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unity8/plugins/ListViewWithPageHeader/listviewwithpageheader.cpp
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1/*
2 * Copyright (C) 2013 Canonical, Ltd.
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; version 3.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License
14 * along with this program. If not, see <http://www.gnu.org/licenses/>.
15 */
17/*
18 * Some documentation on how this thing works:
19 *
20 * A flickable has two very important concepts that define the top and
21 * height of the flickable area.
22 * The top is returned in minYExtent()
23 * The height is set using setContentHeight()
24 * By changing those two values we can make the list grow up or down
25 * as needed. e.g. if we are in the middle of the list
26 * and something that is above the viewport grows, since we do not
27 * want to change the viewport because of that we just adjust the
28 * minYExtent so that the list grows up.
29 *
30 * The implementation on the list relies on the delegateModel doing
31 * most of the instantiation work. You call createItem() when you
32 * need to create an item asking for it async or not. If returns null
33 * it means the item will be created async and the model will call the
34 * itemCreated slot with the item.
35 *
36 * updatePolish is the central point of dispatch for the work of the
37 * class. It is called by the scene graph just before drawing the class.
38 * In it we:
39 * * Make sure all items are positioned correctly
40 * * Add/Remove items if needed
41 * * Update the content height if it was dirty
42 *
43 * m_visibleItems contains all the items we have created at the moment.
44 * Actually not all of them are visible since it includes the ones
45 * in the cache area we create asynchronously to help performance.
46 * The first item in m_visibleItems has the m_firstVisibleIndex in
47 * the model. If you actually want to know what is the first
48 * item in the viewport you have to find the first non culled element
49 * in m_visibleItems
50 *
51 * All the items (except the header) are childs of m_clipItem which
52 * is a child of the contentItem() of the flickable (The contentItem()
53 * is what actually 'moves' in a a flickable). This way
54 * we can implement the clipping needed so we can have the header
55 * shown in the middle of the list over the items without the items
56 * leaking under the header in case it is transparent.
57 *
58 * The first item of m_visibleItems is the one that defines the
59 * positions of all the rest of items (see updatePolish()) and
60 * this is why sometimes we move it even if it's not the item
61 * that has triggered the function (i.e. in itemGeometryChanged())
62 *
63 * m_visibleItems is a list of ListItem. Each ListItem
64 * will contain a item and potentially a sectionItem. The sectionItem
65 * is only there when the list is using sectionDelegate+sectionProperty
66 * and this is the first item of the section. Each ListItem is vertically
67 * layouted with the sectionItem first and then the item.
68 *
69 * For sectioning we also have a section item alone (m_topSectionItem)
70 * that is used for the cases we need to show the sticky section item at
71 * the top of the view.
72 *
73 * Each delegate item has a context property called heightToClip that is
74 * used to communicate to the delegate implementation in case it has to
75 * clip itself because of overlapping with the top sticky section item.
76 * This is an implementation decision since it has been agreed it
77 * is easier to implement the clipping in QML with this info than to
78 * do it at the C++ level.
79 *
80 * Note that minYExtent and height are not always totally accurate, since
81 * we don't have the items created we can't guess their heights
82 * so we can only guarantee the values are correct when the first/last
83 * items of the list are visible, otherwise we just live with good enough
84 * values that make the list scrollable
85 *
86 * There are a few things that are not really implemented or tested properly
87 * which we don't use at the moment like changing the model, changing
88 * the section delegate, having a section delegate that changes its size, etc.
89 * The known missing features are marked with TODOs along the code.
90 */
92#include "listviewwithpageheader.h"
94#include <QDebug>
95#include <qqmlinfo.h>
96#include <qqmlengine.h>
97#pragma GCC diagnostic push
98#pragma GCC diagnostic ignored "-pedantic"
99#if (QT_VERSION < QT_VERSION_CHECK(5, 1, 0))
100#include <private/qquickvisualdatamodel_p.h>
101#else
102#include <private/qqmldelegatemodel_p.h>
103#endif
104#include <private/qqmlglobal_p.h>
105#include <private/qquickitem_p.h>
106#include <private/qquickanimation_p.h>
107#pragma GCC diagnostic pop
108// #include <private/qquickrectangle_p.h>
110static const qreal bufferRatio = 0.5;
112qreal ListViewWithPageHeader::ListItem::height() const
114 return m_item->height() + (m_sectionItem ? m_sectionItem->height() : 0);
117qreal ListViewWithPageHeader::ListItem::y() const
119 return m_item->y() - (m_sectionItem ? m_sectionItem->height() : 0);
122void ListViewWithPageHeader::ListItem::setY(qreal newY)
