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Acid3

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Acid3
File:Acid3 reference webkitr30069.png
The reference image for Acid3.
Type of site
Web standards test
Available inEnglish language
OwnerThe Web Standards Project
Created byIan Hickson
URLhttp://acid3.acidtests.org

Acid3 is a test page from the Web Standards Project that checks how well a web browser follows certain web standards, especially relating to the DOM and JavaScript.

It was in development from April 2007,[1] and released on 3 March 2008.[2] The main developer was Ian Hickson, who also wrote the Acid2 test. Acid2 focused primarily on Cascading Style Sheets, but this third Acid test focuses also on technologies used on modern, highly interactive websites characteristic of Web 2.0, such as ECMAScript and DOM Level 2. A few tests also concern Scalable Vector Graphics, XML and data: URIs. Only elements from specifications as of 2004 are included.[3]

When successful, the Acid3 test displays a gradually increasing percentage counter with colored rectangles in the background. The percentage displayed is based on the number of sub-tests passed. In addition to these the browser also has to render the page exactly like the reference page as rendered in the same browser. Unlike the Acid2 test, the reference rendering is not a bitmap, to allow for certain differences in font rendering.

The test

The main part of Acid3 is written in ECMAScript (JavaScript), and consist of 100 subtests, in six groups, called "buckets", plus four special tests (0, 97, 98, and 99).[4]

  • Bucket 1: DOM Traversal, DOM Range, HTTP
  • Bucket 2: DOM2 Core and DOM2 Events
  • Bucket 3: DOM2 Views, DOM2 Style, CSS 3 selectors and Media Queries
  • Bucket 4: Behavior of HTML tables and forms when manipulated by script and DOM2 HTML
  • Bucket 5: Tests from the Acid3 Competition (SVG,[5] HTML, SMIL, Unicode...)
  • Bucket 6: ECMAScript

The compliance criteria requires that the test is run with a browser's default settings. The final rendering must have a 100/100 score and must not only be pixel-identical with the reference rendering but the animation has to be smooth (taking no more than 33 ms for each subtest on the top-of-the-line Apple laptop[6]) as well.

Acid3 rendered by the now greatly outdated WebKit r30885 nightly build. Buckets 3,4 and 6 pass all 16 subtests, buckets 1 and 2 pass more than 10 subtests while bucket 5 passes more than 5 of these.

As the test is run, rectangles are added to the rendered image; the color of the rectangles is decided by the number of sub-tests passed in the bucket. If all subtests fail in a particular bucket, its associated rendered rectangle will be invisible. If some subtests are cleared the color will change in four steps:

  • 1-5 subtests passed: Black rectangle.
  • 6-10 subtests passed: Grey rectangle.
  • 11-15 subtests passed: Silver rectangle.
  • All 16 subtests passed: Colored rectangle (red, orange, yellow, lime, blue, purple - for each of the six rectangles, in order).

After the Acid3 test page is completely rendered, the capital A in the word Acid3 can be clicked to see an alert (or Shift-Click for a new window) explaining exactly which subtests have failed, and what the error message was.

In order to render the test correctly, user agents need to implement the CSS 3 Text Shadows and the CSS 2.x Downloadable Fonts specifications, which are currently under consideration by W3C to be standardized. This is required as the test uses a custom TrueType font, called "AcidAhemTest" to cover up an "X" on fuchsia colored background. The glyph, when rendered by the downloaded font, is just a square, made white with CSS, and thus invisible.[citation needed]

In addition, the test also uses Base64 encoded images, some more advanced selectors, CSS 3 color values (HSLA) as well as bogus selectors and values that should be ignored.

Development and impact

As stated above, Ian Hickson started working on the test in April 2007, but it progressed slowly. In December 2007 the work restarted and it received public attention on 10 January 2008, when it was mentioned in blogs by Anne van Kesteren[7] and Dustin Brewer.[8] At the time it resided at a URL clearly showing its experimental nature: "http://www.hixie.ch/tests/evil/acid/003/NOT_READY_PLEASE_DO_NOT_USE.html" That did not stop the test from receiving widespread attention within the web development community. At this time only 84 subtests were done, and on 14 January Ian Hickson announced a competition to develop the missing 16.[9]

The following developers contributed to the final test through this competition:

  • Sylvain Pasche. Test 66–67 (DOM).
  • David Chan. Test 68 (UTF-16/UCS-2).
  • Simon Pieters and Anne van Kesteren. Test 71: HTML parsing.
  • Jonas Sicking and Garret Smith. Test 72: dynamic modification of style blocks' text nodes.
  • Jonas Sicking. Test 73: Nested events.
  • Erik Dahlström. Test 74–78: SVG and SMIL.
  • Cameron McCormack. Test 79: SVG fonts.

The impact of the test on browser development was dramatic, already before its official release. WebKit in particular made progress; in less than a month their score rose from 60 to 87.[10]

The test was officially released on March 3, 2008.[2] A guide and commentary is expected within a few months.[10] The announcement that the test is complete means only that it is to be considered "stable enough" for actual use; if problems and bugs are found, it will still be modified to fix it. The test has already been modified to fix several issues including issues regarding to sub-pixel positioning, SVG surrogate pairs and performance.[11] On March 26, 2008—the day both Opera and WebKit teams announced a 100/100 score—developers of WebKit contacted main Acid3 developer Ian Hickson about a critical bug in the Acid3 that presumably may have forced a violation of the SVG 1.1 standard to pass; thus Hickson proceeded to fix it with the help of Cameron McCormack, member of W3C's SVG Working Group.[12][13]

