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      * @param itemRanges Items that must be checked for getting the visible roles sizes.
 164      * @return The size of each visible role in case if KItemListView::itemSize()
 165      *         is empty. This allows to have dynamic but equal role sizes between
 166      *         all items. Per default an empty hash is returned.
 167      */
 168     virtual QHash<QByteArray, QSizeF> visibleRolesSizes(const KItemRangeList& itemRanges) const;
 169
 170     /**
 171      * @return The bounding rectangle of the item relative to the top/left of
 172      *         the currently visible area (see KItemListView::offset()).
 173      */
 174     QRectF itemBoundingRect(int index) const;
 175
 176     /**
 177      * @return The number of items that can be shown in parallel for one offset.
 178      *         Assuming the scrolldirection is vertical then a value of 4 means
 179      *         that 4 columns for items are available. Assuming the scrolldirection
 180      *         is horizontal then a value of 4 means that 4 lines for items are
 181      *         available.
 182      */
 183     int itemsPerOffset() const;
 184
 185     void beginTransaction();
 186     void endTransaction();
 187     bool isTransactionActive() const;
 188
 189     /**
 190      * @return Pixmap that is used for a drag operation based on the
 191      *         items given by \a indexes. The default implementation returns
 192      *         a null-pixmap.
 193      */
 194     virtual QPixmap createDragPixmap(const QSet<int>& indexes) const;
 195
 196     /**
 197      * @reimp
 198      */
 199     virtual void paint(QPainter* painter, const QStyleOptionGraphicsItem* option, QWidget* widget = 0);
 200
 201 signals:
 202     void scrollOffsetChanged(qreal current, qreal previous);
 203     void maximumScrollOffsetChanged(qreal current, qreal previous);
 204     void itemOffsetChanged(qreal current, qreal previous);
 205     void maximumItemOffsetChanged(qreal current, qreal previous);
 206     void scrollTo(qreal newOffset);
 207
 208 protected:
 209     virtual void initializeItemListWidget(KItemListWidget* item);
 210
 211     /**
 212      * @return True if at least one of the changed roles \p changedRoles might result
 213      *         in the need to update the item-size hint (see KItemListView::itemSizeHint()).
 214      *         Per default true is returned which means on each role-change of existing items
 215      *         the item-size hints are recalculated. For performance reasons it is recommended
 216      *         to return false in case if a role-change will not result in a changed
 217      *         item-size hint.
 218      */
 219     virtual bool itemSizeHintUpdateRequired(const QSet<QByteArray>& changedRoles) const;
 220
 221     virtual void onControllerChanged(KItemListController* current, KItemListController* previous);
 222     virtual void onModelChanged(KItemModelBase* current, KItemModelBase* previous);
 223
 224     virtual void onScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous);
 225     virtual void onItemSizeChanged(const QSizeF& current, const QSizeF& previous);
 226     virtual void onScrollOffsetChanged(qreal current, qreal previous);
 227     virtual void onVisibleRolesChanged(const QList<QByteArray>& current, const QList<QByteArray>& previous);
 228     virtual void onStyleOptionChanged(const KItemListStyleOption& current, const KItemListStyleOption& previous);
 229
 230     virtual void onTransactionBegin();
 231     virtual void onTransactionEnd();
 232
 233     virtual bool event(QEvent* event);
 234     virtual void mousePressEvent(QGraphicsSceneMouseEvent* event);
 235     virtual void mouseMoveEvent(QGraphicsSceneMouseEvent* event);
 236     virtual void dragEnterEvent(QGraphicsSceneDragDropEvent* event);
 237     virtual void dragMoveEvent(QGraphicsSceneDragDropEvent* event);
 238     virtual void dragLeaveEvent(QGraphicsSceneDragDropEvent* event);