124 if (m_sectionItem) {
125 m_sectionItem->setY(newY);
126 m_item->setY(newY + m_sectionItem->height());
127 } else {
128 m_item->setY(newY);
129 }
132bool ListViewWithPageHeader::ListItem::culled() const
134 return QQuickItemPrivate::get(m_item)->culled;
137void ListViewWithPageHeader::ListItem::setCulled(bool culled)
139 QQuickItemPrivate::get(m_item)->setCulled(culled);
140 if (m_sectionItem)
141 QQuickItemPrivate::get(m_sectionItem)->setCulled(culled);
144ListViewWithPageHeader::ListViewWithPageHeader()
145 : m_delegateModel(nullptr)
146 , m_asyncRequestedIndex(-1)
147 , m_delegateValidated(false)
148 , m_firstVisibleIndex(-1)
149 , m_minYExtent(0)
150 , m_contentHeightDirty(false)
151 , m_headerItem(nullptr)
152 , m_previousContentY(0)
153 , m_headerItemShownHeight(0)
154 , m_sectionDelegate(nullptr)
155 , m_topSectionItem(nullptr)
156 , m_forceNoClip(false)
157 , m_inLayout(false)
159 m_clipItem = new QQuickItem(contentItem());
160// m_clipItem = new QQuickRectangle(contentItem());
161// ((QQuickRectangle*)m_clipItem)->setColor(Qt::gray);
163 m_contentYAnimation = new QQuickNumberAnimation(this);
164 m_contentYAnimation->setEasing(QEasingCurve::OutQuad);
165 m_contentYAnimation->setProperty("contentY");
166 m_contentYAnimation->setDuration(200);
167 m_contentYAnimation->setTargetObject(this);
169 connect(this, SIGNAL(contentWidthChanged()), this, SLOT(onContentWidthChanged()));
170 connect(this, SIGNAL(contentHeightChanged()), this, SLOT(onContentHeightChanged()));
171 connect(this, SIGNAL(heightChanged()), this, SLOT(onHeightChanged()));
172 connect(m_contentYAnimation, SIGNAL(stopped()), this, SLOT(onShowHeaderAnimationFinished()));
175ListViewWithPageHeader::~ListViewWithPageHeader()
179QAbstractItemModel *ListViewWithPageHeader::model() const
181 return m_delegateModel ? m_delegateModel->model().value<QAbstractItemModel *>() : nullptr;
184void ListViewWithPageHeader::setModel(QAbstractItemModel *model)
186 if (model != this->model()) {
187 if (!m_delegateModel) {
188 createDelegateModel();
189 } else {
190#if (QT_VERSION < QT_VERSION_CHECK(5, 1, 0))
191 disconnect(m_delegateModel, SIGNAL(modelUpdated(QQuickChangeSet,bool)), this, SLOT(onModelUpdated(QQuickChangeSet,bool)));
192 }
193 m_delegateModel->setModel(QVariant::fromValue<QAbstractItemModel *>(model));
194 connect(m_delegateModel, SIGNAL(modelUpdated(QQuickChangeSet,bool)), this, SLOT(onModelUpdated(QQuickChangeSet,bool)));
195#else
196 disconnect(m_delegateModel, SIGNAL(modelUpdated(QQmlChangeSet,bool)), this, SLOT(onModelUpdated(QQmlChangeSet,bool)));
197 }
198 m_delegateModel->setModel(QVariant::fromValue<QAbstractItemModel *>(model));
199 connect(m_delegateModel, SIGNAL(modelUpdated(QQmlChangeSet,bool)), this, SLOT(onModelUpdated(QQmlChangeSet,bool)));
200#endif
201 Q_EMIT modelChanged();
202 // TODO?
203// Q_EMIT contentHeightChanged();
204// Q_EMIT contentYChanged();
205 }
208QQmlComponent *ListViewWithPageHeader::delegate() const
210 return m_delegateModel ? m_delegateModel->delegate() : nullptr;
213void ListViewWithPageHeader::setDelegate(QQmlComponent *delegate)
215 if (delegate != this->delegate()) {
216 if (!m_delegateModel) {
217 createDelegateModel();
218 }
220 // Cleanup the existing items
221 Q_FOREACH(ListItem *item, m_visibleItems)
222 releaseItem(item);
223 m_visibleItems.clear();
224 m_firstVisibleIndex = -1;
225 adjustMinYExtent();
226 setContentY(0);
227 m_clipItem->setY(0);
228 if (m_topSectionItem) {
229 QQuickItemPrivate::get(m_topSectionItem)->setCulled(true);
230 }
232 m_delegateModel->setDelegate(delegate);
234 Q_EMIT delegateChanged();
235 m_delegateValidated = false;
236 m_contentHeightDirty = true;
237 polish();
238 }
241QQuickItem *ListViewWithPageHeader::header() const
243 return m_headerItem;
246void ListViewWithPageHeader::setHeader(QQuickItem *headerItem)
248 if (m_headerItem != headerItem) {
249 qreal oldHeaderHeight = 0;
250 qreal oldHeaderY = 0;
251 if (m_headerItem) {
252 oldHeaderHeight = m_headerItem->height();
253 oldHeaderY = m_headerItem->y();
254 m_headerItem->setParentItem(nullptr);
255 }
256 m_headerItem = headerItem;
257 if (m_headerItem) {
258 m_headerItem->setParentItem(contentItem());
259 m_headerItem->setZ(1);
260 }
261 qreal newHeaderHeight = m_headerItem ? m_headerItem->height() : 0;
262 if (!m_visibleItems.isEmpty() && newHeaderHeight != oldHeaderHeight) {
263 headerHeightChanged(newHeaderHeight, oldHeaderHeight, oldHeaderY);
264 polish();
265 m_contentHeightDirty = true;
266 }
267 Q_EMIT headerChanged();
268 }
271QQmlComponent *ListViewWithPageHeader::sectionDelegate() const
273 return m_sectionDelegate;
276void ListViewWithPageHeader::setSectionDelegate(QQmlComponent *delegate)
278 if (delegate != m_sectionDelegate) {
279 // TODO clean existing sections
281 m_sectionDelegate = delegate;
283 m_topSectionItem = getSectionItem(-1, QString());
284 m_topSectionItem->setZ(3);
285 QQuickItemPrivate::get(m_topSectionItem)->setCulled(true);
287 // TODO create sections for existing items
289 Q_EMIT sectionDelegateChanged();
290 }
293QString ListViewWithPageHeader::sectionProperty() const
295 return m_sectionProperty;
