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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 contentYAnimationType = ContentYAnimationShowHeader;
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 const auto listItemY = m_clipItem->y() + listItem->y();
398 if (listItemY > contentY() && listItemY + listItem->height() > contentY() + height()) {
399 // we can scroll the list up to show more stuff
400 const auto to = qMin(listItemY, listItemY + listItem->height() - height());
401 m_contentYAnimation->setTo(to);
402 contentYAnimationType = ContentYAnimationMaximizeVisibleArea;
403 m_contentYAnimation->start();
404 } else if (listItemY < contentY() && listItemY + listItem->height() < contentY() + height()) {
405 // we can scroll the list down to show more stuff
406 const auto to = qMax(listItemY, listItemY + listItem->height() - height());
407 m_contentYAnimation->setTo(to);
408 contentYAnimationType = ContentYAnimationMaximizeVisibleArea;
409 m_contentYAnimation->start();
410 }
411 }
414qreal ListViewWithPageHeader::minYExtent() const
416// qDebug() << "ListViewWithPageHeader::minYExtent" << m_minYExtent;
417 return m_minYExtent;
420void ListViewWithPageHeader::componentComplete()
422 if (m_delegateModel)
423 m_delegateModel->componentComplete();
425 QQuickFlickable::componentComplete();
427 polish();
430void ListViewWithPageHeader::viewportMoved(Qt::Orientations orient)
432 QQuickFlickable::viewportMoved(orient);
433// qDebug() << "ListViewWithPageHeader::viewportMoved" << contentY();
434 qreal diff = m_previousContentY - contentY();
435 const bool showHeaderAnimationRunning = m_contentYAnimation->isRunning() && contentYAnimationType == ContentYAnimationShowHeader;
436 if (m_headerItem) {
437 auto oldHeaderItemShownHeight = m_headerItemShownHeight;
438 if (contentY() < -m_minYExtent) {
439 // Stick the header item to the top when dragging down
440 m_headerItem->setY(contentY());
441 m_headerItem->setHeight(m_headerItem->implicitHeight() + (-m_minYExtent - contentY()));
442 } else {
443 m_headerItem->setHeight(m_headerItem->implicitHeight());
444 // We are going down (but it's not because of the rebound at the end)
445 // (but the header was not shown by it's own position)
446 // or the header is partially shown and we are not doing a maximizeVisibleArea either
447 const bool scrolledUp = m_previousContentY > contentY();
448 const bool notRebounding = contentY() + height() < contentHeight();
449 const bool notShownByItsOwn = contentY() + diff > m_headerItem->y() + m_headerItem->height();
450 const bool maximizeVisibleAreaRunning = m_contentYAnimation->isRunning() && contentYAnimationType == ContentYAnimationMaximizeVisibleArea;
452 if (!scrolledUp && contentY() == -m_minYExtent) {
453 m_headerItemShownHeight = 0;
454 m_headerItem->setY(contentY());
455 } else if ((scrolledUp && notRebounding && notShownByItsOwn && !maximizeVisibleAreaRunning) || (m_headerItemShownHeight > 0)) {
456 m_headerItemShownHeight += diff;
457 if (contentY() == -m_minYExtent) {
458 m_headerItemShownHeight = 0;
459 } else {
460 m_headerItemShownHeight = qBound(static_cast<qreal>(0.), m_headerItemShownHeight, m_headerItem->height());
461 }
462 if (m_headerItemShownHeight > 0) {
463 m_headerItem->setY(contentY() - m_headerItem->height() + m_headerItemShownHeight);
464 } else {
465 m_headerItem->setY(-m_minYExtent);
466 }
467 }
468 }
469 // We will be changing the clip item, need to accomadate for it
470 // otherwise we move the firstItem down/up twice (unless the
471 // show header animation is running, where we want to keep the viewport stable)
472 if (!showHeaderAnimationRunning) {
