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/kitemliststyleoption.h>
  29 #include <kitemviews/kitemlistviewanimation_p.h>
  30 #include <kitemviews/kitemlistwidget.h>
  31 #include <kitemviews/kitemmodelbase.h>
  32 #include <QGraphicsWidget>
  33 #include <QSet>
  34
  35 class KItemListController;
  36 class KItemListGroupHeader;
  37 class KItemListGroupHeaderCreatorBase;
  38 class KItemListHeader;
  39 class KItemListSizeHintResolver;
  40 class KItemListRubberBand;
  41 class KItemListViewAnimation;
  42 class KItemListViewLayouter;
  43 class KItemListWidget;
  44 class KItemListWidgetCreatorBase;
  45 class KItemListViewCreatorBase;
  46 class QTimer;
  47
  48 /**
  49  * @brief Represents the view of an item-list.
  50  *
  51  * The view is responsible for showing the items of the model within
  52  * a GraphicsItem. Each visible item is represented by a KItemListWidget.
  53  *
  54  * The created view must be applied to the KItemListController with
  55  * KItemListController::setView(). For showing a custom model it is not
  56  * mandatory to derive from KItemListView, all that is necessary is
  57  * to set a widget-creator that is capable to create KItemListWidgets
  58  * showing the model items. A widget-creator can be set with
  59  * KItemListView::setWidgetCreator().
  60  *
  61  * @see KItemListWidget
  62  * @see KItemModelBase
  63  */
  64 class LIBDOLPHINPRIVATE_EXPORT KItemListView : public QGraphicsWidget
  65 {
  66     Q_OBJECT
  67
  68     Q_PROPERTY(qreal scrollOffset READ scrollOffset WRITE setScrollOffset)
  69     Q_PROPERTY(qreal itemOffset READ itemOffset WRITE setItemOffset)
  70
  71 public:
  72     KItemListView(QGraphicsWidget* parent = 0);
  73     virtual ~KItemListView();
  74
  75     void setScrollOrientation(Qt::Orientation orientation);
  76     Qt::Orientation scrollOrientation() const;
  77
  78     void setItemSize(const QSizeF& size);
  79     QSizeF itemSize() const;
  80
  81     // TODO: add note that offset is not checked against maximumOffset, only against 0.
  82     void setScrollOffset(qreal offset);
  83     qreal scrollOffset() const;
  84
  85     qreal maximumScrollOffset() const;
  86
  87     void setItemOffset(qreal scrollOffset);
  88     qreal itemOffset() const;
  89
  90     qreal maximumItemOffset() const;
  91
  92     void setVisibleRoles(const QList<QByteArray>& roles);
  93     QList<QByteArray> visibleRoles() const;
  94
  95     /**
  96      * If set to true an automatic scrolling is done as soon as the
  97      * mouse is moved near the borders of the view. Per default
  98      * the automatic scrolling is turned off.
  99      */
 100     void setAutoScroll(bool enabled);
 101     bool autoScroll() const;
 102
 103     /**
 104      * @return Controller of the item-list. The controller gets
 105      *         initialized by KItemListController::setView() and will
 106      *         result in calling KItemListController::onControllerChanged().
 107      */
 108     KItemListController* controller() const;
 109
 110     /**
 111      * @return Model of the item-list. The model gets
 112      *         initialized by KItemListController::setView() and will
 113      *         result in calling KItemListController::onModelChanged().
 114      */
 115     KItemModelBase* model() const;
 116
 117     /**
 118      * Sets the creator that creates a widget showing the
 119      * content of one model-item. Usually it is sufficient
 120      * to implement a custom widget X derived from KItemListWidget and
 121      * set the creator by:
 122      * <code>
 123      * itemListView->setWidgetCreator(new KItemListWidgetCreator<X>());
 124      * </code>
 125      * Note that the ownership of the widget creator is not transferred to
 126      * the item-list view: One instance of a widget creator might get shared
 127      * by several item-list view instances.
