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 "qquickpositioners_p.h"
5	#include "qquickpositioners_p_p.h"
6
7	#include <QtQml/qqml.h>
8	#include <QtQml/qqmlinfo.h>
9	#include <QtCore/qcoreapplication.h>
10
11	#include <QtQuick/private/qquicktransition_p.h>
12
13	QT_BEGIN_NAMESPACE
14
15	static const QQuickItemPrivate::ChangeTypes watchedChanges
16	= QQuickItemPrivate::Geometry
17	| QQuickItemPrivate::SiblingOrder
18	| QQuickItemPrivate::Visibility
19	| QQuickItemPrivate::Destroyed;
20
21	void QQuickBasePositionerPrivate::watchChanges(QQuickItem *other)
22	{
23	QQuickItemPrivate *otherPrivate = QQuickItemPrivate::get(item: other);
24	otherPrivate->addItemChangeListener(listener: this, types: watchedChanges);
25	}
26
27	void QQuickBasePositionerPrivate::unwatchChanges(QQuickItem* other)
28	{
29	QQuickItemPrivate *otherPrivate = QQuickItemPrivate::get(item: other);
30	otherPrivate->removeItemChangeListener(this, types: watchedChanges);
31	}
32
33
34	QQuickBasePositioner::PositionedItem::PositionedItem(QQuickItem *i)
35	: item(i)
36	#if QT_CONFIG(quick_viewtransitions)
37	, transitionableItem(nullptr)
38	#endif
39	, index(-1)
40	, isNew(false)
41	, isVisible(true)
42	, topPadding(0)
43	, leftPadding(0)
44	, rightPadding(0)
45	, bottomPadding(0)
46	{
47	}
48
49	QQuickBasePositioner::PositionedItem::~PositionedItem()
50	{
51	#if QT_CONFIG(quick_viewtransitions)
52	delete transitionableItem;
53	#endif
54	}
55
56	qreal QQuickBasePositioner::PositionedItem::itemX() const
57	{
58	return
59	#if QT_CONFIG(quick_viewtransitions)
60	transitionableItem ? transitionableItem->itemX() :
61	#endif
62	item->x();
63	}
64
65	qreal QQuickBasePositioner::PositionedItem::itemY() const
66	{
67	return
68	#if QT_CONFIG(quick_viewtransitions)
69	transitionableItem ? transitionableItem->itemY() :
70	#endif
71	item->y();
72	}
73
74	void QQuickBasePositioner::PositionedItem::moveTo(const QPointF &pos)
75	{
76	#if QT_CONFIG(quick_viewtransitions)
77	if (transitionableItem)
78	transitionableItem->moveTo(pos);
79	else
80	#endif
81	item->setPosition(pos);
82	}
83
84	#if QT_CONFIG(quick_viewtransitions)
85	void QQuickBasePositioner::PositionedItem::transitionNextReposition(QQuickItemViewTransitioner *transitioner, QQuickItemViewTransitioner::TransitionType type, bool asTarget)
86	{
87	if (!transitioner)
88	return;
89	if (!transitionableItem)
90	transitionableItem = new QQuickItemViewTransitionableItem(item);
91	transitioner->transitionNextReposition(item: transitionableItem, type, isTarget: asTarget);
92	}
93
94	bool QQuickBasePositioner::PositionedItem::prepareTransition(QQuickItemViewTransitioner *transitioner, const QRectF &viewBounds)
95	{
96	return transitionableItem ? transitionableItem->prepareTransition(transitioner, index, viewBounds) : false;
97	}
98
99	void QQuickBasePositioner::PositionedItem::startTransition(QQuickItemViewTransitioner *transitioner)
100	{
101	if (transitionableItem)
102	transitionableItem->startTransition(transitioner, index);
103	}
104	#endif
105
106	void QQuickBasePositioner::PositionedItem::updatePadding(qreal lp, qreal tp, qreal rp, qreal bp)
107	{
108	leftPadding = lp;
109	topPadding = tp;
110	rightPadding = rp;
111	bottomPadding = bp;
112	}
113
114	QQuickBasePositioner::QQuickBasePositioner(PositionerType at, QQuickItem *parent)
115	: QQuickImplicitSizeItem(*(new QQuickBasePositionerPrivate), parent)
116	{
117	Q_D(QQuickBasePositioner);
118	d->init(at);
119	}
120	/*!
121	\internal
122	\class QQuickBasePositioner
123	\brief For specifying a base for QQuickGraphics layouts
124
125	To create a QQuickGraphics Positioner, simply subclass QQuickBasePositioner and implement
126	doLayout(), which is automatically called when the layout might need
127	updating. In doLayout() use the setX and setY functions from QQuickBasePositioner, and the
128	base class will apply the positions along with the appropriate transitions. The items to
129	position are provided in order as the protected member positionedItems.
130
131	You also need to set a PositionerType, to declare whether you are positioning the x, y or both
132	for the child items. Depending on the chosen type, only x or y changes will be applied.
133
134	Note that the subclass is responsible for adding the spacing in between items.
135
136	Positioning is batched and synchronized with painting to reduce the number of
137	calculations needed. This means that positioners may not reposition items immediately
138	when changes occur, but it will have moved by the next frame.
139	*/
140
141	QQuickBasePositioner::QQuickBasePositioner(QQuickBasePositionerPrivate &dd, PositionerType at, QQuickItem *parent)
142	: QQuickImplicitSizeItem(dd, parent)
143	{
144	Q_D(QQuickBasePositioner);
145	d->init(at);
146	}
147
148	QQuickBasePositioner::~QQuickBasePositioner()
149	{
150	Q_D(QQuickBasePositioner);
151	#if QT_CONFIG(quick_viewtransitions)
152	delete d->transitioner;
153	#endif
154	for (int i = 0; i < positionedItems.count(); ++i)
155	d->unwatchChanges(other: positionedItems.at(idx: i).item);
156	for (int i = 0; i < unpositionedItems.count(); ++i)
157	d->unwatchChanges(other: unpositionedItems.at(idx: i).item);
158	clearPositionedItems(items: &positionedItems);
159	clearPositionedItems(items: &unpositionedItems);
160	}
161
162	void QQuickBasePositioner::updatePolish()
163	{
164	Q_D(QQuickBasePositioner);
165	if (d->positioningDirty)
166	prePositioning();
167	}
168
169	qreal QQuickBasePositioner::spacing() const
170	{
171	Q_D(const QQuickBasePositioner);
172	return d->spacing;
173	}
174
175	void QQuickBasePositioner::setSpacing(qreal s)
176	{
177	Q_D(QQuickBasePositioner);
178	if (s == d->spacing)
179	return;
180	d->spacing = s;
181	d->setPositioningDirty();
182	emit spacingChanged();
183	}
184
185	#if QT_CONFIG(quick_viewtransitions)
186	QQuickTransition *QQuickBasePositioner::populate() const
187	{
188	Q_D(const QQuickBasePositioner);
189	return d->transitioner ? d->transitioner->populateTransition : nullptr;
190	}
191
192	void QQuickBasePositioner::setPopulate(QQuickTransition *transition)
193	{
194	Q_D(QQuickBasePositioner);
195	if (!d->transitioner)
196	d->transitioner = new QQuickItemViewTransitioner;
197	if (d->transitioner->populateTransition != transition) {
198	d->transitioner->populateTransition = transition;
199	emit populateChanged();
200	}
201	}
202
203	QQuickTransition *QQuickBasePositioner::move() const
204	{
205	Q_D(const QQuickBasePositioner);
206	return d->transitioner ? d->transitioner->displacedTransition : nullptr;
207	}
208
209	void QQuickBasePositioner::setMove(QQuickTransition *mt)
210	{
211	Q_D(QQuickBasePositioner);
212	if (!d->transitioner)
213	d->transitioner = new QQuickItemViewTransitioner;
214	if (mt == d->transitioner->displacedTransition)
215	return;
216
217	d->transitioner->displacedTransition = mt;
218	emit moveChanged();
219	}
220
221	QQuickTransition *QQuickBasePositioner::add() const
222	{
223	Q_D(const QQuickBasePositioner);
224	return d->transitioner ? d->transitioner->addTransition : nullptr;
225	}
226
227	void QQuickBasePositioner::setAdd(QQuickTransition *add)
228	{
229	Q_D(QQuickBasePositioner);
230	if (!d->transitioner)
231	d->transitioner = new QQuickItemViewTransitioner;
232	if (add == d->transitioner->addTransition)
233	return;
234
235	d->transitioner->addTransition = add;
236	emit addChanged();
237	}
238	#endif
239
240	void QQuickBasePositioner::componentComplete()
241	{
242	#if QT_CONFIG(quick_viewtransitions)
243	Q_D(QQuickBasePositioner);
244	#endif
245	QQuickItem::componentComplete();
246	#if QT_CONFIG(quick_viewtransitions)
247	if (d->transitioner)
248	d->transitioner->setPopulateTransitionEnabled(true);
249	#endif
250	positionedItems.reserve(count: childItems().size());
251	prePositioning();
252	#if QT_CONFIG(quick_viewtransitions)
253	if (d->transitioner)
254	d->transitioner->setPopulateTransitionEnabled(false);
255	#endif
256	}
257
258	void QQuickBasePositioner::itemChange(ItemChange change, const ItemChangeData &value)
259	{
260	Q_D(QQuickBasePositioner);
261	if (change == ItemChildAddedChange) {
262	d->setPositioningDirty();
263	} else if (change == ItemChildRemovedChange) {
264	QQuickItem *child = value.item;
265	QQuickBasePositioner::PositionedItem posItem(child);
266	int idx = positionedItems.find(v: posItem);
267	if (idx >= 0) {
268	d->unwatchChanges(other: child);
269	removePositionedItem(items: &positionedItems, index: idx);
270	} else if ((idx = unpositionedItems.find(v: posItem)) >= 0) {
271	d->unwatchChanges(other: child);
272	removePositionedItem(items: &unpositionedItems, index: idx);
273	}
274	d->setPositioningDirty();
275	}
276
277	QQuickItem::itemChange(change, value);
278	}
279
280	void QQuickBasePositioner::forceLayout()
281	{
282	updatePolish();
283	}
284
285	void QQuickBasePositioner::prePositioning()
286	{
287	Q_D(QQuickBasePositioner);
288	if (!isComponentComplete())
289	return;
290
291	if (d->doingPositioning)
292	return;
293
294	d->positioningDirty = false;
295	d->doingPositioning = true;
296	//Need to order children by creation order modified by stacking order
297	QList<QQuickItem *> children = childItems();
298
299	QPODVector<PositionedItem,8> oldItems;
300	positionedItems.copyAndClear(other&: oldItems);
301	for (int ii = 0; ii < unpositionedItems.count(); ii++)
302	oldItems.append(v: unpositionedItems[ii]);
303	unpositionedItems.clear();
304	#if QT_CONFIG(quick_viewtransitions)
305	int addedIndex = -1;
306	#endif
307
308	for (int ii = 0; ii < children.size(); ++ii) {
309	QQuickItem *child = children.at(i: ii);
310	if (QQuickItemPrivate::get(item: child)->isTransparentForPositioner())
311	continue;
312	QQuickItemPrivate *childPrivate = QQuickItemPrivate::get(item: child);
313	PositionedItem posItem(child);
314	int wIdx = oldItems.find(v: posItem);
315	if (wIdx < 0) {
316	d->watchChanges(other: child);
317	posItem.isNew = true;
318	if (!childPrivate->explicitVisible || !child->width() || !child->height()) {
319	posItem.isVisible = false;
320	posItem.index = -1;
321	unpositionedItems.append(v: posItem);
322	} else {
323	posItem.index = positionedItems.count();
324	positionedItems.append(v: posItem);
325
326	#if QT_CONFIG(quick_viewtransitions)
327	if (d->transitioner) {
328	if (addedIndex < 0)
329	addedIndex = posItem.index;
330	PositionedItem *theItem = &positionedItems[positionedItems.count()-1];
331	if (d->transitioner->canTransition(type: QQuickItemViewTransitioner::PopulateTransition, asTarget: true))
332	theItem->transitionNextReposition(transitioner: d->transitioner, type: QQuickItemViewTransitioner::PopulateTransition, asTarget: true);
333	else if (!d->transitioner->populateTransitionEnabled())
334	theItem->transitionNextReposition(transitioner: d->transitioner, type: QQuickItemViewTransitioner::AddTransition, asTarget: true);
335	}
336	#endif
337	}
338	} else {
339	PositionedItem *item = &oldItems[wIdx];
340	// Items are only omitted from positioning if they are explicitly hidden
341	// i.e. their positioning is not affected if an ancestor is hidden.