 239     virtual void dropEvent(QGraphicsSceneDragDropEvent* event);
 240
 241     QList<KItemListWidget*> visibleItemListWidgets() const;
 242
 243     /** @reimp */
 244     virtual void resizeEvent(QGraphicsSceneResizeEvent* event);
 245
 246 protected slots:
 247     virtual void slotItemsInserted(const KItemRangeList& itemRanges);
 248     virtual void slotItemsRemoved(const KItemRangeList& itemRanges);
 249     virtual void slotItemsMoved(const KItemRange& itemRange, const QList<int>& movedToIndexes);
 250     virtual void slotItemsChanged(const KItemRangeList& itemRanges,
 251                                   const QSet<QByteArray>& roles);
 252
 253 private slots:
 254     void slotCurrentChanged(int current, int previous);
 255     void slotSelectionChanged(const QSet<int>& current, const QSet<int>& previous);
 256     void slotAnimationFinished(QGraphicsWidget* widget,
 257                                KItemListViewAnimation::AnimationType type);
 258     void slotLayoutTimerFinished();
 259
 260     void slotRubberBandPosChanged();
 261     void slotRubberBandActivationChanged(bool active);
 262
 263     /**
 264      * Is invoked if the visible role-width of one role in the header has
 265      * been changed by the user. It is remembered that the user has modified
 266      * the role-width, so that it won't be changed anymore automatically to
 267      * calculate an optimized width.
 268      */
 269     void slotVisibleRoleWidthChanged(const QByteArray& role,
 270                                      qreal currentWidth,
 271                                      qreal previousWidth);
 272
 273     /**
 274      * Triggers the autoscrolling if autoScroll() is enabled by checking the
 275      * current mouse position. If the mouse position is within the autoscroll
 276      * margins a timer will be started that periodically triggers the autoscrolling.
 277      */
 278     void triggerAutoScrolling();
 279
 280 private:
 281     enum LayoutAnimationHint
 282     {
 283         NoAnimation,
 284         Animation
 285     };
 286
 287     enum SizeType
 288     {
 289         LayouterSize,
 290         ItemSize
 291     };
 292
 293     void setController(KItemListController* controller);
 294     void setModel(KItemModelBase* model);
 295
 296     KItemListRubberBand* rubberBand() const;
 297
 298     void updateLayout();
 299     void doLayout(LayoutAnimationHint hint, int changedIndex, int changedCount);
 300     void doGroupHeadersLayout(LayoutAnimationHint hint, int changedIndex, int changedCount);
 301     void emitOffsetChanges();
 302
 303     KItemListWidget* createWidget(int index);
 304     void recycleWidget(KItemListWidget* widget);
 305     void setWidgetIndex(KItemListWidget* widget, int index);
 306
 307     /**
 308      * Helper method for setGeometry() and setItemSize(): Calling both methods might result
 309      * in a changed number of visible items. To assure that currently invisible items can
 310      * get animated from the old position to the new position prepareLayoutForIncreasedItemCount()
 311      * takes care to create all item widgets that are visible with the old or the new size.
 312      * @param size     Size of the layouter or the item dependent on \p sizeType.
 313      * @param sizeType LayouterSize: KItemListLayouter::setSize() is used.
 314      *                 ItemSize: KItemListLayouter::setItemSize() is used.
 315      */
 316     void prepareLayoutForIncreasedItemCount(const QSizeF& size, SizeType sizeType);
 317
 318     /**
 319      * Helper method for prepareLayoutForIncreasedItemCount().
 320      */
 321     void setLayouterSize(const QSizeF& size, SizeType sizeType);
 322
 323     /**
 324      * Helper method for createWidget() and setWidgetIndex() to update the properties
 325      * of the itemlist widget.
 326      */
 327     void updateWidgetProperties(KItemListWidget* widget, int index);
 328
 329     /**
 330      * Updates the width of the KItemListHeader corresponding to the required width of
 331      * the roles.
