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