298void ListViewWithPageHeader::setSectionProperty(const QString &property)
300 if (property != m_sectionProperty) {
301 m_sectionProperty = property;
303 updateWatchedRoles();
305 // TODO recreate sections
307 Q_EMIT sectionPropertyChanged();
308 }
311bool ListViewWithPageHeader::forceNoClip() const
313 return m_forceNoClip;
316void ListViewWithPageHeader::setForceNoClip(bool noClip)
318 if (noClip != m_forceNoClip) {
319 m_forceNoClip = noClip;
320 updateClipItem();
321 Q_EMIT forceNoClipChanged();
322 }
325void ListViewWithPageHeader::positionAtBeginning()
327 qreal headerHeight = (m_headerItem ? m_headerItem->height() : 0);
328 if (m_firstVisibleIndex != 0) {
329 // TODO This could be optimized by trying to reuse the interesection
330 // of items that may end up intersecting between the existing
331 // m_visibleItems and the items we are creating in the next loop
332 Q_FOREACH(ListItem *item, m_visibleItems)
333 releaseItem(item);
334 m_visibleItems.clear();
335 m_firstVisibleIndex = -1;
337 // Create the item 0, it will be already correctly positioned at createItem()
338 m_clipItem->setY(0);
339 ListItem *item = createItem(0, false);
340 // Create the subsequent items
341 int modelIndex = 1;
342 qreal pos = item->y() + item->height();
343 const qreal buffer = height() * bufferRatio;
344 const qreal bufferTo = height() + buffer;
345 while (modelIndex < m_delegateModel->count() && pos <= bufferTo) {
346 if (!(item = createItem(modelIndex, false)))
347 break;
348 pos += item->height();
349 ++modelIndex;
350 }
352 m_previousContentY = m_visibleItems.first()->y() - headerHeight;
353 }
354 setContentY(m_visibleItems.first()->y() + m_clipItem->y() - headerHeight);
357void ListViewWithPageHeader::showHeader()
359 if (!m_headerItem)
360 return;
362 auto to = qMax(-minYExtent(), contentY() - m_headerItem->height() + m_headerItemShownHeight);
363 if (to != contentY()) {
364 const bool headerShownByItsOwn = contentY() < m_headerItem->y() + m_headerItem->height();
365 if (headerShownByItsOwn && m_headerItemShownHeight == 0) {
366 // We are not clipping since we are just at the top of the viewport
367 // but because of the showHeader animation we will need to, so
368 // enable the clipping without logically moving the items
369 m_headerItemShownHeight = m_headerItem->y() + m_headerItem->height() - contentY();
370 if (!m_visibleItems.isEmpty()) {
371 updateClipItem();
372 ListItem *firstItem = m_visibleItems.first();
373 firstItem->setY(firstItem->y() - m_headerItemShownHeight);
374 layout();
375 }
376 }
377 m_contentYAnimation->setTo(to);
378 contentYAnimationIsShownHeader = true;
379 m_contentYAnimation->start();
380 }
383QQuickItem *ListViewWithPageHeader::item(int modelIndex) const
385 ListItem *item = itemAtIndex(modelIndex);
386 if (item)
387 return item->m_item;
388 else
389 return nullptr;
392void ListViewWithPageHeader::maximizeVisibleArea(int modelIndex)
394 ListItem *listItem = itemAtIndex(modelIndex);
395 if (listItem)
396 {
397 // Check if we can scroll the list up to show more stuff
398 if (m_clipItem->y() + listItem->y() > contentY() && m_clipItem->y() + listItem->y() + listItem->height() > contentY() + height()) {
399 m_contentYAnimation->setTo(m_clipItem->y() + listItem->y());
400 contentYAnimationIsShownHeader = false;
401 m_contentYAnimation->start();
402 }
403 }
406qreal ListViewWithPageHeader::minYExtent() const
408// qDebug() << "ListViewWithPageHeader::minYExtent" << m_minYExtent;
409 return m_minYExtent;
412void ListViewWithPageHeader::componentComplete()
414 if (m_delegateModel)
415 m_delegateModel->componentComplete();
417 QQuickFlickable::componentComplete();
419 polish();
422void ListViewWithPageHeader::viewportMoved(Qt::Orientations orient)
424 QQuickFlickable::viewportMoved(orient);
425// qDebug() << "ListViewWithPageHeader::viewportMoved" << contentY();
426 qreal diff = m_previousContentY - contentY();
427 if (m_headerItem) {
428 auto oldHeaderItemShownHeight = m_headerItemShownHeight;
429 if (contentY() < -m_minYExtent) {
430 // Stick the header item to the top when dragging down
431 m_headerItem->setY(contentY());
432 m_headerItem->setHeight(m_headerItem->implicitHeight() + (-m_minYExtent - contentY()));
433 } else {
434 m_headerItem->setHeight(m_headerItem->implicitHeight());
435 // We are going down (but it's not because of the rebound at the end)
436 // (but the header was not shown by it's own position)
437 // or the header is partially shown
438 const bool scrolledUp = m_previousContentY > contentY();
439 const bool notRebounding = contentY() + height() < contentHeight();
440 const bool notShownByItsOwn = contentY() + diff > m_headerItem->y() + m_headerItem->height();
442 if (!scrolledUp && contentY() == -m_minYExtent) {
443 m_headerItemShownHeight = 0;
444 m_headerItem->setY(contentY());
445 } else if ((scrolledUp && notRebounding && notShownByItsOwn) || (m_headerItemShownHeight > 0)) {
446 m_headerItemShownHeight += diff;
447 if (contentY() == -m_minYExtent) {
448 m_headerItemShownHeight = 0;
449 } else {
450 m_headerItemShownHeight = qBound(static_cast<qreal>(0.), m_headerItemShownHeight, m_headerItem->height());
451 }
452 if (m_headerItemShownHeight > 0) {