 332      */
 333     void updateHeaderWidth();
 334
 335     /**
 336      * @return The widths of each visible role that is shown in the KItemListHeader.
 337      */
 338     QHash<QByteArray, qreal> headerRolesWidths() const;
 339
 340     /**
 341      * Updates m_visibleRolesSizes by calling KItemListView::visibleRolesSizes().
 342      * Nothing will be done if m_itemRect is not empty or custom header-widths
 343      * are used (see m_useHeaderWidths). Also m_strechedVisibleRolesSizes will be adjusted
 344      * to respect the available view-size.
 345      */
 346     void updateVisibleRolesSizes(const KItemRangeList& itemRanges);
 347
 348     /**
 349      * Convenience method for updateVisibleRoleSizes(KItemRangeList() << KItemRange(0, m_model->count()).
 350      */
 351     void updateVisibleRolesSizes();
 352
 353     /**
 354      * Updates m_stretchedVisibleRolesSizes based on m_visibleRolesSizes and the available
 355      * view-size. Nothing will be done if m_itemRect is not empty or custom header-widths
 356      * are used (see m_useHeaderWidths).
 357      */
 358     void updateStretchedVisibleRolesSizes();
 359
 360     /**
 361      * Helper function for triggerAutoScrolling().
 362      * @param pos    Logical position of the mouse relative to the range.
 363      * @param range  Range of the visible area.
 364      * @param oldInc Previous increment. Is used to assure that the increment
 365      *               increases only gradually.
 366      * @return Scroll increment that should be added to the offset().
 367      *         As soon as \a pos is inside the autoscroll-margin a
 368      *         value != 0 will be returned.
 369      */
 370     static int calculateAutoScrollingIncrement(int pos, int range, int oldInc);
 371
 372 private:
 373     bool m_grouped;
 374     int m_activeTransactions; // Counter for beginTransaction()/endTransaction()
 375
 376     QSizeF m_itemSize;
 377     KItemListController* m_controller;
 378     KItemModelBase* m_model;
 379     QList<QByteArray> m_visibleRoles;
 380     QHash<QByteArray, QSizeF> m_visibleRolesSizes;
 381     QHash<QByteArray, QSizeF> m_stretchedVisibleRolesSizes;
 382     KItemListWidgetCreatorBase* m_widgetCreator;
 383     KItemListGroupHeaderCreatorBase* m_groupHeaderCreator;
 384     KItemListStyleOption m_styleOption;
 385
 386     QHash<int, KItemListWidget*> m_visibleItems;
 387     QHash<KItemListWidget*, KItemListGroupHeader*> m_visibleGroups;
 388
 389     int m_scrollBarExtent;
 390     KItemListSizeHintResolver* m_sizeHintResolver;
 391     KItemListViewLayouter* m_layouter;
 392     KItemListViewAnimation* m_animation;
 393
 394     QTimer* m_layoutTimer; // Triggers an asynchronous doLayout() call.
 395     qreal m_oldScrollOffset;
 396     qreal m_oldMaximumScrollOffset;
 397     qreal m_oldItemOffset;
 398     qreal m_oldMaximumItemOffset;
 399
 400     bool m_skipAutoScrollForRubberBand;
 401     KItemListRubberBand* m_rubberBand;
 402
 403     QPointF m_mousePos;
 404     int m_autoScrollIncrement;
 405     QTimer* m_autoScrollTimer;
 406
 407     KItemListHeader* m_header;
 408     bool m_useHeaderWidths;
 409
 410     friend class KItemListController;
 411 };
 412
 413 /**
 414  * Allows to do a fast logical creation and deletion of QGraphicsWidgets
 415  * by recycling existing QGraphicsWidgets instances. Is used by
 416  * KItemListWidgetCreatorBase and KItemListGroupHeaderCreatorBase.
