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The \c Window class contains the application logic and constructs the user interface from a Qt Designer \c{.ui} file as described in the \l{Using a Designer .ui File in Your Application#The Multiple Inheritance Approach}{Qt Designer manual}. It also contains the code to write an SVG file. The \c DisplayWidget class performs all the work of painting a picture on screen. Since we want the SVG to resemble this picture as closely as possible, we make this code available to the \c Window class so that it can be used to generate SVG files. \section1 The DisplayWidget Class The \c DisplayWidget class displays a drawing consisting of a selection of elements chosen by the user. These are defined using \c Shape and \c Background enums that are included within the class definition: \snippet examples/painting/svggenerator/displaywidget.h DisplayWidget class definition Much of this class is used to configure the appearance of the drawing. The \c paintEvent() and \c paint() functions are most relevant to the purpose of this example, so we will describe these here and leave the reader to look at the source code for the example to see how shapes and colors are handled. We reimplement the QWidget::paintEvent() function to display the drawing on screen: \snippet examples/painting/svggenerator/displaywidget.cpp paint event Here, we only construct a QPainter object, begin painting on the device and set a render hint for improved output quality before calling the \c paint() function to perform the painting itself. When this returns, we close the painter and return. The \c paint() function is designed to be used for different painting tasks. In this example, we use it to draw on a \c DisplayWidget instance and on a QSvgGenerator object. We show how the painting is performed to demonstrate that there is nothing device-specific about the process: \snippet examples/painting/svggenerator/displaywidget.cpp paint function \section1 The Window Class The \c Window class represents the example's window, containing the user interface, which has been created using Qt Designer: \snippet examples/painting/svggenerator/window.h Window class definition As with the \c DisplayWidget class, we concentrate on the parts of the code which are concerned with painting and SVG generation. In the \c Window class, the \c saveSvg() function is called whenever the \gui{Save As...} button is clicked; this connection was defined in the \c{window.ui} file using Qt Designer. The start of the \c saveSvg() function performs the task of showing a file dialog so that the user can specify a SVG file to save the drawing to. \snippet examples/painting/svggenerator/window.cpp save SVG In the rest of the function, we set up the generator and configure it to generate output with the appropriate dimensions and write to the user-specified file. We paint on the QSvgGenerator object in the same way that we paint on a widget, calling the \c DisplayWidget::paint() function so that we use exactly the same code that we used to display the drawing. The generation process itself begins with the call to the painter's \l{QPainter::}{begin()} function and ends with call to its \l{QPainter::}{end()} function. The QSvgGenerator paint device relies on the explicit use of these functions to ensure that output is written to the file. \section1 Further Reading The \l{SVG Viewer Example} shows how to display SVG drawings in an application, and can be used to show the contents of SVG files created by this example. See the QtSvg module documentation for more information about SVG and Qt's SVG classes. */