342	if (!childPrivate->explicitVisible || !child->width() || !child->height()) {
343	item->isVisible = false;
344	item->index = -1;
345	unpositionedItems.append(v: *item);
346	} else if (!item->isVisible) {
347	// item changed from non-visible to visible, treat it as a "new" item
348	item->isVisible = true;
349	item->isNew = true;
350	item->index = positionedItems.count();
351	positionedItems.append(v: *item);
352
353	#if QT_CONFIG(quick_viewtransitions)
354	if (d->transitioner) {
355	if (addedIndex < 0)
356	addedIndex = item->index;
357	positionedItems[positionedItems.count()-1].transitionNextReposition(transitioner: d->transitioner, type: QQuickItemViewTransitioner::AddTransition, asTarget: true);
358	}
359	#endif
360	} else {
361	item->isNew = false;
362	item->index = positionedItems.count();
363	positionedItems.append(v: *item);
364	}
365	}
366	}
367
368	#if QT_CONFIG(quick_viewtransitions)
369	if (d->transitioner) {
370	for (int i=0; i<positionedItems.count(); i++) {
371	if (!positionedItems[i].isNew) {
372	if (addedIndex >= 0) {
373	positionedItems[i].transitionNextReposition(transitioner: d->transitioner, type: QQuickItemViewTransitioner::AddTransition, asTarget: false);
374	} else {
375	// just queue the item for a move-type displace - if the item hasn't
376	// moved anywhere, it won't be transitioned anyway
377	positionedItems[i].transitionNextReposition(transitioner: d->transitioner, type: QQuickItemViewTransitioner::MoveTransition, asTarget: false);
378	}
379	}
380	}
381	}
382	#endif
383
384	QSizeF contentSize(0,0);
385	reportConflictingAnchors();
386	if (!d->anchorConflict) {
387	doPositioning(contentSize: &contentSize);
388	updateAttachedProperties();
389	}
390
391	#if QT_CONFIG(quick_viewtransitions)
392	if (d->transitioner) {
393	QRectF viewBounds(QPointF(), contentSize);
394	for (int i=0; i<positionedItems.count(); i++)
395	positionedItems[i].prepareTransition(transitioner: d->transitioner, viewBounds);
396	for (int i=0; i<positionedItems.count(); i++)
397	positionedItems[i].startTransition(transitioner: d->transitioner);
398	d->transitioner->resetTargetLists();
399	}
400	#endif
401
402	d->doingPositioning = false;
403
404	//Set implicit size to the size of its children
405	setImplicitSize(contentSize.width(), contentSize.height());
406
407	emit positioningComplete();
408	}
409
410	void QQuickBasePositioner::positionItem(qreal x, qreal y, PositionedItem *target)
411	{
412	if ( target->itemX() != x || target->itemY() != y )
413	target->moveTo(pos: QPointF(x, y));
414	}
415
416	void QQuickBasePositioner::positionItemX(qreal x, PositionedItem *target)
417	{
418	Q_D(QQuickBasePositioner);
419	if (target->itemX() != x
420	&& (d->type == Horizontal || d->type == Both)) {
421	target->moveTo(pos: QPointF(x, target->itemY()));
422	}
423	}
424
425	void QQuickBasePositioner::positionItemY(qreal y, PositionedItem *target)
426	{
427	Q_D(QQuickBasePositioner);
428	if (target->itemY() != y
429	&& (d->type == Vertical || d->type == Both)) {
430	target->moveTo(pos: QPointF(target->itemX(), y));
431	}
432	}
433
434	/*
435	Since PositionedItem values are stored by value, their internal transitionableItem pointers
436	must be cleaned up when a PositionedItem is removed from a QPODVector, otherwise the pointer
437	is never deleted since QPODVector doesn't invoke the destructor.
438	*/
439	void QQuickBasePositioner::removePositionedItem(QPODVector<PositionedItem,8> *items, int index)
440	{
441	Q_ASSERT(index >= 0 && index < items->count());
442	#if QT_CONFIG(quick_viewtransitions)
443	delete items->at(idx: index).transitionableItem;
444	#endif
445	items->remove(idx: index);
446	}
447	void QQuickBasePositioner::clearPositionedItems(QPODVector<PositionedItem,8> *items)
448	{
449	#if QT_CONFIG(quick_viewtransitions)
450	for (int i=0; i<items->count(); i++)
451	delete items->at(idx: i).transitionableItem;
452	#endif
453	items->clear();
454	}
455
456	QQuickPositionerAttached *QQuickBasePositioner::qmlAttachedProperties(QObject *obj)
457	{
458	return new QQuickPositionerAttached(obj);
459	}
460
461	void QQuickBasePositioner::updateAttachedProperties(QQuickPositionerAttached *specificProperty, QQuickItem *specificPropertyOwner) const
462	{
463	// If this function is deemed too expensive or shows up in profiles, it could
464	// be changed to run only when there are attached properties present. This
465	// could be a flag in the positioner that is set by the attached property
466	// constructor.
467	QQuickPositionerAttached *prevLastProperty = nullptr;
468	QQuickPositionerAttached *lastProperty = nullptr;
469
470	for (int ii = 0; ii < positionedItems.count(); ++ii) {
471	const PositionedItem &child = positionedItems.at(idx: ii);
472	if (!child.item)
473	continue;
474
475	QQuickPositionerAttached *property = nullptr;
476
477	if (specificProperty) {
478	if (specificPropertyOwner == child.item) {
479	property = specificProperty;
480	}
481	} else {
482	property = static_cast<QQuickPositionerAttached *>(qmlAttachedPropertiesObject<QQuickBasePositioner>(obj: child.item, create: false));
483	}
484
485	if (property) {
486	property->setIndex(ii);
487	property->setIsFirstItem(ii == 0);
488
489	if (property->isLastItem()) {
490	if (prevLastProperty)
491	prevLastProperty->setIsLastItem(false); // there can be only one last property
492	prevLastProperty = property;
493	}
494	}
495
496	lastProperty = property;
497	}
498
499	if (prevLastProperty && prevLastProperty != lastProperty)
500	prevLastProperty->setIsLastItem(false);
501	if (lastProperty)
502	lastProperty->setIsLastItem(true);
503
504	// clear attached properties for unpositioned items
505	for (int ii = 0; ii < unpositionedItems.count(); ++ii) {
506	const PositionedItem &child = unpositionedItems.at(idx: ii);
507	if (!child.item)
508	continue;
509
510	QQuickPositionerAttached *property = nullptr;
511
512	if (specificProperty) {
513	if (specificPropertyOwner == child.item) {
514	property = specificProperty;
515	}
516	} else {
517	property = static_cast<QQuickPositionerAttached *>(qmlAttachedPropertiesObject<QQuickBasePositioner>(obj: child.item, create: false));
518	}
519
520	if (property) {
521	property->setIndex(-1);
522	property->setIsFirstItem(false);
523	property->setIsLastItem(false);
524	}
525	}
526	}
527
528	qreal QQuickBasePositioner::padding() const
529	{
530	Q_D(const QQuickBasePositioner);
531	return d->padding();
532	}
533
534	void QQuickBasePositioner::setPadding(qreal padding)
535	{
536	Q_D(QQuickBasePositioner);
537	if (qFuzzyCompare(p1: d->padding(), p2: padding))
538	return;
539
540	d->extra.value().padding = padding;
541	d->setPositioningDirty();
542	emit paddingChanged();
543	if (!d->extra.isAllocated() || !d->extra->explicitTopPadding)
544	emit topPaddingChanged();
545	if (!d->extra.isAllocated() || !d->extra->explicitLeftPadding)
546	emit leftPaddingChanged();
547	if (!d->extra.isAllocated() || !d->extra->explicitRightPadding)
548	emit rightPaddingChanged();
549	if (!d->extra.isAllocated() || !d->extra->explicitBottomPadding)
550	emit bottomPaddingChanged();
551	}
552
553	void QQuickBasePositioner::resetPadding()
554	{
555	setPadding(0);
556	}
557
558	qreal QQuickBasePositioner::topPadding() const
559	{
560	Q_D(const QQuickBasePositioner);
561	if (d->extra.isAllocated() && d->extra->explicitTopPadding)
562	return d->extra->topPadding;
563	return d->padding();
564	}
565
566	void QQuickBasePositioner::setTopPadding(qreal padding)
567	{
568	Q_D(QQuickBasePositioner);
569	d->setTopPadding(value: padding);
570	}
571
572	void QQuickBasePositioner::resetTopPadding()
573	{
574	Q_D(QQuickBasePositioner);
575	d->setTopPadding(value: 0, reset: true);
576	}
577
578	qreal QQuickBasePositioner::leftPadding() const
579	{
580	Q_D(const QQuickBasePositioner);
581	if (d->extra.isAllocated() && d->extra->explicitLeftPadding)
582	return d->extra->leftPadding;
583	return d->padding();
584	}
585
586	void QQuickBasePositioner::setLeftPadding(qreal padding)
587	{
588	Q_D(QQuickBasePositioner);
589	d->setLeftPadding(value: padding);
590	}
591
592	void QQuickBasePositioner::resetLeftPadding()
593	{
594	Q_D(QQuickBasePositioner);
595	d->setLeftPadding(value: 0, reset: true);
596	}
597
598	qreal QQuickBasePositioner::rightPadding() const
599	{
600	Q_D(const QQuickBasePositioner);
601	if (d->extra.isAllocated() && d->extra->explicitRightPadding)
602	return d->extra->rightPadding;
603	return d->padding();
604	}
605
606	void QQuickBasePositioner::setRightPadding(qreal padding)
607	{
608	Q_D(QQuickBasePositioner);
609	d->setRightPadding(value: padding);