473 diff += oldHeaderItemShownHeight - m_headerItemShownHeight;
474 } else {
475 diff = -diff;
476 }
477 }
478 if (!m_visibleItems.isEmpty()) {
479 updateClipItem();
480 ListItem *firstItem = m_visibleItems.first();
481 firstItem->setY(firstItem->y() + diff);
482 if (showHeaderAnimationRunning) {
483 adjustMinYExtent();
484 }
485 }
487 m_previousContentY = contentY();
488 layout();
489 polish();
492void ListViewWithPageHeader::createDelegateModel()
494#if (QT_VERSION < QT_VERSION_CHECK(5, 1, 0))
495 m_delegateModel = new QQuickVisualDataModel(qmlContext(this), this);
496 connect(m_delegateModel, SIGNAL(createdItem(int,QQuickItem*)), this, SLOT(itemCreated(int,QQuickItem*)));
497#else
498 m_delegateModel = new QQmlDelegateModel(qmlContext(this), this);
499 connect(m_delegateModel, SIGNAL(createdItem(int,QObject*)), this, SLOT(itemCreated(int,QObject*)));
500#endif
501 if (isComponentComplete())
502 m_delegateModel->componentComplete();
503 updateWatchedRoles();
506void ListViewWithPageHeader::refill()
508 if (m_inLayout) {
509 return;
510 }
511 if (!isComponentComplete()) {
512 return;
513 }
515 const qreal buffer = height() * bufferRatio;
516 const qreal from = contentY();
517 const qreal to = from + height();
518 const qreal bufferFrom = from - buffer;
519 const qreal bufferTo = to + buffer;
521 bool added = addVisibleItems(from, to, false);
522 bool removed = removeNonVisibleItems(bufferFrom, bufferTo);
523 added |= addVisibleItems(bufferFrom, bufferTo, true);
525 if (added || removed) {
526 m_contentHeightDirty = true;
527 }
530bool ListViewWithPageHeader::addVisibleItems(qreal fillFrom, qreal fillTo, bool asynchronous)
532 if (!delegate())
533 return false;
535 if (m_delegateModel->count() == 0)
536 return false;
538 ListItem *item;
539// qDebug() << "ListViewWithPageHeader::addVisibleItems" << fillFrom << fillTo << asynchronous;
541 int modelIndex = 0;
542 qreal pos = 0;
543 if (!m_visibleItems.isEmpty()) {
544 modelIndex = m_firstVisibleIndex + m_visibleItems.count();
545 item = m_visibleItems.last();
546 pos = item->y() + item->height() + m_clipItem->y();
547 }
548 bool changed = false;
549// qDebug() << (modelIndex < m_delegateModel->count()) << pos << fillTo;
550 while (modelIndex < m_delegateModel->count() && pos <= fillTo) {
551// qDebug() << "refill: append item" << modelIndex << "pos" << pos << "asynchronous" << asynchronous;
552 if (!(item = createItem(modelIndex, asynchronous)))
553 break;
554 pos += item->height();
555 ++modelIndex;
556 changed = true;
557 }
559 modelIndex = 0;
560 pos = 0;
561 if (!m_visibleItems.isEmpty()) {
562 modelIndex = m_firstVisibleIndex - 1;
563 item = m_visibleItems.first();
564 pos = item->y() + m_clipItem->y();
565 }
566 while (modelIndex >= 0 && pos > fillFrom) {
567// qDebug() << "refill: prepend item" << modelIndex << "pos" << pos << "fillFrom" << fillFrom << "asynchronous" << asynchronous;
568 if (!(item = createItem(modelIndex, asynchronous)))
569 break;
570 pos -= item->height();
571 --modelIndex;
572 changed = true;
573 }
575 return changed;
578void ListViewWithPageHeader::reallyReleaseItem(ListItem *listItem)
580 QQuickItem *item = listItem->m_item;
581#if (QT_VERSION < QT_VERSION_CHECK(5, 1, 0))
582 QQuickVisualModel::ReleaseFlags flags = m_delegateModel->release(item);
583 if (flags & QQuickVisualModel::Destroyed) {
584#else
585 QQmlDelegateModel::ReleaseFlags flags = m_delegateModel->release(item);
586 if (flags & QQmlDelegateModel::Destroyed) {
587#endif
588 item->setParentItem(nullptr);
589 }
590 delete listItem->m_sectionItem;
591 delete listItem;
594void ListViewWithPageHeader::releaseItem(ListItem *listItem)