 128      **/
 129     void setWidgetCreator(KItemListWidgetCreatorBase* widgetCreator);
 130     KItemListWidgetCreatorBase* widgetCreator() const;
 131
 132     void setGroupHeaderCreator(KItemListGroupHeaderCreatorBase* groupHeaderCreator);
 133     KItemListGroupHeaderCreatorBase* groupHeaderCreator() const;
 134
 135     void setStyleOption(const KItemListStyleOption& option);
 136     const KItemListStyleOption& styleOption() const;
 137
 138     /** @reimp */
 139     virtual void setGeometry(const QRectF& rect);
 140
 141     int itemAt(const QPointF& pos) const;
 142     bool isAboveSelectionToggle(int index, const QPointF& pos) const;
 143     bool isAboveExpansionToggle(int index, const QPointF& pos) const;
 144
 145     int firstVisibleIndex() const;
 146     int lastVisibleIndex() const;
 147
 148     /**
 149      * @return Required size for the item with the index \p index.
 150      *         Per default KItemListView::itemSize() is returned.
 151      *         When reimplementing this method it is recommended to
 152      *         also reimplement KItemListView::itemSizeHintUpdateRequired().
 153      */
 154     virtual QSizeF itemSizeHint(int index) const;
 155
 156     /**
 157      * @param itemRanges Items that must be checked for getting the visible roles sizes.
 158      * @return The size of each visible role in case if KItemListView::itemSize()
 159      *         is empty. This allows to have dynamic but equal role sizes between
 160      *         all items. Per default an empty hash is returned.
 161      */
 162     virtual QHash<QByteArray, QSizeF> visibleRolesSizes(const KItemRangeList& itemRanges) const;
 163
 164     /**
 165      * @return The bounding rectangle of the item relative to the top/left of
 166      *         the currently visible area (see KItemListView::offset()).
 167      */
 168     QRectF itemBoundingRect(int index) const;
 169
 170     /**
 171      * @return The number of items that can be shown in parallel for one offset.
 172      *         Assuming the scrolldirection is vertical then a value of 4 means
 173      *         that 4 columns for items are available. Assuming the scrolldirection
 174      *         is horizontal then a value of 4 means that 4 lines for items are
 175      *         available.
 176      */
 177     int itemsPerOffset() const;
 178
 179     void beginTransaction();
 180     void endTransaction();
 181     bool isTransactionActive() const;
 182
 183     /**
 184      * Turns on the header if \p show is true. Per default the
 185      * header is not shown.
 186      */
 187     void setHeaderShown(bool show);
 188     bool isHeaderShown() const;
 189
 190     /**
 191      * @return Pixmap that is used for a drag operation based on the
 192      *         items given by \a indexes. The default implementation returns
 193      *         a null-pixmap.
 194      */
 195     virtual QPixmap createDragPixmap(const QSet<int>& indexes) const;
 196
 197     /**
 198      * @reimp
 199      */
 200     virtual void paint(QPainter* painter, const QStyleOptionGraphicsItem* option, QWidget* widget = 0);
 201
 202 signals:
 203     void scrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous);
 204     void scrollOffsetChanged(qreal current, qreal previous);
 205     void maximumScrollOffsetChanged(qreal current, qreal previous);
 206     void itemOffsetChanged(qreal current, qreal previous);
 207     void maximumItemOffsetChanged(qreal current, qreal previous);
 208     void scrollTo(qreal newOffset);
 209
 210 protected:
 211     virtual void initializeItemListWidget(KItemListWidget* item);
 212
 213     /**
 214      * @return True if at least one of the changed roles \p changedRoles might result
 215      *         in the need to update the item-size hint (see KItemListView::itemSizeHint()).
 216      *         Per default true is returned which means on each role-change of existing items
 217      *         the item-size hints are recalculated. For performance reasons it is recommended
 218      *         to return false in case if a role-change will not result in a changed
 219      *         item-size hint.
