Xar Format Specification An open standard file format for vector graphics on the Web. Abstract The Xar file format, previously known as the Flare file format, is an ultra-compact, open, vector graphic format. It is also the native graphics format for Xara X application (and also its predecessors such as CorelXARA). This document describes the format in detail and provides information for third parties interested in converting to or from this graphics format. Why another vector graphics format? The Xar file format is not new. It dates back nearly ten years and so it predates more recent formats such as SVG. It is not designed to compete with SVG, but Xar files are considerably simpler to understand (the SVG spec is 700 pages) and more compact (often one tenth the size). However the primary reason for the existence of the open file format specification is to enable third parties to read and write the Xara X native files. Background The Xar vector graphic structure is that of modern vector programs, based on the Adobe Postscript rendering model, but with additional features. The graphic primitives are broadly similar to those available in Postscript, PDF and SVG. However Xara X, and thus the .xar file format, support more advanced graphic primitives and effects, for example a greater range of graduated fill types, graduated transparency, feathered vector shapes (soft edges), soft shadows and more. These enable the talented artist to create highly realistic and more ‘painterly’ effects with Xara X than is possible with traditional vector graphics solutions. See http://www.xara.com/gallery/ The format is designed so that rendering can be started before the entire file is available. The format is extendible, with a degree of forwards and backwards compatibility (this means older version of the software can still read files produced by newer version of the authoring software – they simply ignore the objects or parts they do not understand). Part of the reason for this compactness is that Xar files are binary, rather than plain text as is SVG (which is XML). But with the recent movement towards a binary XML format, in - 1 - order to overcome the verbose nature of XML (and SVG), it seems things might come full circle. On the other hand Xara X offers a plain text variant of the .xar file (file extension .wix) which can help in understanding the structure of .xar files. Status of this Document This format was previously known as the Flare format but is now called Xar format. This document has been updated to describe the format as implemented by versions of XaraX up to and including Xara Xtreme 3.0. Change log This log lists all updates made to this specification from 1 November 2004. Date Change Description 2nd November 2004 Added Change Log page (Gerry Iles) Updated definition of MATRIX structure and transformation functions in description of Transformed Path records 4th November 2004 Removed broken links from TAG_VARIABLEWIDTHFUNC, (Gerry Iles) TAG_STROKEDEFINITION and TAG_STROKEAIRBRUSH in Appendix A and labelled them as not currently used. 3rd December 2004 Clarified description of path verb values. (Gerry Iles) Added download link for XarLib library. 11th January 2005 Moved download link for XarLib library. (Gerry Iles) Added download link for XPFilter archive. Updated the guidelines for implementors. 13th January 2005 New XaraX import/export filters page. (Gerry Iles) Moved link to XPFilter archive. 25th February 2005 Added detailed description of transparency types. (Gerry Iles) 30th June 2005 Corrected values for line cap and line join attributes. (Gerry Iles) Corrected order of coordinates in all bitmap and fractal fill and transparency attributes. Added note about inversion of alpha in 32 bpp RGBA PNGs. - 2 - 4th July 2005 Replaced diagrams of fill attributes. (Gerry Iles) Added bevel type descriptions and examples. Added more detail to XPE bitmap definition records. Added copyright and usage requirements to XarLib sections and XaraX filter sections. 1st Nov 2005 Details of Xara Xtreme group transparency. (Phil Martin) 4th Nov 2005 Edited general descriptions and background material to be more (Charles Moir) up-to-date. Expanded description of embedded bitmap records and XPE Expanded description of Import / Export filters / converters 10th Nov 2005 Added details of object bounds record. (Gerry Iles) Added descriptions of bitmap effects 23rd Nov 2005 Expanded details of effect attributes, live effects, locked effects, (Phil Martin) feather effects and group transparency. Updated Contents table. 1st December 2005 Fixed TAG_PATH_FLAGS and TAG_PATH_RELATIVE descriptions to not include a count of the items in the record. 4th January 2006 Improved description of colour component values. Improved description of path record variants. 13th June 2006 Removed Plugin Filter specific information. (Gerry Iles) 24th July 2006 Added details of documents containing multiple spreads TAG_CURRENTATTRIBUTES_PHASE2, TAG_SPREAD_PHASE2 and TAG_PRINTERSETTINGS_PHASE2. Added notes about attribute optimisation in Xara programs. Added details of TAG_SPREAD_FLASHPROPS 2nd August 2006 Modified note concerning use of path record variants. 2nd August 2006 Added details of TAG_DOCUMENTINFORMATION record. 8th August 2006 Changed names of bitmap object records from TAG_(CONTONE)BITMAP_OBJECT to TAG_NODE_(CONTONED)BITMAP to match source code. - 3 - 10th August 2006 Corrected bitmap definition records to use Unicode string for bitmap name. 4th September 2006 Corrected values for winding rule attribute. 19th October 2006 Corrected descriptions of simple ellipse and rectangle records. 9th January 2007 Added details of new records: TAG_DEFINEBITMAP_PNG_REAL TAG_CLIPVIEW_PATH TAG_TEXT_STRING_POS TAG_TEXT_LINESPACE_LEADING TAG_TEXT_TAB TAG_TEXT_LEFT_INDENT TAG_TEXT_FIRST_INDENT TAG_TEXT_RIGHT_INDENT TAG_TEXT_RULER TAG_TEXT_STORY_HEIGHT_INFO TAG_TEXT_STORY_LINK_INFO TAG_TEXT_STORY_TRANSLATION_INFO Added details of new flags in TAG_SPREADINFORMATION. 19th July 2007 Various spelling and grammatical errors corrected. 14th September 2007 Added details of new records: TAG_TEXT_SPECIAL_HYPHEN TAG_TEXT_SOFT_RETURN TAG_TEXT_SPACE_BEFORE TAG_TEXT_SPACE_AFTER TAG_TEXT_EXTRA_TT_FONT_DEF TAG_TEXT_EXTRA_ATM_FONT_DEF TAG_TEXT_EXTRA_FONT_INFO Added details to various other record descriptions, in particular TAG_TEXT_RULER and TAG_FONT_DEF_XXX. Copyright Copyright 1997-2007 Xara Group Ltd. Permission is granted to reproduce this specification in complete and unaltered form. Excerpts may be printed with the following notice: "excerpted from the Xar format - 4 - specification." No notice is required in software that follows this specification; notice is only required when reproducing or excerpting from the specification itself. - 5 - Contents Abstract...............................................................................................................................1 Background.........................................................................................................................1 Status of this Document......................................................................................................2 Change log..........................................................................................................................2 Copyright............................................................................................................................4 Contents..................................................................................................................................6 Introduction ..........................................................................................................................14 Why a new format? ..........................................................................................................14 Bitmaps are dumb.........................................................................................................14 Are current Vector formats the answer?.......................................................................15 Xar format - one step beyond .......................................................................................16 What the Xar format can't do (yet)...............................................................................16 Design goals .....................................................................................................................16 Design background...........................................................................................................17 Xar format overview.............................................................................................................18 Feature List...................................................................................................................18 Feature notes.................................................................................................................19 Current Implementations..............................................................................................19 Technical overview...........................................................................................................20 Records .........................................................................................................................20 Record families.............................................................................................................20 Streams and Compression ............................................................................................21