On Fri, May 12, 2006 at 03:10:32PM +0200, Jean-Marc Lasgouttes wrote: > >>>>> "Georg" == Georg Baum <[EMAIL PROTECTED]> writes: > > Georg> Can anybody give me a hint please what goes wrong here: > Georg> http://bugzilla.lyx.org/show_bug.cgi?id=2587 ? I guess this is > Georg> DEPM playing tricks, but unfortunately I don't have any clue > Georg> how it works. This bug is really annyoing if you work with > Georg> keepempty layouts. > > I looked at this and there are several problems. I am not sure how to > handle them > > Let's look at LyXText::erase (text.C) first.
...
> So, it can be changed to be a very simple wrapper around backspace.
> This is what the patch cleanuperase.diff does. With this patch , erase
> looks like:
>
> bool LyXText::erase(LCursor & cur)
> {
> BOOST_ASSERT(this == cur.text());
>
> if (cur.pos() != cur.lastpos()) {
> // move right, avoiding dEPM
> setCursorIntern(cur, cur.pit(), cur.pos() + 1, false,
> cur.boundary());
> } else if (cur.pit() != cur.lastpit()) {
> // move to next paragraph, avoiding dEPM
> setCursorIntern(cur, cur.pit() + 1, 0, false, false);
> } else {
> // nothing to do
> return false;
> }
>
> // Delegate the real work to backspace.
> bool needsUpdate = backspace(cur);
>
> // if in CT mode, go one step to the right
> if (cur.buffer().params().tracking_changes &&
> cur.paragraph().lookupChange(cur.pos()) == Change::DELETED)
> cur.posRight();
>
> return needsUpdate;
> }
>
> I think it is very simple and correct. Comments? Did I get the CT part
> correctly?
I believe so, yes. This looks very clean.
> However, while we have removed an extra test for different layout, we
> are not done since the real problem is in backspacePos0 :( [since we
> are at the beginning of a paragraph, this is the function that
> triggers]
>
> A simple case, without any KeepEmpty paragraph, looks like
> [section] foo foo foo
> [subsection] |<------------ cursor is here
> [subsubsection] bar bar bar
> We have 3 different layouts and one of the paragraphs is empty.
>
> So how does backspace work?
>
> 1/ if paragraph is empty, it tries to just move the cursor and hope
> dEPM will trigger and remove the paragraph. This is nasty and does not
> work with KeepEmpty paragraphs.
>
> This is what you see if you are in second paragraph and hit backspace.
> Note that it does not work if the default layout is KeepEmpty (like in
> this bug). So, the example of the bug, backspace does not work on
> second paragraph, while it works in second paragraph of example above.
>
> This code using dEPM should be replaced by a plain removal of the
> paragraph where cursor is. Question is: how do I do that in a way that
> is correct wrt CT (Michael? Martin?)
This is not simple... is it correct to assume that (in case of the bug
manifesting itself) this paragraph is always empty? In that case you can
just do the following:
1) if CT off: just remove the paragraph from the paragraph list
2) if CT on: mark the position at the end of the paragraph (lastpos, i.e.,
the "carriage return", as Change::DELETED.
3) (reposition cursor as appropriate)
It's only a few weeks ago, but I have already forgotten the gory details
:-(
> 2/ if paragraph is not empty (which is the case if you pressed delete
> while in paragraph 2, because cursor is in paragraph 3 and you do
> delete (lost yet?)), then it tests whether the two paragraphs have
> same layout and does a mergeParagraph. This does not work because the
> layouts are different. Even if we tested for this case, the result
> would be to give to paragraph 3 the layout subsection (this is how
> mergeParagraph work).
But this is not the situation of the bug, is it?
> So I need to know what is the clean code to erase a single paragraph,
> do the right undo stuff (what is Undo::DELETE exactly?) and do the
> right CT stuff. Could someone give me pointers here? Should I use
> eraseSelectionHelper, so that all the logic is in the same place? Or
> is there another function that is better adapted?
>
> Please help, I am lost.
I won't add to your confusiun here.
- Martin
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