596 QQuickItemPrivate *itemPrivate = QQuickItemPrivate::get(listItem->m_item);
597 itemPrivate->removeItemChangeListener(this, QQuickItemPrivate::Geometry);
598 m_itemsToRelease << listItem;
601void ListViewWithPageHeader::updateWatchedRoles()
603 if (m_delegateModel) {
604 QList<QByteArray> roles;
605 if (!m_sectionProperty.isEmpty())
606 roles << m_sectionProperty.toUtf8();
607 m_delegateModel->setWatchedRoles(roles);
608 }
611QQuickItem *ListViewWithPageHeader::getSectionItem(int modelIndex, bool alreadyInserted)
613 if (!m_sectionDelegate)
614 return nullptr;
616 const QString section = m_delegateModel->stringValue(modelIndex, m_sectionProperty);
617 if (modelIndex > 0) {
618 const QString prevSection = m_delegateModel->stringValue(modelIndex - 1, m_sectionProperty);
619 if (section == prevSection)
620 return nullptr;
621 }
622 if (modelIndex + 1 < model()->rowCount() && !alreadyInserted) {
623 // Already inserted items can't steal next section header
624 const QString nextSection = m_delegateModel->stringValue(modelIndex + 1, m_sectionProperty);
625 if (section == nextSection) {
626 // Steal the section header
627 ListItem *nextItem = itemAtIndex(modelIndex); // Not +1 since not yet inserted into m_visibleItems
628 if (nextItem) {
629 QQuickItem *sectionItem = nextItem->m_sectionItem;
630 nextItem->m_sectionItem = nullptr;
631 return sectionItem;
632 }
633 }
634 }
636 return getSectionItem(modelIndex, section);
639QQuickItem *ListViewWithPageHeader::getSectionItem(int modelIndex, const QString &sectionText)
641 QQuickItem *sectionItem = nullptr;
643 QQmlContext *creationContext = m_sectionDelegate->creationContext();
644 QQmlContext *context = new QQmlContext(creationContext ? creationContext : qmlContext(this));
645 context->setContextProperty(QLatin1String("section"), sectionText);
646 context->setContextProperty(QLatin1String("delegateIndex"), modelIndex);
647 QObject *nobj = m_sectionDelegate->beginCreate(context);
648 if (nobj) {
649 QQml_setParent_noEvent(context, nobj);
650 sectionItem = qobject_cast<QQuickItem *>(nobj);
651 if (!sectionItem) {
652 delete nobj;
653 } else {
654 sectionItem->setZ(2);
655 QQml_setParent_noEvent(sectionItem, m_clipItem);
656 sectionItem->setParentItem(m_clipItem);
657 }
658 } else {
659 delete context;
660 }
661 m_sectionDelegate->completeCreate();
663 // TODO attach to sectionItem so we can accomodate to it changing its height
665 return sectionItem;
668bool ListViewWithPageHeader::removeNonVisibleItems(qreal bufferFrom, qreal bufferTo)
670// qDebug() << "ListViewWithPageHeader::removeNonVisibleItems" << bufferFrom << bufferTo;
671 // Do not remove items if we are overshooting up or down, since we'll come back
672 // to the "stable" position and delete/create items without any reason
673 if (contentY() < -m_minYExtent) {
674 return false;
675 } else if (contentY() + height() > contentHeight()) {
676 return false;
677 }
678 bool changed = false;
680 bool foundVisible = false;
681 int i = 0;
682 int removedItems = 0;
683 const auto oldFirstVisibleIndex = m_firstVisibleIndex;
684 while (i < m_visibleItems.count()) {
685 ListItem *item = m_visibleItems[i];
686 const qreal pos = item->y() + m_clipItem->y();
687// qDebug() << i << pos << (pos + item->height()) << bufferFrom << bufferTo;
688 if (pos + item->height() < bufferFrom || pos > bufferTo) {
689// qDebug() << "Releasing" << i << (pos + item->height() < bufferFrom) << pos + item->height() << bufferFrom << (pos > bufferTo) << pos << bufferTo;
690 releaseItem(item);
691 m_visibleItems.removeAt(i);
692 changed = true;
693 ++removedItems;