 220      */
 221     virtual bool itemSizeHintUpdateRequired(const QSet<QByteArray>& changedRoles) const;
 222
 223     virtual void onControllerChanged(KItemListController* current, KItemListController* previous);
 224     virtual void onModelChanged(KItemModelBase* current, KItemModelBase* previous);
 225
 226     virtual void onScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous);
 227     virtual void onItemSizeChanged(const QSizeF& current, const QSizeF& previous);
 228     virtual void onScrollOffsetChanged(qreal current, qreal previous);
 229     virtual void onVisibleRolesChanged(const QList<QByteArray>& current, const QList<QByteArray>& previous);
 230     virtual void onStyleOptionChanged(const KItemListStyleOption& current, const KItemListStyleOption& previous);
 231
 232     virtual void onTransactionBegin();
 233     virtual void onTransactionEnd();
 234
 235     virtual bool event(QEvent* event);
 236     virtual void mousePressEvent(QGraphicsSceneMouseEvent* event);
 237     virtual void mouseMoveEvent(QGraphicsSceneMouseEvent* event);
 238     virtual void dragEnterEvent(QGraphicsSceneDragDropEvent* event);
 239     virtual void dragMoveEvent(QGraphicsSceneDragDropEvent* event);
 240     virtual void dragLeaveEvent(QGraphicsSceneDragDropEvent* event);
 241     virtual void dropEvent(QGraphicsSceneDragDropEvent* event);
 242
 243     QList<KItemListWidget*> visibleItemListWidgets() const;
 244
 245     /** @reimp */
 246     virtual void resizeEvent(QGraphicsSceneResizeEvent* event);
 247
 248 protected slots:
 249     virtual void slotItemsInserted(const KItemRangeList& itemRanges);
 250     virtual void slotItemsRemoved(const KItemRangeList& itemRanges);
 251     virtual void slotItemsMoved(const KItemRange& itemRange, const QList<int>& movedToIndexes);
 252     virtual void slotItemsChanged(const KItemRangeList& itemRanges,
 253                                   const QSet<QByteArray>& roles);
 254
 255 private slots:
 256     void slotCurrentChanged(int current, int previous);
 257     void slotSelectionChanged(const QSet<int>& current, const QSet<int>& previous);
 258     void slotAnimationFinished(QGraphicsWidget* widget,
 259                                KItemListViewAnimation::AnimationType type);
 260     void slotLayoutTimerFinished();
 261
 262     void slotRubberBandPosChanged();
 263     void slotRubberBandActivationChanged(bool active);
 264
 265     /**
 266      * Is invoked if the visible role-width of one role in the header has
 267      * been changed by the user. It is remembered that the user has modified
 268      * the role-width, so that it won't be changed anymore automatically to
 269      * calculate an optimized width.
 270      */
 271     void slotVisibleRoleWidthChanged(const QByteArray& role,
 272                                      qreal currentWidth,
 273                                      qreal previousWidth);
 274
 275     /**
 276      * Triggers the autoscrolling if autoScroll() is enabled by checking the
 277      * current mouse position. If the mouse position is within the autoscroll
 278      * margins a timer will be started that periodically triggers the autoscrolling.
 279      */
 280     void triggerAutoScrolling();
 281
 282 private:
 283     enum LayoutAnimationHint
 284     {
 285         NoAnimation,
 286         Animation
 287     };
 288
 289     enum SizeType
 290     {
 291         LayouterSize,
 292         ItemSize
 293     };
 294
 295     void setController(KItemListController* controller);
 296     void setModel(KItemModelBase* model);
 297
 298     KItemListRubberBand* rubberBand() const;
 299
 300     void updateLayout();
 301     void doLayout(LayoutAnimationHint hint, int changedIndex, int changedCount);
 302     void doGroupHeadersLayout(LayoutAnimationHint hint, int changedIndex, int changedCount);
 303     void emitOffsetChanges();
 304
 305     KItemListWidget* createWidget(int index);
 306     void recycleWidget(KItemListWidget* widget);
 307     void setWidgetIndex(KItemListWidget* widget, int index);
 308
 309     /**
 310      * Helper method for setGeometry() and setItemSize(): Calling both methods might result
 311      * in a changed number of visible items. To assure that currently invisible items can
 312      * get animated from the old position to the new position prepareLayoutForIncreasedItemCount()
 313      * takes care to create all item widgets that are visible with the old or the new size.
 314      * @param size     Size of the layouter or the item dependent on \p sizeType.
 315      * @param sizeType LayouterSize: KItemListLayouter::setSize() is used.
 316      *                 ItemSize: KItemListLayouter::setItemSize() is used.
 317      */
 318     void prepareLayoutForIncreasedItemCount(const QSizeF& size, SizeType sizeType);
 319
 320     /**
 321      * Helper method for prepareLayoutForIncreasedItemCount().
