src/kitemviews/kitemlistview.h

   1 /***************************************************************************
   2  *   Copyright (C) 2011 by Peter Penz <peter.penz19@gmail.com>             *
   3  *                                                                         *
   4  *   Based on the Itemviews NG project from Trolltech Labs:                *
   5  *   http://qt.gitorious.org/qt-labs/itemviews-ng                          *
   6  *                                                                         *
   7  *   This program is free software; you can redistribute it and/or modify  *
   8  *   it under the terms of the GNU General Public License as published by  *
   9  *   the Free Software Foundation; either version 2 of the License, or     *
  10  *   (at your option) any later version.                                   *
  11  *                                                                         *
  12  *   This program is distributed in the hope that it will be useful,       *
  13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  15  *   GNU General Public License for more details.                          *
  16  *                                                                         *
  17  *   You should have received a copy of the GNU General Public License     *
  18  *   along with this program; if not, write to the                         *
  19  *   Free Software Foundation, Inc.,                                       *
  20  *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA            *
  21  ***************************************************************************/
  22
  23 #ifndef KITEMLISTVIEW_H
  24 #define KITEMLISTVIEW_H
  25
  26 #include <libdolphin_export.h>
  27
  28 #include <kitemviews/kitemlistgroupheader.h>
  29 #include <kitemviews/kitemliststyleoption.h>
  30 #include <kitemviews/kitemlistviewanimation_p.h>
  31 #include <kitemviews/kitemlistwidget.h>
  32 #include <kitemviews/kitemmodelbase.h>
  33 #include <QGraphicsWidget>
  34 #include <QSet>
  35
  36 class KItemListController;
  37 class KItemListGroupHeaderCreatorBase;
  38 class KItemListHeader;
  39 class KItemListHeaderWidget;
  40 class KItemListSizeHintResolver;
  41 class KItemListRubberBand;
  42 class KItemListViewAnimation;
  43 class KItemListViewLayouter;
  44 class KItemListWidget;
  45 class KItemListWidgetCreatorBase;
  46 class KItemListViewCreatorBase;
  47 class QTimer;
  48
  49 /**
  50  * @brief Represents the view of an item-list.
  51  *
  52  * The view is responsible for showing the items of the model within
  53  * a GraphicsItem. Each visible item is represented by a KItemListWidget.
  54  *
  55  * The created view must be applied to the KItemListController with
  56  * KItemListController::setView(). For showing a custom model it is not
  57  * mandatory to derive from KItemListView, all that is necessary is
  58  * to set a widget-creator that is capable to create KItemListWidgets
  59  * showing the model items. A widget-creator can be set with
  60  * KItemListView::setWidgetCreator().
  61  *
  62  * @see KItemListWidget
  63  * @see KItemModelBase
  64  */
  65 class LIBDOLPHINPRIVATE_EXPORT KItemListView : public QGraphicsWidget
  66 {
  67     Q_OBJECT
  68
  69     Q_PROPERTY(qreal scrollOffset READ scrollOffset WRITE setScrollOffset)
  70     Q_PROPERTY(qreal itemOffset READ itemOffset WRITE setItemOffset)
  71
  72 public:
  73     KItemListView(QGraphicsWidget* parent = 0);
  74     virtual ~KItemListView();
  75
  76     /**
  77      * If the scroll-orientation is vertical, the items are ordered
  78      * from top to bottom (= default setting). If the scroll-orientation
  79      * is horizontal, the items are ordered from left to right.
  80      */
  81     void setScrollOrientation(Qt::Orientation orientation);
  82     Qt::Orientation scrollOrientation() const;
  83
  84     void setItemSize(const QSizeF& size);
  85     QSizeF itemSize() const;
  86
  87     /**
  88      * Offset of the scrollbar that represents the scroll-orientation
  89      * (see setScrollOrientation()).
  90      */
  91     void setScrollOffset(qreal offset);
  92     qreal scrollOffset() const;
  93
  94     qreal maximumScrollOffset() const;
  95
  96     /**
  97      * Offset related to an item, that does not fit into the available
  98      * size of the listview. If the scroll-orientation is vertical
  99      * the item-offset describes the offset of the horizontal axe, if
 100      * the scroll-orientation is horizontal the item-offset describes
 101      * the offset of the vertical axe.
