src/kitemviews/kitemlistviewlayouter.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 "kitemlistviewlayouter_p.h"
  21
  22 #include "kitemmodelbase.h"
  23 #include "kitemlistsizehintresolver_p.h"
  24
  25 #include <KDebug>
  26
  27 // #define KITEMLISTVIEWLAYOUTER_DEBUG
  28
  29 KItemListViewLayouter::KItemListViewLayouter(QObject* parent) :
  30     QObject(parent),
  31     m_dirty(true),
  32     m_visibleIndexesDirty(true),
  33     m_scrollOrientation(Qt::Vertical),
  34     m_size(),
  35     m_itemSize(128, 128),
  36     m_headerHeight(0),
  37     m_model(0),
  38     m_sizeHintResolver(0),
  39     m_scrollOffset(0),
  40     m_maximumScrollOffset(0),
  41     m_itemOffset(0),
  42     m_maximumItemOffset(0),
  43     m_firstVisibleIndex(-1),
  44     m_lastVisibleIndex(-1),
  45     m_columnWidth(0),
  46     m_xPosInc(0),
  47     m_columnCount(0),
  48     m_groupItemIndexes(),
  49     m_groupHeaderHeight(0),
  50     m_itemRects()
  51 {
  52 }
  53
  54 KItemListViewLayouter::~KItemListViewLayouter()
  55 {
  56 }
  57
  58 void KItemListViewLayouter::setScrollOrientation(Qt::Orientation orientation)
  59 {
  60     if (m_scrollOrientation != orientation) {
  61         m_scrollOrientation = orientation;
  62         m_dirty = true;
  63     }
  64 }
  65
  66 Qt::Orientation KItemListViewLayouter::scrollOrientation() const
  67 {
  68     return m_scrollOrientation;
  69 }
  70
  71 void KItemListViewLayouter::setSize(const QSizeF& size)
  72 {
  73     if (m_size != size) {
  74         m_size = size;
  75         m_dirty = true;
  76     }
  77 }
  78
  79 QSizeF KItemListViewLayouter::size() const
  80 {
  81     return m_size;
  82 }
  83
  84 void KItemListViewLayouter::setItemSize(const QSizeF& size)
  85 {
  86     if (m_itemSize != size) {
  87         m_itemSize = size;
  88         m_dirty = true;
  89     }
  90 }
  91
  92 QSizeF KItemListViewLayouter::itemSize() const
  93 {
  94     return m_itemSize;
  95 }
  96
  97 void KItemListViewLayouter::setHeaderHeight(qreal height)
  98 {
  99     if (m_headerHeight != height) {
 100         m_headerHeight = height;
 101         m_dirty = true;
 102     }
 103 }
 104
 105 qreal KItemListViewLayouter::headerHeight() const
 106 {
 107     return m_headerHeight;
 108 }
 109
 110 void KItemListViewLayouter::setGroupHeaderHeight(qreal height)
 111 {
 112     if (m_groupHeaderHeight != height) {
 113         m_groupHeaderHeight = height;
 114         m_dirty = true;
 115     }
 116 }
 117
 118 qreal KItemListViewLayouter::groupHeaderHeight() const
 119 {
 120     return m_groupHeaderHeight;
 121 }
 122
 123 void KItemListViewLayouter::setScrollOffset(qreal offset)
 124 {
 125     if (m_scrollOffset != offset) {
 126         m_scrollOffset = offset;
 127         m_visibleIndexesDirty = true;
 128     }
 129 }
 130
 131 qreal KItemListViewLayouter::scrollOffset() const
 132 {
 133     return m_scrollOffset;
 134 }
 135
 136 qreal KItemListViewLayouter::maximumScrollOffset() const
 137 {
 138     const_cast<KItemListViewLayouter*>(this)->doLayout();
 139     return m_maximumScrollOffset;
 140 }
 141
 142 void KItemListViewLayouter::setItemOffset(qreal offset)
 143 {
 144     if (m_itemOffset != offset) {
 145         m_itemOffset = offset;
 146         m_visibleIndexesDirty = true;
 147     }
 148 }
 149
 150 qreal KItemListViewLayouter::itemOffset() const
 151 {
 152     return m_itemOffset;
 153 }
 154
 155 qreal KItemListViewLayouter::maximumItemOffset() const
 156 {
 157     const_cast<KItemListViewLayouter*>(this)->doLayout();
 158     return m_maximumItemOffset;
 159 }
 160
 161 void KItemListViewLayouter::setModel(const KItemModelBase* model)
 162 {
 163     if (m_model != model) {
 164         m_model = model;
 165         m_dirty = true;
 166     }
 167 }
 168
 169 const KItemModelBase* KItemListViewLayouter::model() const
