src/kitemviews/private/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.h"
  21
  22 #include <kitemviews/kitemmodelbase.h>
  23 #include "kitemlistsizehintresolver.h"
  24
  25 #include <KDebug>
  26
  27 // #define KITEMLISTVIEWLAYOUTER_DEBUG
  28
  29 KItemListViewLayouter::KItemListViewLayouter(KItemListSizeHintResolver* sizeHintResolver, 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_itemMargin(),
  37     m_headerHeight(0),
  38     m_model(0),
  39     m_sizeHintResolver(sizeHintResolver),
  40     m_scrollOffset(0),
  41     m_maximumScrollOffset(0),
  42     m_itemOffset(0),
  43     m_maximumItemOffset(0),
  44     m_firstVisibleIndex(-1),
  45     m_lastVisibleIndex(-1),
  46     m_columnWidth(0),
  47     m_xPosInc(0),
  48     m_columnCount(0),
  49     m_rowOffsets(),
  50     m_columnOffsets(),
  51     m_groupItemIndexes(),
  52     m_groupHeaderHeight(0),
  53     m_groupHeaderMargin(0),
  54     m_itemInfos()
  55 {
  56     Q_ASSERT(m_sizeHintResolver);
  57 }
  58
  59 KItemListViewLayouter::~KItemListViewLayouter()
  60 {
  61 }
  62
  63 void KItemListViewLayouter::setScrollOrientation(Qt::Orientation orientation)
  64 {
  65     if (m_scrollOrientation != orientation) {
  66         m_scrollOrientation = orientation;
  67         m_dirty = true;
  68     }
  69 }
  70
  71 Qt::Orientation KItemListViewLayouter::scrollOrientation() const
  72 {
  73     return m_scrollOrientation;
  74 }
  75
  76 void KItemListViewLayouter::setSize(const QSizeF& size)
  77 {
  78     if (m_size != size) {
  79         if (m_scrollOrientation == Qt::Vertical) {
  80             if (m_size.width() != size.width()) {
  81                 m_dirty = true;
  82             }
  83         } else if (m_size.height() != size.height()) {
  84             m_dirty = true;
  85         }
  86
  87         m_size = size;
  88         m_visibleIndexesDirty = true;
  89     }
  90 }
  91
  92 QSizeF KItemListViewLayouter::size() const
  93 {
  94     return m_size;
  95 }
  96
  97 void KItemListViewLayouter::setItemSize(const QSizeF& size)
  98 {
  99     if (m_itemSize != size) {
 100         m_itemSize = size;
 101         m_dirty = true;
 102     }
 103 }
 104
 105 QSizeF KItemListViewLayouter::itemSize() const
 106 {
 107     return m_itemSize;
 108 }
 109
 110 void KItemListViewLayouter::setItemMargin(const QSizeF& margin)
 111 {
 112     if (m_itemMargin != margin) {
 113         m_itemMargin = margin;
 114         m_dirty = true;
 115     }
 116 }
 117
 118 QSizeF KItemListViewLayouter::itemMargin() const
 119 {
 120     return m_itemMargin;
 121 }
 122
 123 void KItemListViewLayouter::setHeaderHeight(qreal height)
 124 {
 125     if (m_headerHeight != height) {
 126         m_headerHeight = height;
 127         m_dirty = true;
 128     }
 129 }
 130
 131 qreal KItemListViewLayouter::headerHeight() const
 132 {
 133     return m_headerHeight;
 134 }
 135
 136 void KItemListViewLayouter::setGroupHeaderHeight(qreal height)
 137 {
 138     if (m_groupHeaderHeight != height) {
 139         m_groupHeaderHeight = height;
 140         m_dirty = true;
 141     }
 142 }
 143
 144 qreal KItemListViewLayouter::groupHeaderHeight() const
 145 {
 146     return m_groupHeaderHeight;
 147 }
 148
 149 void KItemListViewLayouter::setGroupHeaderMargin(qreal margin)
 150 {
 151     if (m_groupHeaderMargin != margin) {
 152         m_groupHeaderMargin = margin;
 153         m_dirty = true;
 154     }
 155 }
 156
 157 qreal KItemListViewLayouter::groupHeaderMargin() const
 158 {
 159     return m_groupHeaderMargin;
 160 }
 161
 162 void KItemListViewLayouter::setScrollOffset(qreal offset)