453 m_headerItem->setY(contentY() - m_headerItem->height() + m_headerItemShownHeight);
454 } else {
455 m_headerItem->setY(-m_minYExtent);
456 }
457 }
458 }
459 // We will be changing the clip item, need to accomadate for it
460 // otherwise we move the firstItem down/up twice (unless the
461 // show header animation is running, where we want to keep the viewport stable)
462 if (!(m_contentYAnimation->isRunning() && contentYAnimationIsShownHeader)) {
463 diff += oldHeaderItemShownHeight - m_headerItemShownHeight;
464 } else {
465 diff = -diff;
466 }
467 }
468 if (!m_visibleItems.isEmpty()) {
469 updateClipItem();
470 ListItem *firstItem = m_visibleItems.first();
471 firstItem->setY(firstItem->y() + diff);
472 if (m_contentYAnimation->isRunning() && contentYAnimationIsShownHeader) {
473 adjustMinYExtent();
474 }
475 }
477 m_previousContentY = contentY();
478 layout();
479 polish();
482void ListViewWithPageHeader::createDelegateModel()
484#if (QT_VERSION < QT_VERSION_CHECK(5, 1, 0))
485 m_delegateModel = new QQuickVisualDataModel(qmlContext(this), this);
486 connect(m_delegateModel, SIGNAL(createdItem(int,QQuickItem*)), this, SLOT(itemCreated(int,QQuickItem*)));
487#else
488 m_delegateModel = new QQmlDelegateModel(qmlContext(this), this);
489 connect(m_delegateModel, SIGNAL(createdItem(int,QObject*)), this, SLOT(itemCreated(int,QObject*)));
490#endif
491 if (isComponentComplete())
492 m_delegateModel->componentComplete();
493 updateWatchedRoles();
496void ListViewWithPageHeader::refill()
498 if (m_inLayout) {
499 return;
500 }
501 if (!isComponentComplete()) {
502 return;
503 }
505 const qreal buffer = height() * bufferRatio;
506 const qreal from = contentY();
507 const qreal to = from + height();
508 const qreal bufferFrom = from - buffer;
509 const qreal bufferTo = to + buffer;
511 bool added = addVisibleItems(from, to, false);
512 bool removed = removeNonVisibleItems(bufferFrom, bufferTo);
513 added |= addVisibleItems(bufferFrom, bufferTo, true);
515 if (added || removed) {
516 m_contentHeightDirty = true;
517 }
520bool ListViewWithPageHeader::addVisibleItems(qreal fillFrom, qreal fillTo, bool asynchronous)
522 if (!delegate())
523 return false;
525 if (m_delegateModel->count() == 0)
526 return false;
528 ListItem *item;
529// qDebug() << "ListViewWithPageHeader::addVisibleItems" << fillFrom << fillTo << asynchronous;
531 int modelIndex = 0;
532 qreal pos = 0;
533 if (!m_visibleItems.isEmpty()) {
534 modelIndex = m_firstVisibleIndex + m_visibleItems.count();
535 item = m_visibleItems.last();
536 pos = item->y() + item->height() + m_clipItem->y();
537 }
538 bool changed = false;
539// qDebug() << (modelIndex < m_delegateModel->count()) << pos << fillTo;
540 while (modelIndex < m_delegateModel->count() && pos <= fillTo) {
541// qDebug() << "refill: append item" << modelIndex << "pos" << pos << "asynchronous" << asynchronous;
542 if (!(item = createItem(modelIndex, asynchronous)))
543 break;
544 pos += item->height();
545 ++modelIndex;
546 changed = true;
547 }
549 modelIndex = 0;
550 pos = 0;
551 if (!m_visibleItems.isEmpty()) {
552 modelIndex = m_firstVisibleIndex - 1;
553 item = m_visibleItems.first();
554 pos = item->y() + m_clipItem->y();
555 }
556 while (modelIndex >= 0 && pos > fillFrom) {
557// qDebug() << "refill: prepend item" << modelIndex << "pos" << pos << "fillFrom" << fillFrom << "asynchronous" << asynchronous;
558 if (!(item = createItem(modelIndex, asynchronous)))
559 break;
560 pos -= item->height();
561 --modelIndex;
562 changed = true;
563 }
565 return changed;
568void ListViewWithPageHeader::reallyReleaseItem(ListItem *listItem)
570 QQuickItem *item = listItem->m_item;
571#if (QT_VERSION < QT_VERSION_CHECK(5, 1, 0))
572 QQuickVisualModel::ReleaseFlags flags = m_delegateModel->release(item);
573 if (flags & QQuickVisualModel::Destroyed) {
574#else
575 QQmlDelegateModel::ReleaseFlags flags = m_delegateModel->release(item);
576 if (flags & QQmlDelegateModel::Destroyed) {
577#endif
578 item->setParentItem(nullptr);
579 }
580 delete listItem->m_sectionItem;
581 delete listItem;
584void ListViewWithPageHeader::releaseItem(ListItem *listItem)
586 QQuickItemPrivate *itemPrivate = QQuickItemPrivate::get(listItem->m_item);
587 itemPrivate->removeItemChangeListener(this, QQuickItemPrivate::Geometry);
588 m_itemsToRelease << listItem;
591void ListViewWithPageHeader::updateWatchedRoles()
593 if (m_delegateModel) {
594 QList<QByteArray> roles;
595 if (!m_sectionProperty.isEmpty())
596 roles << m_sectionProperty.toUtf8();
597 m_delegateModel->setWatchedRoles(roles);
598 }
601QQuickItem *ListViewWithPageHeader::getSectionItem(int modelIndex, bool alreadyInserted)
603 if (!m_sectionDelegate)
604 return nullptr;
606 const QString section = m_delegateModel->stringValue(modelIndex, m_sectionProperty);
607 if (modelIndex > 0) {
608 const QString prevSection = m_delegateModel->stringValue(modelIndex - 1, m_sectionProperty);
609 if (section == prevSection)
610 return nullptr;
611 }
612 if (modelIndex + 1 < model()->rowCount() && !alreadyInserted) {
613 // Already inserted items can't steal next section header
614 const QString nextSection = m_delegateModel->stringValue(modelIndex + 1, m_sectionProperty);
