Dazzle 0.1.1

dazzle-net

A DSSSL processor for .NET. It runs DSSSL stylesheets (ISO/IEC 10179) over SGML and XML documents with the OpenJade style engine — the C# port of James Clark's original — and adds two things the original does not have: a flow object class for writing whole directory trees, and a PDF backend.

Packages

All target .NET 10.

The tool

dotnet tool install -g Dazzle.Cli

dazzle -t pdf -o book.pdf -d stylesheet.dsl document.xml

Usage: dazzle [options] DSSSL-spec document
  -t type    Output type (sgml, xml, pdf)
  -o file    Output file
  -d spec    DSSSL specification
  -V var     Define variable
  -c catalog Use SGML catalog

The DTDs of the DSSSL architecture and a catalog for them come with the tool.

Generating files: the directory flow object class

OpenJade's transformation backend (-t sgml, -t xml) writes text files through the entity flow object class. dazzle adds directory, which creates a directory and makes the entities inside it relative to it — so a stylesheet can lay out a whole tree of generated files, which is what makes DSSSL usable as a code generator.

(declare-flow-object-class entity
  "UNREGISTERED::James Clark//Flow Object Class::entity")
(declare-flow-object-class directory
  "UNREGISTERED::Dazzle//Flow Object Class::directory")

(make directory
  path: "generated"
  (make entity
    system-id: "Parser.cs"
    (literal "// ...")))

PDF

The PDF backend sets the pages itself and writes them with PDFsharp, the way the PDF backend of the Scaly port of OpenJade does: blocks flow down the page, paragraphs are broken into lines, tables are set row by row, and the flow object tree is laid out twice so that current-node-page-number-sosofo knows its page. It sets simple page sequences with headers and footers, paragraphs and paragraph-break, display groups, boxes, line fields, leaders, score, rules, external graphics and tables (spanned columns and rows, borders of the table and its cells, header rows again on every page, tables in cells) — enough to set a book with the DocBook print stylesheets.

The characteristics mean what ISO/IEC 10179 says, as the RTF backend of Jade has them:

• line-spacing is the distance of the lines: exactly that with min-leading: #f (the initial value), at least that and the height of the line's text plus min-leading otherwise;
• display space collapses to the larger of the space after one block and the space before the next, and conditional? space is dropped at the start of an area — the top of a page, a table cell;
• the cell margins are the distance between the edges of a cell and its content;
• score draws its line after ('after), through or before the text, or at a length below it, over the spaces only with score-spaces?: #t;
• input-whitespace-treatment: 'preserve keeps every space, and where lines: wraps a line still breaks at them; a tab goes to the next multiple of 36pt;
• a line breaks at a space, after a soft hyphen (which then shows) and after a hyphen between letters;
• a cell is placed in the column after the previous cell of its row unless its column-number says otherwise, also under a cell spanning rows.

One deviation: the initial input-whitespace-treatment is 'collapse, not 'preserve.

Header and footer parts are set as blocks across the width of the page body, center- and right- parts aligned to the middle and the end; they stand at header-margin from the top and footer-margin from the bottom of the page, and without these in the middle of the margin.

The fonts come from PDFsharp's font resolver: the one the program sets in GlobalFontSettings.FontResolver, else the system's fonts.

From a program:

using Dazzle.Pdf;

DssslProcessor.GeneratePdf("document.xml", "stylesheet.dsl", "document.pdf");

byte[] pdf = DssslProcessor.GeneratePdfBytes("document.xml", "stylesheet.dsl");

A third overload writes to a Stream. All take an optional path to an SGML catalog; without one the bundled catalog is used.

Extension characteristics

DSSSL has no height for a table row. The backend takes it as an extension characteristic, which a stylesheet declares and then specifies on a table-row (or anything around it):

(declare-characteristic min-row-height
  "UNREGISTERED::Dazzle//Characteristic::min-row-height" 0pt)
(declare-characteristic row-height
  "UNREGISTERED::Dazzle//Characteristic::row-height" 0pt)

(make table-row min-row-height: 20pt ...)

License

MIT, see LICENSE. OpenJade and OpenSP carry the license of the original.