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 bool KItemListViewLayouter::isFirstGroupItem(int itemIndex) const
 257 {
 258     const_cast<KItemListViewLayouter*>(this)->doLayout();
 259     return m_groupItemIndexes.contains(itemIndex);
 260 }
 261
 262 void KItemListViewLayouter::markAsDirty()
 263 {
 264     m_dirty = true;
 265 }
 266
 267 void KItemListViewLayouter::doLayout()
 268 {
 269     if (m_dirty) {
 270 #ifdef KITEMLISTVIEWLAYOUTER_DEBUG
 271         QElapsedTimer timer;
 272         timer.start();
 273 #endif
 274         m_visibleIndexesDirty = true;
 275
 276         QSizeF itemSize = m_itemSize;
 277         QSizeF size = m_size;
 278
 279         const bool horizontalScrolling = (m_scrollOrientation == Qt::Horizontal);
 280         if (horizontalScrolling) {
 281             itemSize.setWidth(m_itemSize.height());
 282             itemSize.setHeight(m_itemSize.width());
 283             size.setWidth(m_size.height());
 284             size.setHeight(m_size.width());
 285         }
 286
 287         m_columnWidth = itemSize.width();
 288         m_columnCount = qMax(1, int(size.width() / m_columnWidth));
 289         m_xPosInc = 0;
 290
 291         const int itemCount = m_model->count();
 292         if (itemCount > m_columnCount) {
 293             // Apply the unused width equally to each column
 294             const qreal unusedWidth = size.width() - m_columnCount * m_columnWidth;
 295             if (unusedWidth > 0) {
 296                 // [Comment #1] A cast to int is done on purpose to prevent rounding issues when
 297                 // drawing pixmaps and drawing text or other graphic primitives: Qt uses a different
 298                 // rastering algorithm for the upper/left of pixmaps
 299                 const qreal columnInc = int(unusedWidth / (m_columnCount + 1));
 300                 m_columnWidth += columnInc;
 301                 m_xPosInc += columnInc;
 302             }
 303         }
 304
 305         int rowCount = itemCount / m_columnCount;
 306         if (itemCount % m_columnCount != 0) {
 307             ++rowCount;
 308         }
 309
 310         m_itemRects.reserve(itemCount);
 311
 312         qreal y = m_headerHeight;
 313         int rowIndex = 0;
 314
 315         const bool grouped = createGroupHeaders();
 316
 317         int index = 0;
 318         while (index < itemCount) {
 319             qreal x = m_xPosInc;
 320             qreal maxItemHeight = itemSize.height();
 321
 322             if (grouped) {
 323                 if (horizontalScrolling) {
 324                     // All group headers will always be aligned on the top and not
 325                     // flipped like the other properties
 326                     x += m_groupHeaderHeight;
 327                 }
 328
 329                 if (m_groupItemIndexes.contains(index)) {
 330                     if (!horizontalScrolling) {
 331                         // The item is the first item of a group.
 332                         // Increase the y-position to provide space
 333                         // for the group header.
 334                         y += m_groupHeaderHeight;
 335                     }
 336                 }
 337             }
 338
 339             int column = 0;
 340             while (index < itemCount && column < m_columnCount) {
 341                 qreal requiredItemHeight = itemSize.height();
 342                 if (m_sizeHintResolver) {
 343                     const QSizeF sizeHint = m_sizeHintResolver->sizeHint(index);
 344                     const qreal sizeHintHeight = horizontalScrolling ? sizeHint.width() : sizeHint.height();
 345                     if (sizeHintHeight > requiredItemHeight) {
 346                         requiredItemHeight = sizeHintHeight;
 347                     }
 348                 }
 349
 350                 const QRectF bounds(x, y, itemSize.width(), requiredItemHeight);
 351                 if (index < m_itemRects.count()) {
 352                     m_itemRects[index] = bounds;
 353                 } else {
 354                     m_itemRects.append(bounds);
 355                 }
 356
 357                 if (grouped && horizontalScrolling) {
 358                     // When grouping is enabled in the horizontal mode, the header alignment
 359                     // looks like this:
 360                     //   Header-1 Header-2 Header-3
 361                     //   Item 1   Item 4   Item 7
 362                     //   Item 2   Item 5   Item 8
 363                     //   Item 3   Item 6   Item 9
 364                     // In this case 'requiredItemHeight' represents the column-width. We don't
 365                     // check the content of the header in the layouter to determine the required
 366                     // width, hence assure that at least a minimal width of 15 characters is given
 367                     // (in average a character requires the halve width of the font height).
