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diff --git a/doc/src/examples/frozencolumn.qdoc b/doc/src/examples/frozencolumn.qdoc new file mode 100644 index 0000000000..5840444c5d --- /dev/null +++ b/doc/src/examples/frozencolumn.qdoc @@ -0,0 +1,133 @@ +/**************************************************************************** +** +** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies). +** All rights reserved. +** Contact: Nokia Corporation (qt-info@nokia.com) +** +** This file is part of the documentation of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:FDL$ +** No Commercial Usage +** This file contains pre-release code and may not be distributed. +** You may use this file in accordance with the terms and conditions +** contained in the Technology Preview License Agreement accompanying +** this package. +** +** GNU Free Documentation License +** 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. +** +** If you have questions regarding the use of this file, please contact +** Nokia at qt-info@nokia.com. +** $QT_END_LICENSE$ +** +****************************************************************************/ + +/*! + \example itemviews/frozencolumn + \title Frozen Column Example + + This example demonstrates how to freeze a column within a QTableView. + + \image frozencolumn-example.png "Screenshot of the example" + + We use Qt's model/view framework to implement a table with its first + column frozen. This technique can be aplied to several columns or rows, + as long as they are on the edge of the table. + + The model/view framework allows for one model to be displayed in different + ways using multiple views. For this example, we use two views on the same + model - two \l {QTableView}{table views} sharing one model. The frozen + column is a child of the main tableview, and we provide the desired visual + effect using an overlay technique which will be described step by step in + the coming sections. + + \image frozencolumn-tableview.png + + + \section1 FreezeTableWidget Class Definition + + The \c FreezeTableWidget class has a constructor and a destructor. Also, it + has two private members: the table view that we will use as an overlay, and + the shared model for both table views. Two slots are added to help keep the + section sizes in sync, as well as a function to readjust the frozen + column's geometry. In addition, we reimplement two functions: + \l{QAbstractItemView::}{resizeEvent()} and \l{QTableView::}{moveCursor()}. + + \snippet examples/itemviews/frozencolumn/freezetablewidget.h Widget definition + + \note QAbstractItemView is \l{QTableView}'s ancestor. + + + \section1 FreezeTableWidget Class Implementation + + The constructor takes \a model as an argument and creates a table view that + we will use to display the frozen column. Then, within the constructor, we + invoke the \c init() function to set up the frozen column. Finally, we + connect the \l{QHeaderView::sectionResized()} signals (for horizontal and + vertical headers) to the appropriate slots. This ensures that our frozen + column's sections are in sync with the headers. We also connect the + vertical scrollbars together so that the frozen column scrolls vertically + with the rest of our table. + + \snippet examples/itemviews/frozencolumn/freezetablewidget.cpp constructor + + + In the \c init() function, we ensure that the overlay table view + responsible for displaying the frozen column, is set up properly. This + means that this table view, \c frozenTableView, has to have the same model + as the main table view. However, the difference here is: \c frozenTableView's + only visible column is its first column; we hide the others using + \l{QTableView::}{setColumnHidden()} + + \snippet examples/itemviews/frozencolumn/freezetablewidget.cpp init part1 + + + In terms of the frozen column's z-order, we stack it on top of the + viewport. This is achieved by calling \l{QWidget::}{stackUnder()} on the + viewport. For appearance's sake, we prevent the column from stealing focus + from the main tableview. Also, we make sure that both views share the same + selection model, so only one cell can be selected at a time. A few other + tweaks are done to make our application look good and behave consistently + with the main tableview. Note that we called \c updateFrozenTableGeometry() + to make the column occupy the correct spot. + + \snippet examples/itemviews/frozencolumn/freezetablewidget.cpp init part2 + + When you resize the frozen column, the same column on the main table view + must resize accordingly, to provide seamless integration. This is + accomplished by getting the new size of the column from the \c newSize + value from the \l{QHeaderView::}{sectionResized()} signal, emitted by both + the horizontal and vertical header. + + \snippet examples/itemviews/frozencolumn/freezetablewidget.cpp sections + + Since the width of the frozen column is modified, we adjust the geometry of + the widget accordingly by invoking \c updateFrozenTableGeometry(). This + function is further explained below. + + In our reimplementation of QTableView::resizeEvent(), we call + \c updateFrozenTableGeometry() after invoking the base class + implementation. + + \snippet examples/itemviews/frozencolumn/freezetablewidget.cpp resize + + When navigating around the table with the keyboard, we need to ensure that + the current selection does not disappear behind the frozen column. To + synchronize this, we reimplement QTableView::moveCursor() and adjust the + scrollbar positions if needed, after calling the base class implementation. + + \snippet examples/itemviews/frozencolumn/freezetablewidget.cpp navigate + + The frozen column's geometry calculation is based on the geometry of the + table underneath, so it always appears in the right place. Using the + QFrame::frameWidth() function helps to calculate this geometry correctly, + no matter which style is used. We rely on the geometry of the viewport and + headers to set the boundaries for the frozen column. + + \snippet examples/itemviews/frozencolumn/freezetablewidget.cpp geometry + +*/ + |