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      * Turns on the header if \p show is true. Per default the
 105      * header is not shown.
 106      */
 107     void setHeaderShown(bool show);
 108     bool isHeaderShown() const;
 109
 110     /**
 111      * @return Controller of the item-list. The controller gets
 112      *         initialized by KItemListController::setView() and will
 113      *         result in calling KItemListController::onControllerChanged().
 114      */
 115     KItemListController* controller() const;
 116
 117     /**
 118      * @return Model of the item-list. The model gets
 119      *         initialized by KItemListController::setView() and will
 120      *         result in calling KItemListController::onModelChanged().
 121      */
 122     KItemModelBase* model() const;
 123
 124     /**
 125      * Sets the creator that creates a widget showing the
 126      * content of one model-item. Usually it is sufficient
 127      * to implement a custom widget X derived from KItemListWidget and
 128      * set the creator by:
 129      * <code>
 130      * itemListView->setWidgetCreator(new KItemListWidgetCreator<X>());
 131      * </code>
 132      * Note that the ownership of the widget creator is not transferred to
 133      * the item-list view: One instance of a widget creator might get shared
 134      * by several item-list view instances.
 135      **/
 136     void setWidgetCreator(KItemListWidgetCreatorBase* widgetCreator);
 137     KItemListWidgetCreatorBase* widgetCreator() const;
 138
 139     void setGroupHeaderCreator(KItemListGroupHeaderCreatorBase* groupHeaderCreator);
 140     KItemListGroupHeaderCreatorBase* groupHeaderCreator() const;
 141
 142     void setStyleOption(const KItemListStyleOption& option);
 143     const KItemListStyleOption& styleOption() const;
 144
 145     /** @reimp */
 146     virtual void setGeometry(const QRectF& rect);
 147
 148     int itemAt(const QPointF& pos) const;
 149     bool isAboveSelectionToggle(int index, const QPointF& pos) const;
 150     bool isAboveExpansionToggle(int index, const QPointF& pos) const;
 151
 152     int firstVisibleIndex() const;
 153     int lastVisibleIndex() const;
 154
 155     /**
 156      * @return Required size for the item with the index \p index.
 157      *         Per default KItemListView::itemSize() is returned.
 158      *         When reimplementing this method it is recommended to
 159      *         also reimplement KItemListView::itemSizeHintUpdateRequired().
 160      */
 161     virtual QSizeF itemSizeHint(int index) const;
 162
 163     /**
 164      * @param itemRanges Items that must be checked for getting the visible roles sizes.
 165      * @return The size of each visible role in case if KItemListView::itemSize()
 166      *         is empty. This allows to have dynamic but equal role sizes between
 167      *         all items. Per default an empty hash is returned.
 168      */
 169     virtual QHash<QByteArray, QSizeF> visibleRolesSizes(const KItemRangeList& itemRanges) const;
 170
 171     /**
 172      * @return The bounding rectangle of the item relative to the top/left of
 173      *         the currently visible area (see KItemListView::offset()).
 174      */
 175     QRectF itemBoundingRect(int index) const;
 176
 177     /**
 178      * @return The number of items that can be shown in parallel for one offset.
 179      *         Assuming the scrolldirection is vertical then a value of 4 means
 180      *         that 4 columns for items are available. Assuming the scrolldirection
 181      *         is horizontal then a value of 4 means that 4 lines for items are
 182      *         available.
 183      */
 184     int itemsPerOffset() const;
 185
 186     void beginTransaction();
 187     void endTransaction();
 188     bool isTransactionActive() 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      * Updates the width of the KItemListHeader corresponding to the required width of
 333      * the roles.
 334      */
 335     void updateHeaderWidth();
 336
 337     /**
 338      * @return The widths of each visible role that is shown in the KItemListHeader.
 339      */
 340     QHash<QByteArray, qreal> headerRolesWidths() const;
 341
 342     /**
 343      * Updates m_visibleRolesSizes by calling KItemListView::visibleRolesSizes().
 344      * Nothing will be done if m_itemRect is not empty or custom header-widths
 345      * are used (see m_useHeaderWidths). Also m_strechedVisibleRolesSizes will be adjusted
 346      * to respect the available view-size.
 347      */
 348     void updateVisibleRolesSizes(const KItemRangeList& itemRanges);
 349
 350     /**
 351      * Convenience method for updateVisibleRoleSizes(KItemRangeList() << KItemRange(0, m_model->count()).
 352      */
 353     void updateVisibleRolesSizes();
 354
 355     /**
 356      * Updates m_stretchedVisibleRolesSizes based on m_visibleRolesSizes and the available
 357      * view-size. Nothing will be done if m_itemRect is not empty or custom header-widths
 358      * are used (see m_useHeaderWidths).
 359      */
 360     void updateStretchedVisibleRolesSizes();
 361
 362     /**
 363      * Helper function for triggerAutoScrolling().
 364      * @param pos    Logical position of the mouse relative to the range.
 365      * @param range  Range of the visible area.
 366      * @param oldInc Previous increment. Is used to assure that the increment
 367      *               increases only gradually.
 368      * @return Scroll increment that should be added to the offset().
 369      *         As soon as \a pos is inside the autoscroll-margin a
 370      *         value != 0 will be returned.
