Hello all,
I recently made an attempt at implementing Unicode TR14
as well as proper linefeed-treatment, wrap, overflow
and whitespace-treatment.
Here are a few musing which arose during this:
<fo:block>&sp;</fo:block>
Common assuption: the line and therefore the whole block does not generate
an area, or only an area with a BPD=0.
There are several possibilities to arrive at this conclusion:
1. The space is discarded. This is not supported by white-space-treatment
nor white-space-collapse nor suppress-at-line-break. In either case, this
leaves the quistion open whether formally a line area with line-height=0
and IPD=0 is generated or no line area is generated at all.
2. The space is kept but is assumed to have zero height. Obviously, formally
a line area with a space glyph has to be generated.
<fo:block font-size="12pt" line-stacking-strategy="font-height"
background-color="red">&sp;</fo:block>
Same as above, only in case the space is not discarded, a zero BPD cannot
be easily justified.
<fo:block>&sp;&lf;</fo:block>
The space is ignored (default white-space-treatment), then the LF is changed
into a space (default linefeed-treatment), and we have the same situation as
above.
<fo:block white-space-treatment="ignore-if-after-linefeed">&sp;&lf;</fo:block>
The space is kept, then the LF is changed into a space, and default
white-space-collapse drops the space turned LF, and we have the situation as
above.
<fo:block white-space-treatment="ignore-if-after-linefeed"
>&lf;&sp;&lf;</fo:block>
More fun: is the space discarded? I think so: we should get two space
turned LFs, which are collapsed into one space.
<fo:block white-space-treatment="preserve">&lf;<fo:wrapper
white-space-treatment="ignore-if-after-linefeed">&sp;</fo:wrapper
></fo:block>
Is the space discarded? (I still think so)
<fo:block white-space-treatment="ignore-if-before-linefeed">&sp;<fo:wrapper
white-space-treatment="preserve">&sp;</fo:wrapper>&lf;</fo:block>
This is real fun: the second space is preserved and then collapsed to the
first. Is the first space now discarded, as it now precedes the linefeed?
I don't think so, collapsing is done after white space treatment.
<fo:block white-space-treatment="ignore-if-after-linefeed"
linefeed-treatment="ignore">a&lf;&sp;b</fo:block>
Both the linefeed and the space are dropped. Is there still a break
opportunity between the two characters?
<fo:block>&sp;<fo:wrapper text-decoration="underline">&sp;</fo:wrapper
></fo:block>
Is the first space kept? It probably should.
<fo:block>&sp;<fo:wrapper text-decoration="underline">a</fo:wrapper
></fo:block>
Is the first space kept? Common stance seems to be that it is discarded,
but we have essentially the same situation as above.
<fo:block text-decoration="underline">&sp;a</fo:block>
Is the space kept?
<fo:block text-decoration="underline">&sp;</fo:block>
Do we get a standard boring line with an underlined space?
<fo:block>&sp;<fo:wrapper text-decoration="underline"
linefeed-treatment="preserve">&lf;</fo:wrapper></fo:block>
Is there something underlined in this case? Actually, what *is* the glyph
of a LF? The spec mentions that a LF generates an area, thoug details
are sadly lacking.
<fo:block>&sp;<fo:wrapper white-space-collapse="false">&sp;&sp;</fo:wrapper
>a</fo:block>
Is the first space kept? (actually, the second)
<fo:block white-space-collapse="false">&sp;<fo:wrapper
white-space-collapse="true">&sp;&sp;</fo:wrapper>a</fo:block>
How many spaces do we get? One or two?
<fo:block width="1em" white-space-collapse="false">m&sp;&sp;&sp;</fo:block>
Do we get an overflow or an automatic line break? Spaces are automatically
discarded at line breaks (before and after), therefore if there is a line
break, the spaces disappear, and so does the need for a line break...
<fo:block width="1em" white-space-collapse="false">a&sp;&sp;&sp;<fo:character
character="&sp;" suppress-at-line-break="false"/></fo:block>
Does the space in the fo:character cause the other spaces not to be
discarded? Or is the line break before the first space, and the following two
are discarded because of default suppress-at-line-break?
<fo:block width="1em" white-space-collapse="false">a<fo:character
character="&lf;" suppress-at-line-break="false"/></fo:block>
Where does the space turned LF go, a then end of the first line or at the
beginning of the second line?
Comments?
J.Pietschmann
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