !layout->parent();
740 addChildLayout(childLayout: layout);
741 return ok;
742}
743
744#ifdef QT_DEBUG
745static bool layoutDebug()
746{
747 static int checked_env = -1;
748 if (checked_env == -1)
749 checked_env = !!qEnvironmentVariableIntValue(varName: "QT_LAYOUT_DEBUG");
750
751 return checked_env;
752}
753#endif
754
755void QLayoutPrivate::reparentChildWidgets(QWidget *mw)
756{
757 Q_Q(QLayout);
758 int n = q->count();
759
760#if QT_CONFIG(menubar)
761 if (menubar && menubar->parentWidget() != mw) {
762 menubar->setParent(mw);
763 }
764#endif
765 bool mwVisible = mw && mw->isVisible();
766 for (int i = 0; i < n; ++i) {
767 QLayoutItem *item = q->itemAt(index: i);
768 if (QWidget *w = item->widget()) {
769 QWidget *pw = w->parentWidget();
770#ifdef QT_DEBUG
771 if (Q_UNLIKELY(pw && pw != mw && layoutDebug())) {
772 qWarning(msg: "QLayout::addChildLayout: widget %s \"%ls\" in wrong parent; moved to correct parent",
773 w->metaObject()->className(), qUtf16Printable(w->objectName()));
774 }
775#endif
776 bool needShow = mwVisible && !QWidgetPrivate::get(w)->isExplicitlyHidden();
777 if (pw != mw)
778 w->setParent(mw);
779 if (needShow)
780 QMetaObject::invokeMethod(obj: w, member: "_q_showIfNotHidden", c: Qt::QueuedConnection); //show later
781 } else if (QLayout *l = item->layout()) {
782 l->d_func()->reparentChildWidgets(mw);
783 }
784 }
785}
786
787/*!
788 Returns \c true if the \a widget can be added to the \a layout;
789 otherwise returns \c false.
790*/
791bool QLayoutPrivate::checkWidget(QWidget *widget) const
792{
793 Q_Q(const QLayout);
794 if (Q_UNLIKELY(!widget)) {
795 qWarning(msg: "QLayout: Cannot add a null widget to %s/%ls", q->metaObject()->className(),
796 qUtf16Printable(q->objectName()));
797 return false;
798 }
799 if (Q_UNLIKELY(widget == q->parentWidget())) {
800 qWarning(msg: "QLayout: Cannot add parent widget %s/%ls to its child layout %s/%ls",
801 widget->metaObject()->className(), qUtf16Printable(widget->objectName()),
802 q->metaObject()->className(), qUtf16Printable(q->objectName()));
803 return false;
804 }
805 return true;
806}
807
808/*!
809 Returns \c true if the \a otherLayout can be added to the \a layout;
810 otherwise returns \c false.
811*/
812bool QLayoutPrivate::checkLayout(QLayout *otherLayout) const
813{
814 Q_Q(const QLayout);
815 if (Q_UNLIKELY(!otherLayout)) {
816 qWarning(msg: "QLayout: Cannot add a null layout to %s/%ls",
817 q->metaObject()->className(), qUtf16Printable(q->objectName()));
818 return false;
819 }
820 if (Q_UNLIKELY(otherLayout == q)) {
821 qWarning(msg: "QLayout: Cannot add layout %s/%ls to itself",
822 q->metaObject()->className(), qUtf16Printable(q->objectName()));
823 return false;
824 }
825 return true;
826}
827
828/*!
829 This function is called from \c addWidget() functions in
830 subclasses to add \a w as a managed widget of a layout.
831
832 If \a w is already managed by a layout, this function will produce
833 a warning, and remove \a w from that layout. This function must
834 therefore be called before adding \a w to the layout's data
835 structure.
836*/
837void QLayout::addChildWidget(QWidget *w)
838{
839 QWidget *mw = parentWidget();
840 QWidget *pw = w->parentWidget();
841
842 //Qt::WA_LaidOut is never reset. It only means that the widget at some point has
843 //been in a layout.
