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diff --git a/examples/widgets/doc/src/wiggly.qdoc b/examples/widgets/doc/src/wiggly.qdoc deleted file mode 100644 index d70d609e2b..0000000000 --- a/examples/widgets/doc/src/wiggly.qdoc +++ /dev/null @@ -1,168 +0,0 @@ -/**************************************************************************** -** -** 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 widgets/wiggly - \title Wiggly Example - \ingroup examples-widgets - \brief The Wiggly example shows how to animate a widget using - QBasicTimer and \l{QObject::timerEvent()}{timerEvent()}. In - addition, the example demonstrates how to use QFontMetrics to - determine the size of text on screen. - - \borderedimage wiggly-example.png - \caption Screenshot of the Wiggly example - - QBasicTimer is a low-level class for timers. Unlike QTimer, - QBasicTimer doesn't inherit from QObject; instead of emitting a - \l{QTimer::timeout()}{timeout()} signal when a certain amount of - time has passed, it sends a QTimerEvent to a QObject of our - choice. This makes QBasicTimer a more lightweight alternative to - QTimer. Qt's built-in widgets use it internally, and it is - provided in Qt's API for highly-optimized applications (such as - embedded applications). - - The example consists of two classes: - - \list - \li \c WigglyWidget is the custom widget displaying the text - in a wiggly line. - - \li \c Dialog is the dialog widget allowing the user to enter a - text. It combines a \c WigglyWidget and a \c QLineEdit. - \endlist - - We will first take a quick look at the \c Dialog class, then we - will review the \c WigglyWidget class. - - \section1 Dialog Class Definition - - \snippet widgets/wiggly/dialog.h 0 - - The \c Dialog class provides a dialog widget that allows the user - to enter a text. The text is then rendered by \c WigglyWidget. - - \section1 Dialog Class Implementation - - \snippet widgets/wiggly/dialog.cpp 0 - - In the constructor we create a wiggly widget along with a - \l{QLineEdit}{line edit}, and we put the two widgets in a - vertical layout. We connect the line edit's \l - {QLineEdit::textChanged()}{textChanged()} signal to the wiggly - widget's \c setText() slot to obtain the real time interaction - with the wiggly widget. The widget's default text is "Hello - world!". - - \section1 WigglyWidget Class Definition - - \snippet widgets/wiggly/wigglywidget.h 0 - - The \c WigglyWidget class provides the wiggly line displaying the - text. We subclass QWidget and reimplement the standard \l - {QWidget::paintEvent()}{paintEvent()} and \l - {QObject::timerEvent()}{timerEvent()} functions to draw and update - the widget. In addition we implement a public \c setText() slot - that sets the widget's text. - - The \c timer variable, of type QBasicTimer, is used to update the - widget at regular intervals, making the widget move. The \c text - variable is used to store the currently displayed text, and \c - step to calculate position and color for each character on the - wiggly line. - - \section1 WigglyWidget Class Implementation - - \snippet widgets/wiggly/wigglywidget.cpp 0 - - In the constructor, we make the widget's background slightly - lighter than the usual background using the QPalette::Midlight - color role. The background role defines the brush from the - widget's palette that Qt uses to paint the background. Then we - enlarge the widget's font with 20 points. - - Finally we start the timer; the call to QBasicTimer::start() - makes sure that \e this particular wiggly widget will receive the - timer events generated when the timer times out (every 60 - milliseconds). - - \snippet widgets/wiggly/wigglywidget.cpp 1 - \snippet widgets/wiggly/wigglywidget.cpp 2 - - The \c paintEvent() function is called whenever a QPaintEvent is - sent to the widget. Paint events are sent to widgets that need to - update themselves, for instance when part of a widget is exposed - because a covering widget was moved. For the wiggly widget, a - paint event will also be generated every 60 milliseconds from - the \c timerEvent() slot. - - The \c sineTable represents y-values of the sine curve, - multiplied by 100. It is used to make the wiggly widget move - along the sine curve. - - The QFontMetrics object provides information about the widget's - font. The \c x variable is the horizontal position where we start - drawing the text. The \c y variable is the vertical position of - the text's base line. Both variables are computed so that the - text is horizontally and vertically centered. To compute the base - line, we take into account the font's ascent (the height of the - font above the base line) and font's descent (the height of the - font below the base line). If the descent equals the ascent, they - cancel out each other and the base line is at \c height() / 2. - - \snippet widgets/wiggly/wigglywidget.cpp 3 - \snippet widgets/wiggly/wigglywidget.cpp 4 - - Each time the \c paintEvent() function is called, we create a - QPainter object \c painter to draw the contents of the widget. - For each character in \c text, we determine the color and the - position on the wiggly line based on \c step. In addition, \c x - is incremented by the character's width. - - For simplicity, we assume that QFontMetrics::horizontalAdvance(\c text) - returns the sum of the individual character advances - (QFontMetrics::horizontalAdvance(\c text[i])). In practice, this is not - always the case because QFontMetrics::horizontalAdvance(\c text) also takes - into account the kerning between certain letters (e.g., 'A' and - 'V'). The result is that the text isn't perfectly centered. You - can verify this by typing "AVAVAVAVAVAV" in the line edit. - - \snippet widgets/wiggly/wigglywidget.cpp 5 - \snippet widgets/wiggly/wigglywidget.cpp 6 - - The \c timerEvent() function receives all the timer events that - are generated for this widget. If a timer event is sent from the - widget's QBasicTimer, we increment \c step to make the text move, - and call QWidget::update() to refresh the display. Any other - timer event is passed on to the base class's implementation of - the \l{QWidget::timerEvent()}{timerEvent()} function. - - The QWidget::update() slot does not cause an immediate repaint; - instead the slot schedules a paint event for processing when Qt - returns to the main event loop. The paint events are then handled - by \c{WigglyWidget}'s \c paintEvent() function. -*/ |