 163 {
 164     if (m_scrollOffset != offset) {
 165         m_scrollOffset = offset;
 166         m_visibleIndexesDirty = true;
 167     }
 168 }
 169
 170 qreal KItemListViewLayouter::scrollOffset() const
 171 {
 172     return m_scrollOffset;
 173 }
 174
 175 qreal KItemListViewLayouter::maximumScrollOffset() const
 176 {
 177     const_cast<KItemListViewLayouter*>(this)->doLayout();
 178     return m_maximumScrollOffset;
 179 }
 180
 181 void KItemListViewLayouter::setItemOffset(qreal offset)
 182 {
 183     if (m_itemOffset != offset) {
 184         m_itemOffset = offset;
 185         m_visibleIndexesDirty = true;
 186     }
 187 }
 188
 189 qreal KItemListViewLayouter::itemOffset() const
 190 {
 191     return m_itemOffset;
 192 }
 193
 194 qreal KItemListViewLayouter::maximumItemOffset() const
 195 {
 196     const_cast<KItemListViewLayouter*>(this)->doLayout();
 197     return m_maximumItemOffset;
 198 }
 199
 200 void KItemListViewLayouter::setModel(const KItemModelBase* model)
 201 {
 202     if (m_model != model) {
 203         m_model = model;
 204         m_dirty = true;
 205     }
 206 }
 207
 208 const KItemModelBase* KItemListViewLayouter::model() const
 209 {
 210     return m_model;
 211 }
 212
 213 int KItemListViewLayouter::firstVisibleIndex() const
 214 {
 215     const_cast<KItemListViewLayouter*>(this)->doLayout();
 216     return m_firstVisibleIndex;
 217 }
 218
 219 int KItemListViewLayouter::lastVisibleIndex() const
 220 {
 221     const_cast<KItemListViewLayouter*>(this)->doLayout();
 222     return m_lastVisibleIndex;
 223 }
 224
 225 QRectF KItemListViewLayouter::itemRect(int index) const
 226 {
 227     const_cast<KItemListViewLayouter*>(this)->doLayout();
 228     if (index < 0 || index >= m_itemInfos.count()) {
 229         return QRectF();
 230     }
 231
 232     QSizeF sizeHint = m_sizeHintResolver->sizeHint(index);
 233
 234     const qreal x = m_columnOffsets.at(m_itemInfos.at(index).column);
 235     const qreal y = m_rowOffsets.at(m_itemInfos.at(index).row);
 236
 237     if (m_scrollOrientation == Qt::Horizontal) {
 238         // Rotate the logical direction which is always vertical by 90°
 239         // to get the physical horizontal direction
 240         QPointF pos(y, x);
 241         pos.rx() -= m_scrollOffset;
 242         return QRectF(pos, sizeHint);
 243     }
 244
 245     if (sizeHint.width() <= 0) {
 246         // In Details View, a size hint with negative width is used internally.
 247         sizeHint.rwidth() = m_itemSize.width();
 248     }
 249
 250     const QPointF pos(x - m_itemOffset, y - m_scrollOffset);
 251     return QRectF(pos, sizeHint);
 252 }
 253
 254 QRectF KItemListViewLayouter::groupHeaderRect(int index) const
 255 {
 256     const_cast<KItemListViewLayouter*>(this)->doLayout();
 257
 258     const QRectF firstItemRect = itemRect(index);
 259     QPointF pos = firstItemRect.topLeft();
 260     if (pos.isNull()) {
 261         return QRectF();
 262     }
 263
 264     QSizeF size;
 265     if (m_scrollOrientation == Qt::Vertical) {
 266         pos.rx() = 0;
 267         pos.ry() -= m_groupHeaderHeight;
 268         size = QSizeF(m_size.width(), m_groupHeaderHeight);
 269     } else {
 270         pos.rx() -= m_itemMargin.width();
 271         pos.ry() = 0;
 272
 273         // Determine the maximum width used in the current column. As the
 274         // scroll-direction is Qt::Horizontal and m_itemRects is accessed
 275         // directly, the logical height represents the visual width, and
 276         // the logical row represents the column.