610	}
611
612	void QQuickBasePositioner::resetRightPadding()
613	{
614	Q_D(QQuickBasePositioner);
615	d->setRightPadding(value: 0, reset: true);
616	}
617
618	qreal QQuickBasePositioner::bottomPadding() const
619	{
620	Q_D(const QQuickBasePositioner);
621	if (d->extra.isAllocated() && d->extra->explicitBottomPadding)
622	return d->extra->bottomPadding;
623	return d->padding();
624	}
625
626	void QQuickBasePositioner::setBottomPadding(qreal padding)
627	{
628	Q_D(QQuickBasePositioner);
629	d->setBottomPadding(value: padding);
630	}
631
632	void QQuickBasePositioner::resetBottomPadding()
633	{
634	Q_D(QQuickBasePositioner);
635	d->setBottomPadding(value: 0, reset: true);
636	}
637
638	QQuickBasePositionerPrivate::ExtraData::ExtraData()
639	: padding(0)
640	, topPadding(0)
641	, leftPadding(0)
642	, rightPadding(0)
643	, bottomPadding(0)
644	, explicitTopPadding(false)
645	, explicitLeftPadding(false)
646	, explicitRightPadding(false)
647	, explicitBottomPadding(false)
648	{
649	}
650
651	void QQuickBasePositionerPrivate::setTopPadding(qreal value, bool reset)
652	{
653	Q_Q(QQuickBasePositioner);
654	qreal oldPadding = q->topPadding();
655	if (!reset || extra.isAllocated()) {
656	extra.value().topPadding = value;
657	extra.value().explicitTopPadding = !reset;
658	}
659	if ((!reset && !qFuzzyCompare(p1: oldPadding, p2: value)) || (reset && !qFuzzyCompare(p1: oldPadding, p2: padding()))) {
660	setPositioningDirty();
661	emit q->topPaddingChanged();
662	}
663	}
664
665	void QQuickBasePositionerPrivate::setLeftPadding(qreal value, bool reset)
666	{
667	Q_Q(QQuickBasePositioner);
668	qreal oldPadding = q->leftPadding();
669	if (!reset || extra.isAllocated()) {
670	extra.value().leftPadding = value;
671	extra.value().explicitLeftPadding = !reset;
672	}
673	if ((!reset && !qFuzzyCompare(p1: oldPadding, p2: value)) || (reset && !qFuzzyCompare(p1: oldPadding, p2: padding()))) {
674	setPositioningDirty();
675	emit q->leftPaddingChanged();
676	}
677	}
678
679	void QQuickBasePositionerPrivate::setRightPadding(qreal value, bool reset)
680	{
681	Q_Q(QQuickBasePositioner);
682	qreal oldPadding = q->rightPadding();
683	if (!reset || extra.isAllocated()) {
684	extra.value().rightPadding = value;
685	extra.value().explicitRightPadding = !reset;
686	}
687	if ((!reset && !qFuzzyCompare(p1: oldPadding, p2: value)) || (reset && !qFuzzyCompare(p1: oldPadding, p2: padding()))) {
688	setPositioningDirty();
689	emit q->rightPaddingChanged();
690	}
691	}
692
693	void QQuickBasePositionerPrivate::setBottomPadding(qreal value, bool reset)
694	{
695	Q_Q(QQuickBasePositioner);
696	qreal oldPadding = q->bottomPadding();
697	if (!reset || extra.isAllocated()) {
698	extra.value().bottomPadding = value;
699	extra.value().explicitBottomPadding = !reset;
700	}
701	if ((!reset && !qFuzzyCompare(p1: oldPadding, p2: value)) || (reset && !qFuzzyCompare(p1: oldPadding, p2: padding()))) {
702	setPositioningDirty();
703	emit q->bottomPaddingChanged();
704	}
705	}
706
707	/*!
708	\qmltype Positioner
709	\instantiates QQuickPositionerAttached
710	\inqmlmodule QtQuick
711	\ingroup qtquick-positioners
712	\brief Provides attached properties that contain details on where an item exists in a positioner.
713
714	An object of type Positioner is attached to the top-level child item within a
715	Column, Row, Flow or Grid. It provides properties that allow a child item to determine
716	where it exists within the layout of its parent Column, Row, Flow or Grid.
717
718	For example, below is a \l Grid with 16 child rectangles, as created through a \l Repeater.
719	Each \l Rectangle displays its index in the Grid using \l {Positioner::index}{Positioner.index}, and the first
720	item is colored differently by taking \l {Positioner::isFirstItem}{Positioner.isFirstItem} into account:
721
722	\code
723	Grid {
724	Repeater {
725	model: 16
726
727	Rectangle {
728	id: rect
729	width: 30; height: 30
730	border.width: 1
731	color: Positioner.isFirstItem ? "yellow" : "lightsteelblue"
732
733	Text { text: rect.Positioner.index }
734	}
735	}
736	}
737	\endcode
738
739	\image positioner-example.png
740	*/
741
742	QQuickPositionerAttached::QQuickPositionerAttached(QObject *parent) : QObject(parent), m_index(-1), m_isFirstItem(false), m_isLastItem(false)
743	{
744	QQuickItem *attachedItem = qobject_cast<QQuickItem *>(o: parent);
745	if (attachedItem) {
746	QQuickBasePositioner *positioner = qobject_cast<QQuickBasePositioner *>(object: attachedItem->parent());
747	if (positioner) {
748	positioner->updateAttachedProperties(specificProperty: this, specificPropertyOwner: attachedItem);
749	}
750	}
751	}
752
753	/*!
754	\qmlattachedproperty int QtQuick::Positioner::index
755
756	This property allows the item to determine
757	its index within the positioner.
758	*/
759	void QQuickPositionerAttached::setIndex(int index)
760	{
761	if (m_index == index)
762	return;
763	m_index = index;
764	emit indexChanged();
765	}
766
767	/*!
768	\qmlattachedproperty bool QtQuick::Positioner::isFirstItem
769	\qmlattachedproperty bool QtQuick::Positioner::isLastItem
770
771	These properties allow the item to determine if it
772	is the first or last item in the positioner, respectively.
773	*/
774	void QQuickPositionerAttached::setIsFirstItem(bool isFirstItem)
775	{
776	if (m_isFirstItem == isFirstItem)
777	return;
778	m_isFirstItem = isFirstItem;
779	emit isFirstItemChanged();
780	}
781
782	void QQuickPositionerAttached::setIsLastItem(bool isLastItem)
783	{
784	if (m_isLastItem == isLastItem)
785	return;
786	m_isLastItem = isLastItem;
787	emit isLastItemChanged();
788	}
789
790	/*!
791	\qmltype Column
792	\instantiates QQuickColumn
793	\inqmlmodule QtQuick
794	\inherits Item
795	\ingroup qtquick-positioners
796	\brief Positions its children in a column.
797
798	Column is a type that positions its child items along a single column.
799	It can be used as a convenient way to vertically position a series of items without
800	using \l {Positioning with Anchors}{anchors}.
801
802	Below is a Column that contains three rectangles of various sizes:
803
804	\snippet qml/column/vertical-positioner.qml document
805
806	The Column automatically positions these items in a vertical formation, like this:
807
808	\image verticalpositioner_example.png
809
810	If an item within a Column is not \l {Item::}{visible}, or if it has a width or
811	height of 0, the item will not be laid out and it will not be visible within the
812	column. Also, since a Column automatically positions its children vertically, a child
813	item within a Column should not set its \l {Item::y}{y} position or vertically
814	anchor itself using the \l {Item::anchors.top}{top}, \l {Item::anchors.bottom}{bottom},
815	\l {Item::anchors.verticalCenter}{anchors.verticalCenter}, \l {Item::anchors.fill}{fill}
816	or \l {Item::anchors.centerIn}{centerIn} anchors. If you need to perform these actions,
817	consider positioning the items without the use of a Column.
818
819	Note that items in a Column can use the \l Positioner attached property to access
820	more information about its position within the Column.
821
822	For more information on using Column and other related positioner-types, see
823	\l{Item Positioners}.
824
825
826	\section1 Using Transitions
827
828	A Column animate items using specific transitions when items are added to or moved
829	within a Column.
830
831	For example, the Column below sets the \l move property to a specific \l Transition:
832
833	\snippet qml/column/column-transitions.qml document
834
835	When the Space key is pressed, the \l {Item::visible}{visible} value of the green
836	\l Rectangle is toggled. As it appears and disappears, the blue \l Rectangle moves within
837	the Column, and the \l move transition is automatically applied to the blue \l Rectangle:
838
839	\image verticalpositioner_transition.gif
840
841	\sa Row, Grid, Flow, Positioner, ColumnLayout, {Qt Quick Examples - Positioners}
842	*/
843	/*!
844	\since 5.6
845	\qmlproperty real QtQuick::Column::padding
846	\qmlproperty real QtQuick::Column::topPadding
847	\qmlproperty real QtQuick::Column::leftPadding
848	\qmlproperty real QtQuick::Column::bottomPadding
849	\qmlproperty real QtQuick::Column::rightPadding
850
851	These properties hold the padding around the content.
852	*/
853	/*!
854	\qmlproperty Transition QtQuick::Column::populate
855
856	This property holds the transition to be run for items that are part of
857	this positioner at the time of its creation. The transition is run when the positioner
858	is first created.