 322      */
 323     void setLayouterSize(const QSizeF& size, SizeType sizeType);
 324
 325     /**
 326      * Helper method for createWidget() and setWidgetIndex() to update the properties
 327      * of the itemlist widget.
 328      */
 329     void updateWidgetProperties(KItemListWidget* widget, int index);
 330
 331     /**
 332      * @return The widths of each visible role that is shown in the KItemListHeader.
 333      */
 334     QHash<QByteArray, qreal> headerRolesWidths() const;
 335
 336     /**
 337      * Updates m_visibleRolesSizes by calling KItemListView::visibleRolesSizes().
 338      * Nothing will be done if m_itemRect is not empty or custom header-widths
 339      * are used (see m_useHeaderWidths). Also m_strechedVisibleRolesSizes will be adjusted
 340      * to respect the available view-size.
 341      */
 342     void updateVisibleRolesSizes(const KItemRangeList& itemRanges);
 343
 344     /**
 345      * Convenience method for updateVisibleRoleSizes(KItemRangeList() << KItemRange(0, m_model->count()).
 346      */
 347     void updateVisibleRolesSizes();
 348
 349     /**
 350      * Updates m_stretchedVisibleRolesSizes based on m_visibleRolesSizes and the available
 351      * view-size. Nothing will be done if m_itemRect is not empty or custom header-widths
 352      * are used (see m_useHeaderWidths).
 353      */
 354     void updateStretchedVisibleRolesSizes();
 355
 356     /**
 357      * @return Sum of the widths of all visible roles.
 358      */
 359     qreal visibleRolesSizesWidthSum() const;
 360
 361     /**
 362      * @return Sum of the heights of all visible roles.
 363      */
 364     qreal visibleRolesSizesHeightSum() const;
 365
 366     /**
 367      * @return Boundaries of the header. An empty rectangle is returned
 368      *         if no header is shown.
 369      */
 370     QRectF headerBoundaries() const;
 371
 372     /**
 373      * Helper function for triggerAutoScrolling().
 374      * @param pos    Logical position of the mouse relative to the range.
 375      * @param range  Range of the visible area.
 376      * @param oldInc Previous increment. Is used to assure that the increment
 377      *               increases only gradually.
 378      * @return Scroll increment that should be added to the offset().
 379      *         As soon as \a pos is inside the autoscroll-margin a
 380      *         value != 0 will be returned.
 381      */
 382     static int calculateAutoScrollingIncrement(int pos, int range, int oldInc);
 383
 384 private:
 385     bool m_grouped;
 386     int m_activeTransactions; // Counter for beginTransaction()/endTransaction()
 387
 388     QSizeF m_itemSize;
 389     KItemListController* m_controller;
 390     KItemModelBase* m_model;
 391     QList<QByteArray> m_visibleRoles;
 392     QHash<QByteArray, QSizeF> m_visibleRolesSizes;
 393     QHash<QByteArray, QSizeF> m_stretchedVisibleRolesSizes;
 394     KItemListWidgetCreatorBase* m_widgetCreator;
 395     KItemListGroupHeaderCreatorBase* m_groupHeaderCreator;
 396     KItemListStyleOption m_styleOption;
 397
 398     QHash<int, KItemListWidget*> m_visibleItems;
 399     QHash<KItemListWidget*, KItemListGroupHeader*> m_visibleGroups;
 400
 401     int m_scrollBarExtent;
 402     KItemListSizeHintResolver* m_sizeHintResolver;
 403     KItemListViewLayouter* m_layouter;
 404     KItemListViewAnimation* m_animation;
 405
 406     QTimer* m_layoutTimer; // Triggers an asynchronous doLayout() call.
 407     qreal m_oldScrollOffset;
 408     qreal m_oldMaximumScrollOffset;
 409     qreal m_oldItemOffset;
 410     qreal m_oldMaximumItemOffset;
 411
 412     bool m_skipAutoScrollForRubberBand;
 413     KItemListRubberBand* m_rubberBand;
 414
 415     QPointF m_mousePos;
 416     int m_autoScrollIncrement;
 417     QTimer* m_autoScrollTimer;
 418
 419     KItemListHeader* m_header;
 420     bool m_useHeaderWidths;
 421
 422     friend class KItemListController;
 423 };
 424
 425 /**
 426  * Allows to do a fast logical creation and deletion of QGraphicsWidgets
 427  * by recycling existing QGraphicsWidgets instances. Is used by
 428  * KItemListWidgetCreatorBase and KItemListGroupHeaderCreatorBase.