 371      */
 372     static int calculateAutoScrollingIncrement(int pos, int range, int oldInc);
 373
 374 private:
 375     bool m_grouped;
 376     int m_activeTransactions; // Counter for beginTransaction()/endTransaction()
 377
 378     QSizeF m_itemSize;
 379     KItemListController* m_controller;
 380     KItemModelBase* m_model;
 381     QList<QByteArray> m_visibleRoles;
 382     QHash<QByteArray, QSizeF> m_visibleRolesSizes;
 383     QHash<QByteArray, QSizeF> m_stretchedVisibleRolesSizes;
 384     KItemListWidgetCreatorBase* m_widgetCreator;
 385     KItemListGroupHeaderCreatorBase* m_groupHeaderCreator;
 386     KItemListStyleOption m_styleOption;
 387
 388     QHash<int, KItemListWidget*> m_visibleItems;
 389     QHash<KItemListWidget*, KItemListGroupHeader*> m_visibleGroups;
 390
 391     int m_scrollBarExtent;
 392     KItemListSizeHintResolver* m_sizeHintResolver;
 393     KItemListViewLayouter* m_layouter;
 394     KItemListViewAnimation* m_animation;
 395
 396     QTimer* m_layoutTimer; // Triggers an asynchronous doLayout() call.
 397     qreal m_oldScrollOffset;
 398     qreal m_oldMaximumScrollOffset;
 399     qreal m_oldItemOffset;
 400     qreal m_oldMaximumItemOffset;
 401
 402     bool m_skipAutoScrollForRubberBand;
 403     KItemListRubberBand* m_rubberBand;
 404
 405     QPointF m_mousePos;
 406     int m_autoScrollIncrement;
 407     QTimer* m_autoScrollTimer;
 408
 409     KItemListHeader* m_header;
 410     bool m_useHeaderWidths;
 411
 412     friend class KItemListController;
 413 };
 414
 415 /**
 416  * Allows to do a fast logical creation and deletion of QGraphicsWidgets
 417  * by recycling existing QGraphicsWidgets instances. Is used by
 418  * KItemListWidgetCreatorBase and KItemListGroupHeaderCreatorBase.
 419  * @internal
 420  */
 421 class LIBDOLPHINPRIVATE_EXPORT KItemListCreatorBase
 422 {
 423 public:
 424     virtual ~KItemListCreatorBase();
 425
 426 protected:
 427     void addCreatedWidget(QGraphicsWidget* widget);
 428     void pushRecycleableWidget(QGraphicsWidget* widget);
 429     QGraphicsWidget* popRecycleableWidget();
 430
 431 private:
 432     QSet<QGraphicsWidget*> m_createdWidgets;
 433     QList<QGraphicsWidget*> m_recycleableWidgets;
 434 };
 435
 436 /**
 437  * @brief Base class for creating KItemListWidgets.
 438  *
 439  * It is recommended that applications simply use the KItemListWidgetCreator-template class.
 440  * For a custom implementation the methods create() and recyle() must be reimplemented.
 441  * The intention of the widget creator is to prevent repetitive and expensive instantiations and
 442  * deletions of KItemListWidgets by recycling existing widget instances.
 443  */
 444 class LIBDOLPHINPRIVATE_EXPORT KItemListWidgetCreatorBase : public KItemListCreatorBase
 445 {
 446 public:
 447     virtual ~KItemListWidgetCreatorBase();
 448     virtual KItemListWidget* create(KItemListView* view) = 0;
 449     virtual void recycle(KItemListWidget* widget);
 450 };
 451
 452 template <class T>
 453 class LIBDOLPHINPRIVATE_EXPORT KItemListWidgetCreator : public KItemListWidgetCreatorBase
 454 {
 455 public:
 456     virtual ~KItemListWidgetCreator();
 457     virtual KItemListWidget* create(KItemListView* view);
 458 };
 459
 460 template <class T>
 461 KItemListWidgetCreator<T>::~KItemListWidgetCreator()
 462 {
 463 }
 464
 465 template <class T>
 466 KItemListWidget* KItemListWidgetCreator<T>::create(KItemListView* view)
 467 {
 468     KItemListWidget* widget = static_cast<KItemListWidget*>(popRecycleableWidget());
 469     if (!widget) {
 470         widget = new T(view);
 471         addCreatedWidget(widget);
 472     }
 473     return widget;
 474 }
 475
 476 /**
 477  * @brief Base class for creating KItemListGroupHeaders.
 478  *
 479  * It is recommended that applications simply use the KItemListGroupHeaderCreator-template class.
 480  * For a custom implementation the methods create() and recyle() must be reimplemented.
 481  * The intention of the group-header creator is to prevent repetitive and expensive instantiations and
 482  * deletions of KItemListGroupHeaders by recycling existing header instances.
 483  */
 484 class LIBDOLPHINPRIVATE_EXPORT KItemListGroupHeaderCreatorBase : public KItemListCreatorBase
 485 {
 486 public:
 487     virtual ~KItemListGroupHeaderCreatorBase();
 488     virtual KItemListGroupHeader* create(QGraphicsWidget* parent) = 0;
 489     virtual void recycle(KItemListGroupHeader* header);
 490 };
 491
 492 template <class T>
 493 class LIBDOLPHINPRIVATE_EXPORT KItemListGroupHeaderCreator : public KItemListGroupHeaderCreatorBase
 494 {
 495 public:
 496     virtual ~KItemListGroupHeaderCreator();
 497     virtual KItemListGroupHeader* create(QGraphicsWidget* parent);
 498 };
 499
 500 template <class T>
 501 KItemListGroupHeaderCreator<T>::~KItemListGroupHeaderCreator()
 502 {
 503 }
 504
 505 template <class T>
 506 KItemListGroupHeader* KItemListGroupHeaderCreator<T>::create(QGraphicsWidget* parent)
 507 {
 508     KItemListGroupHeader* widget = static_cast<KItemListGroupHeader*>(popRecycleableWidget());
 509     if (!widget) {
 510         widget = new T(parent);
 511         addCreatedWidget(widget);
 512     }
 513     return widget;
 514 }
 515
 516 #endif