 170 {
 171     return m_model;
 172 }
 173
 174 void KItemListViewLayouter::setSizeHintResolver(const KItemListSizeHintResolver* sizeHintResolver)
 175 {
 176     if (m_sizeHintResolver != sizeHintResolver) {
 177         m_sizeHintResolver = sizeHintResolver;
 178         m_dirty = true;
 179     }
 180 }
 181
 182 const KItemListSizeHintResolver* KItemListViewLayouter::sizeHintResolver() const
 183 {
 184     return m_sizeHintResolver;
 185 }
 186
 187 int KItemListViewLayouter::firstVisibleIndex() const
 188 {
 189     const_cast<KItemListViewLayouter*>(this)->doLayout();
 190     return m_firstVisibleIndex;
 191 }
 192
 193 int KItemListViewLayouter::lastVisibleIndex() const
 194 {
 195     const_cast<KItemListViewLayouter*>(this)->doLayout();
 196     return m_lastVisibleIndex;
 197 }
 198
 199 QRectF KItemListViewLayouter::itemRect(int index) const
 200 {
 201     const_cast<KItemListViewLayouter*>(this)->doLayout();
 202     if (index < 0 || index >= m_itemRects.count()) {
 203         return QRectF();
 204     }
 205
 206     if (m_scrollOrientation == Qt::Horizontal) {
 207         // Rotate the logical direction which is always vertical by 90°
 208         // to get the physical horizontal direction
 209         const QRectF& b = m_itemRects[index];
 210         QRectF bounds(b.y(), b.x(), b.height(), b.width());
 211         QPointF pos = bounds.topLeft();
 212         pos.rx() -= m_scrollOffset;
 213         bounds.moveTo(pos);
 214         return bounds;
 215     }
 216
 217     QRectF bounds = m_itemRects[index];
 218     bounds.moveTo(bounds.topLeft() - QPointF(m_itemOffset, m_scrollOffset));
 219     return bounds;
 220 }
 221
 222 QRectF KItemListViewLayouter::groupHeaderRect(int index) const
 223 {
 224     const QRectF firstItemRect = itemRect(index);
 225     QPointF pos = firstItemRect.topLeft();
 226     if (pos.isNull()) {
 227         return QRectF();
 228     }
 229
 230     pos.ry() -= m_groupHeaderHeight;
 231
 232     QSizeF size;
 233     if (m_scrollOrientation == Qt::Vertical) {
 234         pos.rx() = 0;
 235         size = QSizeF(m_size.width(), m_groupHeaderHeight);
 236     } else {
 237         size = QSizeF(firstItemRect.width(), m_groupHeaderHeight);
 238     }
 239     return QRectF(pos, size);
 240 }
 241
 242 int KItemListViewLayouter::maximumVisibleItems() const
 243 {
 244     const_cast<KItemListViewLayouter*>(this)->doLayout();
 245
 246     const int height = static_cast<int>(m_size.height());
 247     const int rowHeight = static_cast<int>(m_itemSize.height());
 248     int rows = height / rowHeight;
 249     if (height % rowHeight != 0) {
 250         ++rows;
 251     }
 252
 253     return rows * m_columnCount;
 254 }
 255
 256 int KItemListViewLayouter::itemsPerOffset() const
 257 {
 258     return m_columnCount;
 259 }
 260
 261 bool KItemListViewLayouter::isFirstGroupItem(int itemIndex) const
 262 {
 263     const_cast<KItemListViewLayouter*>(this)->doLayout();
 264     return m_groupItemIndexes.contains(itemIndex);
 265 }
 266
 267 void KItemListViewLayouter::markAsDirty()
 268 {
 269     m_dirty = true;
 270 }
 271
 272 void KItemListViewLayouter::doLayout()
 273 {
 274     if (m_dirty) {
 275 #ifdef KITEMLISTVIEWLAYOUTER_DEBUG
 276         QElapsedTimer timer;
 277         timer.start();
 278 #endif
 279         m_visibleIndexesDirty = true;
 280
 281         QSizeF itemSize = m_itemSize;
 282         QSizeF size = m_size;
 283
 284         const bool horizontalScrolling = (m_scrollOrientation == Qt::Horizontal);
 285         if (horizontalScrolling) {
 286             itemSize.setWidth(m_itemSize.height());
 287             itemSize.setHeight(m_itemSize.width());
 288             size.setWidth(m_size.height());
 289             size.setHeight(m_size.width());
 290         }
 291
 292         m_columnWidth = itemSize.width();
