New: Flag to control xlink prefix on href #2080
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After some extensive testing it seems that some browsers, in some cases, will not display SVG if the `href` attribute is prefixed with `xlink`, a change that was introduced with SVG 2.0. This is not yet a recognized specification, but the changes in browsers are being enacted nevertheless. On the other hand, some strict SVG 1.1 clients will not render the SVG correctly if it *doesn't* include the `xlink:` prefix. In my testing this included Inkscape. Given that the most likely target for Verovio output is browsers, but still wishing to retain backwards compatibility, this PR changes the default behaviour from producing `xlink:href` to simply `href`. Clients that need the full attribute name can set `--svg-include-xlink` which will insert the xlink prefix on the href attributes. References previous discussions on this topic: #1158, #332
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I've tested it and it seems to work as expected; including or removing Easiest way to test it is to You can control the xlink behaviour by commenting / uncommenting the appropriate option in the test.html source. (It should be obvious). |
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Does it has to be independent from option |
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Laurent and I had a quick discussion about this, and decided that, since 1) SVG2 isn't official yet, but 2) browsers have started to implement it in piecemeal, that it's better to address the specific problem directly, rather than try to do a full SVG2 update. (Not to mention that there's not really a SVG 2 validator out there yet...) |
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For reference, the full issue report is here: elm/svg#31 The issue is that browsers only support |
To retain support for SVG 1.1 by default, the xlink flag is now used to control whether the namespace prefix is removed, rather than added.
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OK, after talking it over a bit more with @lpugin we decided to flip the behaviour of the flag; the old behaviour is now the default, and the new behaviour is enabled with a flag. |
| std::string hrefAttrib = "href"; | ||
| if (m_includeXlink) { | ||
| if (!m_removeXlink) { |
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FYI, I did it this way to avoid needing to strip characters off the string, and instead prepending to the string by default. This avoids needing to make a new copy of the string, or doing any index-based counting to remove the prefix.
After some extensive testing it seems that some browsers, in some cases, will not display SVG if the
hrefattribute is prefixed withxlink, a change that was introduced with SVG 2.0. This is not yet a recognized specification, but the changes in browsers are being enacted nevertheless.On the other hand, some strict SVG 1.1 clients will not render the SVG correctly if it doesn't include the
xlink:prefix. In my testing this included Inkscape.Given that the most likely target for Verovio output is browsers, but still wishing to retain backwards compatibility, this PR changes the default behaviour from producing
xlink:hrefto simplyhref. Clients that need the full attribute name can set--svg-include-xlinkwhich will insert the xlink prefix on the href attributes.References previous discussions on this topic: #1158, #332