Challenge rendering SVGs with links to images binary images

[pboz]

When trying to render a set of content containing an SVG with a link to another image inside the SVG using html5 (or any other transtype), the DITA OT fails with the following error:

patrickbosek@mac dita-ot-4.4 % rm -r out;dita -i ../issue-reproductions/svg_issue/parent-map.ditamap -f pdf Error: Build failed with an exception: The following error occurred while executing this line: /Users/patrickbosek/dev/DITA/dita-ot-4.4/plugins/org.dita.base/build_preprocess2.xml:197: java.lang.NullPointerException: Cannot invoke "java.net.URI.toString()" because the return value of "org.dita.dost.writer.DitaWriterFilter.replaceHREF(String, org.xml.sax.Attributes)" is null

The content will render if the <svg:image .. > tag is deleted. I'm not sure if the issue is with the way I've structured the svg:image tag or it's an issue in the OT. Can someone help me out here?

Attached is the full test content (3 files):
svg_issue.zip

Here is the troublesome SVG XML:

`

        <svg-container class="+ topic/foreign svg-d/svg-container ">
            <svg:svg xmlns:svg="http://www.w3.org/2000/svg" height="50"
                id="svgcontent" overflow="visible" viewBox="0 0 655 50" width="655"
                x="655" y="266.70000000000005">
                <svg:g style="pointer-events:all">
                    <svg:title style="pointer-events:inherit">Layer 1
                    </svg:title>
                    <svg:image xmlns:xlink="http://www.w3.org/1999/xlink"
                        height="120" id="svg_55d1a77d-1aaa-41a9-86cc-32e33f0c4272"
                        width="655" x="1" xlink:actuate="onLoad" xlink:show="embed"
                        xlink:type="simple" y="-27"
                        xlink:href="./search-results-scroll-to-view-more.png" />
                    <svg:rect fill="none" fill-opacity="1"
                        height="16.999999627471038" id="svg_2" rx="5" ry="5"
                        stroke="#142FB2" stroke-opacity="1" stroke-width="2"
                        width="74.99999888241291" x="522.1000190809366"
                        y="45.412482353138515" />
                </svg:g>
            </svg:svg>
        </svg-container>

`

[pboz]

Update! I think I figured out the root cause of this issue. When the DITA OT resolves dependencies it doesn't consider xlink:href attributes inside SVGs, so the image that is embedded in the SVG is never copied to the processing folder (or something like that).

I believe the fix here is for the DITA OT reference resolver to look for xlink:href and include media dependencies referenced in this way.