 102      */
 103     void setItemOffset(qreal scrollOffset);
 104     qreal itemOffset() const;
 105
 106     qreal maximumItemOffset() const;
 107
 108     void setVisibleRoles(const QList<QByteArray>& roles);
 109     QList<QByteArray> visibleRoles() const;
 110
 111     /**
 112      * If set to true an automatic scrolling is done as soon as the
 113      * mouse is moved near the borders of the view. Per default
 114      * the automatic scrolling is turned off.
 115      */
 116     void setAutoScroll(bool enabled);
 117     bool autoScroll() const;
 118
 119     /**
 120      * If set to true selection-toggles will be shown when hovering
 121      * an item. Per default the selection-toggles are disabled.
 122      */
 123     void setEnabledSelectionToggles(bool enabled);
 124     bool enabledSelectionToggles() const;
 125
 126     /**
 127      * @return Controller of the item-list. The controller gets
 128      *         initialized by KItemListController::setView() and will
 129      *         result in calling KItemListController::onControllerChanged().
 130      */
 131     KItemListController* controller() const;
 132
 133     /**
 134      * @return Model of the item-list. The model gets
 135      *         initialized by KItemListController::setModel() and will
 136      *         result in calling KItemListController::onModelChanged().
 137      */
 138     KItemModelBase* model() const;
 139
 140     /**
 141      * Sets the creator that creates a widget showing the
 142      * content of one model-item. Usually it is sufficient
 143      * to implement a custom widget X derived from KItemListWidget and
 144      * set the creator by:
 145      * <code>
 146      * itemListView->setWidgetCreator(new KItemListWidgetCreator<X>());
 147      * </code>
 148      * Note that the ownership of the widget creator is not transferred to
 149      * the item-list view: One instance of a widget creator might get shared
 150      * by several item-list view instances.
 151      **/
 152     void setWidgetCreator(KItemListWidgetCreatorBase* widgetCreator);
 153     KItemListWidgetCreatorBase* widgetCreator() const;
 154
 155     void setGroupHeaderCreator(KItemListGroupHeaderCreatorBase* groupHeaderCreator);
 156     KItemListGroupHeaderCreatorBase* groupHeaderCreator() const;
 157
 158     void setStyleOption(const KItemListStyleOption& option);
 159     const KItemListStyleOption& styleOption() const;
 160
 161     /** @reimp */
 162     virtual void setGeometry(const QRectF& rect);
 163
 164     /**
 165      * @return Index of the item that is below the point \a pos.
 166      *         The position is relative to the upper right of
 167      *         the visible area. Only (at least partly) visible
 168      *         items are considered. -1 is returned if no item is
 169      *         below the position.
 170      */
 171     int itemAt(const QPointF& pos) const;
 172     bool isAboveSelectionToggle(int index, const QPointF& pos) const;
 173     bool isAboveExpansionToggle(int index, const QPointF& pos) const;
 174
 175     /**
 176      * @return Index of the first item that is at least partly visible.
 177      *         -1 is returned if the model contains no items.
 178      */
 179     int firstVisibleIndex() const;
 180
 181     /**
 182      * @return Index of the last item that is at least partly visible.
 183      *         -1 is returned if the model contains no items.
 184      */
 185     int lastVisibleIndex() const;
 186
 187     /**
 188      * @return Required size for the item with the index \p index.
 189      *         The returned value might be larger than KItemListView::itemSize().
 190      *         In this case the layout grid will be stretched to assure an
 191      *         unclipped item.
 192      */
 193     QSizeF itemSizeHint(int index) const;
 194
 195     /**
 196      * If set to true, items having child-items can be expanded to show the child-items as
 197      * part of the view. Per default the expanding of items is is disabled. If expanding of
 198      * items is enabled, the methods KItemModelBase::setExpanded(), KItemModelBase::isExpanded(),
 199      * KItemModelBase::isExpandable() and KItemModelBase::expandedParentsCount()
 200      * must be reimplemented. The view-implementation
 201      * has to take care itself how to visually represent the expanded items provided
 202      * by the model.
 203      */
 204     void setSupportsItemExpanding(bool supportsExpanding);
 205     bool supportsItemExpanding() const;
 206
 207     /**
 208      * @return The rectangle of the item relative to the top/left of
 209      *         the currently visible area (see KItemListView::offset()).