 368                     //
 369                     // TODO: Let the group headers provide a minimum width and respect this width here
 370                     const qreal minimumGroupHeaderWidth = int(m_groupHeaderHeight * 15 / 2); // See [Comment #1]
 371                     if (requiredItemHeight < minimumGroupHeaderWidth) {
 372                         requiredItemHeight = minimumGroupHeaderWidth;
 373                     }
 374                 }
 375
 376                 maxItemHeight = qMax(maxItemHeight, requiredItemHeight);
 377                 x += m_columnWidth;
 378                 ++index;
 379                 ++column;
 380
 381                 if (grouped && m_groupItemIndexes.contains(index)) {
 382                     // The item represents the first index of a group
 383                     // and must aligned in the first column
 384                     break;
 385                 }
 386             }
 387
 388             y += maxItemHeight;
 389             ++rowIndex;
 390         }
 391         if (m_itemRects.count() > itemCount) {
 392             m_itemRects.erase(m_itemRects.begin() + itemCount,
 393                                       m_itemRects.end());
 394         }
 395
 396         if (itemCount > 0) {
 397             // Calculate the maximum y-range of the last row for m_maximumScrollOffset
 398             m_maximumScrollOffset = m_itemRects.last().bottom();
 399             const qreal rowY = m_itemRects.last().y();
 400
 401             int index = m_itemRects.count() - 2;
 402             while (index >= 0 && m_itemRects.at(index).bottom() >= rowY) {
 403                 m_maximumScrollOffset = qMax(m_maximumScrollOffset, m_itemRects.at(index).bottom());
 404                 --index;
 405             }
 406
 407             m_maximumItemOffset = m_columnCount * m_columnWidth;
 408         } else {
 409             m_maximumScrollOffset = 0;
 410             m_maximumItemOffset = 0;
 411         }
 412
 413 #ifdef KITEMLISTVIEWLAYOUTER_DEBUG
 414         kDebug() << "[TIME] doLayout() for " << m_model->count() << "items:" << timer.elapsed();
 415 #endif
 416         m_dirty = false;
 417     }
 418
 419     updateVisibleIndexes();
 420 }
 421
 422 void KItemListViewLayouter::updateVisibleIndexes()
 423 {
 424     if (!m_visibleIndexesDirty) {
 425         return;
 426     }
 427
 428     Q_ASSERT(!m_dirty);
 429
 430     if (m_model->count() <= 0) {
 431         m_firstVisibleIndex = -1;
 432         m_lastVisibleIndex = -1;
 433         m_visibleIndexesDirty = false;
 434         return;
 435     }
 436
 437     const int maxIndex = m_model->count() - 1;
 438
 439     // Calculate the first visible index that is fully visible
 440     int min = 0;
 441     int max = maxIndex;
 442     int mid = 0;
 443     do {
 444         mid = (min + max) / 2;
 445         if (m_itemRects[mid].top() < m_scrollOffset) {
 446             min = mid + 1;
 447         } else {
 448             max = mid - 1;
 449         }
 450     } while (min <= max);
 451
 452     if (mid > 0) {
 453         // Include the row before the first fully visible index, as it might
 454         // be partly visible
 455         if (m_itemRects[mid].top() >= m_scrollOffset) {
 456             --mid;
 457             Q_ASSERT(m_itemRects[mid].top() < m_scrollOffset);
 458         }
 459
 460         const qreal rowTop = m_itemRects[mid].top();
 461         while (mid > 0 && m_itemRects[mid - 1].top() == rowTop) {
 462             --mid;
 463         }
 464     }
 465     m_firstVisibleIndex = mid;
 466
 467     // Calculate the last visible index that is (at least partly) visible
 468     const int visibleHeight = (m_scrollOrientation == Qt::Horizontal) ? m_size.width() : m_size.height();
 469     qreal bottom = m_scrollOffset + visibleHeight;
 470     if (m_model->groupedSorting()) {
 471         bottom += m_groupHeaderHeight;
 472     }
 473
 474     min = m_firstVisibleIndex;
 475     max = maxIndex;
 476     do {
 477         mid = (min + max) / 2;
 478         if (m_itemRects[mid].y() <= bottom) {
 479             min = mid + 1;
 480         } else {
 481             max = mid - 1;
 482         }
 483     } while (min <= max);
 484
 485     while (mid > 0 && m_itemRects[mid].y() > bottom) {
 486         --mid;
 487     }
 488     m_lastVisibleIndex = mid;
 489
 490     m_visibleIndexesDirty = false;
 491 }
 492
 493 bool KItemListViewLayouter::createGroupHeaders()
 494 {
 495     if (!m_model->groupedSorting()) {
 496         return false;
 497     }
 498
 499     m_groupItemIndexes.clear();
 500
 501     const QList<QPair<int, QVariant> > groups = m_model->groups();
 502     if (groups.isEmpty()) {
 503         return false;
 504     }
 505
 506     for (int i = 0; i < groups.count(); ++i) {
 507         const int firstItemIndex = groups.at(i).first;
 508         m_groupItemIndexes.insert(firstItemIndex);
 509     }
 510
 511     return true;
 512 }
 513
 514 #include "kitemlistviewlayouter_p.moc"