src/kitemviews/private/kitemlistsizehintresolver.cpp

   1 /***************************************************************************
   2  *   Copyright (C) 2011 by Peter Penz <peter.penz19@gmail.com>             *
   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; either version 2 of the License, or     *
   7  *   (at your option) any later version.                                   *
   8  *                                                                         *
   9  *   This program is distributed in the hope that it will be useful,       *
  10  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  11  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  12  *   GNU General Public License for more details.                          *
  13  *                                                                         *
  14  *   You should have received a copy of the GNU General Public License     *
  15  *   along with this program; if not, write to the                         *
  16  *   Free Software Foundation, Inc.,                                       *
  17  *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA            *
  18  ***************************************************************************/
  19
  20 #include "kitemlistsizehintresolver.h"
  21 #include "kitemviews/kitemlistview.h"
  22
  23 KItemListSizeHintResolver::KItemListSizeHintResolver(const KItemListView* itemListView) :
  24     m_itemListView(itemListView),
  25     m_logicalHeightHintCache(),
  26     m_logicalWidthHint(0.0),
  27     m_minHeightHint(0.0),
  28     m_needsResolving(false)
  29 {
  30 }
  31
  32 KItemListSizeHintResolver::~KItemListSizeHintResolver()
  33 {
  34 }
  35
  36 QSizeF KItemListSizeHintResolver::minSizeHint()
  37 {
  38     updateCache();
  39     return QSizeF(m_logicalWidthHint, m_minHeightHint);
  40 }
  41
  42 QSizeF KItemListSizeHintResolver::sizeHint(int index)
  43 {
  44     updateCache();
  45     return QSizeF(m_logicalWidthHint, m_logicalHeightHintCache.at(index));
  46 }
  47
  48 void KItemListSizeHintResolver::itemsInserted(const KItemRangeList& itemRanges)
  49 {
  50     int insertedCount = 0;
  51     foreach (const KItemRange& range, itemRanges) {
  52         insertedCount += range.count;
  53     }
  54
  55     const int currentCount = m_logicalHeightHintCache.count();
  56     m_logicalHeightHintCache.reserve(currentCount + insertedCount);
  57
  58     // We build the new list from the end to the beginning to mimize the
  59     // number of moves.
  60     m_logicalHeightHintCache.insert(m_logicalHeightHintCache.end(), insertedCount, 0.0);
  61
  62     int sourceIndex = currentCount - 1;
  63     int targetIndex = m_logicalHeightHintCache.count() - 1;
  64     int itemsToInsertBeforeCurrentRange = insertedCount;
  65
  66     for (int rangeIndex = itemRanges.count() - 1; rangeIndex >= 0; --rangeIndex) {
  67         const KItemRange& range = itemRanges.at(rangeIndex);
  68         itemsToInsertBeforeCurrentRange -= range.count;
  69
  70         // First: move all existing items that must be put behind 'range'.
  71         while (targetIndex >= itemsToInsertBeforeCurrentRange + range.index + range.count) {
  72             m_logicalHeightHintCache[targetIndex] = m_logicalHeightHintCache[sourceIndex];
  73             --sourceIndex;
  74             --targetIndex;
  75         }
  76
  77         // Then: insert QSizeF() for the items which are inserted into 'range'.
  78         while (targetIndex >= itemsToInsertBeforeCurrentRange + range.index) {
  79             m_logicalHeightHintCache[targetIndex] = 0.0;
  80             --targetIndex;
  81         }
  82     }
  83
  84     m_needsResolving = true;
  85
  86     Q_ASSERT(m_logicalHeightHintCache.count() == m_itemListView->model()->count());
  87 }
  88
  89 void KItemListSizeHintResolver::itemsRemoved(const KItemRangeList& itemRanges)
  90 {
  91     const QVector<qreal>::iterator begin = m_logicalHeightHintCache.begin();
  92     const QVector<qreal>::iterator end = m_logicalHeightHintCache.end();
  93
  94     KItemRangeList::const_iterator rangeIt = itemRanges.constBegin();
  95     const KItemRangeList::const_iterator rangeEnd = itemRanges.constEnd();
  96
  97     QVector<qreal>::iterator destIt = begin + rangeIt->index;
  98     QVector<qreal>::iterator srcIt = destIt + rangeIt->count;
  99
 100     ++rangeIt;
 101
 102     while (srcIt != end) {
 103         *destIt = *srcIt;
 104         ++destIt;
 105         ++srcIt;
 106
 107         if (rangeIt != rangeEnd && srcIt == begin + rangeIt->index) {
 108             // Skip the items in the next removed range.
 109             srcIt += rangeIt->count;
 110             ++rangeIt;
 111         }
 112     }
 113
 114     m_logicalHeightHintCache.erase(destIt, end);
 115
 116     // Note that the cache size might temporarily not match the model size if
 117     // this function is called from KItemListView::setModel() to empty the cache.
 118     if (!m_logicalHeightHintCache.isEmpty() && m_itemListView->model()) {
 119         Q_ASSERT(m_logicalHeightHintCache.count() == m_itemListView->model()->count());
 120     }
 121 }
 122
 123 void KItemListSizeHintResolver::itemsMoved(const KItemRange& range, const QList<int>& movedToIndexes)
 124 {
 125     QVector<qreal> newLogicalHeightHintCache(m_logicalHeightHintCache);
 126
 127     const int movedRangeEnd = range.index + range.count;
 128     for (int i = range.index; i < movedRangeEnd; ++i) {
 129         const int newIndex = movedToIndexes.at(i - range.index);
 130         newLogicalHeightHintCache[newIndex] = m_logicalHeightHintCache.at(i);
 131     }
 132
 133     m_logicalHeightHintCache = newLogicalHeightHintCache;
 134 }
 135
 136 void KItemListSizeHintResolver::itemsChanged(int index, int count, const QSet<QByteArray>& roles)
 137 {
 138     Q_UNUSED(roles)
 139     while (count) {
 140         m_logicalHeightHintCache[index] = 0.0;
 141         ++index;
 142         --count;
 143     }
 144
 145     m_needsResolving = true;
 146 }
 147
 148 void KItemListSizeHintResolver::clearCache()
 149 {
 150     m_logicalHeightHintCache.fill(0.0);
 151     m_needsResolving = true;
 152 }
 153
 154 void KItemListSizeHintResolver::updateCache()
 155 {
 156     if (m_needsResolving) {
 157         m_itemListView->calculateItemSizeHints(m_logicalHeightHintCache, m_logicalWidthHint);
 158         m_needsResolving = false;
 159     }
 160 }