src/kitemviews/private/kitemlistsizehintresolver.cpp

   1 /*
   2  * SPDX-FileCopyrightText: 2011 Peter Penz <peter.penz19@gmail.com>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-or-later
   5  */
   6
   7 #include "kitemlistsizehintresolver.h"
   8 #include "kitemviews/kitemlistview.h"
   9
  10 KItemListSizeHintResolver::KItemListSizeHintResolver(const KItemListView* itemListView) :
  11     m_itemListView(itemListView),
  12     m_logicalHeightHintCache(),
  13     m_logicalWidthHint(0.0),
  14     m_minHeightHint(0.0),
  15     m_needsResolving(false)
  16 {
  17 }
  18
  19 KItemListSizeHintResolver::~KItemListSizeHintResolver()
  20 {
  21 }
  22
  23 QSizeF KItemListSizeHintResolver::minSizeHint()
  24 {
  25     updateCache();
  26     return QSizeF(m_logicalWidthHint, m_minHeightHint);
  27 }
  28
  29 QSizeF KItemListSizeHintResolver::sizeHint(int index)
  30 {
  31     updateCache();
  32     return QSizeF(m_logicalWidthHint, m_logicalHeightHintCache.at(index));
  33 }
  34
  35 void KItemListSizeHintResolver::itemsInserted(const KItemRangeList& itemRanges)
  36 {
  37     int insertedCount = 0;
  38     foreach (const KItemRange& range, itemRanges) {
  39         insertedCount += range.count;
  40     }
  41
  42     const int currentCount = m_logicalHeightHintCache.count();
  43     m_logicalHeightHintCache.reserve(currentCount + insertedCount);
  44
  45     // We build the new list from the end to the beginning to mimize the
  46     // number of moves.
  47     m_logicalHeightHintCache.insert(m_logicalHeightHintCache.end(), insertedCount, 0.0);
  48
  49     int sourceIndex = currentCount - 1;
  50     int targetIndex = m_logicalHeightHintCache.count() - 1;
  51     int itemsToInsertBeforeCurrentRange = insertedCount;
  52
  53     for (int rangeIndex = itemRanges.count() - 1; rangeIndex >= 0; --rangeIndex) {
  54         const KItemRange& range = itemRanges.at(rangeIndex);
  55         itemsToInsertBeforeCurrentRange -= range.count;
  56
  57         // First: move all existing items that must be put behind 'range'.
  58         while (targetIndex >= itemsToInsertBeforeCurrentRange + range.index + range.count) {
  59             m_logicalHeightHintCache[targetIndex] = m_logicalHeightHintCache[sourceIndex];
  60             --sourceIndex;
  61             --targetIndex;
  62         }
  63
  64         // Then: insert QSizeF() for the items which are inserted into 'range'.
  65         while (targetIndex >= itemsToInsertBeforeCurrentRange + range.index) {
  66             m_logicalHeightHintCache[targetIndex] = 0.0;
  67             --targetIndex;
  68         }
  69     }
  70
  71     m_needsResolving = true;
  72
  73     Q_ASSERT(m_logicalHeightHintCache.count() == m_itemListView->model()->count());
  74 }
  75
  76 void KItemListSizeHintResolver::itemsRemoved(const KItemRangeList& itemRanges)
  77 {
  78     const QVector<qreal>::iterator begin = m_logicalHeightHintCache.begin();
  79     const QVector<qreal>::iterator end = m_logicalHeightHintCache.end();
  80
  81     KItemRangeList::const_iterator rangeIt = itemRanges.constBegin();
  82     const KItemRangeList::const_iterator rangeEnd = itemRanges.constEnd();
  83
  84     QVector<qreal>::iterator destIt = begin + rangeIt->index;
  85     QVector<qreal>::iterator srcIt = destIt + rangeIt->count;
  86
  87     ++rangeIt;
  88
  89     while (srcIt != end) {
  90         *destIt = *srcIt;
  91         ++destIt;
  92         ++srcIt;
  93
  94         if (rangeIt != rangeEnd && srcIt == begin + rangeIt->index) {
  95             // Skip the items in the next removed range.
  96             srcIt += rangeIt->count;
  97             ++rangeIt;
  98         }
  99     }
 100
 101     m_logicalHeightHintCache.erase(destIt, end);
 102
 103     // Note that the cache size might temporarily not match the model size if
 104     // this function is called from KItemListView::setModel() to empty the cache.
 105     if (!m_logicalHeightHintCache.isEmpty() && m_itemListView->model()) {
 106         Q_ASSERT(m_logicalHeightHintCache.count() == m_itemListView->model()->count());
 107     }
 108 }
 109
 110 void KItemListSizeHintResolver::itemsMoved(const KItemRange& range, const QList<int>& movedToIndexes)
 111 {
 112     QVector<qreal> newLogicalHeightHintCache(m_logicalHeightHintCache);
 113
 114     const int movedRangeEnd = range.index + range.count;
 115     for (int i = range.index; i < movedRangeEnd; ++i) {
 116         const int newIndex = movedToIndexes.at(i - range.index);
 117         newLogicalHeightHintCache[newIndex] = m_logicalHeightHintCache.at(i);
 118     }
 119
 120     m_logicalHeightHintCache = newLogicalHeightHintCache;
 121 }
 122
 123 void KItemListSizeHintResolver::itemsChanged(int index, int count, const QSet<QByteArray>& roles)
 124 {
 125     Q_UNUSED(roles)
 126     while (count) {
 127         m_logicalHeightHintCache[index] = 0.0;
 128         ++index;
 129         --count;
 130     }
 131
 132     m_needsResolving = true;
 133 }
 134
 135 void KItemListSizeHintResolver::clearCache()
 136 {
 137     m_logicalHeightHintCache.fill(0.0);
 138     m_needsResolving = true;
 139 }
 140
 141 void KItemListSizeHintResolver::updateCache()
 142 {
 143     if (m_needsResolving) {
 144         m_itemListView->calculateItemSizeHints(m_logicalHeightHintCache, m_logicalWidthHint);
 145         m_needsResolving = false;
 146     }
 147 }