 293         m_columnCount = qMax(1, int(size.width() / m_columnWidth));
 294         m_xPosInc = 0;
 295
 296         const int itemCount = m_model->count();
 297         if (itemCount > m_columnCount) {
 298             // Apply the unused width equally to each column
 299             const qreal unusedWidth = size.width() - m_columnCount * m_columnWidth;
 300             if (unusedWidth > 0) {
 301                 // [Comment #1] A cast to int is done on purpose to prevent rounding issues when
 302                 // drawing pixmaps and drawing text or other graphic primitives: Qt uses a different
 303                 // rastering algorithm for the upper/left of pixmaps
 304                 const qreal columnInc = int(unusedWidth / (m_columnCount + 1));
 305                 m_columnWidth += columnInc;
 306                 m_xPosInc += columnInc;
 307             }
 308         }
 309
 310         int rowCount = itemCount / m_columnCount;
 311         if (itemCount % m_columnCount != 0) {
 312             ++rowCount;
 313         }
 314
 315         m_itemRects.reserve(itemCount);
 316
 317         qreal y = m_headerHeight;
 318         int rowIndex = 0;
 319
 320         const bool grouped = createGroupHeaders();
 321
 322         int index = 0;
 323         while (index < itemCount) {
 324             qreal x = m_xPosInc;
 325             qreal maxItemHeight = itemSize.height();
 326
 327             if (grouped) {
 328                 if (horizontalScrolling) {
 329                     // All group headers will always be aligned on the top and not
 330                     // flipped like the other properties
 331                     x += m_groupHeaderHeight;
 332                 }
 333
 334                 if (m_groupItemIndexes.contains(index)) {
 335                     if (!horizontalScrolling) {
 336                         // The item is the first item of a group.
 337                         // Increase the y-position to provide space
 338                         // for the group header.
 339                         y += m_groupHeaderHeight;
 340                     }
 341                 }
 342             }
 343
 344             int column = 0;
 345             while (index < itemCount && column < m_columnCount) {
 346                 qreal requiredItemHeight = itemSize.height();
 347                 if (m_sizeHintResolver) {
 348                     const QSizeF sizeHint = m_sizeHintResolver->sizeHint(index);
 349                     const qreal sizeHintHeight = horizontalScrolling ? sizeHint.width() : sizeHint.height();
 350                     if (sizeHintHeight > requiredItemHeight) {
 351                         requiredItemHeight = sizeHintHeight;
 352                     }
 353                 }
 354
 355                 const QRectF bounds(x, y, itemSize.width(), requiredItemHeight);
 356                 if (index < m_itemRects.count()) {
 357                     m_itemRects[index] = bounds;
 358                 } else {
 359                     m_itemRects.append(bounds);
 360                 }
 361
 362                 if (grouped && horizontalScrolling) {
 363                     // When grouping is enabled in the horizontal mode, the header alignment
 364                     // looks like this:
 365                     //   Header-1 Header-2 Header-3
 366                     //   Item 1   Item 4   Item 7
 367                     //   Item 2   Item 5   Item 8
 368                     //   Item 3   Item 6   Item 9
 369                     // In this case 'requiredItemHeight' represents the column-width. We don't
 370                     // check the content of the header in the layouter to determine the required
 371                     // width, hence assure that at least a minimal width of 15 characters is given
 372                     // (in average a character requires the halve width of the font height).