 210      */
 211     QRectF itemRect(int index) const;
 212
 213     /**
 214      * @return The context rectangle of the item relative to the top/left of
 215      *         the currently visible area (see KItemListView::offset()). The
 216      *         context rectangle is defined by by the united rectangle of
 217      *         the icon rectangle and the text rectangle (see KItemListWidget::iconRect()
 218      *         and KItemListWidget::textRect()) and is useful as reference for e.g. aligning
 219      *         a tooltip or a context-menu for an item. Note that a context rectangle will
 220      *         only be returned for (at least partly) visible items. An empty rectangle will
 221      *         be returned for fully invisible items.
 222      */
 223     QRectF itemContextRect(int index) const;
 224
 225     /**
 226      * Scrolls to the item with the index \a index so that the item
 227      * will be fully visible.
 228      */
 229     void scrollToItem(int index);
 230
 231     /**
 232      * If several properties of KItemListView are changed synchronously, it is
 233      * recommended to encapsulate the calls between beginTransaction() and endTransaction().
 234      * This prevents unnecessary and expensive layout-calculations.
 235      */
 236     void beginTransaction();
 237
 238     /**
 239      * Counterpart to beginTransaction(). The layout changes will only be animated if
 240      * all property changes between beginTransaction() and endTransaction() support
 241      * animations.
 242      */
 243     void endTransaction();
 244
 245     bool isTransactionActive() const;
 246
 247     /**
 248      * Turns on the header if \p visible is true. Per default the
 249      * header is not visible. Usually the header is turned on when
 250      * showing a classic "table-view" to describe the shown columns.
 251      */
 252     void setHeaderVisible(bool visible);
 253     bool isHeaderVisible() const;
 254
 255     /**
 256      * @return Header of the list. The header is also available if it is not shown
 257      *         (see KItemListView::setHeaderShown()).
 258      */
 259     KItemListHeader* header() const;
 260
 261     /**
 262      * @return Pixmap that is used for a drag operation based on the
 263      *         items given by \a indexes. The default implementation returns
 264      *         a null-pixmap.
 265      */
 266     virtual QPixmap createDragPixmap(const QSet<int>& indexes) const;
 267
 268     /**
 269      * @reimp
 270      */
 271     virtual void paint(QPainter* painter, const QStyleOptionGraphicsItem* option, QWidget* widget = 0);
 272
 273 signals:
 274     void scrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous);
 275     void scrollOffsetChanged(qreal current, qreal previous);
 276     void maximumScrollOffsetChanged(qreal current, qreal previous);
 277     void itemOffsetChanged(qreal current, qreal previous);
 278     void maximumItemOffsetChanged(qreal current, qreal previous);
 279     void scrollTo(qreal newOffset);
 280
 281     /**
 282      * Is emitted if the user has changed the sort order by clicking on a
 283      * header item (see KItemListView::setHeaderShown()). The sort order
 284      * of the model has already been adjusted to
 285      * the current sort order. Note that no signal will be emitted if the
 286      * sort order of the model has been changed without user interaction.
 287      */
 288     void sortOrderChanged(Qt::SortOrder current, Qt::SortOrder previous);
 289
 290     /**
 291      * Is emitted if the user has changed the sort role by clicking on a
 292      * header item (see KItemListView::setHeaderShown()). The sort role
 293      * of the model has already been adjusted to
 294      * the current sort role. Note that no signal will be emitted if the
 295      * sort role of the model has been changed without user interaction.
 296      */
 297     void sortRoleChanged(const QByteArray& current, const QByteArray& previous);
 298
 299     /**
 300      * Is emitted if the user has changed the visible roles by moving a header
 301      * item (see KItemListView::setHeaderShown()). Note that no signal will be
 302      * emitted if the roles have been changed without user interaction by
 303      * KItemListView::setVisibleRoles().
 304      */
 305     void visibleRolesChanged(const QList<QByteArray>& current, const QList<QByteArray>& previous);
 306
 307 protected:
 308     virtual void initializeItemListWidget(KItemListWidget* item);
 309
 310     /**
 311      * @return True if at least one of the changed roles \p changedRoles might result
 312      *         in the need to update the item-size hint (see KItemListView::itemSizeHint()).