 417  * @internal
 418  */
 419 class LIBDOLPHINPRIVATE_EXPORT KItemListCreatorBase
 420 {
 421 public:
 422     virtual ~KItemListCreatorBase();
 423
 424 protected:
 425     void addCreatedWidget(QGraphicsWidget* widget);
 426     void pushRecycleableWidget(QGraphicsWidget* widget);
 427     QGraphicsWidget* popRecycleableWidget();
 428
 429 private:
 430     QSet<QGraphicsWidget*> m_createdWidgets;
 431     QList<QGraphicsWidget*> m_recycleableWidgets;
 432 };
 433
 434 /**
 435  * @brief Base class for creating KItemListWidgets.
 436  *
 437  * It is recommended that applications simply use the KItemListWidgetCreator-template class.
 438  * For a custom implementation the methods create() and recyle() must be reimplemented.
 439  * The intention of the widget creator is to prevent repetitive and expensive instantiations and
 440  * deletions of KItemListWidgets by recycling existing widget instances.
 441  */
 442 class LIBDOLPHINPRIVATE_EXPORT KItemListWidgetCreatorBase : public KItemListCreatorBase
 443 {
 444 public:
 445     virtual ~KItemListWidgetCreatorBase();
 446     virtual KItemListWidget* create(KItemListView* view) = 0;
 447     virtual void recycle(KItemListWidget* widget);
 448 };
 449
 450 template <class T>
 451 class LIBDOLPHINPRIVATE_EXPORT KItemListWidgetCreator : public KItemListWidgetCreatorBase
 452 {
 453 public:
 454     virtual ~KItemListWidgetCreator();
 455     virtual KItemListWidget* create(KItemListView* view);
 456 };
 457
 458 template <class T>
 459 KItemListWidgetCreator<T>::~KItemListWidgetCreator()
 460 {
 461 }
 462
 463 template <class T>
 464 KItemListWidget* KItemListWidgetCreator<T>::create(KItemListView* view)
 465 {
 466     KItemListWidget* widget = static_cast<KItemListWidget*>(popRecycleableWidget());
 467     if (!widget) {
 468         widget = new T(view);
 469         addCreatedWidget(widget);
 470     }
 471     return widget;
 472 }
 473
 474 /**
 475  * @brief Base class for creating KItemListGroupHeaders.
 476  *
 477  * It is recommended that applications simply use the KItemListGroupHeaderCreator-template class.
 478  * For a custom implementation the methods create() and recyle() must be reimplemented.
 479  * The intention of the group-header creator is to prevent repetitive and expensive instantiations and
 480  * deletions of KItemListGroupHeaders by recycling existing header instances.
 481  */
 482 class LIBDOLPHINPRIVATE_EXPORT KItemListGroupHeaderCreatorBase : public KItemListCreatorBase
 483 {
 484 public:
 485     virtual ~KItemListGroupHeaderCreatorBase();
 486     virtual KItemListGroupHeader* create(QGraphicsWidget* parent) = 0;
 487     virtual void recycle(KItemListGroupHeader* header);
 488 };
 489
 490 template <class T>
 491 class LIBDOLPHINPRIVATE_EXPORT KItemListGroupHeaderCreator : public KItemListGroupHeaderCreatorBase
 492 {
 493 public:
 494     virtual ~KItemListGroupHeaderCreator();
 495     virtual KItemListGroupHeader* create(QGraphicsWidget* parent);
 496 };
 497
 498 template <class T>
 499 KItemListGroupHeaderCreator<T>::~KItemListGroupHeaderCreator()
 500 {
 501 }
 502
 503 template <class T>
 504 KItemListGroupHeader* KItemListGroupHeaderCreator<T>::create(QGraphicsWidget* parent)
 505 {
 506     KItemListGroupHeader* widget = static_cast<KItemListGroupHeader*>(popRecycleableWidget());
 507     if (!widget) {
 508         widget = new T(parent);
 509         addCreatedWidget(widget);
 510     }
 511     return widget;
 512 }
 513
 514 #endif