859
860	The transition can use the \l ViewTransition property to access more details about
861	the item that is being added. See the \l ViewTransition documentation for more details
862	and examples on using these transitions.
863
864	\sa add, ViewTransition, {Qt Quick Examples - Positioners}
865	*/
866	/*!
867	\qmlproperty Transition QtQuick::Column::add
868
869	This property holds the transition to be run for items that are added to this
870	positioner. For a positioner, this applies to:
871
872	\list
873	\li Items that are created or reparented as a child of the positioner after the
874	positioner has been created
875	\li Child items that change their \l Item::visible property from false to true, and thus
876	are now visible
877	\endlist
878
879	The transition can use the \l ViewTransition property to access more details about
880	the item that is being added. See the \l ViewTransition documentation for more details
881	and examples on using these transitions.
882
883	\note This transition is not applied to the items that are already part of the positioner
884	at the time of its creation. In this case, the \l populate transition is applied instead.
885
886	\sa populate, ViewTransition, {Qt Quick Examples - Positioners}
887	*/
888	/*!
889	\qmlproperty Transition QtQuick::Column::move
890
891	This property holds the transition to run for items that have moved within the
892	positioner. For a positioner, this applies to:
893
894	\list
895	\li Child items that move when they are displaced due to the addition, removal or
896	rearrangement of other items in the positioner
897	\li Child items that are repositioned due to the resizing of other items in the positioner
898	\endlist
899
900	The transition can use the \l ViewTransition property to access more details about
901	the item that is being moved. Note, however, that for this move transition, the
902	ViewTransition.targetIndexes and ViewTransition.targetItems lists are only set when
903	this transition is triggered by the addition of other items in the positioner; in other
904	cases, these lists will be empty. See the \l ViewTransition documentation for more details
905	and examples on using these transitions.
906
907	\sa add, populate, ViewTransition, {Qt Quick Examples - Positioners}
908	*/
909	/*!
910	\qmlproperty real QtQuick::Column::spacing
911
912	The spacing is the amount in pixels left empty between adjacent
913	items. The default spacing is 0.
914
915	\sa Grid::spacing
916	*/
917	/*!
918	\qmlmethod QtQuick::Column::forceLayout()
919	\since 5.9
920
921	Column typically positions its children once per frame. This means that
922	inside script blocks it is possible for the underlying children to have changed,
923	but the Column to have not yet been updated accordingly.
924
925	This method forces the Column to immediately respond to any outstanding
926	changes in its children.
927
928	\b Note: methods in general should only be called after the Component has completed.
929	*/
930	/*!
931	\qmlsignal QtQuick::Column::positioningComplete()
932	\since 5.9
933
934	This signal is emitted when positioning has been completed.
935	*/
936
937	QQuickColumn::QQuickColumn(QQuickItem *parent)
938	: QQuickBasePositioner(Vertical, parent)
939	{
940	}
941
942	void QQuickColumn::doPositioning(QSizeF *contentSize)
943	{
944	//Precondition: All items in the positioned list have a valid item pointer and should be positioned
945	qreal voffset = topPadding();
946	const qreal padding = leftPadding() + rightPadding();
947	contentSize->setWidth(qMax(a: contentSize->width(), b: padding));
948
949	for (int ii = 0; ii < positionedItems.count(); ++ii) {
950	PositionedItem &child = positionedItems[ii];
951	positionItem(x: child.itemX() + leftPadding() - child.leftPadding, y: voffset, target: &child);
952	child.updatePadding(lp: leftPadding(), tp: topPadding(), rp: rightPadding(), bp: bottomPadding());
953	contentSize->setWidth(qMax(a: contentSize->width(), b: child.item->width() + padding));
954
955	voffset += child.item->height();
956	voffset += spacing();
957	}
958
959	if (voffset - topPadding() != 0)//If we positioned any items, undo the spacing from the last item
960	voffset -= spacing();
961	contentSize->setHeight(voffset + bottomPadding());
962	}
963
964	void QQuickColumn::reportConflictingAnchors()
965	{
966	QQuickBasePositionerPrivate *d = static_cast<QQuickBasePositionerPrivate*>(QQuickBasePositionerPrivate::get(item: this));
967	for (int ii = 0; ii < positionedItems.count(); ++ii) {
968	const PositionedItem &child = positionedItems.at(idx: ii);
969	if (child.item) {
970	QQuickAnchors *anchors = QQuickItemPrivate::get(item: static_cast<QQuickItem *>(child.item))->_anchors;
971	if (anchors) {
972	QQuickAnchors::Anchors usedAnchors = anchors->usedAnchors();
973	if (usedAnchors & QQuickAnchors::TopAnchor ||
974	usedAnchors & QQuickAnchors::BottomAnchor ||
975	usedAnchors & QQuickAnchors::VCenterAnchor ||
976	anchors->fill() || anchors->centerIn()) {
977	d->anchorConflict = true;
978	break;
979	}
980	}
981	}
982	}
983	if (d->anchorConflict) {
984	qmlWarning(me: this) << "Cannot specify top, bottom, verticalCenter, fill or centerIn anchors for items inside Column."
985	<< " Column will not function.";
986	}
987	}
988	/*!
989	\qmltype Row
990	\instantiates QQuickRow
991	\inqmlmodule QtQuick
992	\inherits Item
993	\ingroup qtquick-positioners
994	\brief Positions its children in a row.
995
996	Row is a type that positions its child items along a single row.
997	It can be used as a convenient way to horizontally position a series of items without
998	using \l {Positioning with Anchors}{anchors}.
999
1000	Below is a Row that contains three rectangles of various sizes:
1001
1002	\snippet qml/row/row.qml document
1003
1004	The Row automatically positions these items in a horizontal formation, like this:
1005
1006	\image horizontalpositioner_example.png
1007
1008	If an item within a Row is not \l {Item::}{visible}, or if it has a width or
1009	height of 0, the item will not be laid out and it will not be visible within the
1010	row. Also, since a Row automatically positions its children horizontally, a child
1011	item within a Row should not set its \l {Item::x}{x} position or horizontally
1012	anchor itself using the \l {Item::anchors.left}{left}, \l {Item::anchors.right}{right},
1013	\l {Item::anchors.horizontalCenter}{anchors.horizontalCenter}, \l {Item::anchors.fill}{fill}
1014	or \l {Item::anchors.centerIn}{centerIn} anchors. If you need to perform these actions,
1015	consider positioning the items without the use of a Row.
1016
1017	Note that items in a Row can use the \l Positioner attached property to access
1018	more information about its position within the Row.
1019
1020	For more information on using Row and other related positioner-types, see
1021	\l{Item Positioners}.
1022
1023
1024	\sa Column, Grid, Flow, Positioner, RowLayout, {Qt Quick Examples - Positioners}
1025	*/
1026	/*!
1027	\since 5.6
1028	\qmlproperty real QtQuick::Row::padding
1029	\qmlproperty real QtQuick::Row::topPadding
1030	\qmlproperty real QtQuick::Row::leftPadding
1031	\qmlproperty real QtQuick::Row::bottomPadding
1032	\qmlproperty real QtQuick::Row::rightPadding
1033
1034	These properties hold the padding around the content.
1035	*/
1036	/*!
1037	\qmlproperty Transition QtQuick::Row::populate
1038
1039	This property holds the transition to be run for items that are part of
1040	this positioner at the time of its creation. The transition is run when the positioner
1041	is first created.
1042
1043	The transition can use the \l ViewTransition property to access more details about
1044	the item that is being added. See the \l ViewTransition documentation for more details
1045	and examples on using these transitions.
1046
1047	\sa add, ViewTransition, {Qt Quick Examples - Positioners}
1048	*/
1049	/*!
1050	\qmlproperty Transition QtQuick::Row::add
1051
1052	This property holds the transition to be run for items that are added to this
1053	positioner. For a positioner, this applies to:
1054
1055	\list
1056	\li Items that are created or reparented as a child of the positioner after the
1057	positioner has been created
1058	\li Child items that change their \l Item::visible property from false to true, and thus
1059	are now visible
1060	\endlist
1061
1062	The transition can use the \l ViewTransition property to access more details about
1063	the item that is being added. See the \l ViewTransition documentation for more details
1064	and examples on using these transitions.
1065
1066	\note This transition is not applied to the items that are already part of the positioner
1067	at the time of its creation. In this case, the \l populate transition is applied instead.
1068
1069	\sa populate, ViewTransition, {Qt Quick Examples - Positioners}
1070	*/
1071	/*!
1072	\qmlproperty Transition QtQuick::Row::move
1073
1074	This property holds the transition to run for items that have moved within the
1075	positioner. For a positioner, this applies to:
1076
1077	\list
1078	\li Child items that move when they are displaced due to the addition, removal or
1079	rearrangement of other items in the positioner
1080	\li Child items that are repositioned due to the resizing of other items in the positioner
1081	\endlist
1082
1083	The transition can use the \l ViewTransition property to access more details about
1084	the item that is being moved. Note, however, that for this move transition, the
1085	ViewTransition.targetIndexes and ViewTransition.targetItems lists are only set when
1086	this transition is triggered by the addition of other items in the positioner; in other
1087	cases, these lists will be empty. See the \l ViewTransition documentation for more details
1088	and examples on using these transitions.
1089
1090	\sa add, populate, ViewTransition, {Qt Quick Examples - Positioners}
1091	*/
1092	/*!
1093	\qmlproperty real QtQuick::Row::spacing
1094
1095	The spacing is the amount in pixels left empty between adjacent
1096	items. The default spacing is 0.
1097
1098	\sa Grid::spacing
1099	*/
1100	/*!
1101	\qmlmethod QtQuick::Row::forceLayout()
1102	\since 5.9
1103
1104	Row typically positions its children once per frame. This means that
1105	inside script blocks it is possible for the underlying children to have changed,
1106	but the Row to have not yet been updated accordingly.
1107
1108	This method forces the Row to immediately respond to any outstanding
1109	changes in its children.
1110
1111	\b Note: methods in general should only be called after the Component has completed.
1112	*/
1113	/*!
1114	\qmlsignal QtQuick::Row::positioningComplete()
1115	\since 5.9
1116
1117	This signal is emitted when positioning has been completed.
1118	*/
1119
1120	class QQuickRowPrivate : public QQuickBasePositionerPrivate
1121	{
1122	Q_DECLARE_PUBLIC(QQuickRow)
1123
1124	public:
1125	QQuickRowPrivate()
1126	: QQuickBasePositionerPrivate()
1127	{}
1128
1129	void effectiveLayoutDirectionChange() override
1130	{
1131	Q_Q(QQuickRow);
1132	// For RTL layout the positioning changes when the width changes.
