XSL-FO fo:repeatable-page-master-alternatives not working properly

问题

I want to add the page number in footer if the number of pages is more than one, but not for if there is only one page.

I tried the following code but it shows the page number in all cases :

<fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format">
        <fo:layout-master-set>
            <fo:simple-page-master master-name="singlePage" page-height="800pt" page-width="612pt" margin-top="0pt" margin-bottom="46pt" margin-left="26pt" margin-right="26pt">
                <fo:region-body margin-top="110pt" margin-bottom="65pt" />
                <fo:region-before extent="72pt" />
                <fo:region-after region-name="xsl-region-after-single" extent="75pt" />
            </fo:simple-page-master>

            <fo:simple-page-master master-name="multiPage" page-height="800pt" page-width="612pt" margin-top="0pt" margin-bottom="46pt" margin-left="26pt" margin-right="26pt">
                <fo:region-body margin-top="110pt" margin-bottom="65pt" />
                <fo:region-before extent="72pt" />
                <fo:region-after region-name="xsl-region-after-multi" extent="75pt" />
            </fo:simple-page-master>

            <fo:page-sequence-master master-name="allPages">
                <fo:repeatable-page-master-alternatives>
                   <fo:conditional-page-master-reference page-position="any" master-reference="multiPage"/>
                   <fo:conditional-page-master-reference page-position="only" master-reference="singlePage"/>
                </fo:repeatable-page-master-alternatives>
            </fo:page-sequence-master>
        </fo:layout-master-set>

        <fo:page-sequence master-reference="allPages">
            <fo:static-content flow-name="xsl-region-before">
                <fo:block>content</fo:block>
            </fo:static-content>
            <fo:static-content flow-name="xsl-region-after-single">
                <fo:block>content</fo:block>
            </fo:static-content>
            <fo:static-content flow-name="xsl-region-after-multi">
                    <fo:block>content</fo:block>
                    <fo:block text-align="right">
                        <fo:inline><fo:page-number font-weight="normal"/>/<fo:page-number-citation ref-id = "lastPage"/></fo:inline>
                    </fo:block>
            </fo:static-content>
            <fo:flow flow-name="xsl-region-body" font-size="12pt" line-height="11pt">
                <fo:block>content</fo:block>
                <fo:block id = "lastPage"/>
            </fo:flow>
        </fo:page-sequence>
    </fo:root>

If I change the order of alternatives, then page number is never shown:

<fo:page-sequence-master master-name="allPages">
    <fo:repeatable-page-master-alternatives>
        <fo:conditional-page-master-reference page-position="only" master-reference="singlePage"/>
        <fo:conditional-page-master-reference page-position="any" master-reference="multiPage"/>
    </fo:repeatable-page-master-alternatives>
</fo:page-sequence-master>

I'm using FOP 2.0

Thanks for your answers.

回答1:

Your second alternative works for me with both FOP 2.0 and FOP 2.2:

<fo:page-sequence-master master-name="allPages">
    <fo:repeatable-page-master-alternatives>
        <fo:conditional-page-master-reference page-position="only" master-reference="singlePage"/>
        <fo:conditional-page-master-reference page-position="any" master-reference="multiPage"/>
    </fo:repeatable-page-master-alternatives>
</fo:page-sequence-master>

Did you try it with enough content to make a second page? E.g., add <fo:block break-before="page">content</fo:block> to force a second page.

If you change the 'content' text in your fo:static-content for the fo:region-after then you'll get a better idea of which fo:conditional-page-master-reference is being used; e.g.:

<fo:static-content flow-name="xsl-region-after-single">
   <fo:block>after single</fo:block>
</fo:static-content>

The way that fo:conditional-page-master-reference (https://www.w3.org/TR/xsl11/#fo_conditional-page-master-reference) works is that it is selected if it is the first alternative for which all of its sub-conditions are true. If there is enough content to make a second page, then the page-position="only" sub-condition is no longer true, so the formatter should try again with other alternatives.

The formatter should try again because if it doesn't, then the fo:repeatable-page-master-alternatives (https://www.w3.org/TR/xsl11/#fo_repeatable-page-master-alternatives) doesn't satisfy its constraints (my emphasis):

The sub-sequence of pages mapped to this sub-sequence-specifier satisfies the constraints of this sub-sequence-specifier if (a) the sub-sequence of pages consists of zero or more pages, (b) each page is generated using the fo:simple-page-master referenced by the one of the alternatives that are the children of the fo:repeatable-page-master-alternatives, (c) the conditions on that alternative are true, (d) that alternative is the first alternative in the sequence of children for which all the conditions are true, and (e) the length of the sub-sequence is less than or equal to the value of 'maximum-repeats'.

来源：https://stackoverflow.com/questions/53193217/xsl-fo-forepeatable-page-master-alternatives-not-working-properly