Add support for TracLinks in Mermaid flow chart diagrams

[Christian Boos]

It seems this is the only type of diagram which supports adding links, in mermaid.

The patch will be on top of the patch from #13039.

In this patch, I also add a link to mermaid.css. You can obtain it from ​https://github.com/knsv/mermaid/raw/master/dist/mermaid.css and copy it below tracmermaid/htdocs.

[Christian Boos]

incremental patch, on top of patch 002 in #13039 (003 was the upgrade to mermaid 6.0.0, too big and not interesting as a patch)

[tkob-trac]

Thank you for the enhancement patch. I would like to see how this works. Could you show me some working Mermaid text?

[Christian Boos]

Ah, well, it's in the patch ;-)

82	            # TracLinks link (transformed to native):
83	            #   click A trac TracLinks
84	            #   click A trac r123
85	            #   click A trac [123]
86	            #   click A trac [[TracLinks|Anything that can be parsed as a link]]

i.e. I hijacked the "​click" syntax from mermaid. If the click callback is named "trac", we transform the click parameters to take the resulting url.

Full example:

{{{#!Mermaid
%% Subgraph example
graph TB

    subgraph one
        a1(This is the text in the box)-->|label 1|a2
    end

    subgraph two
        b1((B1))-->b2((B2))
    end

    subgraph three
        c1>C1]-->c2{C2}
        subgraph four
            d4-->d5
            d4-->d4
        end
    end

    c1-.->d5
    b1-->a2
    a1==>b2


    click a1 callback "Tooltip for a callback"
    click b2 trac [[TracMermaid|This is a tooltip for a (Trac) link]]
}}}

The "B2" node would link to the TracMermaid page.

[Christian Boos]

Note that besides adding the mermaid.css from 6.0.0 as I suggested above, you could also upgrade mermaid.min.js itself to 6.0.0. It works fine for me.

[tkob-trac]

OK, I have been puzzled by its behavior, but finally understand that the click syntax is relatively new feature of mermaid and upgrade to 0.5.2+ is prerequisite anyway. I will apply this.

[tkob-trac]

In 16178:

Add support for TracLinks in Mermaid flow chart diagrams

An enhancement patch by cboos, closes #13042

This commit also upgrade mermaid.js to 6.0.0.