 373                     //
 374                     // TODO: Let the group headers provide a minimum width and respect this width here
 375                     const qreal minimumGroupHeaderWidth = int(m_groupHeaderHeight * 15 / 2); // See [Comment #1]
 376                     if (requiredItemHeight < minimumGroupHeaderWidth) {
 377                         requiredItemHeight = minimumGroupHeaderWidth;
 378                     }
 379                 }
 380
 381                 maxItemHeight = qMax(maxItemHeight, requiredItemHeight);
 382                 x += m_columnWidth;
 383                 ++index;
 384                 ++column;
 385
 386                 if (grouped && m_groupItemIndexes.contains(index)) {
 387                     // The item represents the first index of a group
 388                     // and must aligned in the first column
 389                     break;
 390                 }
 391             }
 392
 393             y += maxItemHeight;
 394             ++rowIndex;
 395         }
 396         if (m_itemRects.count() > itemCount) {
 397             m_itemRects.erase(m_itemRects.begin() + itemCount,
 398                                       m_itemRects.end());
 399         }
 400
 401         if (itemCount > 0) {
 402             // Calculate the maximum y-range of the last row for m_maximumScrollOffset
 403             m_maximumScrollOffset = m_itemRects.last().bottom();
 404             const qreal rowY = m_itemRects.last().y();
 405
 406             int index = m_itemRects.count() - 2;
 407             while (index >= 0 && m_itemRects.at(index).bottom() >= rowY) {
 408                 m_maximumScrollOffset = qMax(m_maximumScrollOffset, m_itemRects.at(index).bottom());
 409                 --index;
 410             }
 411
 412             m_maximumItemOffset = m_columnCount * m_columnWidth;
 413         } else {
 414             m_maximumScrollOffset = 0;
 415             m_maximumItemOffset = 0;
 416         }
 417
 418 #ifdef KITEMLISTVIEWLAYOUTER_DEBUG
 419         kDebug() << "[TIME] doLayout() for " << m_model->count() << "items:" << timer.elapsed();
 420 #endif
 421         m_dirty = false;
 422     }
 423
 424     updateVisibleIndexes();
 425 }
 426
 427 void KItemListViewLayouter::updateVisibleIndexes()
 428 {
 429     if (!m_visibleIndexesDirty) {
 430         return;
 431     }
 432
 433     Q_ASSERT(!m_dirty);
 434
 435     if (m_model->count() <= 0) {
 436         m_firstVisibleIndex = -1;
 437         m_lastVisibleIndex = -1;
 438         m_visibleIndexesDirty = false;
 439         return;
 440     }
 441
 442     const int maxIndex = m_model->count() - 1;
 443
 444     // Calculate the first visible index that is fully visible
 445     int min = 0;
 446     int max = maxIndex;
 447     int mid = 0;
 448     do {
 449         mid = (min + max) / 2;
 450         if (m_itemRects[mid].top() < m_scrollOffset) {
 451             min = mid + 1;
 452         } else {
 453             max = mid - 1;
 454         }
 455     } while (min <= max);
 456
 457     if (mid > 0) {
 458         // Include the row before the first fully visible index, as it might
 459         // be partly visible
 460         if (m_itemRects[mid].top() >= m_scrollOffset) {
 461             --mid;
 462             Q_ASSERT(m_itemRects[mid].top() < m_scrollOffset);
 463         }
 464
 465         const qreal rowTop = m_itemRects[mid].top();
 466         while (mid > 0 && m_itemRects[mid - 1].top() == rowTop) {
 467             --mid;
 468         }
 469     }
 470     m_firstVisibleIndex = mid;
 471
 472     // Calculate the last visible index that is (at least partly) visible
 473     const int visibleHeight = (m_scrollOrientation == Qt::Horizontal) ? m_size.width() : m_size.height();
 474     qreal bottom = m_scrollOffset + visibleHeight;
 475     if (m_model->groupedSorting()) {
 476         bottom += m_groupHeaderHeight;
 477     }
 478
 479     min = m_firstVisibleIndex;
 480     max = maxIndex;
 481     do {
 482         mid = (min + max) / 2;
 483         if (m_itemRects[mid].y() <= bottom) {
 484             min = mid + 1;
 485         } else {
 486             max = mid - 1;
 487         }
 488     } while (min <= max);
 489
 490     while (mid > 0 && m_itemRects[mid].y() > bottom) {
 491         --mid;
 492     }
 493     m_lastVisibleIndex = mid;
 494
 495     m_visibleIndexesDirty = false;
 496 }
 497
 498 bool KItemListViewLayouter::createGroupHeaders()
 499 {
 500     if (!m_model->groupedSorting()) {
 501         return false;
 502     }
 503
 504     m_groupItemIndexes.clear();
 505
 506     const QList<QPair<int, QVariant> > groups = m_model->groups();
 507     if (groups.isEmpty()) {
 508         return false;
 509     }
 510
 511     for (int i = 0; i < groups.count(); ++i) {
 512         const int firstItemIndex = groups.at(i).first;
 513         m_groupItemIndexes.insert(firstItemIndex);
 514     }
 515
 516     return true;
 517 }
 518
 519 #include "kitemlistviewlayouter_p.moc"