615 if (section == nextSection) {
616 // Steal the section header
617 ListItem *nextItem = itemAtIndex(modelIndex); // Not +1 since not yet inserted into m_visibleItems
618 if (nextItem) {
619 QQuickItem *sectionItem = nextItem->m_sectionItem;
620 nextItem->m_sectionItem = nullptr;
621 return sectionItem;
622 }
623 }
624 }
626 return getSectionItem(modelIndex, section);
629QQuickItem *ListViewWithPageHeader::getSectionItem(int modelIndex, const QString &sectionText)
631 QQuickItem *sectionItem = nullptr;
633 QQmlContext *creationContext = m_sectionDelegate->creationContext();
634 QQmlContext *context = new QQmlContext(creationContext ? creationContext : qmlContext(this));
635 context->setContextProperty(QLatin1String("section"), sectionText);
636 context->setContextProperty(QLatin1String("delegateIndex"), modelIndex);
637 QObject *nobj = m_sectionDelegate->beginCreate(context);
638 if (nobj) {
639 QQml_setParent_noEvent(context, nobj);
640 sectionItem = qobject_cast<QQuickItem *>(nobj);
641 if (!sectionItem) {
642 delete nobj;
643 } else {
644 sectionItem->setZ(2);
645 QQml_setParent_noEvent(sectionItem, m_clipItem);
646 sectionItem->setParentItem(m_clipItem);
647 }
648 } else {
649 delete context;
650 }
651 m_sectionDelegate->completeCreate();
653 // TODO attach to sectionItem so we can accomodate to it changing its height
655 return sectionItem;
658bool ListViewWithPageHeader::removeNonVisibleItems(qreal bufferFrom, qreal bufferTo)
660// qDebug() << "ListViewWithPageHeader::removeNonVisibleItems" << bufferFrom << bufferTo;
661 // Do not remove items if we are overshooting up or down, since we'll come back
662 // to the "stable" position and delete/create items without any reason
663 if (contentY() < -m_minYExtent) {
664 return false;
665 } else if (contentY() + height() > contentHeight()) {
666 return false;
667 }
668 bool changed = false;
670 bool foundVisible = false;
671 int i = 0;
672 int removedItems = 0;
673 const auto oldFirstVisibleIndex = m_firstVisibleIndex;
674 while (i < m_visibleItems.count()) {
675 ListItem *item = m_visibleItems[i];
676 const qreal pos = item->y() + m_clipItem->y();
677// qDebug() << i << pos << (pos + item->height()) << bufferFrom << bufferTo;
678 if (pos + item->height() < bufferFrom || pos > bufferTo) {
679// qDebug() << "Releasing" << i << (pos + item->height() < bufferFrom) << pos + item->height() << bufferFrom << (pos > bufferTo) << pos << bufferTo;
680 releaseItem(item);
681 m_visibleItems.removeAt(i);
682 changed = true;
683 ++removedItems;
684 } else {
685 if (!foundVisible) {
686 foundVisible = true;
687 const int itemIndex = m_firstVisibleIndex + removedItems + i;
688 m_firstVisibleIndex = itemIndex;
689 }
690 ++i;
691 }
692 }
693 if (m_firstVisibleIndex != oldFirstVisibleIndex) {
694 adjustMinYExtent();
695 }
697 return changed;
700ListViewWithPageHeader::ListItem *ListViewWithPageHeader::createItem(int modelIndex, bool asynchronous)
702// qDebug() << "CREATE ITEM" << modelIndex;
703 if (asynchronous && m_asyncRequestedIndex != -1)
704 return nullptr;
706 m_asyncRequestedIndex = -1;
707#if (QT_VERSION < QT_VERSION_CHECK(5, 1, 0))
708 QQuickItem *item = m_delegateModel->item(modelIndex, asynchronous);
709#else
710 QObject* object = m_delegateModel->object(modelIndex, asynchronous);
711 QQuickItem *item = qmlobject_cast<QQuickItem*>(object);
712#endif
713 if (!item) {
714#if (QT_VERSION < QT_VERSION_CHECK(5, 1, 0))
715 m_asyncRequestedIndex = modelIndex;
716#else
717 if (object) {
718 m_delegateModel->release(object);
719 if (!m_delegateValidated) {
720 m_delegateValidated = true;
721 QObject* delegateObj = delegate();
722 qmlInfo(delegateObj ? delegateObj : this) << "Delegate must be of Item type";
723 }
724 } else {
725 m_asyncRequestedIndex = modelIndex;
726 }
727#endif
728 return 0;
729 } else {
730// qDebug() << "ListViewWithPageHeader::createItem::We have the item" << modelIndex << item;
731 ListItem *listItem = new ListItem;
732 listItem->m_item = item;
733 listItem->m_sectionItem = getSectionItem(modelIndex, false /*Not yet inserted into m_visibleItems*/);
734 QQuickItemPrivate::get(item)->addItemChangeListener(this, QQuickItemPrivate::Geometry);
735 ListItem *prevItem = itemAtIndex(modelIndex - 1);
736 bool lostItem = false; // Is an item that we requested async but because of model changes
737 // it is no longer attached to any of the existing items (has no prev nor next item)
738 // nor is the first item
739 if (prevItem) {
740 listItem->setY(prevItem->y() + prevItem->height());
741 } else {
742 ListItem *currItem = itemAtIndex(modelIndex);
743 if (currItem) {
744 // There's something already in m_visibleItems at out index, meaning this is an insert, so attach to its top
745 listItem->setY(currItem->y() - listItem->height());
746 } else {
747 ListItem *nextItem = itemAtIndex(modelIndex + 1);
748 if (nextItem) {
749 listItem->setY(nextItem->y() - listItem->height());
750 } else if (modelIndex == 0 && m_headerItem) {
751 listItem->setY(m_headerItem->height());
752 } else if (!m_visibleItems.isEmpty()) {
753 lostItem = true;
754 }
755 }
756 }
757 if (lostItem) {
758 releaseItem(listItem);