694 } else {
695 if (!foundVisible) {
696 foundVisible = true;
697 const int itemIndex = m_firstVisibleIndex + removedItems + i;
698 m_firstVisibleIndex = itemIndex;
699 }
700 ++i;
701 }
702 }
703 if (m_firstVisibleIndex != oldFirstVisibleIndex) {
704 adjustMinYExtent();
705 }
707 return changed;
710ListViewWithPageHeader::ListItem *ListViewWithPageHeader::createItem(int modelIndex, bool asynchronous)
712// qDebug() << "CREATE ITEM" << modelIndex;
713 if (asynchronous && m_asyncRequestedIndex != -1)
714 return nullptr;
716 m_asyncRequestedIndex = -1;
717#if (QT_VERSION < QT_VERSION_CHECK(5, 1, 0))
718 QQuickItem *item = m_delegateModel->item(modelIndex, asynchronous);
719#else
720 QObject* object = m_delegateModel->object(modelIndex, asynchronous);
721 QQuickItem *item = qmlobject_cast<QQuickItem*>(object);
722#endif
723 if (!item) {
724#if (QT_VERSION < QT_VERSION_CHECK(5, 1, 0))
725 m_asyncRequestedIndex = modelIndex;
726#else
727 if (object) {
728 m_delegateModel->release(object);
729 if (!m_delegateValidated) {
730 m_delegateValidated = true;
731 QObject* delegateObj = delegate();
732 qmlInfo(delegateObj ? delegateObj : this) << "Delegate must be of Item type";
733 }
734 } else {
735 m_asyncRequestedIndex = modelIndex;
736 }
737#endif
738 return 0;
739 } else {
740// qDebug() << "ListViewWithPageHeader::createItem::We have the item" << modelIndex << item;
741 ListItem *listItem = new ListItem;
742 listItem->m_item = item;
743 listItem->m_sectionItem = getSectionItem(modelIndex, false /*Not yet inserted into m_visibleItems*/);
744 QQuickItemPrivate::get(item)->addItemChangeListener(this, QQuickItemPrivate::Geometry);
745 ListItem *prevItem = itemAtIndex(modelIndex - 1);
746 bool lostItem = false; // Is an item that we requested async but because of model changes
747 // it is no longer attached to any of the existing items (has no prev nor next item)
748 // nor is the first item
749 if (prevItem) {
750 listItem->setY(prevItem->y() + prevItem->height());
751 } else {
752 ListItem *currItem = itemAtIndex(modelIndex);
753 if (currItem) {
754 // There's something already in m_visibleItems at out index, meaning this is an insert, so attach to its top
755 listItem->setY(currItem->y() - listItem->height());
756 } else {
757 ListItem *nextItem = itemAtIndex(modelIndex + 1);
758 if (nextItem) {
759 listItem->setY(nextItem->y() - listItem->height());
760 } else if (modelIndex == 0 && m_headerItem) {
761 listItem->setY(m_headerItem->height());
762 } else if (!m_visibleItems.isEmpty()) {
763 lostItem = true;
764 }
765 }
766 }
767 if (lostItem) {
768 releaseItem(listItem);
769 listItem = nullptr;
770 } else {
771 listItem->setCulled(listItem->y() + listItem->height() + m_clipItem->y() <= contentY() || listItem->y() + m_clipItem->y() >= contentY() + height());
772 if (m_visibleItems.isEmpty()) {
773 m_visibleItems << listItem;
774 } else {
775 m_visibleItems.insert(modelIndex - m_firstVisibleIndex, listItem);
776 }
777 if (m_firstVisibleIndex < 0 || modelIndex < m_firstVisibleIndex) {
778 m_firstVisibleIndex = modelIndex;
779 polish();
780 }
781 adjustMinYExtent();
782 m_contentHeightDirty = true;
783 }
784 return listItem;
785 }
788#if (QT_VERSION < QT_VERSION_CHECK(5, 1, 0))
789void ListViewWithPageHeader::itemCreated(int modelIndex, QQuickItem *item)
791#else
792void ListViewWithPageHeader::itemCreated(int modelIndex, QObject *object)
794 QQuickItem *item = qmlobject_cast<QQuickItem*>(object);
795 if (!item) {
796 qWarning() << "ListViewWithPageHeader::itemCreated got a non item for index" << modelIndex;
797 return;
798 }
799#endif
