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Published byVivian Hutchinson Modified over 8 years ago
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A Constraint Extension to Scalable Vector Graphics Greg J. Badros Jojada J. Tirtowidjojo Kim Marriott Bernd Meyer Will Portnoy Alan Borning May 1-5,2001,Hong Kong. ACM
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Introduction SVG is not enough SVG background CSVG (constraint scalable vector graphic) Implementation Performance Conclusion Future work
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SVG is not enough It does not provide for flexible layout given different viewer and browser capabilities,such as screen format and font preferences. –EX. Format.X rignt + horiz_spacing <= DataFormat.X left –ExampleExample
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SVG is not enough(Cont.) Interactive manipulation –Semantic zooming (Example)Example –Differential scaling –Semantic preserving manipulation (Example)Example Animation –We can also make these properties dependent on a timer variable.
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SVG is not enough(Cont.) Extending SVG— main technical contribution: –A motivation for using constraints and alternative layouts for a wide class of SVG diagrams –A description of Constraint Scalable Vector Graphics as an extension of SVG –A prototype implementation of a CSVG viewer based on the CSIRO SVG viewer
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SVG BACKGROUND Basic: – Animate: – < animate atrributeName=“x” atrributeType=“XML” begin=“0s” dur=“0s” fill=“freeze” from=“20” to=“120” /> Example
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CSVG (constraint scalable vector graphic) Four extensions to the SVG language: –We store all SVG standard element attributes in predefined constraint variables and support identifier in addition to literal. –Six predefined variable based on it’s id : rectA_x; rectA_y; rectA_width; rectA_height; rectA_rx; rectA_ry Constraint variables may also be declared explicitly by using a new var element.
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CSVG (Cont.) –Add another new element type called constraint Require attribute rule Optional attribute strength =50” strength=“strong” />
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CSVG (Cont.) –Add several built-in read-only constraint variables. Viewport_width Viewport_height
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CSVG (Cont.) –Added alternate layouts for groups of SVG elements. docase gcase Example Layout example(109 constraints)Layout example Interactive example(185 constraints)Interactive example Animation example(30 constraints)Animation example
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Implementation CSVG DTD –Children of SVG group elements(svg,g),add elements: Var Constraint Docase Constraint Solving engine Architecture of implementation
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PERFORMANCE Class hierarchy example –266ms Abacus example –485ms –Moving a bead — 16ms Machine: –Pentium II 450MHz –Java 1.2 with the Hotspot virtual machine
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CONCLUSION Constraint-based graphics documents are difficult to author No authoring environments for generating CSVG
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FUTURE WORK Could support referencing other elements’ attributes directly. To better describe the semantics of SVG in terms of constraints and constraint hierarchy theory.
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