 313      *         Per default true is returned which means on each role-change of existing items
 314      *         the item-size hints are recalculated. For performance reasons it is recommended
 315      *         to return false in case if a role-change will not result in a changed
 316      *         item-size hint.
 317      */
 318     virtual bool itemSizeHintUpdateRequired(const QSet<QByteArray>& changedRoles) const;
 319
 320     virtual void onControllerChanged(KItemListController* current, KItemListController* previous);
 321     virtual void onModelChanged(KItemModelBase* current, KItemModelBase* previous);
 322
 323     virtual void onScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous);
 324     virtual void onItemSizeChanged(const QSizeF& current, const QSizeF& previous);
 325     virtual void onScrollOffsetChanged(qreal current, qreal previous);
 326     virtual void onVisibleRolesChanged(const QList<QByteArray>& current, const QList<QByteArray>& previous);
 327     virtual void onStyleOptionChanged(const KItemListStyleOption& current, const KItemListStyleOption& previous);
 328     virtual void onSupportsItemExpandingChanged(bool supportsExpanding);
 329
 330     virtual void onTransactionBegin();
 331     virtual void onTransactionEnd();
 332
 333     virtual bool event(QEvent* event);
 334     virtual void mousePressEvent(QGraphicsSceneMouseEvent* event);
 335     virtual void mouseMoveEvent(QGraphicsSceneMouseEvent* event);
 336     virtual void dragEnterEvent(QGraphicsSceneDragDropEvent* event);
 337     virtual void dragMoveEvent(QGraphicsSceneDragDropEvent* event);
 338     virtual void dragLeaveEvent(QGraphicsSceneDragDropEvent* event);
 339     virtual void dropEvent(QGraphicsSceneDragDropEvent* event);
 340
 341     QList<KItemListWidget*> visibleItemListWidgets() const;
 342
 343 protected slots:
 344     virtual void slotItemsInserted(const KItemRangeList& itemRanges);
 345     virtual void slotItemsRemoved(const KItemRangeList& itemRanges);
 346     virtual void slotItemsMoved(const KItemRange& itemRange, const QList<int>& movedToIndexes);
 347     virtual void slotItemsChanged(const KItemRangeList& itemRanges,
 348                                   const QSet<QByteArray>& roles);
 349
 350     virtual void slotGroupedSortingChanged(bool current);
 351     virtual void slotSortOrderChanged(Qt::SortOrder current, Qt::SortOrder previous);
 352     virtual void slotSortRoleChanged(const QByteArray& current, const QByteArray& previous);
 353     virtual void slotCurrentChanged(int current, int previous);
 354     virtual void slotSelectionChanged(const QSet<int>& current, const QSet<int>& previous);
 355
 356 private slots:
 357     void slotAnimationFinished(QGraphicsWidget* widget,
 358                                KItemListViewAnimation::AnimationType type);
 359     void slotLayoutTimerFinished();
 360
 361     void slotRubberBandPosChanged();
 362     void slotRubberBandActivationChanged(bool active);
 363
 364     /**
 365      * Is invoked if the column-width of one role in the header has
 366      * been changed by the user. The automatic resizing of columns
 367      * will be turned off as soon as this method has been called at
 368      * least once.
 369      */
 370     void slotHeaderColumnWidthChanged(const QByteArray& role,
 371                                       qreal currentWidth,
 372                                       qreal previousWidth);
 373
 374     /**
 375      * Is invoked if a column has been moved by the user. Applies
 376      * the moved role to the view.
 377      */
 378     void slotHeaderColumnMoved(const QByteArray& role,
 379                                int currentIndex,
 380                                int previousIndex);
 381
 382     /**
 383      * Triggers the autoscrolling if autoScroll() is enabled by checking the
 384      * current mouse position. If the mouse position is within the autoscroll
 385      * margins a timer will be started that periodically triggers the autoscrolling.
 386      */
 387     void triggerAutoScrolling();
 388
 389     /**
 390      * Is invoked if the geometry of the parent-widget from a group-header has been
 391      * changed. The x-position and width of the group-header gets adjusted to assure
 392      * that it always spans the whole width even during temporary transitions of the
 393      * parent widget.