1133	if (getEffectiveLayoutDirection(positioner: q) == Qt::RightToLeft)
1134	addItemChangeListener(listener: this, types: QQuickItemPrivate::Geometry);
1135	else
1136	removeItemChangeListener(this, types: QQuickItemPrivate::Geometry);
1137	// Don't postpone, as it might be the only trigger for visible changes.
1138	q->prePositioning();
1139	emit q->effectiveLayoutDirectionChanged();
1140	}
1141	};
1142
1143	QQuickRow::QQuickRow(QQuickItem *parent)
1144	: QQuickBasePositioner(*new QQuickRowPrivate, Horizontal, parent)
1145	{
1146	}
1147	/*!
1148	\qmlproperty enumeration QtQuick::Row::layoutDirection
1149
1150	This property holds the layoutDirection of the row.
1151
1152	Possible values:
1153
1154	\value Qt.LeftToRight (default) Items are laid out from left to right. If the width of the row is
1155	explicitly set, the left anchor remains to the left of the row.
1156	\value Qt.RightToLeft Items are laid out from right to left. If the width of the row is
1157	explicitly set, the right anchor remains to the right of the row.
1158
1159	\sa Grid::layoutDirection, Flow::layoutDirection
1160	*/
1161
1162	Qt::LayoutDirection QQuickRow::layoutDirection() const
1163	{
1164	return QQuickBasePositionerPrivate::getLayoutDirection(positioner: this);
1165	}
1166
1167	void QQuickRow::setLayoutDirection(Qt::LayoutDirection layoutDirection)
1168	{
1169	QQuickBasePositionerPrivate *d = static_cast<QQuickBasePositionerPrivate* >(QQuickBasePositionerPrivate::get(item: this));
1170	if (d->layoutDirection != layoutDirection) {
1171	d->layoutDirection = layoutDirection;
1172	emit layoutDirectionChanged();
1173	d->effectiveLayoutDirectionChange();
1174	}
1175	}
1176	/*!
1177	\qmlproperty enumeration QtQuick::Row::effectiveLayoutDirection
1178	This property holds the effective layout direction of the row.
1179
1180	When using the attached property \l {LayoutMirroring::enabled}{LayoutMirroring::enabled} for locale layouts,
1181	the visual layout direction of the row positioner will be mirrored. However, the
1182	property \l {Row::layoutDirection}{layoutDirection} will remain unchanged.
1183
1184	\sa Row::layoutDirection, {LayoutMirroring}{LayoutMirroring}
1185	*/
1186
1187	Qt::LayoutDirection QQuickRow::effectiveLayoutDirection() const
1188	{
1189	return QQuickBasePositionerPrivate::getEffectiveLayoutDirection(positioner: this);
1190	}
1191
1192	void QQuickRow::doPositioning(QSizeF *contentSize)
1193	{
1194	//Precondition: All items in the positioned list have a valid item pointer and should be positioned
1195	QQuickBasePositionerPrivate *d = static_cast<QQuickBasePositionerPrivate* >(QQuickBasePositionerPrivate::get(item: this));
1196	qreal hoffset1 = leftPadding();
1197	qreal hoffset2 = rightPadding();
1198	if (!d->isLeftToRight())
1199	qSwap(value1&: hoffset1, value2&: hoffset2);
1200	qreal hoffset = hoffset1;
1201	const qreal padding = topPadding() + bottomPadding();
1202	contentSize->setHeight(qMax(a: contentSize->height(), b: padding));
1203
1204	QList<qreal> hoffsets;
1205	for (int ii = 0; ii < positionedItems.count(); ++ii) {
1206	PositionedItem &child = positionedItems[ii];
1207
1208	if (d->isLeftToRight()) {
1209	positionItem(x: hoffset, y: child.itemY() + topPadding() - child.topPadding, target: &child);
1210	child.updatePadding(lp: leftPadding(), tp: topPadding(), rp: rightPadding(), bp: bottomPadding());
1211	} else {
1212	hoffsets << hoffset;
1213	}
1214
1215	contentSize->setHeight(qMax(a: contentSize->height(), b: child.item->height() + padding));
1216
1217	hoffset += child.item->width();
1218	hoffset += spacing();
1219	}
1220
1221	if (hoffset - hoffset1 != 0)//If we positioned any items, undo the extra spacing from the last item
1222	hoffset -= spacing();
1223	contentSize->setWidth(hoffset + hoffset2);
1224
1225	if (d->isLeftToRight())
1226	return;
1227
1228	//Right to Left layout
1229	qreal end = 0;
1230	if (!widthValid())
1231	end = contentSize->width();
1232	else
1233	end = width();
1234
1235	int acc = 0;
1236	for (int ii = 0; ii < positionedItems.count(); ++ii) {
1237	PositionedItem &child = positionedItems[ii];
1238	hoffset = end - hoffsets[acc++] - child.item->width();
1239	positionItem(x: hoffset, y: child.itemY() + topPadding() - child.topPadding, target: &child);
1240	child.updatePadding(lp: leftPadding(), tp: topPadding(), rp: rightPadding(), bp: bottomPadding());
1241	}
1242	}
1243
1244	void QQuickRow::reportConflictingAnchors()
1245	{
1246	QQuickBasePositionerPrivate *d = static_cast<QQuickBasePositionerPrivate*>(QQuickBasePositionerPrivate::get(item: this));
1247	for (int ii = 0; ii < positionedItems.count(); ++ii) {
1248	const PositionedItem &child = positionedItems.at(idx: ii);
1249	if (child.item) {
1250	QQuickAnchors *anchors = QQuickItemPrivate::get(item: static_cast<QQuickItem *>(child.item))->_anchors;
1251	if (anchors) {
1252	QQuickAnchors::Anchors usedAnchors = anchors->usedAnchors();
1253	if (usedAnchors & QQuickAnchors::LeftAnchor ||
1254	usedAnchors & QQuickAnchors::RightAnchor ||
1255	usedAnchors & QQuickAnchors::HCenterAnchor ||
1256	anchors->fill() || anchors->centerIn()) {
1257	d->anchorConflict = true;
1258	break;
1259	}
1260	}
1261	}
1262	}
1263	if (d->anchorConflict)
1264	qmlWarning(me: this) << "Cannot specify left, right, horizontalCenter, fill or centerIn anchors for items inside Row."
1265	<< " Row will not function.";
1266	}
1267
1268	/*!
1269	\qmltype Grid
1270	\instantiates QQuickGrid
1271	\inqmlmodule QtQuick
1272	\inherits Item
1273	\ingroup qtquick-positioners
1274	\brief Positions its children in grid formation.
1275
1276	Grid is a type that positions its child items in grid formation.
1277
1278	A Grid creates a grid of cells that is large enough to hold all of its
1279	child items, and places these items in the cells from left to right
1280	and top to bottom. Each item is positioned at the top-left corner of its
1281	cell with position (0, 0).
1282
1283	A Grid defaults to four columns, and creates as many rows as are necessary to
1284	fit all of its child items. The number of rows and columns can be constrained
1285	by setting the \l rows and \l columns properties.
1286
1287	For example, below is a Grid that contains five rectangles of various sizes:
1288
1289	\snippet qml/grid/grid.qml document
1290
1291	The Grid automatically positions the child items in a grid formation:
1292
1293	\image gridLayout_example.png
1294
1295	If an item within a Grid is not \l {Item::}{visible}, or if it has a width or
1296	height of 0, the item will not be laid out and it will not be visible within the
1297	column. Also, since a Grid automatically positions its children, a child
1298	item within a Grid should not set its \l {Item::x}{x} or \l {Item::y}{y} positions
1299	or anchor itself with any of the \l {Item::anchors}{anchor} properties.
1300
1301	For more information on using Grid and other related positioner-types, see
1302	\l{Item Positioners}.
1303
1304
1305	\sa Flow, Row, Column, Positioner, GridLayout, {Qt Quick Examples - Positioners}
1306	*/
1307	/*!
1308	\since 5.6
1309	\qmlproperty real QtQuick::Grid::padding
1310	\qmlproperty real QtQuick::Grid::topPadding
1311	\qmlproperty real QtQuick::Grid::leftPadding
1312	\qmlproperty real QtQuick::Grid::bottomPadding
1313	\qmlproperty real QtQuick::Grid::rightPadding
1314
1315	These properties hold the padding around the content.
1316	*/
1317	/*!
1318	\qmlproperty Transition QtQuick::Grid::populate
1319
1320	This property holds the transition to be run for items that are part of
1321	this positioner at the time of its creation. The transition is run when the positioner
1322	is first created.
1323
1324	The transition can use the \l ViewTransition property to access more details about
1325	the item that is being added. See the \l ViewTransition documentation for more details
1326	and examples on using these transitions.
1327
1328	\sa add, ViewTransition, {Qt Quick Examples - Positioners}
1329	*/
1330	/*!
1331	\qmlproperty Transition QtQuick::Grid::add
1332
1333	This property holds the transition to be run for items that are added to this
1334	positioner. For a positioner, this applies to:
1335
1336	\list
1337	\li Items that are created or reparented as a child of the positioner after the
1338	positioner has been created
1339	\li Child items that change their \l Item::visible property from false to true, and thus
1340	are now visible
1341	\endlist
1342
1343	The transition can use the \l ViewTransition property to access more details about
1344	the item that is being added. See the \l ViewTransition documentation for more details
1345	and examples on using these transitions.
1346
1347	\note This transition is not applied to the items that are already part of the positioner
1348	at the time of its creation. In this case, the \l populate transition is applied instead.
1349
1350	\sa populate, ViewTransition, {Qt Quick Examples - Positioners}
1351	*/
1352	/*!
1353	\qmlproperty Transition QtQuick::Grid::move
1354
1355	This property holds the transition to run for items that have moved within the
1356	positioner. For a positioner, this applies to:
1357
1358	\list
1359	\li Child items that move when they are displaced due to the addition, removal or
1360	rearrangement of other items in the positioner
1361	\li Child items that are repositioned due to the resizing of other items in the positioner
1362	\endlist
1363
1364	The transition can use the \l ViewTransition property to access more details about
1365	the item that is being moved. Note, however, that for this move transition, the
1366	ViewTransition.targetIndexes and ViewTransition.targetItems lists are only set when
1367	this transition is triggered by the addition of other items in the positioner; in other
1368	cases, these lists will be empty. See the \l ViewTransition documentation for more details
1369	and examples on using these transitions.
