Escape tabs in HTML preview of files

[jyrki@…]

Displaying files where leading (or trailing) white-space matters is broken with the current development version. For example viewing Makefiles is broken because of this.

Adding "white-space: pre;" line to code.css's "table.code-block tbody td" block fixes the problem.

I'm currently using enscript for code highlighting. I'm not sure if the problem exists with silvercity.

[cmlenz]

The spaces should be replaced by non-breaking spaces. The problem with white-space: pre is that it completely disables line-breaks. If white-space: pre-wrap were better supported, we'd use that. Unfortunately, it isn't.

Can you please paste a snippet of the generated HTML? Maybe it's the tabs that are messing up the display?

[cboos]

On a related note, when no highlighter is used, the display of C/C++ files containing tabs is indeed messed up (a tab should be replaced by the appropriate number of &nbsp;<space> pairs).

[jyrki@…]

Here's the output from enscript, leading tab characters in the rm lines

<B><FONT COLOR="#A020F0">clean-state:</FONT></B>
	-rm -f $(<B><FONT COLOR="#5F9EA0">STATEDIR</FONT></B>)/*

<B><FONT COLOR="#A020F0">clean-state-%:</FONT></B>
	-rm -f $(<B><FONT COLOR="#5F9EA0">STATEDIR</FONT></B>)/$*

And here's the Trac's output, also has tab characters in front of "-rm -f ..."

<tr><th id="l75">75</th>
<td>	-rm -f $(<B><span class="code-keyword">STATEDIR</span></B>)/*</td>
</tr><tr><th id="l76">76</th>
<td></td>
</tr><tr><th id="l77">77</th>

<td><B><span class="code-lang">clean-state-%:</span></B></td>
</tr><tr><th id="l78">78</th>
<td>	-rm -f $(<B><span class="code-keyword">STATEDIR</span></B>)/$*</td>
</tr><tr>

Now that I think of it, it is true that "white-space: pre;" doesn't allow line wrapping. But replacing every tab character with a static amount of (non-breaking) spaces isn't the right solution either.

[cmlenz]

But replacing every tab character with a static amount of (non-breaking) spaces isn't the right solution either.

Why? Or, what would be the right solution?

[jyrki@…]

IMHO, it's better to let the long lines be long. An overkill solution would be to calculate the right amount of spaces to insert. For example in the following expand tabs to 5 and 4 spaces

foo\tbar
xyzz\tasdf

foo     bar
xyzz    asdf

And well, there is a way to do it in CSS, but it's a butt ugly solution too. Check the first code block of this blog entry (has some other good points of CSS's white-space stuff too).

[cmlenz]

Python has a string.expandtabs() function built right in, so it's not overkill to implement properly.

[jyrki@…]

Oh, I'm impressed. Well that's the cleanest solution then.

[cmlenz]

Actually, tabs were already being replaced with spaces, but the number of spaces were not configurable.

[1944] adds this configurability. In trac.ini, you can say:

[mimeviewer]
tab_width = 4

to configure a displayed tab width of 4.

Anyway, I'm not sure whether this fixes the issue raised in this ticket, as I had suspected that tabs were not getting escaped, when in fact they were. Reopen if you're still seeing a problem here.