 394      */
 395     void slotGeometryOfGroupHeaderParentChanged();
 396
 397 private:
 398     enum LayoutAnimationHint
 399     {
 400         NoAnimation,
 401         Animation
 402     };
 403
 404     enum SizeType
 405     {
 406         LayouterSize,
 407         ItemSize
 408     };
 409
 410     void setController(KItemListController* controller);
 411     void setModel(KItemModelBase* model);
 412
 413     KItemListRubberBand* rubberBand() const;
 414
 415     void doLayout(LayoutAnimationHint hint, int changedIndex = 0, int changedCount = 0);
 416
 417     /**
 418      * Helper method for doLayout: Returns a list of items that can be reused for the visible
 419      * area. Invisible group headers get recycled. The reusable items are items that are
 420      * invisible. If the animation hint is 'Animation' then items that are currently animated
 421      * won't be reused. Reusing items is faster in comparison to deleting invisible
 422      * items and creating a new instance for visible items.
 423      */
 424     QList<int> recycleInvisibleItems(int firstVisibleIndex,
 425                                      int lastVisibleIndex,
 426                                      LayoutAnimationHint hint);
 427
 428     /**
 429      * Helper method for doLayout: Starts a moving-animation for the widget to the given
 430      * new position. The moving-animation is only started if the new position is within
 431      * the same row or column, otherwise the create-animation is used instead.
 432      * @return True if the moving-animation has been applied.
 433      */
 434     bool moveWidget(KItemListWidget* widget, const QPointF& newPos);
 435
 436     void emitOffsetChanges();
 437
 438     KItemListWidget* createWidget(int index);
 439     void recycleWidget(KItemListWidget* widget);
 440
 441     /**
 442      * Changes the index of the widget to \a index and assures a consistent
 443      * update for m_visibleItems and m_visibleCells. The cell-information
 444      * for the new index will not be updated and be initialized as empty cell.
 445      */
 446     void setWidgetIndex(KItemListWidget* widget, int index);
 447
 448     /**
 449      * Changes the index of the widget to \a index. In opposite to
 450      * setWidgetIndex() the cell-information for the widget gets updated.
 451      * This update gives doLayout() the chance to animate the moving
 452      * of the item visually (see moveWidget()).
 453      */
 454     void moveWidgetToIndex(KItemListWidget* widget, int index);
 455
 456     /**
 457      * Helper method for prepareLayoutForIncreasedItemCount().
 458      */
 459     void setLayouterSize(const QSizeF& size, SizeType sizeType);
 460
 461     /**
 462      * Helper method for createWidget() and setWidgetIndex() to update the properties
 463      * of the itemlist widget.
 464      */
 465     void updateWidgetProperties(KItemListWidget* widget, int index);
 466
 467     /**
 468      * Helper method for updateWidgetPropertes() to create or update
 469      * the itemlist group-header.
 470      */
 471     void updateGroupHeaderForWidget(KItemListWidget* widget);
 472
 473     /**
 474      * Updates the position and size of the group-header that belongs
 475      * to the itemlist widget \a widget. The given widget must represent
 476      * the first item of a group.
 477      */
 478     void updateGroupHeaderLayout(KItemListWidget* widget);
 479
 480     /**
 481      * Recycles the group-header for the widget.
 482      */
 483     void recycleGroupHeaderForWidget(KItemListWidget* widget);
 484
 485     /**
 486      * Helper method for slotGroupedSortingChanged(), slotSortOrderChanged()
 487      * and slotSortRoleChanged(): Iterates through all visible items and updates
 488      * the group-header widgets.
 489      */
 490     void updateVisibleGroupHeaders();
 491
 492     /**
 493      * @return Index for the item in the list returned by KItemModelBase::groups()
 494      *         that represents the group where the item with the index \a index
 495      *         belongs to. -1 is returned if no groups are available.
 496      */
 497     int groupIndexForItem(int index) const;
 498
 499     /**
 500      * Updates the alternate background for all visible items.
 501      * @see updateAlternateBackgroundForWidget()
 502      */
 503     void updateAlternateBackgrounds();
 504
 505     /**
 506      * Updates the alternateBackground-property of the widget dependent
 507      * on the state of useAlternateBackgrounds() and the grouping state.
