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Stylable CGM

Stylable CGM. Dave Cruikshank The Boeing Company Lofton Henderson Henderson Consulting. CGM Version 4. The CGM standard (ISO 8632:1999) CGM V4 - Application Structuring Syntax to define application structures (APS) as graphical groups Syntax to associate attributes to APS

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Stylable CGM

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  1. Stylable CGM Dave Cruikshank The Boeing Company Lofton Henderson Henderson Consulting Stylable CGM XML Europe 2003, London

  2. CGM Version 4 • The CGM standard (ISO 8632:1999) • CGM V4 - Application Structuring • Syntax to define application structures (APS) as graphical groups • Syntax to associate attributes to APS • Definition of Semantics accomplished through profiles Stylable CGM XML Europe 2003, London

  3. WebCGM Functionality • WebCGM developed by CGM Open in collaboration with W3C graphics experts • WebCGM profile approved by W3C – 1999 • WebCGM Release 2 published - 2001 Stylable CGM XML Europe 2003, London

  4. WebCGM Functionality • Requirements • Navigation • Graphical object to graphical object within a CGM file • Graphical object to graphical object in another CGM file • Graphical object to a text objet • Query • Search for a graphical object based on an attribute • Data extraction • Retrieve non-graphical metadata from a graphical object Stylable CGM XML Europe 2003, London

  5. WebCGM Functionality • Graphical Format Capabilities • Structuring -- hierarchical object tagging • Non-graphical properties • Object id/naming • IG requirements • Navigation • Query • Extraction CGM Capability Begin APS <id> <type> <inh> ... APS Attribute <type> <val> ... Begin APS Body ...graphics to draw object... ...and/or, nested ApS... End Application Structure Stylable CGM XML Europe 2003, London

  6. WebCGM Functionality • Semantics • APS Attributes: • Region • LinkURI • ViewContext • LayerName • LayerDescription • ScreenTip • Name • Content • 4 APS types: • grobject • layer • para • subpara Stylable CGM XML Europe 2003, London

  7. WebCGM Structure Picture body layer grobject para grobject para grobject subpara grobject para subpara subpara Stylable CGM XML Europe 2003, London

  8. Motivation for Stylability • Interoperability among vendors demonstrated several times • Proprietary DOM implementations being developed for external browser control Stylable CGM XML Europe 2003, London

  9. Approach • CGM has inherent style, but… • WebCGM profile says: • ‘While WebCGM is a binary file format and is not “stylable”, nevertheless WebCGM follows published W3C requirements for scalable graphics format where such are applicable’ • CSS2 says: • ‘CSS can be used with any structured document format …’ • WebCGM is a structured document format Stylable CGM XML Europe 2003, London

  10. Approach • Application of CSS2 to WebCGM much the way CSS1 was applied to legacy HTML • Use of attribute selectors for specifying a style scheme to WebCGM Stylable CGM XML Europe 2003, London

  11. Requirements • Scope • Granularity of application • Picture • APS • Control of individual graphical primitives out of scope Stylable CGM XML Europe 2003, London

  12. Requirements - color • Functions • PictureScopeLineColor - RBG or relative scale • PictureScopeEdgeColor - RBG or relative scale • PictureScopeFillColor - RBG or relative scale • PictureScopeMarkerColor - RBG or relative scale • APSScopeLineColor - RBG or relative scale • APSScopeEdgeColor - RBG or relative scale • APSFillColor - RBG or relative scale • APSScopeMarkerColor - RBG or relative scale • PictureScopeRasterIntensity – relative scale • APSScopeRasterIntensity - relative scale Stylable CGM XML Europe 2003, London

  13. HEADREST SHOULDER STRAPS A LUMBAR SUPPORT ARMREST ADJUSTMENT PAD WAIST STRAPS ARMREST FLIGHT CREW SEAT QUICK RELEASE BUCKLE CROTCH BELT B SAFETY VEST TOP (BELOW THE SEAT) MID BOTTOM UP/DOWN LEVER INBD/OUTBD LEVER INERTIA A REALS Requirements - color Stylable CGM XML Europe 2003, London

  14. HEADREST SHOULDER STRAPS A B LUMBAR SUPPORT ARMREST ADJUSTMENT PAD WAIST STRAPS INERTIA A REALS ARMREST FLIGHT CREW SEAT QUICK RELEASE BUCKLE CROTCH BELT SAFETY VEST TOP (BELOW THE SEAT) MID BOTTOM UP/DOWN LEVER INBD/OUTBD LEVER Requirements - color Stylable CGM XML Europe 2003, London

  15. Requirements – line/edge weight • Functions • PictureScopeLineWeight – absolute mm or relative scale • PictureScopeEdgeWeight – absolute mm or relative scale • APSScopeLineWeight – absolute mm or relative scale • APSScopeEdgeWeight – absolute mm or relative scale Stylable CGM XML Europe 2003, London

  16. HEADREST SHOULDER STRAPS A LUMBAR SUPPORT ARMREST ADJUSTMENT PAD WAIST STRAPS ARMREST FLIGHT CREW SEAT QUICK RELEASE BUCKLE CROTCH BELT B SAFETY VEST TOP (BELOW THE SEAT) MID BOTTOM UP/DOWN LEVER INBD/OUTBD LEVER INERTIA A REALS Requirements – line/edge weight Stylable CGM XML Europe 2003, London