 277         qreal headerWidth = minimumGroupHeaderWidth();
 278         const int row = m_itemInfos[index].row;
 279         const int maxIndex = m_itemInfos.count() - 1;
 280         while (index <= maxIndex) {
 281             if (m_itemInfos[index].row != row) {
 282                 break;
 283             }
 284
 285             const qreal itemWidth = m_sizeHintResolver->sizeHint(index).width();
 286
 287             if (itemWidth > headerWidth) {
 288                 headerWidth = itemWidth;
 289             }
 290
 291             ++index;
 292         }
 293
 294         size = QSizeF(headerWidth, m_size.height());
 295     }
 296     return QRectF(pos, size);
 297 }
 298
 299 int KItemListViewLayouter::itemColumn(int index) const
 300 {
 301     const_cast<KItemListViewLayouter*>(this)->doLayout();
 302     if (index < 0 || index >= m_itemInfos.count()) {
 303         return -1;
 304     }
 305
 306     return (m_scrollOrientation == Qt::Vertical)
 307             ? m_itemInfos[index].column
 308             : m_itemInfos[index].row;
 309 }
 310
 311 int KItemListViewLayouter::itemRow(int index) const
 312 {
 313     const_cast<KItemListViewLayouter*>(this)->doLayout();
 314     if (index < 0 || index >= m_itemInfos.count()) {
 315         return -1;
 316     }
 317
 318     return (m_scrollOrientation == Qt::Vertical)
 319             ? m_itemInfos[index].row
 320             : m_itemInfos[index].column;
 321 }
 322
 323 int KItemListViewLayouter::maximumVisibleItems() const
 324 {
 325     const_cast<KItemListViewLayouter*>(this)->doLayout();
 326
 327     const int height = static_cast<int>(m_size.height());
 328     const int rowHeight = static_cast<int>(m_itemSize.height());
 329     int rows = height / rowHeight;
 330     if (height % rowHeight != 0) {
 331         ++rows;
 332     }
 333
 334     return rows * m_columnCount;
 335 }
 336
 337 bool KItemListViewLayouter::isFirstGroupItem(int itemIndex) const
 338 {
 339     const_cast<KItemListViewLayouter*>(this)->doLayout();
 340     return m_groupItemIndexes.contains(itemIndex);
 341 }
 342
 343 void KItemListViewLayouter::markAsDirty()
 344 {
 345     m_dirty = true;
 346 }
 347
 348
 349 #ifndef QT_NO_DEBUG
 350     bool KItemListViewLayouter::isDirty()
 351     {
 352         return m_dirty;
 353     }
 354 #endif
 355
 356 void KItemListViewLayouter::doLayout()
 357 {
 358     if (m_dirty) {
 359 #ifdef KITEMLISTVIEWLAYOUTER_DEBUG
 360         QElapsedTimer timer;
 361         timer.start();
 362 #endif
 363         m_visibleIndexesDirty = true;
 364
 365         QSizeF itemSize = m_itemSize;
 366         QSizeF itemMargin = m_itemMargin;
 367         QSizeF size = m_size;
 368
 369         const bool grouped = createGroupHeaders();
 370
 371         const bool horizontalScrolling = (m_scrollOrientation == Qt::Horizontal);
 372         if (horizontalScrolling) {
 373             // Flip everything so that the layout logically can work like having
 374             // a vertical scrolling
 375             itemSize.transpose();
 376             itemMargin.transpose();
 377             size.transpose();
 378
 379             if (grouped) {
 380                 // In the horizontal scrolling case all groups are aligned
 381                 // at the top, which decreases the available height. For the
 382                 // flipped data this means that the width must be decreased.
 383                 size.rwidth() -= m_groupHeaderHeight;
 384             }
 385         }
 386
 387         m_columnWidth = itemSize.width() + itemMargin.width();
 388         const qreal widthForColumns = size.width() - itemMargin.width();
 389         m_columnCount = qMax(1, int(widthForColumns / m_columnWidth));
 390         m_xPosInc = itemMargin.width();
 391
 392         const int itemCount = m_model->count();
 393         if (itemCount > m_columnCount && m_columnWidth >= 32) {
 394             // Apply the unused width equally to each column
 395             const qreal unusedWidth = widthForColumns - m_columnCount * m_columnWidth;
 396             if (unusedWidth > 0) {
 397                 const qreal columnInc = unusedWidth / (m_columnCount + 1);
 398                 m_columnWidth += columnInc;
 399                 m_xPosInc += columnInc;
 400             }
 401         }
 402
 403         m_itemInfos.resize(itemCount);
 404
 405         // Calculate the offset of each column, i.e., the x-coordinate where the column starts.
