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_minHeightHint(0.0),
  30     m_needsResolving(false)
  31 {
  32 }
  33
  34 KItemListSizeHintResolver::~KItemListSizeHintResolver()
  35 {
  36 }
  37
  38 QSizeF KItemListSizeHintResolver::maxSizeHint()
  39 {
  40     updateCache();
  41     return QSizeF(m_logicalWidthHint, m_logicalHeightHint);
  42 }
  43
  44 QSizeF KItemListSizeHintResolver::minSizeHint()
  45 {
  46     updateCache();
  47     return QSizeF(m_logicalWidthHint, m_minHeightHint);
  48 }
  49
  50 QSizeF KItemListSizeHintResolver::sizeHint(int index)
  51 {
  52     updateCache();
  53     return QSizeF(m_logicalWidthHint, m_logicalHeightHintCache.at(index));
  54 }
  55
  56 void KItemListSizeHintResolver::itemsInserted(const KItemRangeList& itemRanges)
  57 {
  58     int insertedCount = 0;
  59     foreach (const KItemRange& range, itemRanges) {
  60         insertedCount += range.count;
  61     }
  62
  63     const int currentCount = m_logicalHeightHintCache.count();
  64     m_logicalHeightHintCache.reserve(currentCount + insertedCount);
  65
  66     // We build the new list from the end to the beginning to mimize the
  67     // number of moves.
  68     m_logicalHeightHintCache.insert(m_logicalHeightHintCache.end(), insertedCount, 0.0);
  69
  70     int sourceIndex = currentCount - 1;
  71     int targetIndex = m_logicalHeightHintCache.count() - 1;
  72     int itemsToInsertBeforeCurrentRange = insertedCount;
  73
  74     for (int rangeIndex = itemRanges.count() - 1; rangeIndex >= 0; --rangeIndex) {
  75         const KItemRange& range = itemRanges.at(rangeIndex);
  76         itemsToInsertBeforeCurrentRange -= range.count;
  77
  78         // First: move all existing items that must be put behind 'range'.
  79         while (targetIndex >= itemsToInsertBeforeCurrentRange + range.index + range.count) {
  80             m_logicalHeightHintCache[targetIndex] = m_logicalHeightHintCache[sourceIndex];
  81             --sourceIndex;
  82             --targetIndex;
  83         }
  84
  85         // Then: insert QSizeF() for the items which are inserted into 'range'.
  86         while (targetIndex >= itemsToInsertBeforeCurrentRange + range.index) {
  87             m_logicalHeightHintCache[targetIndex] = 0.0;
  88             --targetIndex;
  89         }
  90     }
  91
  92     m_needsResolving = true;
  93
  94     Q_ASSERT(m_logicalHeightHintCache.count() == m_itemListView->model()->count());
  95 }
  96
  97 void KItemListSizeHintResolver::itemsRemoved(const KItemRangeList& itemRanges)
  98 {
  99     const QVector<qreal>::iterator begin = m_logicalHeightHintCache.begin();
 100     const QVector<qreal>::iterator end = m_logicalHeightHintCache.end();
 101
 102     KItemRangeList::const_iterator rangeIt = itemRanges.constBegin();
 103     const KItemRangeList::const_iterator rangeEnd = itemRanges.constEnd();
 104
 105     QVector<qreal>::iterator destIt = begin + rangeIt->index;
 106     QVector<qreal>::iterator srcIt = destIt + rangeIt->count;
 107
 108     ++rangeIt;
 109
 110     while (srcIt != end) {
 111         *destIt = *srcIt;
 112         ++destIt;
 113         ++srcIt;
 114
 115         if (rangeIt != rangeEnd && srcIt == begin + rangeIt->index) {
 116             // Skip the items in the next removed range.
 117             srcIt += rangeIt->count;
 118             ++rangeIt;
 119         }
 120     }
 121
 122     m_logicalHeightHintCache.erase(destIt, end);
 123
 124     // Note that the cache size might temporarily not match the model size if
 125     // this function is called from KItemListView::setModel() to empty the cache.
 126     if (!m_logicalHeightHintCache.isEmpty() && m_itemListView->model()) {
 127         Q_ASSERT(m_logicalHeightHintCache.count() == m_itemListView->model()->count());
 128     }
 129 }
 130
 131 void KItemListSizeHintResolver::itemsMoved(const KItemRange& range, const QList<int>& movedToIndexes)
 132 {
 133     QVector<qreal> newLogicalHeightHintCache(m_logicalHeightHintCache);
 134
 135     const int movedRangeEnd = range.index + range.count;
 136     for (int i = range.index; i < movedRangeEnd; ++i) {
 137         const int newIndex = movedToIndexes.at(i - range.index);
 138         newLogicalHeightHintCache[newIndex] = m_logicalHeightHintCache.at(i);
 139     }
 140
 141     m_logicalHeightHintCache = newLogicalHeightHintCache;
 142 }
 143
 144 void KItemListSizeHintResolver::itemsChanged(int index, int count, const QSet<QByteArray>& roles)
 145 {
 146     Q_UNUSED(roles);
 147     while (count) {
 148         m_logicalHeightHintCache[index] = 0.0;
 149         ++index;
 150         --count;
 151     }
 152
 153     m_needsResolving = true;
 154 }
 155
 156 void KItemListSizeHintResolver::clearCache()
 157 {
 158     m_logicalHeightHintCache.fill(0.0);
 159     m_needsResolving = true;
 160 }
 161
 162 void KItemListSizeHintResolver::updateCache()
 163 {
 164     if (m_needsResolving) {
 165         m_itemListView->calculateItemSizeHints(m_logicalHeightHintCache, m_logicalWidthHint);
 166         // Set logical height as the max cached height (if the cache is not empty).
 167         if (m_logicalHeightHintCache.isEmpty()) {
 168             m_logicalHeightHint = 0.0;
 169         } else {
 170             m_logicalHeightHint = *std::max_element(m_logicalHeightHintCache.begin(), m_logicalHeightHintCache.end());
 171             m_minHeightHint = *std::min_element(m_logicalHeightHintCache.begin(), m_logicalHeightHintCache.end());
 172         }
 173         m_needsResolving = false;
 174     }
 175 }