  17. HEADREST SHOULDER STRAPS A LUMBAR SUPPORT B ARMREST ADJUSTMENT PAD WAIST STRAPS INERTIA A REALS ARMREST FLIGHT CREW SEAT QUICK RELEASE BUCKLE CROTCH BELT SAFETY VEST TOP (BELOW THE SEAT) MID BOTTOM UP/DOWN LEVER INBD/OUTBD LEVER Requirements – line/edge weight Stylable CGM XML Europe 2003, London

  18. Requirements – character height • Functions • PictureScopeCharacterHeight – absolute mm or relative scale • APSScopeCharacterHeight – absolute mm or relative scale Stylable CGM XML Europe 2003, London

  19. HEADREST SHOULDER STRAPS A LUMBAR SUPPORT ARMREST ADJUSTMENT PAD WAIST STRAPS ARMREST FLIGHT CREW SEAT QUICK RELEASE BUCKLE CROTCH BELT B SAFETY VEST TOP (BELOW THE SEAT) MID BOTTOM UP/DOWN LEVER INBD/OUTBD LEVER INERTIA A REALS Requirements – character height Stylable CGM XML Europe 2003, London

  20. HEADREST SHOULDER STRAPS A B LUMBAR SUPPORT ARMREST ADJUSTMENT PAD WAIST STRAPS INERTIA A REALS ARMREST FLIGHT CREW SEAT QUICK RELEASE BUCKLE CROTCH BELT SAFETY VEST TOP (BELOW THE SEAT) MID BOTTOM UP/DOWN LEVER INBD/OUTBD LEVER Requirements – character height Stylable CGM XML Europe 2003, London

  21. Requirements • Caveats • Applying style using CSS2 deviates from the actual CGM attribute model • Character height scaling does not exist • Line weight scaling behaves differently • “Undoing” style requires special handling • Remembering attributes of various primitives, or • Re-interpreting a picture or APS Stylable CGM XML Europe 2003, London

  22. Issues/Resolution • Binary/clear text • CGM is binary format • Style sheet should be ASCII text • APSScopelinecolor grobject#xyz {color: red} – turn the lines in grobject with an apsid of xyz to red • CGM Structured Data Record (SDR) • An issue for the WebCGM DOM when we deal with multiple fields for attribute values of APS attributes Stylable CGM XML Europe 2003, London

  23. Issues/Resolution • WebCGM tree model • Pictures contain: • APS elements (nested) contain: • Graphical primitives (leaf nodes) • Nodes at the APS level • <layer .. > | <grobject .. > | <para .. > | <subpara> • Simplest with a tree with four kinds of element nodes Stylable CGM XML Europe 2003, London

  24. Issues/Resolution • Alignment with CSS • Possible to align element names with SVG • CSS style sheet parsing might be reusable • But not much else • Appropriate solution • Borrow principles from CSS, including matching mechanisms • Customize solution for WebCGM DOM requirements Stylable CGM XML Europe 2003, London

  25. Issues/Resolution • CSS selectors • Minimal selector pattern matching set * – matches any element (universal selector) grobject – matches any grobject APS (type selector) grobject#xyz – matches any grobject APS with an apsid of xyz • Attribute selectors grobject[name] – matches any grobject APS whose “name” attribute is set grobject[name=“bolt”] – matches any grobject APS whose “name” attribute is set to “bolt” Stylable CGM XML Europe 2003, London

  26. Issues/Resolution • WebCGM element names • For styling solution • Elements selectors • picture layer • grobject para • subpara • Attrubute selectors • Linkuri name • screentip viewcontext • region content • layerdescription layername Stylable CGM XML Europe 2003, London

  27. Issues/Resolution • Style rules declaration • Attribute types deviate • LineColour is a CGM attribute applying to individual line primitives • PictureScopeLineColor would apply to all lines in a picture • Attribute values deviate • LineColour specified in WebCGM as an index into a color table, or an RGB n-tuple, or an sRGB n-tuple • PictureScopeLinecolor would have an RGB n-tuple, or a relative scale • Align with CSS data types (RBG, scale, mm) Stylable CGM XML Europe 2003, London

  28. Issues/Resolution • CSS inheritance model • Styling attributes should inherit • Nested APS are affected by styling Stylable CGM XML Europe 2003, London

  29. Issues/Resolution • Cascading precedence • Opposite of CSS • User agent supplied style overrides author style • Specificity • CSS rules apply • In clashes, most specific rules Stylable CGM XML Europe 2003, London

  30. Issues/Resolution • Processing model • Open questions • How are styling rules communicated to the viewer? • Is there some sort of rule-by-rule interface? • Or, so you have to pass an entire style sheet at a time? • How do you turn off a style sheet after it has been applied and return to author rules? (unapply rules) • How the the styling interface relate to the DOM? (DOM will ‘get’ and ‘set’ all APSattr parameters) Stylable CGM XML Europe 2003, London

  31. Conclusions • Preliminary design completed • ACSII text style sheet • Align with principles from CSS • Use a subset of CSS selectors • Use CGM clear text APS types and attributes • Apply CSS inheritance model • Override CSS cascading • Apply CSS specificity Stylable CGM XML Europe 2003, London

  32. Next Steps • Define processing model • WebCGM DOM • Adopt “appropriate” DOM Core elements (level 1) • Adopt “appropriate” DOM Event elements (levels 2 & 3) • Integrate CSS solution Stylable CGM XML Europe 2003, London

  33. ? Stylable CGM XML Europe 2003, London

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