 406         m_columnOffsets.resize(m_columnCount);
 407         qreal currentOffset = m_xPosInc;
 408
 409         if (grouped && horizontalScrolling) {
 410             // All group headers will always be aligned on the top and not
 411             // flipped like the other properties.
 412             currentOffset += m_groupHeaderHeight;
 413         }
 414
 415         for (int column = 0; column < m_columnCount; ++column) {
 416             m_columnOffsets[column] = currentOffset;
 417             currentOffset += m_columnWidth;
 418         }
 419
 420         // Prepare the QVector which stores the y-coordinate for each new row.
 421         int numberOfRows = (itemCount + m_columnCount - 1) / m_columnCount;
 422         if (grouped && m_columnCount > 1) {
 423             // In the worst case, a new row will be started for every group.
 424             // We could calculate the exact number of rows now to prevent that we reserve
 425             // too much memory, but the code required to do that might need much more
 426             // memory than it would save in the average case.
 427             numberOfRows += m_groupItemIndexes.count();
 428         }
 429         m_rowOffsets.resize(numberOfRows);
 430
 431         qreal y = m_headerHeight + itemMargin.height();
 432         int row = 0;
 433
 434         int index = 0;
 435         while (index < itemCount) {
 436             qreal maxItemHeight = itemSize.height();
 437
 438             if (grouped) {
 439                 if (m_groupItemIndexes.contains(index)) {
 440                     // The item is the first item of a group.
 441                     // Increase the y-position to provide space
 442                     // for the group header.
 443                     if (index > 0) {
 444                         // Only add a margin if there has been added another
 445                         // group already before
 446                         y += m_groupHeaderMargin;
 447                     } else if (!horizontalScrolling) {
 448                         // The first group header should be aligned on top
 449                         y -= itemMargin.height();
 450                     }
 451
 452                     if (!horizontalScrolling) {
 453                         y += m_groupHeaderHeight;
 454                     }
 455                 }
 456             }
 457
 458             m_rowOffsets[row] = y;
 459
 460             int column = 0;
 461             while (index < itemCount && column < m_columnCount) {
 462                 qreal requiredItemHeight = itemSize.height();
 463                 const QSizeF sizeHint = m_sizeHintResolver->sizeHint(index);
 464                 const qreal sizeHintHeight = horizontalScrolling ? sizeHint.width() : sizeHint.height();
 465                 if (sizeHintHeight > requiredItemHeight) {
 466                     requiredItemHeight = sizeHintHeight;
 467                 }
 468
 469                 ItemInfo& itemInfo = m_itemInfos[index];
 470                 itemInfo.column = column;
 471                 itemInfo.row = row;
 472
 473                 if (grouped && horizontalScrolling) {
 474                     // When grouping is enabled in the horizontal mode, the header alignment
 475                     // looks like this:
 476                     //   Header-1 Header-2 Header-3
 477                     //   Item 1   Item 4   Item 7
 478                     //   Item 2   Item 5   Item 8
 479                     //   Item 3   Item 6   Item 9
 480                     // In this case 'requiredItemHeight' represents the column-width. We don't
 481                     // check the content of the header in the layouter to determine the required
 482                     // width, hence assure that at least a minimal width of 15 characters is given
 483                     // (in average a character requires the halve width of the font height).
