代码编辑器实现缺少 Qt 的 QFontMetrics::horizo​​ntalAdvance()

Question

I'm implementing a code editor for a simple scripting language and have been using the Qt Code Editor Example (http://doc.qt.io/qt-5/qtwidgets-widgets-codeeditor-example.html ) as a guide for implementing a QPlainTextEdit with line numbers. The example uses the base widget's fontMetrics() method 'horizontalAdvance' to query the width (or better the advance) of a single character.

The method QFontMetrics::horizontalAdvance(QChar) (see http://doc.qt.io/qt-5/qfontmetrics.html#horizontalAdvance-1 ) can be found in the Qt documentation but my implementation seems to be missing this method .

I am using Qt 5.10.1 'msvc2017_64' on Windows 10 with Visual Studio Enterprise 2017 Version 15.7.3. I have searched the headers for the missing method, but only found QTextLine::horizontalAdvance() which is not what I need.

I have replaced the QFontMetrics::horizontalAdvance(QChar) call with a call to QFontMetrics::width(QChar) which is working with my current font (Consolas) but I am not sure if its ok for every possible font.

Question 1) Has QFontMetrics::horizontalAdvance() been removed from current version of Qt, is my installation buggy or have I missed something?

Question 2) What is the correct way of getting the advance for a specific (non propotional) font?

Thank you for reading this and trying to help!

Answer 1

As GM told me in a comment:

The documentation states that QFontMetrics::horizontalAdvance(QChar) wasn't available until Qt5.11 .

So switching to Qt 5.11 fixes this problem.

Answer 2

You might use width instead of horizontalAdvance .

The member function width is listed in Obsolete Members for QFontMetrics and it suggests to use horizontalAdvance instead of width . I guess these two member functions have a similar behaviour.