[TW5] Render WikiText into attribute strings?

Evan Balster

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Sep 12, 2015, 12:52:24 PM9/12/15

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Use Case:

Suppose within my TiddlyWiki I'm rendering an infographic as SVG. The SVG contains a path, which is defined by a string containing a list of vertices. Suppose further I want to use an operation with at least one <$list> widget to populate this path, as below. Because the path is an attribute string, any transclusion into it will not be wikified. I can paste transclusions together using macros, but that isn't practical for lists. So is there a way to force wikification?

Obviously any HTML would be undesirable in the output, so I would need to be able to use a render mode like the one which applies in this typed block:

$$$text/vnd.tiddlywiki>text/plain

<$list filter="[tag[Vertex]first[]]">M {{!!x}} {{!!y}}

</$list>

<$list filter="[tag[Vertex]rest[]]">L {{!!x}} {{!!y}}

</$list>

$$$

(I ran into this problem a few months ago while creating a graphical timeline generator and never managed to solve it. I know this is possible, because TiddlyWiki does something very similar to support customized stylesheets with basic parsing rules -- but I've investigated how it's done, and the mechanism uses calls to the rendering engine in core code rather than any accessible macro. The discussion I started at that time did not lead anywhere.)

As far as I can tell, all that would be necessary would be a macro to the effect of:

<<parse_and_render {{MySVGCode}} text/vnd.tiddlywiki>text/plain>>

Which makes the appropriate calls into core code. Would this be reasonable to request as a core feature? If not, is there a plug-in?

(I anticipate someone will mention that this is possible by way of storing data to a temporary tiddler and then transcluding it. If so, I would love to know how -- but I also point out that such is a significant deviation from TiddlyWiki's "normal" way of rendering things and makes unnecessary use of long-term storage. I'd also rather avoid "refresh" trigger buttons.)

Evan Balster

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Sep 12, 2015, 1:21:33 PM9/12/15

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I noticed another ongoing thread where the user in question was expecting to be able to render wikitext into an attribute: Read here.

He is trying to generate a filter expression using <$list> widgets, presumably to cull duplicated items in a recursive search. His calling code is thus:

<$set name="myList" value=<<listDescendants "NameOfConceptTiddler">> >
<$list filter=<<myList>> />
</$set>

(where <<myList>> is a recursive macro involving <$list>.)

I suspect this isn't an entirely uncommon sticking point.

Mark S.

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Sep 15, 2015, 1:31:02 PM9/15/15

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I'm not real up-to-date on SVG. Could you explain a little what you're trying to do in your example? I would think that you were trying to draw an SVG figure, except that it looks like you want to render it as text. I think what's wanted is a way to accumulate the output of a <$list> widget so that it can then be subsequently used inside of something else (like SVG code). What is in X and Y that you want wikified? Wouldn't they just be numbers, or are X and Y wrapped in some type of SVG formatting?

Thanks,
Mark

Evan Balster

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Sep 15, 2015, 4:02:51 PM9/15/15

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I would want to render, at minimum, widgets, into a plaintext format for use in SVG tag attributes. Specifically, the d (data) attribute of the <path> tag.

As far as I know, there is no direct means to achieve this. Apparently the developers have discussed it extensively, but implementation is complicated by use-cases involving automatic refresh and use of this functionality to generate widget attributes.

BJ

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Sep 15, 2015, 4:32:26 PM9/15/15

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HI Evan,
it is possible to do this with one of my plugins
http://bjtools.tiddlyspot.com/#Flexitype Demo

However I think that using the $list widget it is going to be hard to give the correct order of your x,y coordinates (how to list the tiddlers in the correct order?)

cheers bj

Mark S.

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Sep 15, 2015, 4:50:22 PM9/15/15

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Just to be clear, you want text that you can cut and paste into your svg editor? Or are you hoping to render right there into SVG (in which case I don't understand why you want to see the plain text).

About BJ's comment ... you probably would need to add a field that orders the points. I imagine you left that out to keep things simple.

Mark

BJ

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Sep 15, 2015, 5:19:40 PM9/15/15

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This is one of the things that I need to do as well. I think that it would be better to put the data in to json tiddlers - they can contain ordered lists (arrays), and then have some widgets like the ractive.js templates (see http://mlarocca.github.io/01-22-2014/pathsjs_ractive.html for an example) that can handle json tiddlers.

Evan Balster

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Sep 15, 2015, 5:34:29 PM9/15/15

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My actual scheme for rendering the SVG path is a bit more complicated -- my example code is meant to be as simple as possible for purposes of explaining the problem. (I'm making a timeline display system for a story wiki.)

I'll look into the FlexiType tool; it looks like it could be well-suited to this use-case. (Re-parsing is an interesting way to solve the problem! How well does it deal with automatic updates?)

Evan Balster

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Sep 15, 2015, 5:41:34 PM9/15/15

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BJ: I should note that while FlexiType looks like what I need, your example shows a case where standard TiddlyWiki functionality actually works! Try the code below in your wiki:

<defs>

</defs>

<use xlink:href="#MyPath" fill="none" stroke="#ddd"/>plain

====To The Top=====on the bottom=======================

</textPath>

</text>

</svg>

It's quite possible to transclude into attributes with TW5 -- it's just that such transclusions are never wikified.

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