759 listItem = nullptr;
760 } else {
761 listItem->setCulled(listItem->y() + listItem->height() + m_clipItem->y() < contentY() || listItem->y() + m_clipItem->y() >= contentY() + height());
762 if (m_visibleItems.isEmpty()) {
763 m_visibleItems << listItem;
764 } else {
765 m_visibleItems.insert(modelIndex - m_firstVisibleIndex, listItem);
766 }
767 if (m_firstVisibleIndex < 0 || modelIndex < m_firstVisibleIndex) {
768 m_firstVisibleIndex = modelIndex;
769 polish();
770 }
771 adjustMinYExtent();
772 m_contentHeightDirty = true;
773 }
774 return listItem;
775 }
778#if (QT_VERSION < QT_VERSION_CHECK(5, 1, 0))
779void ListViewWithPageHeader::itemCreated(int modelIndex, QQuickItem *item)
781#else
782void ListViewWithPageHeader::itemCreated(int modelIndex, QObject *object)
784 QQuickItem *item = qmlobject_cast<QQuickItem*>(object);
785 if (!item) {
786 qWarning() << "ListViewWithPageHeader::itemCreated got a non item for index" << modelIndex;
787 return;
788 }
789#endif
790// qDebug() << "ListViewWithPageHeader::itemCreated" << modelIndex << item;
792 item->setParentItem(m_clipItem);
793 QQmlContext *context = QQmlEngine::contextForObject(item)->parentContext();
794 context->setContextProperty(QLatin1String("ListViewWithPageHeader"), this);
795 context->setContextProperty(QLatin1String("heightToClip"), QVariant::fromValue<int>(0));
796 if (modelIndex == m_asyncRequestedIndex) {
797 createItem(modelIndex, false);
798 refill();
799 }
802void ListViewWithPageHeader::updateClipItem()
804 m_clipItem->setHeight(height() - m_headerItemShownHeight);
805 m_clipItem->setY(contentY() + m_headerItemShownHeight);
806 m_clipItem->setClip(!m_forceNoClip && m_headerItemShownHeight > 0);
809void ListViewWithPageHeader::onContentHeightChanged()
811 updateClipItem();
814void ListViewWithPageHeader::onContentWidthChanged()
816 m_clipItem->setWidth(contentItem()->width());
819void ListViewWithPageHeader::onHeightChanged()
821 polish();
825#if (QT_VERSION < QT_VERSION_CHECK(5, 1, 0))
826void ListViewWithPageHeader::onModelUpdated(const QQuickChangeSet &changeSet, bool /*reset*/)
827#else
828void ListViewWithPageHeader::onModelUpdated(const QQmlChangeSet &changeSet, bool /*reset*/)
829#endif
831 // TODO Do something with reset
832// qDebug() << "ListViewWithPageHeader::onModelUpdated" << changeSet << reset;
833 const auto oldFirstVisibleIndex = m_firstVisibleIndex;
835#if (QT_VERSION < QT_VERSION_CHECK(5, 1, 0))
836 Q_FOREACH(const QQuickChangeSet::Remove &remove, changeSet.removes()) {
837#else
838 Q_FOREACH(const QQmlChangeSet::Remove &remove, changeSet.removes()) {
839#endif
840// qDebug() << "ListViewWithPageHeader::onModelUpdated Remove" << remove.index << remove.count;
841 if (remove.index + remove.count > m_firstVisibleIndex && remove.index < m_firstVisibleIndex + m_visibleItems.count()) {
842 const qreal oldFirstValidIndexPos = m_visibleItems.first()->y();
843 // If all the items we are removing are either not created or culled
844 // we have to grow down to avoid viewport changing
845 bool growDown = true;
846 for (int i = 0; growDown && i < remove.count; ++i) {
847 const int modelIndex = remove.index + i;
848 ListItem *item = itemAtIndex(modelIndex);
849 if (item && !item->culled()) {
850 growDown = false;
851 }
852 }
853 for (int i = remove.count - 1; i >= 0; --i) {
854 const int visibleIndex = remove.index + i - m_firstVisibleIndex;
855 if (visibleIndex >= 0 && visibleIndex < m_visibleItems.count()) {
856 ListItem *item = m_visibleItems[visibleIndex];
857 // Pass the section item down if needed
858 if (item->m_sectionItem && visibleIndex + 1 < m_visibleItems.count()) {
859 ListItem *nextItem = m_visibleItems[visibleIndex + 1];
860 if (!nextItem->m_sectionItem) {
861 nextItem->m_sectionItem = item->m_sectionItem;
862 item->m_sectionItem = nullptr;
863 }
864 }
865 releaseItem(item);
866 m_visibleItems.removeAt(visibleIndex);
867 }
868 }
869 if (growDown) {
870 adjustMinYExtent();
871 } else if (remove.index <= m_firstVisibleIndex) {
872 if (!m_visibleItems.isEmpty()) {
873 // We removed the first item that is the one that positions the rest
874 // position the new first item correctly
875 m_visibleItems.first()->setY(oldFirstValidIndexPos);
876 } else {
877 m_firstVisibleIndex = -1;
878 }
879 }
880 } else if (remove.index + remove.count <= m_firstVisibleIndex) {
881 m_firstVisibleIndex -= remove.count;
882 }
883 for (int i = remove.count - 1; i >= 0; --i) {
884 const int modelIndex = remove.index + i;
885 if (modelIndex == m_asyncRequestedIndex) {
886 m_asyncRequestedIndex = -1;
887 } else if (modelIndex < m_asyncRequestedIndex) {
888 m_asyncRequestedIndex--;
889 }
890 }
891 }
893#if (QT_VERSION < QT_VERSION_CHECK(5, 1, 0))
894 Q_FOREACH(const QQuickChangeSet::Insert &insert, changeSet.inserts()) {
895#else
896 Q_FOREACH(const QQmlChangeSet::Insert &insert, changeSet.inserts()) {
897#endif
898// qDebug() << "ListViewWithPageHeader::onModelUpdated Insert" << insert.index << insert.count;
899 const bool insertingInValidIndexes = insert.index > m_firstVisibleIndex && insert.index < m_firstVisibleIndex + m_visibleItems.count();
