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