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