1370
1371	\sa add, populate, ViewTransition, {Qt Quick Examples - Positioners}
1372	*/
1373	/*!
1374	\qmlproperty qreal QtQuick::Grid::spacing
1375
1376	The spacing is the amount in pixels left empty between adjacent
1377	items. The amount of spacing applied will be the same in the
1378	horizontal and vertical directions. The default spacing is 0.
1379
1380	The below example places a Grid containing a red, a blue and a
1381	green rectangle on a gray background. The area the grid positioner
1382	occupies is colored white. The positioner on the left has the
1383	no spacing (the default), and the positioner on the right has
1384	a spacing of 6.
1385
1386	\inlineimage qml-grid-no-spacing.png
1387	\inlineimage qml-grid-spacing.png
1388
1389	\sa rows, columns
1390	*/
1391	/*!
1392	\qmlmethod QtQuick::Grid::forceLayout()
1393	\since 5.9
1394
1395	Grid typically positions its children once per frame. This means that
1396	inside script blocks it is possible for the underlying children to have changed,
1397	but the Grid to have not yet been updated accordingly.
1398
1399	This method forces the Grid to immediately respond to any outstanding
1400	changes in its children.
1401
1402	\b Note: methods in general should only be called after the Component has completed.
1403	*/
1404	/*!
1405	\qmlsignal QtQuick::Grid::positioningComplete()
1406	\since 5.9
1407
1408	This signal is emitted when positioning has been completed.
1409	*/
1410
1411	class QQuickGridPrivate : public QQuickBasePositionerPrivate
1412	{
1413	Q_DECLARE_PUBLIC(QQuickGrid)
1414
1415	public:
1416	QQuickGridPrivate()
1417	: QQuickBasePositionerPrivate()
1418	{}
1419
1420	void effectiveLayoutDirectionChange() override
1421	{
1422	Q_Q(QQuickGrid);
1423	// For RTL layout the positioning changes when the width changes.
1424	if (getEffectiveLayoutDirection(positioner: q) == Qt::RightToLeft)
1425	addItemChangeListener(listener: this, types: QQuickItemPrivate::Geometry);
1426	else
1427	removeItemChangeListener(this, types: QQuickItemPrivate::Geometry);
1428	// Don't postpone, as it might be the only trigger for visible changes.
1429	q->prePositioning();
1430	emit q->effectiveLayoutDirectionChanged();
1431	emit q->effectiveHorizontalAlignmentChanged(alignment: q->effectiveHAlign());
1432	}
1433	};
1434
1435	QQuickGrid::QQuickGrid(QQuickItem *parent)
1436	: QQuickBasePositioner(*new QQuickGridPrivate, Both, parent)
1437	, m_rows(-1)
1438	, m_columns(-1)
1439	, m_rowSpacing(-1)
1440	, m_columnSpacing(-1)
1441	, m_useRowSpacing(false)
1442	, m_useColumnSpacing(false)
1443	, m_flow(LeftToRight)
1444	, m_hItemAlign(AlignLeft)
1445	, m_vItemAlign(AlignTop)
1446	{
1447	}
1448
1449	/*!
1450	\qmlproperty int QtQuick::Grid::columns
1451
1452	This property holds the number of columns in the grid. The default
1453	number of columns is 4.
1454
1455	If the grid does not have enough items to fill the specified
1456	number of columns, some columns will be of zero width.
1457	*/
1458
1459	/*!
1460	\qmlproperty int QtQuick::Grid::rows
1461	This property holds the number of rows in the grid.
1462
1463	If the grid does not have enough items to fill the specified
1464	number of rows, some rows will be of zero width.
1465	*/
1466
1467	void QQuickGrid::setColumns(const int columns)
1468	{
1469	if (columns == m_columns)
1470	return;
1471	m_columns = columns;
1472	prePositioning();
1473	emit columnsChanged();
1474	}
1475
1476	void QQuickGrid::setRows(const int rows)
1477	{
1478	if (rows == m_rows)
1479	return;
1480	m_rows = rows;
1481	prePositioning();
1482	emit rowsChanged();
1483	}
1484
1485	/*!
1486	\qmlproperty enumeration QtQuick::Grid::flow
1487	This property holds the flow of the layout.
1488
1489	Possible values are:
1490
1491	\list
1492	\li Grid.LeftToRight (default) - Items are positioned next to
1493	each other in the \l layoutDirection, then wrapped to the next line.
1494	\li Grid.TopToBottom - Items are positioned next to each
1495	other from top to bottom, then wrapped to the next column.
1496	\endlist
1497	*/
1498	QQuickGrid::Flow QQuickGrid::flow() const
1499	{
1500	return m_flow;
1501	}
1502
1503	void QQuickGrid::setFlow(Flow flow)
1504	{
1505	if (m_flow != flow) {
1506	m_flow = flow;
1507	prePositioning();
1508	emit flowChanged();
1509	}
1510	}
1511
1512	/*!
1513	\qmlproperty qreal QtQuick::Grid::rowSpacing
1514
1515	This property holds the spacing in pixels between rows.
1516
1517	If this property is not set, then spacing is used for the row spacing.
1518
1519	By default this property is not set.
1520
1521	\sa columnSpacing
1522	\since 5.0
1523	*/
1524	void QQuickGrid::setRowSpacing(const qreal rowSpacing)
1525	{
1526	if (rowSpacing == m_rowSpacing)
1527	return;
1528	m_rowSpacing = rowSpacing;
1529	m_useRowSpacing = true;
1530	prePositioning();
1531	emit rowSpacingChanged();
1532	}
1533
1534	/*!
1535	\qmlproperty qreal QtQuick::Grid::columnSpacing
1536
1537	This property holds the spacing in pixels between columns.
1538
1539	If this property is not set, then spacing is used for the column spacing.
1540
1541	By default this property is not set.
1542
1543	\sa rowSpacing
1544	\since 5.0
1545	*/
1546	void QQuickGrid::setColumnSpacing(const qreal columnSpacing)
1547	{
1548	if (columnSpacing == m_columnSpacing)
1549	return;
1550	m_columnSpacing = columnSpacing;
1551	m_useColumnSpacing = true;
1552	prePositioning();
1553	emit columnSpacingChanged();
1554	}
1555
1556	/*!
1557	\qmlproperty enumeration QtQuick::Grid::layoutDirection
1558
1559	This property holds the layout direction of the layout.
1560
1561	Possible values are:
1562
1563	\list
1564	\li Qt.LeftToRight (default) - Items are positioned from the top to bottom,
1565	and left to right. The flow direction is dependent on the
1566	\l Grid::flow property.
1567	\li Qt.RightToLeft - Items are positioned from the top to bottom,
1568	and right to left. The flow direction is dependent on the
1569	\l Grid::flow property.
1570	\endlist
1571
1572	\sa Flow::layoutDirection, Row::layoutDirection
1573	*/
1574	Qt::LayoutDirection QQuickGrid::layoutDirection() const
1575	{
1576	return QQuickBasePositionerPrivate::getLayoutDirection(positioner: this);
1577	}
1578
1579	void QQuickGrid::setLayoutDirection(Qt::LayoutDirection layoutDirection)
1580	{
1581	QQuickBasePositionerPrivate *d = static_cast<QQuickBasePositionerPrivate*>(QQuickBasePositionerPrivate::get(item: this));
1582	if (d->layoutDirection != layoutDirection) {
1583	d->layoutDirection = layoutDirection;
1584	emit layoutDirectionChanged();
1585	d->effectiveLayoutDirectionChange();
1586	}
1587	}
1588
1589	/*!
1590	\qmlproperty enumeration QtQuick::Grid::effectiveLayoutDirection
1591	This property holds the effective layout direction of the grid.
1592
1593	When using the attached property \l {LayoutMirroring::enabled}{LayoutMirroring::enabled} for locale layouts,
1594	the visual layout direction of the grid positioner will be mirrored. However, the
1595	property \l {Grid::layoutDirection}{layoutDirection} will remain unchanged.
1596
1597	\sa Grid::layoutDirection, {LayoutMirroring}{LayoutMirroring}
1598	*/
1599	Qt::LayoutDirection QQuickGrid::effectiveLayoutDirection() const
1600	{
1601	return QQuickBasePositionerPrivate::getEffectiveLayoutDirection(positioner: this);
1602	}
1603
1604	/*!
1605	\qmlproperty enumeration QtQuick::Grid::horizontalItemAlignment
1606	\qmlproperty enumeration QtQuick::Grid::verticalItemAlignment
1607	\qmlproperty enumeration QtQuick::Grid::effectiveHorizontalItemAlignment
1608	\since 5.1
1609
1610	Sets the horizontal and vertical alignment of items in the Grid. By default,
1611	the items are vertically aligned to the top. Horizontal
1612	alignment follows the layoutDirection of the Grid, for example when having a layoutDirection
1613	from LeftToRight, the items will be aligned on the left.
1614
1615	The valid values for \c horizontalItemAlignment are, \c Grid.AlignLeft, \c Grid.AlignRight and
1616	\c Grid.AlignHCenter.
1617
1618	The valid values for \c verticalItemAlignment are \c Grid.AlignTop, \c Grid.AlignBottom
1619	and \c Grid.AlignVCenter.
1620
1621	The below images show three examples of how to align items.
1622
1623	\table
1624	\row
1625	\li
1626	\li \inlineimage gridLayout_aligntopleft.png
1627	\li \inlineimage gridLayout_aligntop.png
1628	\li \inlineimage gridLayout_aligncenter.png
1629	\row
1630	\li Horizontal alignment
1631	\li AlignLeft
1632	\li AlignHCenter
1633	\li AlignHCenter
1634	\row
1635	\li Vertical alignment
1636	\li AlignTop
1637	\li AlignTop
1638	\li AlignVCenter
1639	\endtable
1640
1641
1642	When mirroring the layout using either the attached property LayoutMirroring::enabled or
1643	by setting the layoutDirection, the horizontal alignment of items will be mirrored as well.
1644	However, the property \c horizontalItemAlignment will remain unchanged.
1645	To query the effective horizontal alignment of items, use the read-only property
1646	\c effectiveHorizontalItemAlignment.