900 const bool firstItemWithViewOnTop = insert.index == 0 && m_firstVisibleIndex == 0 && m_visibleItems.first()->y() + m_clipItem->y() > contentY();
901 if (insertingInValidIndexes || firstItemWithViewOnTop)
902 {
903 // If the items we are adding won't be really visible
904 // we grow up instead of down to not change the viewport
905 bool growUp = false;
906 if (!firstItemWithViewOnTop) {
907 for (int i = 0; i < m_visibleItems.count(); ++i) {
908 if (!m_visibleItems[i]->culled()) {
909 if (insert.index <= m_firstVisibleIndex + i) {
910 growUp = true;
911 }
912 break;
913 }
914 }
915 }
917 const qreal oldFirstValidIndexPos = m_visibleItems.first()->y();
918 for (int i = insert.count - 1; i >= 0; --i) {
919 const int modelIndex = insert.index + i;
920 ListItem *item = createItem(modelIndex, false);
921 if (growUp) {
922 ListItem *firstItem = m_visibleItems.first();
923 firstItem->setY(firstItem->y() - item->height());
924 adjustMinYExtent();
925 }
926 // Adding an item may break a "same section" chain, so check
927 // if we need adding a new section item
928 if (m_sectionDelegate) {
929 ListItem *nextItem = itemAtIndex(modelIndex + 1);
930 if (nextItem && !nextItem->m_sectionItem) {
931 nextItem->m_sectionItem = getSectionItem(modelIndex + 1, true /* alredy inserted into m_visibleItems*/);
932 if (growUp && nextItem->m_sectionItem) {
933 ListItem *firstItem = m_visibleItems.first();
934 firstItem->setY(firstItem->y() - nextItem->m_sectionItem->height());
935 adjustMinYExtent();
936 }
937 }
938 }
939 }
940 if (firstItemWithViewOnTop) {
941 ListItem *firstItem = m_visibleItems.first();
942 firstItem->setY(oldFirstValidIndexPos);
943 }
944 } else if (insert.index <= m_firstVisibleIndex) {
945 m_firstVisibleIndex += insert.count;
946 }
948 for (int i = insert.count - 1; i >= 0; --i) {
949 const int modelIndex = insert.index + i;
950 if (modelIndex <= m_asyncRequestedIndex) {
951 m_asyncRequestedIndex++;
952 }
953 }
954 }
956 if (m_firstVisibleIndex != oldFirstVisibleIndex) {
957 adjustMinYExtent();
958 }
960 for (int i = 0; i < m_visibleItems.count(); ++i) {
961 ListItem *item = m_visibleItems[i];
962 if (item->m_sectionItem) {
963 QQmlContext *context = QQmlEngine::contextForObject(item->m_sectionItem)->parentContext();
964 context->setContextProperty(QLatin1String("delegateIndex"), m_firstVisibleIndex + i);
965 }
966 }
968 layout();
969 polish();
970 m_contentHeightDirty = true;
973void ListViewWithPageHeader::onShowHeaderAnimationFinished()
975 m_contentHeightDirty = true;
976 polish();
979void ListViewWithPageHeader::itemGeometryChanged(QQuickItem * /*item*/, const QRectF &newGeometry, const QRectF &oldGeometry)
981 const qreal heightDiff = newGeometry.height() - oldGeometry.height();
982 if (heightDiff != 0) {
983 if (oldGeometry.y() + oldGeometry.height() + m_clipItem->y() < contentY() && !m_visibleItems.isEmpty()) {
984 ListItem *firstItem = m_visibleItems.first();
985 firstItem->setY(firstItem->y() - heightDiff);
986 adjustMinYExtent();
987 layout();
988 }
989 refill();
990 adjustMinYExtent();
991 polish();
992 m_contentHeightDirty = true;
993 }
996void ListViewWithPageHeader::headerHeightChanged(qreal newHeaderHeight, qreal oldHeaderHeight, qreal oldHeaderY)
998 const qreal heightDiff = newHeaderHeight - oldHeaderHeight;
999 if (m_headerItemShownHeight > 0) {
1000 // If the header is shown because of the clip
1001 // Change its size
1002 m_headerItemShownHeight += heightDiff;
1003 m_headerItemShownHeight = qBound(static_cast<qreal>(0.), m_headerItemShownHeight, newHeaderHeight);
1004 updateClipItem();
1005 adjustMinYExtent();
1006 } else {
1007 if (oldHeaderY + oldHeaderHeight > contentY()) {
1008 // If the header is shown because its position
1009 // Change its size
1010 ListItem *firstItem = m_visibleItems.first();
1011 firstItem->setY(firstItem->y() + heightDiff);
1012 layout();
1013 } else {
1014 // If the header is not on screen, just change the start of the list
1015 // so the viewport is not changed
1016 adjustMinYExtent();
1022void ListViewWithPageHeader::adjustMinYExtent()
1024 if (m_visibleItems.isEmpty()) {
1025 m_minYExtent = 0;
1026 } else {
1027 qreal nonCreatedHeight = 0;
1028 if (m_firstVisibleIndex != 0) {
1029 // Calculate the average height of items to estimate the position of the list start
1030 const int visibleItems = m_visibleItems.count();
1031 qreal visibleItemsHeight = 0;
1032 Q_FOREACH(ListItem *item, m_visibleItems) {
1033 visibleItemsHeight += item->height();
1035 nonCreatedHeight = m_firstVisibleIndex * visibleItemsHeight / visibleItems;
1036// qDebug() << m_firstVisibleIndex << visibleItemsHeight << visibleItems << nonCreatedHeight;
1038 m_minYExtent = nonCreatedHeight - m_visibleItems.first()->y() - m_clipItem->y() + (m_headerItem ? m_headerItem->implicitHeight() : 0);
1042ListViewWithPageHeader::ListItem *ListViewWithPageHeader::itemAtIndex(int modelIndex) const
1044 const int visibleIndexedModelIndex = modelIndex - m_firstVisibleIndex;
1045 if (visibleIndexedModelIndex >= 0 && visibleIndexedModelIndex < m_visibleItems.count())
1046 return m_visibleItems[visibleIndexedModelIndex];
1048 return nullptr;
1051void ListViewWithPageHeader::layout()
1053 if (m_inLayout)
1054 return;
1056 m_inLayout = true;