800// qDebug() << "ListViewWithPageHeader::itemCreated" << modelIndex << item;
802 item->setParentItem(m_clipItem);
803 QQmlContext *context = QQmlEngine::contextForObject(item)->parentContext();
804 context->setContextProperty(QLatin1String("ListViewWithPageHeader"), this);
805 context->setContextProperty(QLatin1String("heightToClip"), QVariant::fromValue<int>(0));
806 if (modelIndex == m_asyncRequestedIndex) {
807 createItem(modelIndex, false);
808 refill();
809 }
812void ListViewWithPageHeader::updateClipItem()
814 m_clipItem->setHeight(height() - m_headerItemShownHeight);
815 m_clipItem->setY(contentY() + m_headerItemShownHeight);
816 m_clipItem->setClip(!m_forceNoClip && m_headerItemShownHeight > 0);
819void ListViewWithPageHeader::onContentHeightChanged()
821 updateClipItem();
824void ListViewWithPageHeader::onContentWidthChanged()
826 m_clipItem->setWidth(contentItem()->width());
829void ListViewWithPageHeader::onHeightChanged()
831 polish();
835#if (QT_VERSION < QT_VERSION_CHECK(5, 1, 0))
836void ListViewWithPageHeader::onModelUpdated(const QQuickChangeSet &changeSet, bool /*reset*/)
837#else
838void ListViewWithPageHeader::onModelUpdated(const QQmlChangeSet &changeSet, bool /*reset*/)
839#endif
841 // TODO Do something with reset
842// qDebug() << "ListViewWithPageHeader::onModelUpdated" << changeSet << reset;
843 const auto oldFirstVisibleIndex = m_firstVisibleIndex;
845#if (QT_VERSION < QT_VERSION_CHECK(5, 1, 0))
846 Q_FOREACH(const QQuickChangeSet::Remove &remove, changeSet.removes()) {
847#else
848 Q_FOREACH(const QQmlChangeSet::Remove &remove, changeSet.removes()) {
849#endif
850// qDebug() << "ListViewWithPageHeader::onModelUpdated Remove" << remove.index << remove.count;
851 if (remove.index + remove.count > m_firstVisibleIndex && remove.index < m_firstVisibleIndex + m_visibleItems.count()) {
852 const qreal oldFirstValidIndexPos = m_visibleItems.first()->y();
853 // If all the items we are removing are either not created or culled
854 // we have to grow down to avoid viewport changing
855 bool growDown = true;
856 for (int i = 0; growDown && i < remove.count; ++i) {
857 const int modelIndex = remove.index + i;
858 ListItem *item = itemAtIndex(modelIndex);
859 if (item && !item->culled()) {
860 growDown = false;
861 }
862 }
863 for (int i = remove.count - 1; i >= 0; --i) {
864 const int visibleIndex = remove.index + i - m_firstVisibleIndex;
865 if (visibleIndex >= 0 && visibleIndex < m_visibleItems.count()) {
866 ListItem *item = m_visibleItems[visibleIndex];
867 // Pass the section item down if needed
868 if (item->m_sectionItem && visibleIndex + 1 < m_visibleItems.count()) {
869 ListItem *nextItem = m_visibleItems[visibleIndex + 1];
870 if (!nextItem->m_sectionItem) {
871 nextItem->m_sectionItem = item->m_sectionItem;
872 item->m_sectionItem = nullptr;
873 }
874 }
875 releaseItem(item);
876 m_visibleItems.removeAt(visibleIndex);
877 }
878 }
879 if (growDown) {
880 adjustMinYExtent();
881 } else if (remove.index <= m_firstVisibleIndex) {
882 if (!m_visibleItems.isEmpty()) {
883 // We removed the first item that is the one that positions the rest
884 // position the new first item correctly
885 m_visibleItems.first()->setY(oldFirstValidIndexPos);
886 } else {
887 m_firstVisibleIndex = -1;
888 }
889 }
890 } else if (remove.index + remove.count <= m_firstVisibleIndex) {
891 m_firstVisibleIndex -= remove.count;
892 }
893 for (int i = remove.count - 1; i >= 0; --i) {
894 const int modelIndex = remove.index + i;
895 if (modelIndex == m_asyncRequestedIndex) {
896 m_asyncRequestedIndex = -1;
897 } else if (modelIndex < m_asyncRequestedIndex) {
898 m_asyncRequestedIndex--;
899 }
900 }