1647
1648	\sa Grid::layoutDirection, {LayoutMirroring}{LayoutMirroring}
1649	*/
1650	QQuickGrid::HAlignment QQuickGrid::hItemAlign() const
1651	{
1652	return m_hItemAlign;
1653	}
1654	void QQuickGrid::setHItemAlign(HAlignment align)
1655	{
1656	if (m_hItemAlign != align) {
1657	m_hItemAlign = align;
1658	prePositioning();
1659	emit horizontalAlignmentChanged(alignment: align);
1660	emit effectiveHorizontalAlignmentChanged(alignment: effectiveHAlign());
1661	}
1662	}
1663
1664	QQuickGrid::HAlignment QQuickGrid::effectiveHAlign() const
1665	{
1666	HAlignment effectiveAlignment = m_hItemAlign;
1667	if (effectiveLayoutDirection() == Qt::RightToLeft) {
1668	switch (hItemAlign()) {
1669	case AlignLeft:
1670	effectiveAlignment = AlignRight;
1671	break;
1672	case AlignRight:
1673	effectiveAlignment = AlignLeft;
1674	break;
1675	default:
1676	break;
1677	}
1678	}
1679	return effectiveAlignment;
1680	}
1681
1682
1683	QQuickGrid::VAlignment QQuickGrid::vItemAlign() const
1684	{
1685	return m_vItemAlign;
1686	}
1687	void QQuickGrid::setVItemAlign(VAlignment align)
1688	{
1689	if (m_vItemAlign != align) {
1690	m_vItemAlign = align;
1691	prePositioning();
1692	emit verticalAlignmentChanged(alignment: align);
1693	}
1694	}
1695
1696	void QQuickGrid::doPositioning(QSizeF *contentSize)
1697	{
1698	//Precondition: All items in the positioned list have a valid item pointer and should be positioned
1699	QQuickBasePositionerPrivate *d = static_cast<QQuickBasePositionerPrivate*>(QQuickBasePositionerPrivate::get(item: this));
1700	int c = m_columns;
1701	int r = m_rows;
1702	const int numVisible = positionedItems.count();
1703
1704	if (m_columns <= 0 && m_rows <= 0) {
1705	c = 4;
1706	r = (numVisible+3)/4;
1707	} else if (m_rows <= 0) {
1708	r = (numVisible+(m_columns-1))/m_columns;
1709	} else if (m_columns <= 0) {
1710	c = (numVisible+(m_rows-1))/m_rows;
1711	}
1712
1713	if (r == 0 || c == 0) {
1714	contentSize->setHeight(topPadding() + bottomPadding());
1715	contentSize->setWidth(leftPadding() + rightPadding());
1716	return; //Nothing else to do
1717	}
1718
1719	if (numVisible > r * c) {
1720	qmlWarning(me: this) << "Grid contains more visible items (" << numVisible << ") than rows*columns (" << r * c << ")";
1721	}
1722
1723	QList<qreal> maxColWidth;
1724	QList<qreal> maxRowHeight;
1725	int childIndex =0;
1726	if (m_flow == LeftToRight) {
1727	for (int i = 0; i < r; i++) {
1728	for (int j = 0; j < c; j++) {
1729	if (j == 0)
1730	maxRowHeight << 0;
1731	if (i == 0)
1732	maxColWidth << 0;
1733
1734	if (childIndex == numVisible)
1735	break;
1736
1737	const PositionedItem &child = positionedItems.at(idx: childIndex++);
1738	if (child.item->width() > maxColWidth[j])
1739	maxColWidth[j] = child.item->width();
1740	if (child.item->height() > maxRowHeight[i])
1741	maxRowHeight[i] = child.item->height();
1742	}
1743	}
1744	} else {
1745	for (int j = 0; j < c; j++) {
1746	for (int i = 0; i < r; i++) {
1747	if (j == 0)
1748	maxRowHeight << 0;
1749	if (i == 0)
1750	maxColWidth << 0;
1751
1752	if (childIndex == numVisible)
1753	break;
1754
1755	const PositionedItem &child = positionedItems.at(idx: childIndex++);
1756	if (child.item->width() > maxColWidth[j])
1757	maxColWidth[j] = child.item->width();
1758	if (child.item->height() > maxRowHeight[i])
1759	maxRowHeight[i] = child.item->height();
1760	}
1761	}
1762	}
1763
1764	qreal columnSpacing = m_useColumnSpacing ? m_columnSpacing : spacing();
1765	qreal rowSpacing = m_useRowSpacing ? m_rowSpacing : spacing();
1766
1767	qreal widthSum = 0;
1768	for (int j = 0; j < maxColWidth.size(); j++) {
1769	if (j)
1770	widthSum += columnSpacing;
1771	widthSum += maxColWidth[j];
1772	}
1773	widthSum += leftPadding() + rightPadding();
1774
1775	qreal heightSum = 0;
1776	for (int i = 0; i < maxRowHeight.size(); i++) {
1777	if (i)
1778	heightSum += rowSpacing;
1779	heightSum += maxRowHeight[i];
1780	}
1781	heightSum += topPadding() + bottomPadding();
1782
1783	contentSize->setHeight(heightSum);
1784	contentSize->setWidth(widthSum);
1785
1786	int end = 0;
1787	if (widthValid())
1788	end = width();
1789	else
1790	end = widthSum;
1791
1792	qreal xoffset = leftPadding();
1793	if (!d->isLeftToRight())
1794	xoffset = end - rightPadding();
1795	qreal yoffset = topPadding();
1796	int curRow =0;
1797	int curCol =0;
1798	for (int i = 0; i < positionedItems.count(); ++i) {
1799	PositionedItem &child = positionedItems[i];
1800	qreal childXOffset = xoffset;
1801
1802	if (effectiveHAlign() == AlignRight)
1803	childXOffset += maxColWidth[curCol] - child.item->width();
1804	else if (hItemAlign() == AlignHCenter)
1805	childXOffset += (maxColWidth[curCol] - child.item->width())/2.0;
1806
1807	if (!d->isLeftToRight())
1808	childXOffset -= maxColWidth[curCol];
1809
1810	qreal alignYOffset = yoffset;
1811	if (m_vItemAlign == AlignVCenter)
1812	alignYOffset += (maxRowHeight[curRow] - child.item->height())/2.0;
1813	else if (m_vItemAlign == AlignBottom)
1814	alignYOffset += maxRowHeight[curRow] - child.item->height();
1815
1816	positionItem(x: childXOffset, y: alignYOffset, target: &child);
1817	child.updatePadding(lp: leftPadding(), tp: topPadding(), rp: rightPadding(), bp: bottomPadding());
1818
1819	if (m_flow == LeftToRight) {
1820	if (d->isLeftToRight())
1821	xoffset += maxColWidth[curCol]+columnSpacing;
1822	else
1823	xoffset -= maxColWidth[curCol]+columnSpacing;
1824	curCol++;
1825	curCol %= c;
1826	if (!curCol) {
1827	yoffset += maxRowHeight[curRow]+rowSpacing;
1828	if (d->isLeftToRight())
1829	xoffset = leftPadding();
1830	else
1831	xoffset = end - rightPadding();
1832	curRow++;
1833	if (curRow>=r)
1834	break;
1835	}
1836	} else {
1837	yoffset += maxRowHeight[curRow]+rowSpacing;
1838	curRow++;
1839	curRow %= r;
1840	if (!curRow) {
1841	if (d->isLeftToRight())
1842	xoffset += maxColWidth[curCol]+columnSpacing;
1843	else
1844	xoffset -= maxColWidth[curCol]+columnSpacing;
1845	yoffset = topPadding();
1846	curCol++;
1847	if (curCol>=c)
1848	break;
1849	}
1850	}
1851	}
1852	}
1853
1854	void QQuickGrid::reportConflictingAnchors()
1855	{
1856	QQuickBasePositionerPrivate *d = static_cast<QQuickBasePositionerPrivate*>(QQuickBasePositionerPrivate::get(item: this));
1857	for (int ii = 0; ii < positionedItems.count(); ++ii) {
1858	const PositionedItem &child = positionedItems.at(idx: ii);
1859	if (child.item) {
1860	QQuickAnchors *anchors = QQuickItemPrivate::get(item: static_cast<QQuickItem *>(child.item))->_anchors;
1861	if (anchors && (anchors->usedAnchors() || anchors->fill() || anchors->centerIn())) {
1862	d->anchorConflict = true;
1863	break;
1864	}
1865	}
1866	}
1867	if (d->anchorConflict)
1868	qmlWarning(me: this) << "Cannot specify anchors for items inside Grid." << " Grid will not function.";
1869	}
1870
1871	/*!
1872	\qmltype Flow
1873	\instantiates QQuickFlow
1874	\inqmlmodule QtQuick
1875	\inherits Item
1876	\ingroup qtquick-positioners
1877	\brief Positions its children side by side, wrapping as necessary.
1878
1879	The Flow item positions its child items like words on a page, wrapping them
1880	to create rows or columns of items.
1881
1882	Below is a Flow that contains various \l Text items:
1883
1884	\snippet qml/flow.qml flow item
1885
1886	The Flow item automatically positions the child \l Text items side by
1887	side, wrapping as necessary:
1888
1889	\image qml-flow-snippet.png
1890
1891	If an item within a Flow is not \l {Item::}{visible}, or if it has a width or
1892	height of 0, the item will not be laid out and it will not be visible within the
1893	Flow. Also, since a Flow automatically positions its children, a child
1894	item within a Flow should not set its \l {Item::x}{x} or \l {Item::y}{y} positions
1895	or anchor itself with any of the \l {Item::anchors}{anchor} properties.
1896
1897	For more information on using Flow and other related positioner-types, see
1898	\l{Item Positioners}.
1899
1900	\sa Column, Row, Grid, Positioner, {Qt Quick Examples - Positioners}
1901	*/
1902	/*!
1903	\since 5.6
1904	\qmlproperty real QtQuick::Flow::padding
1905	\qmlproperty real QtQuick::Flow::topPadding
1906	\qmlproperty real QtQuick::Flow::leftPadding
1907	\qmlproperty real QtQuick::Flow::bottomPadding
1908	\qmlproperty real QtQuick::Flow::rightPadding
1909
1910	These properties hold the padding around the content.
1911	*/
1912	/*!
1913	\qmlproperty Transition QtQuick::Flow::populate
1914
1915	This property holds the transition to be run for items that are part of
1916	this positioner at the time of its creation. The transition is run when the positioner
1917	is first created.
1918
1919	The transition can use the \l ViewTransition property to access more details about
1920	the item that is being added. See the \l ViewTransition documentation for more details
1921	and examples on using these transitions.
1922
1923	\sa add, ViewTransition, {Qt Quick Examples - Positioners}
1924	*/
1925	/*!