844 if (pw && w->testAttribute(attribute: Qt::WA_LaidOut)) {
845 QLayout *l = pw->layout();
846 if (l && removeWidgetRecursively(li: l, w)) {
847#ifdef QT_DEBUG
848 if (Q_UNLIKELY(layoutDebug()))
849 qWarning(msg: "QLayout::addChildWidget: %s \"%ls\" is already in a layout; moved to new layout",
850 w->metaObject()->className(), qUtf16Printable(w->objectName()));
851#endif
852 }
853 }
854 if (pw && mw && pw != mw) {
855#ifdef QT_DEBUG
856 if (Q_UNLIKELY(layoutDebug()))
857 qWarning(msg: "QLayout::addChildWidget: %s \"%ls\" in wrong parent; moved to correct parent",
858 w->metaObject()->className(), qUtf16Printable(w->objectName()));
859#endif
860 pw = nullptr;
861 }
862 bool needShow = mw && mw->isVisible() && !QWidgetPrivate::get(w)->isExplicitlyHidden();
863 if (!pw && mw)
864 w->setParent(mw);
865 w->setAttribute(Qt::WA_LaidOut);
866 if (needShow)
867 QMetaObject::invokeMethod(obj: w, member: "_q_showIfNotHidden", c: Qt::QueuedConnection); //show later
868}
869
870
871
872
873
874
875
876
877/*!
878 Tells the geometry manager to place the menu bar \a widget at the
879 top of parentWidget(), outside QWidget::contentsMargins(). All
880 child widgets are placed below the bottom edge of the menu bar.
881*/
882void QLayout::setMenuBar(QWidget *widget)
883{
884 Q_D(QLayout);
885 if (widget)
886 addChildWidget(w: widget);
887 d->menubar = widget;
888}
889
890/*!
891 Returns the menu bar set for this layout, or \nullptr if no
892 menu bar is set.
893*/
894
895QWidget *QLayout::menuBar() const
896{
897 Q_D(const QLayout);
898 return d->menubar;
899}
900
901
902/*!
903 Returns the minimum size of this layout. This is the smallest
904 size that the layout can have while still respecting the
905 specifications.
906
907 The returned value doesn't include the space required by
908 QWidget::setContentsMargins() or menuBar().
909
910 The default implementation allows unlimited resizing.
911*/
912QSize QLayout::minimumSize() const
913{
914 return QSize(0, 0);
915}
916
917/*!
918 Returns the maximum size of this layout. This is the largest size
919 that the layout can have while still respecting the
920 specifications.
921
922 The returned value doesn't include the space required by
923 QWidget::setContentsMargins() or menuBar().
924
925 The default implementation allows unlimited resizing.
926*/
927QSize QLayout::maximumSize() const
928{
929 return QSize(QLAYOUTSIZE_MAX, QLAYOUTSIZE_MAX);
930}
931
932/*!
933 Returns whether this layout can make use of more space than
934 sizeHint(). A value of Qt::Vertical or Qt::Horizontal means that
935 it wants to grow in only one dimension, whereas Qt::Vertical |
936 Qt::Horizontal means that it wants to grow in both dimensions.
937
938 The default implementation returns Qt::Horizontal | Qt::Vertical.
939 Subclasses reimplement it to return a meaningful value based on
940 their child widgets's \l{QSizePolicy}{size policies}.
941
942 \sa sizeHint()
943*/
944Qt::Orientations QLayout::expandingDirections() const
945{
946 return Qt::Horizontal | Qt::Vertical;
947}
948
949void QLayout::activateRecursiveHelper(QLayoutItem *item)
950{
951 item->invalidate();
952 QLayout *layout = item->layout();
953 if (layout) {
954 QLayoutItem *child;
955 int i=0;
956 while ((child = layout->itemAt(index: i++)))
957 activateRecursiveHelper(item: child);
958 layout->d_func()->activated = true;
959 }
960}
961
962/*!
963 Updates the layout for parentWidget().
964
965 You should generally not need to call this because it is
966 automatically called at the most appropriate times.
