Unity 8
listviewwithpageheader.h
1 /*
2  * Copyright (C) 2013 Canonical, Ltd.
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License as published by
6  * the Free Software Foundation; version 3.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11  * GNU General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public License
14  * along with this program. If not, see <http://www.gnu.org/licenses/>.
15  */
16 
17 #ifndef LISTVIEWWITHPAGEHEADER_H
18 #define LISTVIEWWITHPAGEHEADER_H
19 
20 #include <private/qquickitemchangelistener_p.h>
21 #include <private/qquickflickable_p.h>
22 
23 class QAbstractItemModel;
24 class QQuickNumberAnimation;
25 class QQmlChangeSet;
26 class QQmlDelegateModel;
27 
28 
46 class ListViewWithPageHeader : public QQuickFlickable, public QQuickItemChangeListener
47 {
48  Q_OBJECT
49  Q_PROPERTY(QAbstractItemModel *model READ model WRITE setModel NOTIFY modelChanged)
50  Q_PROPERTY(QQmlComponent *delegate READ delegate WRITE setDelegate NOTIFY delegateChanged)
51  Q_PROPERTY(QQuickItem *pageHeader READ header WRITE setHeader NOTIFY headerChanged)
52  Q_PROPERTY(QQmlComponent *sectionDelegate READ sectionDelegate WRITE setSectionDelegate NOTIFY sectionDelegateChanged)
53  Q_PROPERTY(QString sectionProperty READ sectionProperty WRITE setSectionProperty NOTIFY sectionPropertyChanged)
54  Q_PROPERTY(bool forceNoClip READ forceNoClip WRITE setForceNoClip NOTIFY forceNoClipChanged)
55  Q_PROPERTY(int stickyHeaderHeight READ stickyHeaderHeight NOTIFY stickyHeaderHeightChanged)
56  Q_PROPERTY(qreal headerItemShownHeight READ headerItemShownHeight NOTIFY headerItemShownHeightChanged)
57  Q_PROPERTY(int cacheBuffer READ cacheBuffer WRITE setCacheBuffer NOTIFY cacheBufferChanged)
58 
59  friend class ListViewWithPageHeaderTest;
60  friend class ListViewWithPageHeaderTestSection;
61  friend class ListViewWithPageHeaderTestExternalModel;
62 
63 public:
66 
67  QAbstractItemModel *model() const;
68  void setModel(QAbstractItemModel *model);
69 
70  QQmlComponent *delegate() const;
71  void setDelegate(QQmlComponent *delegate);
72 
73  QQuickItem *header() const;
74  void setHeader(QQuickItem *header);
75 
76  QQmlComponent *sectionDelegate() const;
77  void setSectionDelegate(QQmlComponent *delegate);
78 
79  QString sectionProperty() const;
80  void setSectionProperty(const QString &property);
81 
82  bool forceNoClip() const;
83  void setForceNoClip(bool noClip);
84 
85  int stickyHeaderHeight() const;
86  qreal headerItemShownHeight() const;
87 
88  int cacheBuffer() const;
89  void setCacheBuffer(int cacheBuffer);
90 
91  Q_INVOKABLE void positionAtBeginning();
92  Q_INVOKABLE void showHeader();
93  Q_INVOKABLE int firstCreatedIndex() const;
94  Q_INVOKABLE int createdItemCount() const;
95  Q_INVOKABLE QQuickItem *item(int modelIndex) const;
96 
97  // The index has to be created for this to try to do something
98  // Created items are those visible and the precached ones
99  // Returns if the item existed or not
100  Q_INVOKABLE bool maximizeVisibleArea(int modelIndex);
101  Q_INVOKABLE bool maximizeVisibleArea(int modelIndex, int itemHeight);
102 
103 Q_SIGNALS:
104  void modelChanged();
105  void delegateChanged();
106  void headerChanged();
107  void sectionDelegateChanged();
108  void sectionPropertyChanged();
109  void forceNoClipChanged();
110  void stickyHeaderHeightChanged();
111  void headerItemShownHeightChanged();
112  void cacheBufferChanged();
113 
114 protected:
115  void componentComplete() override;