 484                     //
 485                     // TODO: Let the group headers provide a minimum width and respect this width here
 486                     const qreal headerWidth = minimumGroupHeaderWidth();
 487                     if (requiredItemHeight < headerWidth) {
 488                         requiredItemHeight = headerWidth;
 489                     }
 490                 }
 491
 492                 maxItemHeight = qMax(maxItemHeight, requiredItemHeight);
 493                 ++index;
 494                 ++column;
 495
 496                 if (grouped && m_groupItemIndexes.contains(index)) {
 497                     // The item represents the first index of a group
 498                     // and must aligned in the first column
 499                     break;
 500                 }
 501             }
 502
 503             y += maxItemHeight + itemMargin.height();
 504             ++row;
 505         }
 506
 507         if (itemCount > 0) {
 508             m_maximumScrollOffset = y;
 509             m_maximumItemOffset = m_columnCount * m_columnWidth;
 510         } else {
 511             m_maximumScrollOffset = 0;
 512             m_maximumItemOffset = 0;
 513         }
 514
 515 #ifdef KITEMLISTVIEWLAYOUTER_DEBUG
 516         kDebug() << "[TIME] doLayout() for " << m_model->count() << "items:" << timer.elapsed();
 517 #endif
 518         m_dirty = false;
 519     }
 520
 521     updateVisibleIndexes();
 522 }
 523
 524 void KItemListViewLayouter::updateVisibleIndexes()
 525 {
 526     if (!m_visibleIndexesDirty) {
 527         return;
 528     }
 529
 530     Q_ASSERT(!m_dirty);
 531
 532     if (m_model->count() <= 0) {
 533         m_firstVisibleIndex = -1;
 534         m_lastVisibleIndex = -1;
 535         m_visibleIndexesDirty = false;
 536         return;
 537     }
 538
 539     const int maxIndex = m_model->count() - 1;
 540
 541     // Calculate the first visible index that is fully visible
 542     int min = 0;
 543     int max = maxIndex;
 544     int mid = 0;
 545     do {
 546         mid = (min + max) / 2;
 547         if (m_rowOffsets.at(m_itemInfos[mid].row) < m_scrollOffset) {
 548             min = mid + 1;
 549         } else {
 550             max = mid - 1;
 551         }
 552     } while (min <= max);
 553
 554     if (mid > 0) {
 555         // Include the row before the first fully visible index, as it might
 556         // be partly visible
 557         if (m_rowOffsets.at(m_itemInfos[mid].row) >= m_scrollOffset) {
 558             --mid;
 559             Q_ASSERT(m_rowOffsets.at(m_itemInfos[mid].row) < m_scrollOffset);
 560         }
 561
 562         const int firstVisibleRow = m_itemInfos[mid].row;
 563         while (mid > 0 && m_itemInfos[mid - 1].row == firstVisibleRow) {
 564             --mid;
 565         }
 566     }
 567     m_firstVisibleIndex = mid;
 568
 569     // Calculate the last visible index that is (at least partly) visible
 570     const int visibleHeight = (m_scrollOrientation == Qt::Horizontal) ? m_size.width() : m_size.height();
 571     qreal bottom = m_scrollOffset + visibleHeight;
 572     if (m_model->groupedSorting()) {
 573         bottom += m_groupHeaderHeight;
 574     }
 575
 576     min = m_firstVisibleIndex;
 577     max = maxIndex;
 578     do {
 579         mid = (min + max) / 2;
 580         if (m_rowOffsets.at(m_itemInfos[mid].row) <= bottom) {
 581             min = mid + 1;
 582         } else {
 583             max = mid - 1;
 584         }
 585     } while (min <= max);
 586
 587     while (mid > 0 && m_rowOffsets.at(m_itemInfos[mid].row) > bottom) {
 588         --mid;
 589     }
 590     m_lastVisibleIndex = mid;
 591
 592     m_visibleIndexesDirty = false;
 593 }
 594
 595 bool KItemListViewLayouter::createGroupHeaders()
 596 {
 597     if (!m_model->groupedSorting()) {
 598         return false;
 599     }
 600
 601     m_groupItemIndexes.clear();
 602
 603     const QList<QPair<int, QVariant> > groups = m_model->groups();
 604     if (groups.isEmpty()) {
 605         return false;
 606     }
 607
 608     for (int i = 0; i < groups.count(); ++i) {
 609         const int firstItemIndex = groups.at(i).first;
 610         m_groupItemIndexes.insert(firstItemIndex);
 611     }
 612
 613     return true;
 614 }
 615
 616 qreal KItemListViewLayouter::minimumGroupHeaderWidth() const
 617 {
 618     return 100;
 619 }
 620
 621 #include "kitemlistviewlayouter.moc"