967
968 \sa activate(), invalidate()
969*/
970
971void QLayout::update()
972{
973 QLayout *layout = this;
974 while (layout && layout->d_func()->activated) {
975 layout->d_func()->activated = false;
976 if (layout->d_func()->topLevel) {
977 Q_ASSERT(layout->parent()->isWidgetType());
978 QWidget *mw = static_cast<QWidget*>(layout->parent());
979 QCoreApplication::postEvent(receiver: mw, event: new QEvent(QEvent::LayoutRequest));
980 break;
981 }
982 layout = static_cast<QLayout*>(layout->parent());
983 }
984}
985
986/*!
987 Redoes the layout for parentWidget() if necessary.
988
989 You should generally not need to call this because it is
990 automatically called at the most appropriate times. It returns
991 true if the layout was redone.
992
993 \sa update(), QWidget::updateGeometry()
994*/
995bool QLayout::activate()
996{
997 Q_D(QLayout);
998 if (!d->enabled || !parent())
999 return false;
1000 if (!d->topLevel)
1001 return static_cast<QLayout*>(parent())->activate();
1002 if (d->activated)
1003 return false;
1004 QWidget *mw = static_cast<QWidget*>(parent());
1005 if (Q_UNLIKELY(!mw)) {
1006 qWarning(msg: "QLayout::activate: %s \"%ls\" does not have a main widget",
1007 metaObject()->className(), qUtf16Printable(objectName()));
1008 return false;
1009 }
1010 activateRecursiveHelper(item: this);
1011
1012 QWidgetPrivate *md = mw->d_func();
1013 uint explMin = md->extra ? md->extra->explicitMinSize : 0;
1014 uint explMax = md->extra ? md->extra->explicitMaxSize : 0;
1015
1016 switch (d->constraint) {
1017 case SetFixedSize:
1018 // will trigger resize
1019 mw->setFixedSize(totalSizeHint());
1020 break;
1021 case SetMinimumSize:
1022 mw->setMinimumSize(totalMinimumSize());
1023 break;
1024 case SetMaximumSize:
1025 mw->setMaximumSize(totalMaximumSize());
1026 break;
1027 case SetMinAndMaxSize:
1028 mw->setMinimumSize(totalMinimumSize());
1029 mw->setMaximumSize(totalMaximumSize());
1030 break;
1031 case SetDefaultConstraint: {
1032 bool widthSet = explMin & Qt::Horizontal;
1033 bool heightSet = explMin & Qt::Vertical;
1034 if (mw->isWindow()) {
1035 QSize ms = totalMinimumSize();
1036 if (widthSet)
1037 ms.setWidth(mw->minimumSize().width());
1038 if (heightSet)
1039 ms.setHeight(mw->minimumSize().height());
1040 mw->setMinimumSize(ms);
1041 } else if (!widthSet || !heightSet) {
1042 QSize ms = mw->minimumSize();
1043 if (!widthSet)
1044 ms.setWidth(0);
1045 if (!heightSet)
1046 ms.setHeight(0);
1047 mw->setMinimumSize(ms);
1048 }
1049 break;
1050 }
1051 case SetNoConstraint:
1052 break;
1053 }
1054
1055 d->doResize();
1056
1057 if (md->extra) {
1058 md->extra->explicitMinSize = explMin;
1059 md->extra->explicitMaxSize = explMax;
1060 }
1061 // ideally only if sizeHint() or sizePolicy() has changed
1062 mw->updateGeometry();
1063 return true;
1064}
1065
1066/*!
1067 \since 5.2
1068
1069 Searches for widget \a from and replaces it with widget \a to if found.
1070 Returns the layout item that contains the widget \a from on success.
1071 Otherwise \nullptr is returned.
1072 If \a options contains \c Qt::FindChildrenRecursively (the default),
1073 sub-layouts are searched for doing the replacement.
1074 Any other flag in \a options is ignored.
1075
1076 Notice that the returned item therefore might not belong to this layout,
1077 but to a sub-layout.
1078
1079 The returned layout item is no longer owned by the layout and should be
1080 either deleted or inserted to another layout. The widget \a from is no
1081 longer managed by the layout and may need to be deleted or hidden. The
1082 parent of widget \a from is left unchanged.
1083
1084 This function works for the built-in Qt layouts, but might not work for
1085 custom layouts.