1926	\qmlproperty Transition QtQuick::Flow::add
1927
1928	This property holds the transition to be run for items that are added to this
1929	positioner. For a positioner, this applies to:
1930
1931	\list
1932	\li Items that are created or reparented as a child of the positioner after the
1933	positioner has been created
1934	\li Child items that change their \l Item::visible property from false to true, and thus
1935	are now visible
1936	\endlist
1937
1938	The transition can use the \l ViewTransition property to access more details about
1939	the item that is being added. See the \l ViewTransition documentation for more details
1940	and examples on using these transitions.
1941
1942	\note This transition is not applied to the items that are already part of the positioner
1943	at the time of its creation. In this case, the \l populate transition is applied instead.
1944
1945	\sa populate, ViewTransition, {Qt Quick Examples - Positioners}
1946	*/
1947	/*!
1948	\qmlproperty Transition QtQuick::Flow::move
1949
1950	This property holds the transition to run for items that have moved within the
1951	positioner. For a positioner, this applies to:
1952
1953	\list
1954	\li Child items that move when they are displaced due to the addition, removal or
1955	rearrangement of other items in the positioner
1956	\li Child items that are repositioned due to the resizing of other items in the positioner
1957	\endlist
1958
1959	The transition can use the \l ViewTransition property to access more details about
1960	the item that is being moved. Note, however, that for this move transition, the
1961	ViewTransition.targetIndexes and ViewTransition.targetItems lists are only set when
1962	this transition is triggered by the addition of other items in the positioner; in other
1963	cases, these lists will be empty. See the \l ViewTransition documentation for more details
1964	and examples on using these transitions.
1965
1966	\sa add, populate, ViewTransition, {Qt Quick Examples - Positioners}
1967	*/
1968	/*!
1969	\qmlproperty real QtQuick::Flow::spacing
1970
1971	spacing is the amount in pixels left empty between each adjacent
1972	item, and defaults to 0.
1973
1974	\sa Grid::spacing
1975	*/
1976	/*!
1977	\qmlmethod QtQuick::Flow::forceLayout()
1978	\since 5.9
1979
1980	Flow typically positions its children once per frame. This means that
1981	inside script blocks it is possible for the underlying children to have changed,
1982	but the Flow to have not yet been updated accordingly.
1983
1984	This method forces the Flow to immediately respond to any outstanding
1985	changes in its children.
1986
1987
1988	\b Note: methods in general should only be called after the Component has completed.
1989	*/
1990	/*!
1991	\qmlsignal QtQuick::Flow::positioningComplete()
1992	\since 5.9
1993
1994	This signal is emitted when positioning has been completed.
1995	*/
1996
1997	class QQuickFlowPrivate : public QQuickBasePositionerPrivate
1998	{
1999	Q_DECLARE_PUBLIC(QQuickFlow)
2000
2001	public:
2002	QQuickFlowPrivate()
2003	: QQuickBasePositionerPrivate(), flow(QQuickFlow::LeftToRight)
2004	{}
2005
2006	void effectiveLayoutDirectionChange() override
2007	{
2008	Q_Q(QQuickFlow);
2009	// Don't postpone, as it might be the only trigger for visible changes.
2010	q->prePositioning();
2011	emit q->effectiveLayoutDirectionChanged();
2012	}
2013
2014	QQuickFlow::Flow flow;
2015	};
2016
2017	QQuickFlow::QQuickFlow(QQuickItem *parent)
2018	: QQuickBasePositioner(*(new QQuickFlowPrivate), Both, parent)
2019	{
2020	Q_D(QQuickFlow);
2021	// Flow layout requires relayout if its own size changes too.
2022	d->addItemChangeListener(listener: d, types: QQuickItemPrivate::Geometry);
2023	}
2024
2025	/*!
2026	\qmlproperty enumeration QtQuick::Flow::flow
2027	This property holds the flow of the layout.
2028
2029	Possible values are:
2030
2031	\list
2032	\li Flow.LeftToRight (default) - Items are positioned next to
2033	to each other according to the \l layoutDirection until the width of the Flow
2034	is exceeded, then wrapped to the next line.
2035	\li Flow.TopToBottom - Items are positioned next to each
2036	other from top to bottom until the height of the Flow is exceeded,
2037	then wrapped to the next column.
2038	\endlist
2039	*/
2040	QQuickFlow::Flow QQuickFlow::flow() const
2041	{
2042	Q_D(const QQuickFlow);
2043	return d->flow;
2044	}
2045
2046	void QQuickFlow::setFlow(Flow flow)
2047	{
2048	Q_D(QQuickFlow);
2049	if (d->flow != flow) {
2050	d->flow = flow;
2051	prePositioning();
2052	emit flowChanged();
2053	}
2054	}
2055
2056	/*!
2057	\qmlproperty enumeration QtQuick::Flow::layoutDirection
2058
2059	This property holds the layout direction of the layout.
2060
2061	Possible values are:
2062
2063	\list
2064	\li Qt.LeftToRight (default) - Items are positioned from the top to bottom,
2065	and left to right. The flow direction is dependent on the
2066	\l Flow::flow property.
2067	\li Qt.RightToLeft - Items are positioned from the top to bottom,
2068	and right to left. The flow direction is dependent on the
2069	\l Flow::flow property.
2070	\endlist
2071
2072	\sa Grid::layoutDirection, Row::layoutDirection
2073	*/
2074
2075	Qt::LayoutDirection QQuickFlow::layoutDirection() const
2076	{
2077	Q_D(const QQuickFlow);
2078	return d->layoutDirection;
2079	}
2080
2081	void QQuickFlow::setLayoutDirection(Qt::LayoutDirection layoutDirection)
2082	{
2083	Q_D(QQuickFlow);
2084	if (d->layoutDirection != layoutDirection) {
2085	d->layoutDirection = layoutDirection;
2086	emit layoutDirectionChanged();
2087	d->effectiveLayoutDirectionChange();
2088	}
2089	}
2090
2091	/*!
2092	\qmlproperty enumeration QtQuick::Flow::effectiveLayoutDirection
2093	This property holds the effective layout direction of the flow.
2094
2095	When using the attached property \l {LayoutMirroring::enabled}{LayoutMirroring::enabled} for locale layouts,
2096	the visual layout direction of the grid positioner will be mirrored. However, the
2097	property \l {Flow::layoutDirection}{layoutDirection} will remain unchanged.
2098
2099	\sa Flow::layoutDirection, {LayoutMirroring}{LayoutMirroring}
2100	*/
2101
2102	Qt::LayoutDirection QQuickFlow::effectiveLayoutDirection() const
2103	{
2104	return QQuickBasePositionerPrivate::getEffectiveLayoutDirection(positioner: this);
2105	}
2106
2107	void QQuickFlow::doPositioning(QSizeF *contentSize)
2108	{
2109	//Precondition: All items in the positioned list have a valid item pointer and should be positioned
2110	Q_D(QQuickFlow);
2111
2112	qreal hoffset1 = leftPadding();
2113	qreal hoffset2 = rightPadding();
2114	if (!d->isLeftToRight())
2115	qSwap(value1&: hoffset1, value2&: hoffset2);
2116	qreal hoffset = hoffset1;
2117	const qreal voffset1 = topPadding();
2118	qreal voffset = voffset1;
2119	qreal linemax = 0;
2120	QList<qreal> hoffsets;
2121	contentSize->setWidth(qMax(a: contentSize->width(), b: hoffset1 + hoffset2));
2122	contentSize->setHeight(qMax(a: contentSize->height(), b: voffset + bottomPadding()));
2123
2124	for (int i = 0; i < positionedItems.count(); ++i) {
2125	PositionedItem &child = positionedItems[i];
2126
2127	if (d->flow == LeftToRight) {
2128	if (widthValid() && hoffset != hoffset1 && hoffset + child.item->width() + hoffset2 > width()) {
2129	hoffset = hoffset1;
2130	voffset += linemax + spacing();
2131	linemax = 0;
2132	}
2133	} else {
2134	if (heightValid() && voffset != voffset1 && voffset + child.item->height() + bottomPadding() > height()) {
2135	voffset = voffset1;
2136	hoffset += linemax + spacing();
2137	linemax = 0;
2138	}
2139	}
2140
2141	if (d->isLeftToRight()) {
2142	positionItem(x: hoffset, y: voffset, target: &child);
2143	child.updatePadding(lp: leftPadding(), tp: topPadding(), rp: rightPadding(), bp: bottomPadding());
2144	} else {
2145	hoffsets << hoffset;
2146	positionItemY(y: voffset, target: &child);
2147	child.topPadding = topPadding();
2148	child.bottomPadding = bottomPadding();
2149	}
2150
2151	contentSize->setWidth(qMax(a: contentSize->width(), b: hoffset + child.item->width() + hoffset2));
2152	contentSize->setHeight(qMax(a: contentSize->height(), b: voffset + child.item->height() + bottomPadding()));
2153
2154	if (d->flow == LeftToRight) {
2155	hoffset += child.item->width();
2156	hoffset += spacing();
2157	linemax = qMax(a: linemax, b: child.item->height());
2158	} else {
2159	voffset += child.item->height();
2160	voffset += spacing();
2161	linemax = qMax(a: linemax, b: child.item->width());
2162	}
2163	}
2164
2165	if (d->isLeftToRight())
2166	return;
2167
2168	qreal end;
2169	if (widthValid())
2170	end = width();
2171	else
2172	end = contentSize->width();
2173	int acc = 0;
2174	for (int i = 0; i < positionedItems.count(); ++i) {
2175	PositionedItem &child = positionedItems[i];
2176	hoffset = end - hoffsets[acc++] - child.item->width();
2177	positionItemX(x: hoffset, target: &child);
2178	child.leftPadding = leftPadding();
2179	child.rightPadding = rightPadding();
2180	}
2181	}
2182
2183	void QQuickFlow::reportConflictingAnchors()
2184	{
2185	Q_D(QQuickFlow);
2186	for (int ii = 0; ii < positionedItems.count(); ++ii) {
2187	const PositionedItem &child = positionedItems.at(idx: ii);
2188	if (child.item) {
2189	QQuickAnchors *anchors = QQuickItemPrivate::get(item: static_cast<QQuickItem *>(child.item))->_anchors;
2190	if (anchors && (anchors->usedAnchors() || anchors->fill() || anchors->centerIn())) {
2191	d->anchorConflict = true;
2192	break;
2193	}
2194	}
2195	}
2196	if (d->anchorConflict)
2197	qmlWarning(me: this) << "Cannot specify anchors for items inside Flow." << " Flow will not function.";
2198	}
2199
2200	QT_END_NAMESPACE
2201
2202	#include "moc_qquickpositioners_p.cpp"
2203