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
  22 #include <kitemviews/kitemlistview.h>
  23
  24 KItemListSizeHintResolver::KItemListSizeHintResolver(const KItemListView* itemListView) :
  25     m_itemListView(itemListView),
  26     m_logicalHeightHintCache(),
  27     m_logicalWidthHint(0.0),
  28     m_logicalHeightHint(0.0),
  29     m_needsResolving(false)
  30 {
  31 }
  32
  33 KItemListSizeHintResolver::~KItemListSizeHintResolver()
  34 {
  35 }
  36
  37 QSizeF KItemListSizeHintResolver::maxSizeHint()
  38 {
  39     updateCache();
  40     return QSizeF(m_logicalWidthHint, m_logicalHeightHint);
  41 }
  42
  43 QSizeF KItemListSizeHintResolver::sizeHint(int index)
  44 {
  45     updateCache();
  46     return QSizeF(m_logicalWidthHint, m_logicalHeightHintCache.at(index));
  47 }
  48
  49 void KItemListSizeHintResolver::itemsInserted(const KItemRangeList& itemRanges)
  50 {
  51     int insertedCount = 0;
  52     foreach (const KItemRange& range, itemRanges) {
  53         insertedCount += range.count;
  54     }
  55
  56     const int currentCount = m_logicalHeightHintCache.count();
  57     m_logicalHeightHintCache.reserve(currentCount + insertedCount);
  58
  59     // We build the new list from the end to the beginning to mimize the
  60     // number of moves.
  61     m_logicalHeightHintCache.insert(m_logicalHeightHintCache.end(), insertedCount, 0.0);
  62
  63     int sourceIndex = currentCount - 1;
  64     int targetIndex = m_logicalHeightHintCache.count() - 1;
  65     int itemsToInsertBeforeCurrentRange = insertedCount;
  66
  67     for (int rangeIndex = itemRanges.count() - 1; rangeIndex >= 0; --rangeIndex) {
  68         const KItemRange& range = itemRanges.at(rangeIndex);
  69         itemsToInsertBeforeCurrentRange -= range.count;
  70
  71         // First: move all existing items that must be put behind 'range'.
  72         while (targetIndex >= itemsToInsertBeforeCurrentRange + range.index + range.count) {
  73             m_logicalHeightHintCache[targetIndex] = m_logicalHeightHintCache[sourceIndex];
  74             --sourceIndex;
  75             --targetIndex;
  76         }
  77
  78         // Then: insert QSizeF() for the items which are inserted into 'range'.
  79         while (targetIndex >= itemsToInsertBeforeCurrentRange + range.index) {
  80             m_logicalHeightHintCache[targetIndex] = 0.0;
  81             --targetIndex;
  82         }
  83     }
  84
  85     m_needsResolving = true;
  86
  87     Q_ASSERT(m_logicalHeightHintCache.count() == m_itemListView->model()->count());
  88 }
  89
  90 void KItemListSizeHintResolver::itemsRemoved(const KItemRangeList& itemRanges)
  91 {
  92     const QVector<qreal>::iterator begin = m_logicalHeightHintCache.begin();
  93     const QVector<qreal>::iterator end = m_logicalHeightHintCache.end();
  94
  95     KItemRangeList::const_iterator rangeIt = itemRanges.constBegin();
  96     const KItemRangeList::const_iterator rangeEnd = itemRanges.constEnd();
  97
  98     QVector<qreal>::iterator destIt = begin + rangeIt->index;
  99     QVector<qreal>::iterator srcIt = destIt + rangeIt->count;
 100
 101     ++rangeIt;
 102
 103     while (srcIt != end) {
 104         *destIt = *srcIt;
 105         ++destIt;
 106         ++srcIt;
 107
 108         if (rangeIt != rangeEnd && srcIt == begin + rangeIt->index) {
 109             // Skip the items in the next removed range.
 110             srcIt += rangeIt->count;
 111             ++rangeIt;
 112         }
 113     }
 114
 115     m_logicalHeightHintCache.erase(destIt, end);
 116
 117     // Note that the cache size might temporarily not match the model size if
 118     // this function is called from KItemListView::setModel() to empty the cache.
 119     if (!m_logicalHeightHintCache.isEmpty() && m_itemListView->model()) {
 120         Q_ASSERT(m_logicalHeightHintCache.count() == m_itemListView->model()->count());
 121     }
 122 }
 123
 124 void KItemListSizeHintResolver::itemsMoved(const KItemRange& range, const QList<int>& movedToIndexes)
 125 {
 126     QVector<qreal> newLogicalHeightHintCache(m_logicalHeightHintCache);
 127
 128     const int movedRangeEnd = range.index + range.count;
 129     for (int i = range.index; i < movedRangeEnd; ++i) {
 130         const int newIndex = movedToIndexes.at(i - range.index);
 131         newLogicalHeightHintCache[newIndex] = m_logicalHeightHintCache.at(i);
 132     }
 133
 134     m_logicalHeightHintCache = newLogicalHeightHintCache;
 135 }
 136
 137 void KItemListSizeHintResolver::itemsChanged(int index, int count, const QSet<QByteArray>& roles)
 138 {
 139     Q_UNUSED(roles);
 140     while (count) {
 141         m_logicalHeightHintCache[index] = 0.0;
 142         ++index;
 143         --count;
 144     }
 145
 146     m_needsResolving = true;
 147 }
 148
 149 void KItemListSizeHintResolver::clearCache()
 150 {
 151     m_logicalHeightHintCache.fill(0.0);
 152     m_needsResolving = true;
 153 }
 154
 155 void KItemListSizeHintResolver::updateCache()
 156 {
 157     if (m_needsResolving) {
 158         m_itemListView->calculateItemSizeHints(m_logicalHeightHintCache, m_logicalWidthHint);
 159         // Set logical height as the max cached height (if the cache is not empty).
 160         if (m_logicalHeightHintCache.isEmpty()) {
 161             m_logicalHeightHint = 0.0;
 162         } else {
 163             m_logicalHeightHint = *std::max_element(m_logicalHeightHintCache.begin(), m_logicalHeightHintCache.end());
 164         }
 165         m_needsResolving = false;
 166     }
 167 }