1086
1087 \sa indexOf()
1088*/
1089
1090QLayoutItem *QLayout::replaceWidget(QWidget *from, QWidget *to, Qt::FindChildOptions options)
1091{
1092 Q_D(QLayout);
1093 if (!from || !to)
1094 return nullptr;
1095 if (from == to) // Do not return a QLayoutItem for \a from, since ownership still
1096 return nullptr; // belongs to the layout (since nothing was changed)
1097
1098 int index = -1;
1099 QLayoutItem *item = nullptr;
1100 for (int u = 0; u < count(); ++u) {
1101 item = itemAt(index: u);
1102 if (!item)
1103 continue;
1104
1105 if (item->widget() == from) {
1106 index = u;
1107 break;
1108 }
1109
1110 if (item->layout() && (options & Qt::FindChildrenRecursively)) {
1111 QLayoutItem *r = item->layout()->replaceWidget(from, to, options);
1112 if (r)
1113 return r;
1114 }
1115 }
1116 if (index == -1)
1117 return nullptr;
1118
1119 addChildWidget(w: to);
1120 QLayoutItem *newitem = new QWidgetItem(to);
1121 newitem->setAlignment(item->alignment());
1122 QLayoutItem *r = d->replaceAt(index, newitem);
1123 if (!r)
1124 delete newitem;
1125 return r;
1126}
1127
1128/*!
1129 \fn QLayoutItem *QLayout::itemAt(int index) const
1130
1131 Must be implemented in subclasses to return the layout item at \a
1132 index. If there is no such item, the function must return \nullptr.
1133 Items are numbered consecutively from 0. If an item is deleted, other items will be renumbered.
1134
1135 This function can be used to iterate over a layout. The following
1136 code will draw a rectangle for each layout item in the layout structure of the widget.
1137
1138 \snippet code/src_gui_kernel_qlayout.cpp 0
1139
1140 \sa count(), takeAt()
1141*/
1142
1143/*!
1144 \fn QLayoutItem *QLayout::takeAt(int index)
1145
1146 Must be implemented in subclasses to remove the layout item at \a
1147 index from the layout, and return the item. If there is no such
1148 item, the function must do nothing and return 0. Items are numbered
1149 consecutively from 0. If an item is removed, other items will be
1150 renumbered.
1151
1152 The following code fragment shows a safe way to remove all items
1153 from a layout:
1154
1155 \snippet code/src_gui_kernel_qlayout.cpp 1
1156
1157 \sa itemAt(), count()
1158*/
1159
1160/*!
1161 \fn int *QLayout::count() const
1162
1163 Must be implemented in subclasses to return the number of items
1164 in the layout.
1165
1166 \sa itemAt()
1167*/
1168
1169/*!
1170 Searches for widget \a widget in this layout (not including child
1171 layouts).
1172
1173 Returns the index of \a widget, or -1 if \a widget is not found.
1174
1175 The default implementation iterates over all items using itemAt().
1176*/
1177int QLayout::indexOf(const QWidget *widget) const
1178{
1179 const int c = count();
1180
1181 for (int i = 0; i < c; ++i) {
1182 if (itemAt(index: i)->widget() == widget)
1183 return i;
1184 }
1185
1186 return -1;
1187}
1188
1189/*!
1190 \since 5.12
1191 Searches for layout item \a layoutItem in this layout (not including child
1192 layouts).
1193
1194 Returns the index of \a layoutItem, or -1 if \a layoutItem is not found.
1195*/
1196int QLayout::indexOf(const QLayoutItem *layoutItem) const
1197{
1198 const int c = count();
1199
1200 for (int i = 0; i < c; ++i) {
1201 if (itemAt(index: i) == layoutItem)
1202 return i;
1203 }
1204
1205 return -1;
1206}
1207
1208/*!
1209 \enum QLayout::SizeConstraint
1210
1211 The possible values are:
1212
1213 \value SetDefaultConstraint The main widget's minimum size is set
1214 to minimumSize(), unless the widget already has
1215 a minimum size.
