# Result rendering SWISH allows for _rendering_ a Prolog answer in a domain specific way. This can be compared to the Prolog _hook_ portray/1, although it currently only applies to the answer as a whole and *not* recursively on terms embedded in an answer. A renderer is selected using use_rendering/1 or use_rendering/2, for example:
:- use_rendering(table).
The [table renderer](example/render_table.swinb) recognises a table and renders it as an HTML table. Press the _play_ button to run the simple example below.
X = [ [ 'Amsterdam', 'The Netherlands' ], [ 'London', 'United Kingdom' ], [ 'Paris', 'France' ] ].
## Provided renderers The following rendering plugins are currently supported. Please visit the linked notebook for more documentation and examples exploiting these renderers. - General purpose renderers - [table](example/render_table.swinb) renders tables - [svgtree](example/render_svgtree.swinb) renders Prolog terms as trees - [graphviz](example/render_graphviz.swinb) render graphs using [Graphviz](http://www.graphviz.org/). - [c3](example/render_c3.swinb) renders =c3= dicts as charts (line, bar, pie etc.) using [C3.js](http://www.c3js.org) - [codes](example/render_codes.swinb) renders lists of code-points as text. - Domain specific renderers - [bdd](example/render_bdd.swinb) renders CLP(B) residual goals as Binary Decision Diagrams (BDDs) - [chess](example/render_chess.swinb) renders chess positions (currently only N-queen boards). - [sudoku](example/render_sudoku.swinb) renders sudoku puzzles.
## Adding a new render plugin The rendering infrastructure is specialized using a series of _plugins_ provided as Prolog libraries in the directory =lib/render= of the SWISH sources. A render plugin is a _module_ that performs these steps: 1. Registering the renderer using register_renderer/2 2. Define a rule for term_rendering//3, which - Identifies the Prolog term as suitable for the plugin. For example, a _table_ renderer requires a datastructure that can be interpreted as a table. - Define the translation to an HTML fragment using library(http/html_write). The HTML fragment can include _style_ and (JavaScript) scripts. ### Embedded JavaScript Embedded JavaScript is executed explicitly after the provided HTML DOM node has been added to the document. The infrastructure sets =|$.ajaxScript|= to a `jQuery` object that refers to the script element. This can be used to find the inserted DOM node without generating an `id` attribute. The typical JavaScript skeleton that avoids poluting the namespace and ensures executing if the node is properly embedded is given below. ``` (function() { if ( $.ajaxScript ) { // do the work } })(); ``` SWISH uses [RequireJS](http://requirejs.org/) for dependency tracking. This functionality can be exploited to load JavaScript only once. For example, the [svgtree](example/render_svgtree.swinb) uses this fragment. ``` require(["render/svg-tree-drawer", "jquery"], function(svgtree) { // setup the tree }); ``` The RequireJS paths `c3` and `d3` are preconfigured to load [D3.js](http://www.d3js.org) and [C3.js](http://www.c3js.org)