[xep-support] Re: Issue with change bars and external graphics

On 03/21/2012 11:22 AM, Patricia Piolon wrote:
> With the following fo I get a change bar in pdf that is only 1 line
> high, even though the graphic is much higher. Is this normal behaviour?

Hi Patricia,

I believe this is normal. Imagine you had just one short word changed
and surrounded with change-bar-begin and change-bar-end, in the middle
of the line. When rendered, both virtual points for the Begin and the
End are on the same position vertically - at the baseline of that word.
So, you see 1 line tall change bar actually because XEP has special
treatment for this case: as if the Start was at baseline plus
font-size*1.2 (iirc).

Now, if you consider a tall image instead of that word - nothing
changes, the bar is still just 1 line-height tall, and it does not mark
the whole image (which is an inline-mode element, like fo:character).

> I know I can fix it by wrapping the graphic in a block and
> starting/ending the change bars before/after the block, but then it's
> possible for the block to start on page 1 while the graphic gets pushed
> to page 2 due to lack of space, resulting in a change bar on 'empty
> space' on page 1 as well as the graphic itself on page 2. This is highly
> undesirable.

I understand your intention. Apparently, you assume that a matched pair
of change-bar-begin and change-bar-end atomic elements tends to shrink
in order to produce a change bar as short as possible, marking all
that's between. But actually this is not the case. Change bar points are
completely transparent for the core algorithms.

To get the desired layout, indeed, you would need to wrap the graphics
in a block, surround with the change-bar points, and place altogether in
yet another block or a block-container with
keep-together.within-column="always". This is likely to prevent bars on
empty space near page break.

Regards,
Mike

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Received on Wed Mar 21 17:24:15 2012