1216
1217 \value SetFixedSize The main widget's size is set to sizeHint(); it
1218 cannot be resized at all.
1219 \value SetMinimumSize The main widget's minimum size is set to
1220 minimumSize(); it cannot be smaller.
1221
1222 \value SetMaximumSize The main widget's maximum size is set to
1223 maximumSize(); it cannot be larger.
1224
1225 \value SetMinAndMaxSize The main widget's minimum size is set to
1226 minimumSize() and its maximum size is set to
1227 maximumSize().
1228
1229 \value SetNoConstraint The widget is not constrained.
1230
1231 \sa setSizeConstraint()
1232*/
1233
1234/*!
1235 \property QLayout::sizeConstraint
1236 \brief the resize mode of the layout
1237
1238 The default mode is \l {QLayout::SetDefaultConstraint}
1239 {SetDefaultConstraint}.
1240*/
1241void QLayout::setSizeConstraint(SizeConstraint constraint)
1242{
1243 Q_D(QLayout);
1244 if (constraint == d->constraint)
1245 return;
1246
1247 d->constraint = constraint;
1248 invalidate();
1249}
1250
1251QLayout::SizeConstraint QLayout::sizeConstraint() const
1252{
1253 Q_D(const QLayout);
1254 return d->constraint;
1255}
1256
1257/*!
1258 Returns the rectangle that should be covered when the geometry of
1259 this layout is set to \a r, provided that this layout supports
1260 setAlignment().
1261
1262 The result is derived from sizeHint() and expandingDirections(). It is never
1263 larger than \a r.
1264*/
1265QRect QLayout::alignmentRect(const QRect &r) const
1266{
1267 QSize s = sizeHint();
1268 Qt::Alignment a = alignment();
1269
1270 /*
1271 This is a hack to obtain the real maximum size, not
1272 QSize(QLAYOUTSIZE_MAX, QLAYOUTSIZE_MAX), the value consistently
1273 returned by QLayoutItems that have an alignment.
1274 */
1275 QLayout *that = const_cast<QLayout *>(this);
1276 that->setAlignment({ });
1277 QSize ms = that->maximumSize();
1278 that->setAlignment(a);
1279
1280 if ((expandingDirections() & Qt::Horizontal) ||
1281 !(a & Qt::AlignHorizontal_Mask)) {
1282 s.setWidth(qMin(a: r.width(), b: ms.width()));
1283 }
1284 if ((expandingDirections() & Qt::Vertical) ||
1285 !(a & Qt::AlignVertical_Mask)) {
1286 s.setHeight(qMin(a: r.height(), b: ms.height()));
1287 } else if (hasHeightForWidth()) {
1288 int hfw = heightForWidth(s.width());
1289 if (hfw < s.height())
1290 s.setHeight(qMin(a: hfw, b: ms.height()));
1291 }
1292
1293 s = s.boundedTo(otherSize: r.size());
1294 int x = r.x();
1295 int y = r.y();
1296
1297 if (a & Qt::AlignBottom)
1298 y += (r.height() - s.height());
1299 else if (!(a & Qt::AlignTop))
1300 y += (r.height() - s.height()) / 2;
1301
1302 QWidget *parent = parentWidget();
1303 a = QStyle::visualAlignment(direction: parent ? parent->layoutDirection() : QGuiApplication::layoutDirection(), alignment: a);
1304 if (a & Qt::AlignRight)
1305 x += (r.width() - s.width());
1306 else if (!(a & Qt::AlignLeft))
1307 x += (r.width() - s.width()) / 2;
1308
1309 return QRect(x, y, s.width(), s.height());
1310}
1311
1312/*!
1313 Removes the widget \a widget from the layout. After this call, it
1314 is the caller's responsibility to give the widget a reasonable
1315 geometry or to put the widget back into a layout or to explicitly
1316 hide it if necessary.
1317
1318 \b{Note:} The ownership of \a widget remains the same as
1319 when it was added.
