Text Object Example

Window Class Implementation

We will now take a closer look at the functions that are relevant to our text object, starting with the setupTextObject() function.

 void Window::setupTextObject()
 {
     QObject *svgInterface = new SvgTextObject;
     textEdit->document()->documentLayout()->registerHandler(SvgTextFormat, svgInterface);
 }

SvgTextFormat's value is the number of our object type. It is used to identify object types by the document layout.

Note that we only create one SvgTextObject instance; it will be used for all QTextCharFormat's with the SvgTextFormat object type.

Let's move on to the insertTextObject() function:

 void Window::insertTextObject()
 {
     QString fileName = fileNameLineEdit->text();
     QFile file(fileName);
     if (!file.open(QIODevice::ReadOnly)) {
         QMessageBox::warning(this, tr("Error Opening File"),
                              tr("Could not open '%1'").arg(fileName));
     }

     QByteArray svgData = file.readAll();

First, the .svg file is opened and its contents are read into the svgData array.

     QTextCharFormat svgCharFormat;
     svgCharFormat.setObjectType(SvgTextFormat);
     QSvgRenderer renderer(svgData);

     QImage svgBufferImage(renderer.defaultSize(), QImage::Format_ARGB32);
     QPainter painter(&svgBufferImage);
     renderer.render(&painter, svgBufferImage.rect());

     svgCharFormat.setProperty(SvgData, svgBufferImage);

     QTextCursor cursor = textEdit->textCursor();
     cursor.insertText(QString(QChar::ObjectReplacementCharacter), svgCharFormat);
     textEdit->setTextCursor(cursor);
 }

To speed things up, we buffer the SVG image in a QImage. We use setProperty() to store the QImage in the in the QTextCharFormat. We can retrieve it later with property().

We insert the char format in the standard way - using a QTextCursor. Notice that we use the special QChar ObjectReplacementCharacter.