901 }
903#if (QT_VERSION < QT_VERSION_CHECK(5, 1, 0))
904 Q_FOREACH(const QQuickChangeSet::Insert &insert, changeSet.inserts()) {
905#else
906 Q_FOREACH(const QQmlChangeSet::Insert &insert, changeSet.inserts()) {
907#endif
908// qDebug() << "ListViewWithPageHeader::onModelUpdated Insert" << insert.index << insert.count;
909 const bool insertingInValidIndexes = insert.index > m_firstVisibleIndex && insert.index < m_firstVisibleIndex + m_visibleItems.count();
910 const bool firstItemWithViewOnTop = insert.index == 0 && m_firstVisibleIndex == 0 && m_visibleItems.first()->y() + m_clipItem->y() > contentY();
911 if (insertingInValidIndexes || firstItemWithViewOnTop)
912 {
913 // If the items we are adding won't be really visible
914 // we grow up instead of down to not change the viewport
915 bool growUp = false;
916 if (!firstItemWithViewOnTop) {
917 for (int i = 0; i < m_visibleItems.count(); ++i) {
918 if (!m_visibleItems[i]->culled()) {
919 if (insert.index <= m_firstVisibleIndex + i) {
920 growUp = true;
921 }
922 break;
923 }
924 }
925 }
927 const qreal oldFirstValidIndexPos = m_visibleItems.first()->y();
928 for (int i = insert.count - 1; i >= 0; --i) {
929 const int modelIndex = insert.index + i;
930 ListItem *item = createItem(modelIndex, false);
931 if (growUp) {
932 ListItem *firstItem = m_visibleItems.first();
933 firstItem->setY(firstItem->y() - item->height());
934 adjustMinYExtent();
935 }
936 // Adding an item may break a "same section" chain, so check
937 // if we need adding a new section item
938 if (m_sectionDelegate) {
939 ListItem *nextItem = itemAtIndex(modelIndex + 1);
940 if (nextItem && !nextItem->m_sectionItem) {
941 nextItem->m_sectionItem = getSectionItem(modelIndex + 1, true /* alredy inserted into m_visibleItems*/);
942 if (growUp && nextItem->m_sectionItem) {
943 ListItem *firstItem = m_visibleItems.first();
944 firstItem->setY(firstItem->y() - nextItem->m_sectionItem->height());
945 adjustMinYExtent();
946 }
947 }
948 }
949 }
950 if (firstItemWithViewOnTop) {
951 ListItem *firstItem = m_visibleItems.first();
952 firstItem->setY(oldFirstValidIndexPos);
953 }
954 } else if (insert.index <= m_firstVisibleIndex) {
955 m_firstVisibleIndex += insert.count;
956 }
958 for (int i = insert.count - 1; i >= 0; --i) {
959 const int modelIndex = insert.index + i;
960 if (modelIndex <= m_asyncRequestedIndex) {
961 m_asyncRequestedIndex++;
962 }
963 }
964 }
966 if (m_firstVisibleIndex != oldFirstVisibleIndex) {
967 adjustMinYExtent();
968 }
970 for (int i = 0; i < m_visibleItems.count(); ++i) {
971 ListItem *item = m_visibleItems[i];
972 if (item->m_sectionItem) {
973 QQmlContext *context = QQmlEngine::contextForObject(item->m_sectionItem)->parentContext();
974 context->setContextProperty(QLatin1String("delegateIndex"), m_firstVisibleIndex + i);
975 }
976 }
978 layout();
979 polish();
980 m_contentHeightDirty = true;
983void ListViewWithPageHeader::onShowHeaderAnimationFinished()
985 m_contentHeightDirty = true;
986 polish();
989void ListViewWithPageHeader::itemGeometryChanged(QQuickItem * /*item*/, const QRectF &newGeometry, const QRectF &oldGeometry)
991 const qreal heightDiff = newGeometry.height() - oldGeometry.height();
992 if (heightDiff != 0) {
993 if (oldGeometry.y() + oldGeometry.height() + m_clipItem->y() < contentY() && !m_visibleItems.isEmpty()) {
994 ListItem *firstItem = m_visibleItems.first();
995 firstItem->setY(firstItem->y() - heightDiff);
996 adjustMinYExtent();
997 layout();
998 }
999 refill();
1000 adjustMinYExtent();
1001 polish();
1002 m_contentHeightDirty = true;
