| /**************************************************************************** |
| ** |
| ** Copyright (C) 2016 The Qt Company Ltd. |
| ** Contact: https://www.qt.io/licensing/ |
| ** |
| ** This file is part of the documentation of the Qt Toolkit. |
| ** |
| ** $QT_BEGIN_LICENSE:FDL$ |
| ** Commercial License Usage |
| ** Licensees holding valid commercial Qt licenses may use this file in |
| ** accordance with the commercial license agreement provided with the |
| ** Software or, alternatively, in accordance with the terms contained in |
| ** a written agreement between you and The Qt Company. For licensing terms |
| ** and conditions see https://www.qt.io/terms-conditions. For further |
| ** information use the contact form at https://www.qt.io/contact-us. |
| ** |
| ** GNU Free Documentation License Usage |
| ** Alternatively, this file may be used under the terms of the GNU Free |
| ** Documentation License version 1.3 as published by the Free Software |
| ** Foundation and appearing in the file included in the packaging of |
| ** this file. Please review the following information to ensure |
| ** the GNU Free Documentation License version 1.3 requirements |
| ** will be met: https://www.gnu.org/licenses/fdl-1.3.html. |
| ** $QT_END_LICENSE$ |
| ** |
| ****************************************************************************/ |
| |
| /*! |
| \example itemviews/chart |
| \title Chart Example |
| \ingroup examples-itemviews |
| \brief The Chart example shows how to create a custom view for the model/view framework. |
| |
| \image chart-example.png |
| |
| In this example, the items in a table model are represented as slices in a pie chart, |
| relying on the flexibility of the model/view architecture to handle custom editing |
| and selection features. |
| |
| \b{Note that you only need to create a new view class if your data requires a |
| specialized representation.} You should first consider using a standard QListView, |
| QTableView, or QTreeView with a custom QItemDelegate subclass if you need to |
| represent data in a special way. |
| |
| \omit |
| \section1 PieView Class Definition |
| |
| The \c PieView class is a subclass of QAbstractItemView. The base class provides |
| much of the functionality required by view classes, so we only need to provide |
| implementations for three public functions: visualRect(), scrollTo(), and |
| indexAt(). However, the view needs to maintain strict control over its look and |
| feel, so we also provide implementations for a number of other functions: |
| |
| \snippet itemviews/chart/pieview.h 0 |
| |
| |
| |
| \section1 PieView Class Implementation |
| |
| The paint event renders the data from the standard item model as a pie chart. |
| We interpret the data in the following way: |
| |
| \list |
| \li Column 0 contains data in two different roles: |
| The \l{Qt::ItemDataRole}{DisplayRole} contains a label, and the |
| \l{Qt::ItemDataRole}{DecorationRole} contains the color of the pie slice. |
| \li Column 1 contains a quantity which we will convert to the angular extent of |
| the slice. |
| \endlist |
| |
| The figure is always drawn with the chart on the left and the key on |
| the right. This means that we must try and obtain an area that is wider |
| than it is tall. We do this by imposing a particular aspect ratio on |
| the chart and applying it to the available vertical space. This ensures |
| that we always obtain the maximum horizontal space for the aspect ratio |
| used. |
| We also apply fixed size margin around the figure. |
| |
| We use logical coordinates to draw the chart and key, and position them |
| on the view using viewports. |
| \endomit |
| */ |