Monthly Archives: May 2012

GPAC, SVG, Testing

Automated Testing Script Generation

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During a recent SVG Working group discussion, we talked about how to improve the SVG test suite. Part of the problems in the development of the test suite is the sheer number of tests to be produced (i.e. written + reviewed + approved) and then tested against every implementation. The purpose of the testing is to check if every feature passes in at least two independent implementation: that is the criteria to exit Candidate Recommendation. The SVG Tiny 1.2 test suite already contains 496 tests, the SVG 1.1 2nd edition has 526. The SVG 2 spec will probably have more. Having one person test all features is not realistic anymore.

The CSS WG has been working for a long time on this issue. CSS 2.1 has 9685 tests! Together with a team from W3C, the WG set up a test suite server, where one can browse the CSS Test Suite, test its viewer and report the results. All results are then aggregated. The W3C architecture allows for 2 types of tests:

  • ref tests (see Mozilla’s use of ref tests), where a test is provided together with an alternative way of producing the same result (visually).
  • JavaScript tests, where together with the test, one provides JavaScript calls to test that the DOM tree is in the expected state.

Both of these types require quite some work to produce either the reference image or the expected results. This can be tedious. Also, for interactive cases, one would have to create the script to test all interaction paths. And for animation, one would have to author the JavaScript to test changes at some point in time.

In GPAC, we experimented a different approach. Continue reading Automated Testing Script Generation →

Diffusion Curves, Vector Graphics

Experimenting with Freeform Vector Graphics

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As part of my interest for Vector Graphics technologies, I had look at the Freeform Vector Graphics (FVG) technology proposed by Microsoft Research. After all, it differs from SVG only by one letter.

The paper describing the technology is available here. A video presenting the approach is also provided by the authors here. The approach is in general an extension or alternative to the work on Diffusion Curves. It enables the control of the interpolation of colors between diffusion curves (or points), with a higher order of smoothness if necessary.

This post reports on my understanding of the method and of its implementation, focusing on the use of the software and on some aspects not dealt with in the paper and is intended for people who have already a good understanding of the paper. If you notice any mistake, if it is unclear or if you disagree, please leave a comment. Continue reading Experimenting with Freeform Vector Graphics →