1006void ListViewWithPageHeader::headerHeightChanged(qreal newHeaderHeight, qreal oldHeaderHeight, qreal oldHeaderY)
1008 const qreal heightDiff = newHeaderHeight - oldHeaderHeight;
1009 if (m_headerItemShownHeight > 0) {
1010 // If the header is shown because of the clip
1011 // Change its size
1012 m_headerItemShownHeight += heightDiff;
1013 m_headerItemShownHeight = qBound(static_cast<qreal>(0.), m_headerItemShownHeight, newHeaderHeight);
1014 updateClipItem();
1015 adjustMinYExtent();
1016 } else {
1017 if (oldHeaderY + oldHeaderHeight > contentY()) {
1018 // If the header is shown because its position
1019 // Change its size
1020 ListItem *firstItem = m_visibleItems.first();
1021 firstItem->setY(firstItem->y() + heightDiff);
1022 layout();
1023 } else {
1024 // If the header is not on screen, just change the start of the list
1025 // so the viewport is not changed
1026 adjustMinYExtent();
1032void ListViewWithPageHeader::adjustMinYExtent()
1034 if (m_visibleItems.isEmpty()) {
1035 m_minYExtent = 0;
1036 } else {
1037 qreal nonCreatedHeight = 0;
1038 if (m_firstVisibleIndex != 0) {
1039 // Calculate the average height of items to estimate the position of the list start
1040 const int visibleItems = m_visibleItems.count();
1041 qreal visibleItemsHeight = 0;
1042 Q_FOREACH(ListItem *item, m_visibleItems) {
1043 visibleItemsHeight += item->height();
1045 nonCreatedHeight = m_firstVisibleIndex * visibleItemsHeight / visibleItems;
1046// qDebug() << m_firstVisibleIndex << visibleItemsHeight << visibleItems << nonCreatedHeight;
1048 m_minYExtent = nonCreatedHeight - m_visibleItems.first()->y() - m_clipItem->y() + (m_headerItem ? m_headerItem->implicitHeight() : 0);
1052ListViewWithPageHeader::ListItem *ListViewWithPageHeader::itemAtIndex(int modelIndex) const
1054 const int visibleIndexedModelIndex = modelIndex - m_firstVisibleIndex;
1055 if (visibleIndexedModelIndex >= 0 && visibleIndexedModelIndex < m_visibleItems.count())
1056 return m_visibleItems[visibleIndexedModelIndex];
1058 return nullptr;
1061void ListViewWithPageHeader::layout()
1063 if (m_inLayout)
1064 return;
1066 m_inLayout = true;
1067 if (!m_visibleItems.isEmpty()) {
1068 const qreal visibleFrom = contentY() - m_clipItem->y() + m_headerItemShownHeight;
1069 const qreal visibleTo = contentY() + height() - m_clipItem->y();
1071 qreal pos = m_visibleItems.first()->y();
1073// qDebug() << "ListViewWithPageHeader::layout Updating positions and heights. contentY" << contentY() << "minYExtent" << minYExtent();
1074 int firstReallyVisibleItem = -1;
1075 int modelIndex = m_firstVisibleIndex;
1076 Q_FOREACH(ListItem *item, m_visibleItems) {
1077 const bool cull = pos + item->height() <= visibleFrom || pos >= visibleTo;
1078 item->setCulled(cull);
1079 item->setY(pos);
1080 if (!cull && firstReallyVisibleItem == -1) {
1081 firstReallyVisibleItem = modelIndex;
1082 if (m_topSectionItem) {
1083 // Positing the top section sticky item is a two step process
1084 // First we set it either we cull it (because it doesn't need to be sticked to the top)
1085 // or stick it to the top
1086 // Then after the loop we'll make sure that if there's another section just below it
1087 // pushed the sticky section up to make it disappear
1088 const qreal topSectionStickPos = m_headerItemShownHeight + contentY() - m_clipItem->y();
1089 if (topSectionStickPos <= pos) {
1090 QQuickItemPrivate::get(m_topSectionItem)->setCulled(true);
1091 if (item->m_sectionItem) {
1092 // This seems it should happen since why would we cull the top section
1093 // if the first visible item has no section header? This only happens briefly
1094 // when increasing the height of a list that is at the bottom, the m_topSectionItem