 508      */
 509     void updateAlternateBackgroundForWidget(KItemListWidget* widget);
 510
 511     /**
 512      * @return True if alternate backgrounds should be used for the items.
 513      *         This is the case if an empty item-size is given and if there
 514      *         is more than one visible role.
 515      */
 516     bool useAlternateBackgrounds() const;
 517
 518     /**
 519      * @param itemRanges Items that must be checked for getting the widths of columns.
 520      * @return           The preferred width of the column of each visible role. The width will
 521      *                   be respected if the width of the item size is <= 0 (see
 522      *                   KItemListView::setItemSize()). Per default an empty hash
 523      *                   is returned.
 524      */
 525     QHash<QByteArray, qreal> preferredColumnWidths(const KItemRangeList& itemRanges) const;
 526
 527     /**
 528      * Applies the column-widths from m_headerWidget to the layout
 529      * of the view.
 530      */
 531     void applyColumnWidthsFromHeader();
 532
 533     /**
 534      * Applies the column-widths from m_headerWidget to \a widget.
 535      */
 536     void updateWidgetColumnWidths(KItemListWidget* widget);
 537
 538     /**
 539      * Updates the preferred column-widths of m_groupHeaderWidget by
 540      * invoking KItemListView::columnWidths().
 541      */
 542     void updatePreferredColumnWidths(const KItemRangeList& itemRanges);
 543
 544     /**
 545      * Convenience method for
 546      * updatePreferredColumnWidths(KItemRangeList() << KItemRange(0, m_model->count()).
 547      */
 548     void updatePreferredColumnWidths();
 549
 550     /**
 551      * Resizes the column-widths of m_headerWidget based on the preferred widths
 552      * and the vailable view-size.
 553      */
 554     void applyAutomaticColumnWidths();
 555
 556     /**
 557      * @return Sum of the widths of all columns.
 558      */
 559     qreal columnWidthsSum() const;
 560
 561     /**
 562      * @return Boundaries of the header. An empty rectangle is returned
 563      *         if no header is shown.
 564      */
 565     QRectF headerBoundaries() const;
 566
 567     /**
 568      * @return True if the number of columns or rows will be changed when applying
 569      *         the new grid- and item-size. Used to determine whether an animation
 570      *         should be done when applying the new layout.
 571      */
 572     bool changesItemGridLayout(const QSizeF& newGridSize,
 573                                const QSizeF& newItemSize,
 574                                const QSizeF& newItemMargin) const;
 575
 576     /**
 577      * @param changedItemCount Number of inserted  or removed items.
 578      * @return                 True if the inserting or removing of items should be animated.
 579      *                         No animation should be done if the number of items is too large
 580      *                         to provide a pleasant animation.
 581      */
 582     bool animateChangedItemCount(int changedItemCount) const;
 583
 584     /**
 585      * @return True if a scrollbar for the given scroll-orientation is required
 586      *         when using a size of \p size for the view. Calling the method is rather
 587      *         expansive as a temporary relayout needs to be done.
 588      */
 589     bool scrollBarRequired(const QSizeF& size) const;
 590
 591     /**
 592      * Applies the height of the group header to the layouter. The height
 593      * depends on the used scroll orientation.
 594      */
 595     void updateGroupHeaderHeight();
 596
 597     /**
 598      * Updates the siblings-information for all visible items that are inside
 599      * the range of \p firstIndex and \p lastIndex. If firstIndex or lastIndex
 600      * is smaller than 0, the siblings-information for all visible items gets
 601      * updated.
 602      * @see KItemListWidget::setSiblingsInformation()
 603      */
 604     void updateSiblingsInformation(int firstIndex = -1, int lastIndex = -1);
 605
 606     /**
 607      * Helper method for updateExpansionIndicators().
 608      * @return True if the item with the index \a index has a sibling successor
 609      *         (= the item is not the last item of the current hierarchy).
 610      */
 611     bool hasSiblingSuccessor(int index) const;
 612
 613     /**
 614      * Helper function for triggerAutoScrolling().
 615      * @param pos    Logical position of the mouse relative to the range.
 616      * @param range  Range of the visible area.
 617      * @param oldInc Previous increment. Is used to assure that the increment
 618      *               increases only gradually.
 619      * @return Scroll increment that should be added to the offset().
