protect some text in a QTextEdit

[GrahamLabdon]

Hi
Is there a way of making some text within a QTextEdit non editable?
I want to insert some text programatically but prevent the user from editing this text.

thanks

[wysota]

I think you'd need to implement your own QTextObject subclass.

[GrahamLabdon]

Thanks for the hint
How would I make my QTextObject read only?

[wysota]

You can start by reading the docs, especially the Text Object Example.

[GrahamLabdon]

Hi
OK, I have read the relevant docs and started to implement my own text object for inserting a string.
I can now get this displayed, but am struggling with how to correctly implement the 'intrinsicSize' method.

inside this method I can obtain the string to be inserted and then i tried to calculate the size required to display it

QString str = qVariantValue<QString>(format.property(Window::ProtectedTextData));
    QTextBlock block = doc->findBlock(posInDocument);
    QTextCharFormat fmt = block.charFormat();
 
    qreal pointSize = fmt.fontPointSize();
    size.setHeight(pointSize);
    size.setWidth(pointSize*str.length());

QString str = qVariantValue<QString>(format.property(Window::ProtectedTextData));
    QTextBlock block = doc->findBlock(posInDocument);
    QTextCharFormat fmt = block.charFormat();

    qreal pointSize = fmt.fontPointSize();
    size.setHeight(pointSize);
    size.setWidth(pointSize*str.length());

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but he size is always 0.
I would appreciate any hint as to how to correctly implement this

Thanks

[wysota]

QFontMetrics::boundingRect()

[GrahamLabdon]

Hi
Thanks for the help

Inside the 'intrinsicSize' method I retrive the font by -

QTextBlock block = doc->findBlock(posInDocument);
    QTextCharFormat fmt = block.charFormat();
    QFont font = fmt.font();
    QFontMetrics fm(font);
    QRect rect = fm.boundingRect(str);

QTextBlock block = doc->findBlock(posInDocument);
    QTextCharFormat fmt = block.charFormat();
    QFont font = fmt.font();
    QFontMetrics fm(font);
    QRect rect = fm.boundingRect(str);

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But this always returns the same thing, I want the font being used in the document at the point that I insert the text.
Why does my code not work?

Thanks

[wysota]

This returns the text format of the whole block. If you want the format for your item, use QTextObject::format() and convert it to the proper type. You can also use QTextCursor::charFormat().

[GrahamLabdon]

Hi
Within the intrinsicSize method I cannot get on object of type QTextObject or QTextCursor.

QTextObject *textObject = doc->objectForFormat(format);

QTextObject *textObject = doc->objectForFormat(format);

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returns a null pointer.
QTextCursor belongs to the QTextEdit class which does not seem to be available in this method

Am I missing something?

Graham

[wysota]

QTextCursor doesn't belong to QTextEdit class. You can have as many cursors as you want, have a look at available constructors. And I have no idea what your objectForFormat() call was supposed to do. You are implementing QTextObject subclass so just calling format() will return a QTextFormat which you can then convert to another type using the API available in QTextFormat.

[GrahamLabdon]

OK now I am confused
You say I am implementing a QTextObject subclass, but I am just following the TextObject example that implements
QTextObjectInterface.
Where should I be creating a QTextObject ?

Thanks

[wysota]

True. However you get a QTextFormat as the argument to intrinsicSize(), haven't you noticed?

[GrahamLabdon]

I have made some progress with he following implementation

QSizeF SvgTextObject::intrinsicSize(QTextDocument * doc, int posInDocument,
                                    const QTextFormat &format)
{
    QSize size;
 
    QString str = qVariantValue<QString>(format.property(Window::SvgData));
 
    QTextCursor cursor(doc);
    QTextCharFormat fmt = cursor.charFormat();
 
    QFont font = fmt.font();
    QFontMetrics fm(font);
    QRect rect = fm.boundingRect(str);
 
    size.setHeight(rect.height());
    size.setWidth(rect.width());
    return QSizeF(size);
}

QSizeF SvgTextObject::intrinsicSize(QTextDocument * doc, int posInDocument,
                                    const QTextFormat &format)
{
    QSize size;
    
    QString str = qVariantValue<QString>(format.property(Window::SvgData));

    QTextCursor cursor(doc);
    QTextCharFormat fmt = cursor.charFormat();

    QFont font = fmt.font();
    QFontMetrics fm(font);
    QRect rect = fm.boundingRect(str);

    size.setHeight(rect.height());
    size.setWidth(rect.width());
    return QSizeF(size);
}

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void SvgTextObject::drawObject(QPainter *painter, const QRectF &rect,
                               QTextDocument * /*doc*/, int /*posInDocument*/,
                               const QTextFormat &format)
{
    const QString str = qVariantValue<QString>(format.property(Window::SvgData));
    QTextCursor cursor(doc);
    QTextCharFormat fmt = cursor.charFormat();
 
    QFont font = fmt.font();
    painter->setFont(font);
    painter->drawText(rect,str);
}

void SvgTextObject::drawObject(QPainter *painter, const QRectF &rect,
                               QTextDocument * /*doc*/, int /*posInDocument*/,
                               const QTextFormat &format)
{
    const QString str = qVariantValue<QString>(format.property(Window::SvgData));
    QTextCursor cursor(doc);
    QTextCharFormat fmt = cursor.charFormat();

    QFont font = fmt.font();
    painter->setFont(font);
    painter->drawText(rect,str);
}

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Is this the correct way or is there a better way?

Thanks for your help

[wysota]

If it works for you, it is fine with me.

[GrahamLabdon]

Thanks for your assistance
But I'm not sure that its going to help me!
I need to be able to save the document but when I do so the custom object is not saved
Need some more research
Any hints on this

Thanks

[wysota]

How are you "saving" it?

[GrahamLabdon]

I tried converting the contents to html and saving that
I also tried saving as an odt document

[wysota]

HTML doesn't allow any "protected text" so there is no way you are going to succeed. ODT writer only allows simple things, so no joy here too.

[GrahamLabdon]

Is there anything that might work?

[wysota]

You can implement your own writer and your own reader if you need to recreate the text document from a file.