1095 // gets shown shortly in the next polish call
1096 QQuickItemPrivate::get(item->m_sectionItem)->setCulled(false);
1098 } else {
1099 // Update the top sticky section header
1100 const QString section = m_delegateModel->stringValue(modelIndex, m_sectionProperty);
1101 QQmlContext *context = QQmlEngine::contextForObject(m_topSectionItem)->parentContext();
1102 context->setContextProperty(QLatin1String("section"), section);
1104 QQuickItemPrivate::get(m_topSectionItem)->setCulled(false);
1105 m_topSectionItem->setY(topSectionStickPos);
1106 int delegateIndex = modelIndex;
1107 // Look for the first index with this section text
1108 while (delegateIndex > 0) {
1109 const QString prevSection = m_delegateModel->stringValue(delegateIndex - 1, m_sectionProperty);
1110 if (prevSection != section)
1111 break;
1112 delegateIndex--;
1114 context->setContextProperty(QLatin1String("delegateIndex"), delegateIndex);
1115 if (item->m_sectionItem) {
1116 QQuickItemPrivate::get(item->m_sectionItem)->setCulled(true);
1121 QQmlContext *context = QQmlEngine::contextForObject(item->m_item)->parentContext();
1122 const qreal clipFrom = visibleFrom + (!item->m_sectionItem && m_topSectionItem && !QQuickItemPrivate::get(m_topSectionItem)->culled ? m_topSectionItem->height() : 0);
1123 if (!cull && pos < clipFrom) {
1124 context->setContextProperty(QLatin1String("heightToClip"), clipFrom - pos);
1125 } else {
1126 context->setContextProperty(QLatin1String("heightToClip"), QVariant::fromValue<int>(0));
1128// qDebug() << "ListViewWithPageHeader::layout" << item->m_item;
1129 pos += item->height();
1130 ++modelIndex;
1133 // Second step of section sticky item positioning
1134 // Look at the next section header, check if it's pushing up the sticky one
1135 if (m_topSectionItem) {
1136 if (firstReallyVisibleItem >= 0) {
1137 for (int i = firstReallyVisibleItem - m_firstVisibleIndex + 1; i < m_visibleItems.count(); ++i) {
1138 ListItem *item = m_visibleItems[i];
1139 if (item->m_sectionItem) {
1140 if (m_topSectionItem->y() + m_topSectionItem->height() > item->y()) {
1141 m_topSectionItem->setY(item->y() - m_topSectionItem->height());
1143 break;
1149 m_inLayout = false;
1152void ListViewWithPageHeader::updatePolish()
1154 Q_FOREACH(ListItem *item, m_itemsToRelease)
1155 reallyReleaseItem(item);
1156 m_itemsToRelease.clear();
1158 if (!model())
1159 return;
1161 layout();
1163 refill();
1165 if (m_contentHeightDirty) {
1166 qreal contentHeight;
1167 if (m_visibleItems.isEmpty()) {
1168 contentHeight = m_headerItem ? m_headerItem->height() : 0;
1169 } else {
1170 const int modelCount = model()->rowCount();
1171 const int visibleItems = m_visibleItems.count();
1172 const int lastValidIndex = m_firstVisibleIndex + visibleItems - 1;
1173 qreal nonCreatedHeight = 0;
1174 if (lastValidIndex != modelCount - 1) {
1175 const int visibleItems = m_visibleItems.count();
1176 qreal visibleItemsHeight = 0;
1177 Q_FOREACH(ListItem *item, m_visibleItems) {
1178 visibleItemsHeight += item->height();
1180 const int unknownSizes = modelCount - (m_firstVisibleIndex + visibleItems);
1181 nonCreatedHeight = unknownSizes * visibleItemsHeight / visibleItems;
1183 ListItem *item = m_visibleItems.last();
1184 contentHeight = nonCreatedHeight + item->y() + item->height() + m_clipItem->y();
1185 if (m_firstVisibleIndex != 0) {
1186 // Make sure that if we are shrinking we tell the view we still fit
1187 m_minYExtent = qMax(m_minYExtent, -(contentHeight - height()));
1191 m_contentHeightDirty = false;
1192 setContentHeight(contentHeight);
1196#include "moc_listviewwithpageheader.cpp"