 620      *         As soon as \a pos is inside the autoscroll-margin a
 621      *         value != 0 will be returned.
 622      */
 623     static int calculateAutoScrollingIncrement(int pos, int range, int oldInc);
 624
 625     /**
 626      * Helper functions for changesItemCount().
 627      * @return The number of items that fit into the available size by
 628      *         respecting the size of the item and the margin between the items.
 629      */
 630     static int itemsPerSize(qreal size, qreal itemSize, qreal itemMargin);
 631
 632 private:
 633     bool m_enabledSelectionToggles;
 634     bool m_grouped;
 635     bool m_supportsItemExpanding;
 636     int m_activeTransactions; // Counter for beginTransaction()/endTransaction()
 637     LayoutAnimationHint m_endTransactionAnimationHint;
 638
 639     QSizeF m_itemSize;
 640     KItemListController* m_controller;
 641     KItemModelBase* m_model;
 642     QList<QByteArray> m_visibleRoles;
 643     KItemListWidgetCreatorBase* m_widgetCreator;
 644     KItemListGroupHeaderCreatorBase* m_groupHeaderCreator;
 645     KItemListStyleOption m_styleOption;
 646
 647     QHash<int, KItemListWidget*> m_visibleItems;
 648     QHash<KItemListWidget*, KItemListGroupHeader*> m_visibleGroups;
 649
 650     struct Cell
 651     {
 652         Cell() : column(-1), row(-1) {}
 653         Cell(int c, int r) : column(c), row(r) {}
 654         int column;
 655         int row;
 656     };
 657     QHash<int, Cell> m_visibleCells;
 658
 659     int m_scrollBarExtent;
 660     KItemListSizeHintResolver* m_sizeHintResolver;
 661     KItemListViewLayouter* m_layouter;
 662     KItemListViewAnimation* m_animation;
 663
 664     QTimer* m_layoutTimer; // Triggers an asynchronous doLayout() call.
 665     qreal m_oldScrollOffset;
 666     qreal m_oldMaximumScrollOffset;
 667     qreal m_oldItemOffset;
 668     qreal m_oldMaximumItemOffset;
 669
 670     bool m_skipAutoScrollForRubberBand;
 671     KItemListRubberBand* m_rubberBand;
 672
 673     QPointF m_mousePos;
 674     int m_autoScrollIncrement;
 675     QTimer* m_autoScrollTimer;
 676
 677     KItemListHeader* m_header;
 678     KItemListHeaderWidget* m_headerWidget;
 679
 680     friend class KItemListContainer; // Accesses scrollBarRequired()
 681     friend class KItemListHeader;    // Accesses m_headerWidget
 682     friend class KItemListController;
 683     friend class KItemListControllerTest;
 684 };
 685
 686 /**
 687  * Allows to do a fast logical creation and deletion of QGraphicsWidgets
 688  * by recycling existing QGraphicsWidgets instances. Is used by
 689  * KItemListWidgetCreatorBase and KItemListGroupHeaderCreatorBase.
 690  * @internal
 691  */
 692 class LIBDOLPHINPRIVATE_EXPORT KItemListCreatorBase
 693 {
 694 public:
 695     virtual ~KItemListCreatorBase();
 696
 697 protected:
 698     void addCreatedWidget(QGraphicsWidget* widget);
 699     void pushRecycleableWidget(QGraphicsWidget* widget);
 700     QGraphicsWidget* popRecycleableWidget();
 701
 702 private:
 703     QSet<QGraphicsWidget*> m_createdWidgets;
 704     QList<QGraphicsWidget*> m_recycleableWidgets;
 705 };
 706
 707 /**
 708  * @brief Base class for creating KItemListWidgets.
 709  *
 710  * It is recommended that applications simply use the KItemListWidgetCreator-template class.
 711  * For a custom implementation the methods create(), itemSizeHint() and preferredColumnWith()
 712  * must be reimplemented. The intention of the widget creator is to prevent repetitive and
 713  * expensive instantiations and deletions of KItemListWidgets by recycling existing widget
 714  * instances.
