wrong length of edit line width

[octaeder]

Environment

• TeXstudio: 4.8.5beta1 latest local msys2 build (without last 3 commits regarding hidden files)
• Qt: latest msys2 (mingw-w64-ucrt-x86_64-qt6-base 6.8.0-2)
• OS: Windows(10)
• TeX distribution: miktex

Expected behavior

Using Idefix>Hard Line Break... from main menu should use whole line.

Actual behavior

In the upper half of the image you see a before-after-demo for txs 4.8.2 installed (same results up to alpha1 portable, beta1 port. not testable), while the lower half is from 4.8.5beta1 (local msys2 build, s. above). The latex code (given at the end) is pasted from the clipboard into a new editor.

As you can see, after applying Hard Line Breaks the text still uses the full line width in the first case. In the second case enough space for the next word remains at the end of the line after applying the function (and line seems to be longer). It may be important to test beta1 because Qt 6.8.0 (not 6.8.0-2) is used there.

How to reproduce

Editor Setup

Font Family: JetBrains Mono
Font Size: 9
Line Spacing: 100%

Adv. Editor Setup

Line Wrapping: Soft Line Wrap after max. Characters
Maximal Characters: 160

Hard Line Break...

... so many characters: 160
Smart scope selecting: checked
Join lines before wrapping: checked

latex code

```latex \documentclass[10pt,a5paper]{article} \begin{document} Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, \end{document} ```

[sunderme]

looks like a rounding issue.
As it is rather cosmetic and I really don't like to hard line wrap, a leave it for someone else to igre out.

[octaeder]

also with Qt6.8.2

[octaeder]

It seems that Qt now has a problem with calculating the average character width in QEditor::setWrapAfterNumChars with some fonts (including Lucida Console):

qreal w=QFontMetricsF(QDocument::font()).averageCharWidth()*(m_wrapAfterNumChars+0.5) + 5;

The average width value is 7.1875 (JetBrains Mono, size 9). So a line with 160 characters should have a width of 160.5*7.1875+5=1158. Compared to txs 4.8.4 the line is 29px longer. This is 29px/160.5=0,1807px per character. Thus the average width per character should be 7.0068. I changed drawing of the line at the right end. The x value of the lower end is 29 less than the x value of the upper end:

There is plenty of space for characters at the end. But the line breaking tools calculate with the max. number of characaters, i.e. 160. The s in dolores is exactly the 160th character of the line. The tools do not know about the extra space available.

[octaeder]

Consolas is a font where average character width is underestimated such that line width is too small:

(Edit): But not with txs 4.8.4 release (WWin10):

[octaeder]

@sunderme I reworked the issue description. No more Hard line wrapping here.