1057 if (!m_visibleItems.isEmpty()) {
1058 const qreal visibleFrom = contentY() - m_clipItem->y() + m_headerItemShownHeight;
1059 const qreal visibleTo = contentY() + height() - m_clipItem->y();
1061 qreal pos = m_visibleItems.first()->y();
1063// qDebug() << "ListViewWithPageHeader::layout Updating positions and heights. contentY" << contentY() << "minYExtent" << minYExtent();
1064 int firstReallyVisibleItem = -1;
1065 int modelIndex = m_firstVisibleIndex;
1066 Q_FOREACH(ListItem *item, m_visibleItems) {
1067 const bool cull = pos + item->height() < visibleFrom || pos >= visibleTo;
1068 item->setCulled(cull);
1069 item->setY(pos);
1070 if (!cull && firstReallyVisibleItem == -1) {
1071 firstReallyVisibleItem = modelIndex;
1072 if (m_topSectionItem) {
1073 // Positing the top section sticky item is a two step process
1074 // First we set it either we cull it (because it doesn't need to be sticked to the top)
1075 // or stick it to the top
1076 // Then after the loop we'll make sure that if there's another section just below it
1077 // pushed the sticky section up to make it disappear
1078 const qreal topSectionStickPos = m_headerItemShownHeight + contentY() - m_clipItem->y();
1079 if (topSectionStickPos <= pos) {
1080 QQuickItemPrivate::get(m_topSectionItem)->setCulled(true);
1081 if (item->m_sectionItem) {
1082 // This seems it should happen since why would we cull the top section
1083 // if the first visible item has no section header? This only happens briefly
1084 // when increasing the height of a list that is at the bottom, the m_topSectionItem
1085 // gets shown shortly in the next polish call
1086 QQuickItemPrivate::get(item->m_sectionItem)->setCulled(false);
1088 } else {
1089 // Update the top sticky section header
1090 const QString section = m_delegateModel->stringValue(modelIndex, m_sectionProperty);
1091 QQmlContext *context = QQmlEngine::contextForObject(m_topSectionItem)->parentContext();
1092 context->setContextProperty(QLatin1String("section"), section);
1094 QQuickItemPrivate::get(m_topSectionItem)->setCulled(false);
1095 m_topSectionItem->setY(topSectionStickPos);
1096 int delegateIndex = modelIndex;
1097 // Look for the first index with this section text
1098 while (delegateIndex > 0) {
1099 const QString prevSection = m_delegateModel->stringValue(delegateIndex - 1, m_sectionProperty);
1100 if (prevSection != section)
1101 break;
1102 delegateIndex--;
1104 context->setContextProperty(QLatin1String("delegateIndex"), delegateIndex);
1105 if (item->m_sectionItem) {
1106 QQuickItemPrivate::get(item->m_sectionItem)->setCulled(true);
1111 QQmlContext *context = QQmlEngine::contextForObject(item->m_item)->parentContext();
1112 const qreal clipFrom = visibleFrom + (!item->m_sectionItem && m_topSectionItem && !QQuickItemPrivate::get(m_topSectionItem)->culled ? m_topSectionItem->height() : 0);
1113 if (!cull && pos < clipFrom) {
1114 context->setContextProperty(QLatin1String("heightToClip"), clipFrom - pos);
1115 } else {
1116 context->setContextProperty(QLatin1String("heightToClip"), QVariant::fromValue<int>(0));
1118// qDebug() << "ListViewWithPageHeader::layout" << item->m_item;
1119 pos += item->height();
1120 ++modelIndex;
1123 // Second step of section sticky item positioning
1124 // Look at the next section header, check if it's pushing up the sticky one
1125 if (m_topSectionItem) {
1126 if (firstReallyVisibleItem >= 0) {
1127 for (int i = firstReallyVisibleItem - m_firstVisibleIndex + 1; i < m_visibleItems.count(); ++i) {
1128 ListItem *item = m_visibleItems[i];
1129 if (item->m_sectionItem) {
1130 if (m_topSectionItem->y() + m_topSectionItem->height() > item->y()) {
1131 m_topSectionItem->setY(item->y() - m_topSectionItem->height());
1133 break;
1139 m_inLayout = false;
1142void ListViewWithPageHeader::updatePolish()
1144 Q_FOREACH(ListItem *item, m_itemsToRelease)
1145 reallyReleaseItem(item);
1146 m_itemsToRelease.clear();
1148 if (!model())
1149 return;
1151 layout();
1153 refill();
1155 if (m_contentHeightDirty) {
1156 qreal contentHeight;
1157 if (m_visibleItems.isEmpty()) {
1158 contentHeight = m_headerItem ? m_headerItem->height() : 0;
1159 } else {
1160 const int modelCount = model()->rowCount();
1161 const int visibleItems = m_visibleItems.count();
1162 const int lastValidIndex = m_firstVisibleIndex + visibleItems - 1;
1163 qreal nonCreatedHeight = 0;
1164 if (lastValidIndex != modelCount - 1) {
1165 const int visibleItems = m_visibleItems.count();
1166 qreal visibleItemsHeight = 0;
1167 Q_FOREACH(ListItem *item, m_visibleItems) {
1168 visibleItemsHeight += item->height();
1170 const int unknownSizes = modelCount - (m_firstVisibleIndex + visibleItems);
1171 nonCreatedHeight = unknownSizes * visibleItemsHeight / visibleItems;
1173 ListItem *item = m_visibleItems.last();
1174 contentHeight = nonCreatedHeight + item->y() + item->height() + m_clipItem->y();
1175 if (m_firstVisibleIndex != 0) {
1176 // Make sure that if we are shrinking we tell the view we still fit
1177 m_minYExtent = qMax(m_minYExtent, -(contentHeight - height()));
1181 m_contentHeightDirty = false;
1182 setContentHeight(contentHeight);
1186#include "moc_listviewwithpageheader.cpp"