 715  */
 716 class LIBDOLPHINPRIVATE_EXPORT KItemListWidgetCreatorBase : public KItemListCreatorBase
 717 {
 718 public:
 719     virtual ~KItemListWidgetCreatorBase();
 720
 721     virtual KItemListWidget* create(KItemListView* view) = 0;
 722
 723     virtual void recycle(KItemListWidget* widget);
 724
 725     virtual QSizeF itemSizeHint(int index, const KItemListView* view) const = 0;
 726
 727     virtual qreal preferredRoleColumnWidth(const QByteArray& role,
 728                                            int index,
 729                                            const KItemListView* view) const = 0;
 730 };
 731
 732 /**
 733  * @brief Template class for creating KItemListWidgets.
 734  *
 735  * The template class must provide the following two static methods:
 736  * - QSizeF itemSizeHint(int index, const KItemListView* view)
 737  * - preferredRoleColumnWidth(const QByteArray& role, int index, const KItemListView* view)
 738  * Those static methods are used as implementation for
 739  * KItemListWidgetCreatorBase::itemSizeHint() and
 740  * KItemListWidgetCreatorBase::preferedRoleColumnWidth().
 741  */
 742 template <class T>
 743 class KItemListWidgetCreator : public KItemListWidgetCreatorBase
 744 {
 745 public:
 746     virtual ~KItemListWidgetCreator();
 747
 748     virtual KItemListWidget* create(KItemListView* view);
 749
 750     virtual QSizeF itemSizeHint(int index, const KItemListView* view) const;
 751
 752     virtual qreal preferredRoleColumnWidth(const QByteArray& role,
 753                                            int index,
 754                                            const KItemListView* view) const;
 755 };
 756
 757 template <class T>
 758 KItemListWidgetCreator<T>::~KItemListWidgetCreator()
 759 {
 760 }
 761
 762 template <class T>
 763 KItemListWidget* KItemListWidgetCreator<T>::create(KItemListView* view)
 764 {
 765     KItemListWidget* widget = static_cast<KItemListWidget*>(popRecycleableWidget());
 766     if (!widget) {
 767         widget = new T(view);
 768         addCreatedWidget(widget);
 769     }
 770     return widget;
 771 }
 772
 773 template<class T>
 774 QSizeF KItemListWidgetCreator<T>::itemSizeHint(int index, const KItemListView* view) const
 775 {
 776     return T::itemSizeHint(index, view);
 777 }
 778
 779 template<class T>
 780 qreal KItemListWidgetCreator<T>::preferredRoleColumnWidth(const QByteArray& role,
 781                                                           int index,
 782                                                           const KItemListView* view) const
 783 {
 784     return T::preferredRoleColumnWidth(role, index, view);
 785 }
 786
 787 /**
 788  * @brief Base class for creating KItemListGroupHeaders.
 789  *
 790  * It is recommended that applications simply use the KItemListGroupHeaderCreator-template class.
 791  * For a custom implementation the methods create() and recyle() must be reimplemented.
 792  * The intention of the group-header creator is to prevent repetitive and expensive instantiations and
 793  * deletions of KItemListGroupHeaders by recycling existing header instances.
 794  */
 795 class LIBDOLPHINPRIVATE_EXPORT KItemListGroupHeaderCreatorBase : public KItemListCreatorBase
 796 {
 797 public:
 798     virtual ~KItemListGroupHeaderCreatorBase();
 799     virtual KItemListGroupHeader* create(KItemListView* view) = 0;
 800     virtual void recycle(KItemListGroupHeader* header);
 801 };
 802
 803 template <class T>
 804 class KItemListGroupHeaderCreator : public KItemListGroupHeaderCreatorBase
 805 {
 806 public:
 807     virtual ~KItemListGroupHeaderCreator();
 808     virtual KItemListGroupHeader* create(KItemListView* view);
 809 };
 810
 811 template <class T>
 812 KItemListGroupHeaderCreator<T>::~KItemListGroupHeaderCreator()
 813 {
 814 }
 815
 816 template <class T>
 817 KItemListGroupHeader* KItemListGroupHeaderCreator<T>::create(KItemListView* view)
 818 {
 819     KItemListGroupHeader* widget = static_cast<KItemListGroupHeader*>(popRecycleableWidget());
 820     if (!widget) {
 821         widget = new T(view);
 822         addCreatedWidget(widget);
 823     }
 824     return widget;
 825 }
 826
 827 #endif