1320
1321 \sa removeItem(), QWidget::setGeometry(), addWidget()
1322*/
1323void QLayout::removeWidget(QWidget *widget)
1324{
1325 if (Q_UNLIKELY(!widget)) {
1326 qWarning(msg: "QLayout::removeWidget: Cannot remove a null widget.");
1327 return;
1328 }
1329
1330 int i = 0;
1331 QLayoutItem *child;
1332 while ((child = itemAt(index: i))) {
1333 if (child->widget() == widget) {
1334 delete takeAt(index: i);
1335 invalidate();
1336 } else {
1337 ++i;
1338 }
1339 }
1340}
1341
1342/*!
1343 Removes the layout item \a item from the layout. It is the
1344 caller's responsibility to delete the item.
1345
1346 Notice that \a item can be a layout (since QLayout inherits
1347 QLayoutItem).
1348
1349 \sa removeWidget(), addItem()
1350*/
1351void QLayout::removeItem(QLayoutItem *item)
1352{
1353 int i = 0;
1354 QLayoutItem *child;
1355 while ((child = itemAt(index: i))) {
1356 if (child == item) {
1357 takeAt(index: i);
1358 invalidate();
1359 } else {
1360 ++i;
1361 }
1362 }
1363}
1364
1365/*!
1366 Enables this layout if \a enable is true, otherwise disables it.
1367
1368 An enabled layout adjusts dynamically to changes; a disabled
1369 layout acts as if it did not exist.
1370
1371 By default all layouts are enabled.
1372
1373 \sa isEnabled()
1374*/
1375void QLayout::setEnabled(bool enable)
1376{
1377 Q_D(QLayout);
1378 d->enabled = enable;
1379}
1380
1381/*!
1382 Returns \c true if the layout is enabled; otherwise returns \c false.
1383
1384 \sa setEnabled()
1385*/
1386bool QLayout::isEnabled() const
1387{
1388 Q_D(const QLayout);
1389 return d->enabled;
1390}
1391
1392/*!
1393 Returns a size that satisfies all size constraints on \a widget,
1394 including heightForWidth() and that is as close as possible to \a
1395 size.
1396*/
1397
1398QSize QLayout::closestAcceptableSize(const QWidget *widget, const QSize &size)
1399{
1400 QSize result = size.boundedTo(otherSize: qSmartMaxSize(w: widget));
1401 result = result.expandedTo(otherSize: qSmartMinSize(w: widget));
1402 QLayout *l = widget->layout();
1403 if (l && l->hasHeightForWidth() && result.height() < l->minimumHeightForWidth(result.width()) ) {
1404 QSize current = widget->size();
1405 int currentHfw = l->minimumHeightForWidth(current.width());
1406 int newHfw = l->minimumHeightForWidth(result.width());
1407 if (current.height() < currentHfw || currentHfw == newHfw) {
1408 //handle the constant hfw case and the vertical-only case, as well as the
1409 // current-size-is-not-correct case
1410 result.setHeight(newHfw);
1411 } else {
1412 // binary search; assume hfw is decreasing ###
1413
1414 int maxw = qMax(a: widget->width(),b: result.width());
1415 int maxh = qMax(a: widget->height(), b: result.height());
1416 int minw = qMin(a: widget->width(),b: result.width());
1417 int minh = qMin(a: widget->height(), b: result.height());
1418
1419 int minhfw = l->minimumHeightForWidth(minw);
1420 int maxhfw = l->minimumHeightForWidth(maxw);
1421 while (minw < maxw) {
1422 if (minhfw > maxh) { //assume decreasing
1423 minw = maxw - (maxw-minw)/2;
1424 minhfw = l->minimumHeightForWidth(minw);
1425 } else if (maxhfw < minh ) { //assume decreasing
1426 maxw = minw + (maxw-minw)/2;
1427 maxhfw = l->minimumHeightForWidth(maxw);
1428 } else {
1429 break;
1430 }
1431 }
1432 result = result.expandedTo(otherSize: QSize(minw, minhfw));
1433 }
1434 }
1435 return result;
1436}
1437
1438QT_END_NAMESPACE
1439
1440#include "moc_qlayout.cpp"
1441

Provided by KDAB

Privacy Policy
Learn Advanced QML with KDAB
Find out more

source code of qtbase/src/widgets/kernel/qlayout.cpp