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