 429  * @internal
 430  */
 431 class LIBDOLPHINPRIVATE_EXPORT KItemListCreatorBase
 432 {
 433 public:
 434     virtual ~KItemListCreatorBase();
 435
 436 protected:
 437     void addCreatedWidget(QGraphicsWidget* widget);
 438     void pushRecycleableWidget(QGraphicsWidget* widget);
 439     QGraphicsWidget* popRecycleableWidget();
 440
 441 private:
 442     QSet<QGraphicsWidget*> m_createdWidgets;
 443     QList<QGraphicsWidget*> m_recycleableWidgets;
 444 };
 445
 446 /**
 447  * @brief Base class for creating KItemListWidgets.
 448  *
 449  * It is recommended that applications simply use the KItemListWidgetCreator-template class.
 450  * For a custom implementation the methods create() and recyle() must be reimplemented.
 451  * The intention of the widget creator is to prevent repetitive and expensive instantiations and
 452  * deletions of KItemListWidgets by recycling existing widget instances.
 453  */
 454 class LIBDOLPHINPRIVATE_EXPORT KItemListWidgetCreatorBase : public KItemListCreatorBase
 455 {
 456 public:
 457     virtual ~KItemListWidgetCreatorBase();
 458     virtual KItemListWidget* create(KItemListView* view) = 0;
 459     virtual void recycle(KItemListWidget* widget);
 460 };
 461
 462 template <class T>
 463 class LIBDOLPHINPRIVATE_EXPORT KItemListWidgetCreator : public KItemListWidgetCreatorBase
 464 {
 465 public:
 466     virtual ~KItemListWidgetCreator();
 467     virtual KItemListWidget* create(KItemListView* view);
 468 };
 469
 470 template <class T>
 471 KItemListWidgetCreator<T>::~KItemListWidgetCreator()
 472 {
 473 }
 474
 475 template <class T>
 476 KItemListWidget* KItemListWidgetCreator<T>::create(KItemListView* view)
 477 {
 478     KItemListWidget* widget = static_cast<KItemListWidget*>(popRecycleableWidget());
 479     if (!widget) {
 480         widget = new T(view);
 481         addCreatedWidget(widget);
 482     }
 483     return widget;
 484 }
 485
 486 /**
 487  * @brief Base class for creating KItemListGroupHeaders.
 488  *
 489  * It is recommended that applications simply use the KItemListGroupHeaderCreator-template class.
 490  * For a custom implementation the methods create() and recyle() must be reimplemented.
 491  * The intention of the group-header creator is to prevent repetitive and expensive instantiations and
 492  * deletions of KItemListGroupHeaders by recycling existing header instances.
 493  */
 494 class LIBDOLPHINPRIVATE_EXPORT KItemListGroupHeaderCreatorBase : public KItemListCreatorBase
 495 {
 496 public:
 497     virtual ~KItemListGroupHeaderCreatorBase();
 498     virtual KItemListGroupHeader* create(QGraphicsWidget* parent) = 0;
 499     virtual void recycle(KItemListGroupHeader* header);
 500 };
 501
 502 template <class T>
 503 class LIBDOLPHINPRIVATE_EXPORT KItemListGroupHeaderCreator : public KItemListGroupHeaderCreatorBase
 504 {
 505 public:
 506     virtual ~KItemListGroupHeaderCreator();
 507     virtual KItemListGroupHeader* create(QGraphicsWidget* parent);
 508 };
 509
 510 template <class T>
 511 KItemListGroupHeaderCreator<T>::~KItemListGroupHeaderCreator()
 512 {
 513 }
 514
 515 template <class T>
 516 KItemListGroupHeader* KItemListGroupHeaderCreator<T>::create(QGraphicsWidget* parent)
 517 {
 518     KItemListGroupHeader* widget = static_cast<KItemListGroupHeader*>(popRecycleableWidget());
 519     if (!widget) {
 520         widget = new T(parent);
 521         addCreatedWidget(widget);
 522     }
 523     return widget;
 524 }
 525
 526 #endif