116  void viewportMoved(Qt::Orientations orient) override;
117  qreal minYExtent() const override;
118  void itemGeometryChanged(QQuickItem *item, const QRectF &newGeometry, const QRectF &oldGeometry) override;
119  void itemImplicitHeightChanged(QQuickItem *item) override;
120  void updatePolish() override;
121 
122 private Q_SLOTS:
123  void itemCreated(int modelIndex, QObject *object);
124  void onContentHeightChanged();
125  void onContentWidthChanged();
126  void onHeightChanged();
127  void onModelUpdated(const QQmlChangeSet &changeSet, bool reset);
128  void contentYAnimationRunningChanged(bool running);
129 
130 private:
131  class ListItem
132  {
133  public:
134  qreal height() const;
135 
136  qreal y() const;
137  void setY(qreal newY);
138 
139  bool culled() const;
140  void setCulled(bool culled);
141 
142  QQuickItem *sectionItem() const { return m_sectionItem; }
143  void setSectionItem(QQuickItem *sectionItem);
144 
145  QQuickItem *m_item;
146  private:
147  QQuickItem *m_sectionItem;
148  };
149 
150  bool maximizeVisibleArea(ListItem *listItem, int listItemHeight);
151 
152  void createDelegateModel();
153 
154  void layout();
155  void refill();
156  bool addVisibleItems(qreal fillFrom, qreal fillTo, bool asynchronous);
157  bool removeNonVisibleItems(qreal bufferFrom, qreal bufferTo);
158  ListItem *createItem(int modelIndex, bool asynchronous);
159 
160  void adjustHeader(qreal diff);
161  void adjustMinYExtent();
162  void updateClipItem();
163  void headerHeightChanged(qreal newHeaderHeight, qreal oldHeaderHeight, qreal oldHeaderY);
164  ListItem *itemAtIndex(int modelIndex) const; // Returns the item at modelIndex if has been created
165  void releaseItem(ListItem *item);
166  void reallyReleaseItem(ListItem *item);
167  void updateWatchedRoles();
168  QQuickItem *getSectionItem(int modelIndex, bool alreadyInserted);
169  QQuickItem *getSectionItem(const QString &sectionText);
170 
171  QQmlDelegateModel *m_delegateModel;
172 
173  // Index we are waiting because we requested it asynchronously
174  int m_asyncRequestedIndex;
175 
176  // Used to only give a warning once if the delegate does not return objects
177  bool m_delegateValidated;
178 
179  // Visible indexes, [0] is m_firstValidIndex, [0+1] is m_firstValidIndex +1, ...
180  QList<ListItem *> m_visibleItems;
181  int m_firstVisibleIndex;
182 
183  qreal m_minYExtent;
184 
185  QQuickItem *m_clipItem;
186 
187  // If any of the heights has changed
188  // or new items have been added/removed
189  bool m_contentHeightDirty;
190 
191  QQuickItem *m_headerItem;
192  qreal m_previousContentY;
193  qreal m_previousHeaderImplicitHeight;
194  qreal m_headerItemShownHeight; // The height of header shown when the header is shown outside its topmost position
195  // i.e. it's being shown after dragging down in the middle of the list
196  enum ContentYAnimationType { ContentYAnimationShowHeader, ContentYAnimationMaximizeVisibleArea };
197  ContentYAnimationType contentYAnimationType;
198  QQuickNumberAnimation *m_contentYAnimation;
199 
200  QQmlComponent *m_sectionDelegate;
201  QString m_sectionProperty;
202  QQuickItem *m_topSectionItem;
203 
204  bool m_forceNoClip;
205  bool m_inLayout;
206  bool m_inContentHeightKeepHeaderShown;
207  int m_cacheBuffer;
208 
209  // Qt 5.0 doesn't like releasing the items just after itemCreated
210  // so we delay the releasing until the next updatePolish
211  QList<ListItem *> m_itemsToRelease;
212 };
213 
214 
215 #endif