diff options
Diffstat (limited to 'doc/src/examples/moveblocks.qdoc')
| -rw-r--r-- | doc/src/examples/moveblocks.qdoc | 214 |
1 files changed, 0 insertions, 214 deletions
diff --git a/doc/src/examples/moveblocks.qdoc b/doc/src/examples/moveblocks.qdoc deleted file mode 100644 index 38551abd28..0000000000 --- a/doc/src/examples/moveblocks.qdoc +++ /dev/null @@ -1,214 +0,0 @@ -/**************************************************************************** -** -** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies). -** Contact: http://www.qt-project.org/ -** -** This file is part of the documentation of the Qt Toolkit. -** -** $QT_BEGIN_LICENSE:FDL$ -** 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. -** -** Other Usage -** Alternatively, this file may be used in accordance with the terms -** and conditions contained in a signed written agreement between you -** and Nokia. -** -** -** -** -** -** $QT_END_LICENSE$ -** -****************************************************************************/ - -/*! - \example animation/moveblocks - \title Move Blocks Example - - The Move Blocks example shows how to animate items in a - QGraphicsScene using a QStateMachine with a custom transition. - - \image moveblocks-example.png - - The example animates the blue blocks that you can see in the image - above. The animation moves the blocks between four preset positions. - - The example consists of the following classes: - - \list - \li \c StateSwitcher inherits QState and can add - \c {StateSwitchTransition}s to other states. - When entered, it will randomly transition to one of these - states. - \li \c StateSwitchTransition is a custom transition that - triggers on \c{StateSwitchEvent}s. - \li \c StateSwitchEvent is a QEvent that triggers \c{StateSwitchTransition}s. - \li \c QGraphicsRectWidget is a QGraphicsWidget that simply - paints its background in a solid \l{Qt::}{blue} color. - \endlist - - The blocks are instances of \c QGraphicsRectWidget and are - animated in a QGraphicsScene. We do this by building a state - graph, which we insert animations into. The graph is then executed - in a QStateMachine. All this is done in \c main(). - Let's look at the \c main() function first. - - \section1 The \c main() Function - - After QApplication has been initialized, we set up the - QGraphicsScene with its \c{QGraphicsRectWidget}s. - - \snippet examples/animation/moveblocks/main.cpp 1 - - After adding the scene to a QGraphicsView, it is time to build the - state graph. Let's first look at a statechart of what we are - trying to build. - - \image move-blocks-chart.png - - Note that the \c group has seven sub states, but we have only - included three of them in the diagram. The code that builds this - graph will be examined line-by-line, and will show how the graph - works. First off, we construct the \c group state: - - \snippet examples/animation/moveblocks/main.cpp 2 - - The timer is used to add a delay between each time the blocks are - moved. The timer is started when \c group is entered. As we will - see later, \c group has a transition back to the \c StateSwitcher - when the timer times out. \c group is the initial state in the - machine, so an animation will be scheduled when the example is - started. - - \snippet examples/animation/moveblocks/main.cpp 3 - \dots - \snippet examples/animation/moveblocks/main.cpp 4 - - \c createGeometryState() returns a QState that will set the - geometry of our items upon entry. It also assigns \c group as the - parent of this state. - - A QPropertyAnimation inserted into a transition will use the - values assigned to a QState (with QState::assignProperty()), i.e., - the animation will interpolate between the current values of the - properties and the values in the target state. We add animated - transitions to the state graph later. - - \snippet examples/animation/moveblocks/main.cpp 5 - - We move the items in parallel. Each item is added to \c - animationGroup, which is the animation that is inserted into the - transitions. - - \snippet examples/animation/moveblocks/main.cpp 6 - - The sequential animation group, \c subGroup, helps us insert a - delay between the animation of each item. - - \snippet examples/animation/moveblocks/main.cpp 7 - \dots - \snippet examples/animation/moveblocks/main.cpp 8 - - A StateSwitchTransition is added to the state switcher - in \c StateSwitcher::addState(). We also add the animation in this - function. Since QPropertyAnimation uses the values from the - states, we can insert the same QPropertyAnimation instance in all - \c {StateSwitchTransition}s. - - As mentioned previously, we add a transition to the state switcher - that triggers when the timer times out. - - \snippet examples/animation/moveblocks/main.cpp 9 - - Finally, we can create the state machine, add our initial state, - and start execution of the state graph. - - \section2 The \c createGeometryState() Function - - In \c createGeometryState(), we set up the geometry for each - graphics item. - - \snippet examples/animation/moveblocks/main.cpp 13 - - As mentioned before, QAbstractTransition will set up an animation - added with \l{QAbstractTransition::}{addAnimation()} using - property values set with \l{QState::}{assignProperty()}. - - \section1 The StateSwitcher Class - - \c StateSwitcher has state switch transitions to each \l{QState}s - we created with \c createGeometryState(). Its job is to transition - to one of these states at random when it is entered. - - All functions in \c StateSwitcher are inlined. We'll step through - its definition. - - \snippet examples/animation/moveblocks/main.cpp 10 - - \c StateSwitcher is a state designed for a particular purpose and - will always be a top-level state. We use \c m_stateCount to keep - track of how many states we are managing, and \c m_lastIndex to - remember which state was the last state to which we transitioned. - - \snippet examples/animation/moveblocks/main.cpp 11 - - We select the next state we are going to transition to, and post a - \c StateSwitchEvent, which we know will trigger the \c - StateSwitchTransition to the selected state. - - \snippet examples/animation/moveblocks/main.cpp 12 - - This is where the magic happens. We assign a number to each state - added. This number is given to both a StateSwitchTransition and to - StateSwitchEvents. As we have seen, state switch events will - trigger a transition with the same number. - - \section1 The StateSwitchTransition Class - - \c StateSwitchTransition inherits QAbstractTransition and triggers - on \c{StateSwitchEvent}s. It contains only inline functions, so - let's take a look at its \l{QAbstractTransition::}{eventTest()} - function, which is the only function that we define.. - - \snippet examples/animation/moveblocks/main.cpp 14 - - \c eventTest is called by QStateMachine when it checks whether a - transition should be triggered--a return value of true means that - it will. We simply check if our assigned number is equal to the - event's number (in which case we fire away). - - \section1 The StateSwitchEvent Class - - \c StateSwitchEvent inherits QEvent, and holds a number that has - been assigned to a state and state switch transition by - \c StateSwitcher. We have already seen how it is used to trigger - \c{StateSwitchTransition}s in \c StateSwitcher. - - \snippet examples/animation/moveblocks/main.cpp 15 - - We only have inlined functions in this class, so a look at its - definition will do. - - \section1 The QGraphicsRectWidget Class - - QGraphicsRectWidget inherits QGraphicsWidget and simply paints its - \l{QWidget::}{rect()} blue. We inline \l{QWidget::}{paintEvent()}, - which is the only function we define. Here is the - QGraphicsRectWidget class definition: - - \snippet examples/animation/moveblocks/main.cpp 16 - - \section1 Moving On - - The technique shown in this example works equally well for all - \l{QPropertyAnimation}s. As long as the value to be animated is a - Qt property, you can insert an animation of it into a state graph. - - QState::addAnimation() takes a QAbstractAnimation, so any type - of animation can be inserted into the graph. -*/ - |