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 {
  28 }
  29
  30 KItemListSizeHintResolver::~KItemListSizeHintResolver()
  31 {
  32 }
  33
  34 QSizeF KItemListSizeHintResolver::sizeHint(int index) const
  35 {
  36     QSizeF size = m_sizeHintCache.at(index);
  37     if (size.isEmpty()) {
  38         size = m_itemListView->itemSizeHint(index);
  39         m_sizeHintCache[index] = size;
  40     }
  41     return size;
  42 }
  43
  44 void KItemListSizeHintResolver::itemsInserted(const KItemRangeList& itemRanges)
  45 {
  46     int insertedCount = 0;
  47     foreach (const KItemRange& range, itemRanges) {
  48         insertedCount += range.count;
  49     }
  50
  51     const int currentCount = m_sizeHintCache.count();
  52     m_sizeHintCache.reserve(currentCount + insertedCount);
  53
  54     // We build the new list from the end to the beginning to mimize the
  55     // number of moves.
  56     m_sizeHintCache.insert(m_sizeHintCache.end(), insertedCount, QSizeF());
  57
  58     int sourceIndex = currentCount - 1;
  59     int targetIndex = m_sizeHintCache.count() - 1;
  60     int itemsToInsertBeforeCurrentRange = insertedCount;
  61
  62     for (int rangeIndex = itemRanges.count() - 1; rangeIndex >= 0; --rangeIndex) {
  63         const KItemRange& range = itemRanges.at(rangeIndex);
  64         itemsToInsertBeforeCurrentRange -= range.count;
  65
  66         // First: move all existing items that must be put behind 'range'.
  67         while (targetIndex >= itemsToInsertBeforeCurrentRange + range.index + range.count) {
  68             m_sizeHintCache[targetIndex] = m_sizeHintCache[sourceIndex];
  69             --sourceIndex;
  70             --targetIndex;
  71         }
  72
  73         // Then: insert QSizeF() for the items which are inserted into 'range'.
  74         while (targetIndex >= itemsToInsertBeforeCurrentRange + range.index) {
  75             m_sizeHintCache[targetIndex] = QSizeF();
  76             --targetIndex;
  77         }
  78     }
  79
  80     Q_ASSERT(m_sizeHintCache.count() == m_itemListView->model()->count());
  81 }
  82
  83 void KItemListSizeHintResolver::itemsRemoved(const KItemRangeList& itemRanges)
  84 {
  85     const QVector<QSizeF>::iterator begin = m_sizeHintCache.begin();
  86     const QVector<QSizeF>::iterator end = m_sizeHintCache.end();
  87
  88     KItemRangeList::const_iterator rangeIt = itemRanges.constBegin();
  89     const KItemRangeList::const_iterator rangeEnd = itemRanges.constEnd();
  90
  91     QVector<QSizeF>::iterator destIt = begin + rangeIt->index;
  92     QVector<QSizeF>::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_sizeHintCache.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_sizeHintCache.isEmpty() && m_itemListView->model()) {
 113         Q_ASSERT(m_sizeHintCache.count() == m_itemListView->model()->count());
 114     }
 115 }
 116
 117 void KItemListSizeHintResolver::itemsMoved(int index, int count)
 118 {
 119     while (count) {
 120         m_sizeHintCache[index] = QSizeF();
 121         ++index;
 122         --count;
 123     }
 124 }
 125
 126 void KItemListSizeHintResolver::itemsChanged(int index, int count, const QSet<QByteArray>& roles)
 127 {
 128     Q_UNUSED(roles);
 129     while (count) {
 130         m_sizeHintCache[index] = QSizeF();
 131         ++index;
 132         --count;
 133     }
 134 }
 135
 136 void KItemListSizeHintResolver::clearCache()
 137 {
 138     const int count = m_sizeHintCache.count();
 139     for (int i = 0; i < count; ++i) {
 140         m_sizeHintCache[i] = QSizeF();
 141     }
 142 }