By the end of March 2008, early development versions of the Presto and WebKit layout engines scored 100/100 on the test and rendered the test page correctly.[14][13][15] Both WebKit and Presto still have performance issues in producing a smooth animation in the test, thus they have not passed the Acid3 test yet. Firefox developers are preparing for the imminent release of Firefox 3, as a result they are focusing on stability rather than passing the Acid3 test.[16] Microsoft, developers of the Internet Explorer browser, said that Acid3 does not map to the goal of Internet Explorer 8 and that IE8 will improve only some of the standards being tested by Acid3.[17]

On April 22, 2008, Hickson again fixed a bug in the Acid3 test discovered by a Mozilla developer. This change possibly invalidates the previously reported scores of 100/100 for development versions of Presto and WebKit.[18]

Layout engines

Acid3 was deliberately written in such a way that every web browser failed upon the test's release. Many of the browser teams are actively working to improve test results. Some have internal or released versions that achieve 100/100 on Acid3 (but do not pass the smoothness criterion).

Non-compliant layout engines

Template:WebSlice-begin{| class="wikitable" style="width: auto; table-layout: fixed;" |+ Layout engine progress for the Acid3 test |- ! style="width:10%" | Layout Engine ! style="width:10%" | Main Browser ! style="width:25%" | Stable Build Screenshot ! style="width:25%" | Development Build Screenshot ! style="width:30%" | Notes |- |- |Trident |Internet Explorer

|

14/100
14/100

|

18/100
18/100

|Microsoft has stated that Internet Explorer 8 will improve only some of the standards being tested by Acid3.[17] |- |Gecko |Firefox

|

53/100
53/100

|

71/100
71/100

|Mozilla developers have a tracking bug[19] and a public spreadsheet[20] for the status of their work regarding this test. |- |KHTML |Konqueror

|

73/100
73/100

|

75/100
75/100

|The tracking bug for Konqueror was filed on 30 January 2008.[21] |- |Presto |Opera

|

46/100
46/100

|

100/100
100/100

|Opera 9.5 beta 2 scores 78/100.[22] The latest post-9.5 build scores 100/100 and renders the test correctly, but still fails the smoothness criterion.[15] |- |WebKit |Safari

|

75/100
75/100

|

100/100
100/100

|The team that develops WebKit has a tracking bug.[23]. WebKit build r31356 scores 100/100 and produces a correct rendering, but still fails the smoothness criterion.[13]

|}Template:WebSlice-end

References

  1. ^ "HTML5 IRC logs: freenode / #whatwg / 20070422". Retrieved 2007-12-28.
  2. ^ a b "Acid3: Putting Browser Makers on Notice, Again. (WaSP Press Release)". Retrieved 2007-03-04.
  3. ^ "HTML5 IRC logs: freenode / #whatwg / 20071228". Retrieved 2007-12-28.
  4. ^ Hickson, Ian. "Comments in the source code of the test page". Retrieved 2008-02-16.
  5. ^ Dahlström, Erik (2008-01-22). "Getting to the core of the web". Retrieved 2008-02-16. {{cite web}}: Check date values in: |date= (help)
  6. ^ Ian Hickson (2008-04-01). "The performance aspect of Acid3". Retrieved 2008-04-03.
  7. ^ van Kesteren, Anne (2008-01-10). "Acid3". Retrieved 2008-03-04. {{cite web}}: Check date values in: |date= (help)
  8. ^ Brewer, Dustin (2008-01-10). "Developers are working on ACID3 test". Retrieved 2008-03-04. {{cite web}}: Check date values in: |date= (help)
  9. ^ Hickson, Ian (2008-01-14). "The competition for you to come up with the best test for Acid3". Retrieved 2008-03-04. {{cite web}}: Check date values in: |date= (help)
  10. ^ a b Hickson, Ian (2008-03-04). "Moebius (announcement of the completion of the test)". Retrieved 2008-03-04. {{cite web}}: Check date values in: |date= (help)
  11. ^ Ian Hickson. "Tests that are never quite finished". Retrieved 2008-03-30.
  12. ^ Ian Hickson. "Last minute changes to Acid3". Retrieved 2008-03-30.
  13. ^ a b c Maciej Stachowiak (2008-03-26). "WebKit achieves Acid3 100/100 in public build". Retrieved 2008-03-26. {{cite web}}: Check date values in: |date= (help)
  14. ^ Junyor (March 2008). "Opera and the Acid3 Test". Retrieved 2008-03-28.
  15. ^ a b Lars Erik Bolstad (March 2008). "Public Acid3 build". Retrieved 2008-03-28.
  16. ^ Mike Shaver (2008-03-27). "The missed opportunity of acid 3". Retrieved 2008-03-30.
  17. ^ a b Chris Wilson. "Windows Internet Explorer 8 Expert Zone Chat (March 20, 2008)". Retrieved 2008-04-15. The ACID3 test is a collection of interesting tests, spread across a large set of standards. Some of those standards will see improvements in IE8 - in fact, IE8 already improves on IE7's score - but we are focused on the most important features and standards to make web developers' lives easier. The ACID3 test does not map directly to that goal.
  18. ^ Ian Hickson (2008-04-22). "Media queries and performance in Acid3 (and an error on my part)". Retrieved 2008-04-24.
  19. ^ "Bug 410460 (acid3) – Acid3 tracking bug". Retrieved 2008-02-16.
  20. ^ "Google document - Acid3 spreadsheet". Retrieved 2008-02-18.
  21. ^ "Bug 156947: Konqueror 4 fails Acid3 test". Retrieved 2008-03-02.
  22. ^ "Opera 9.50 / Windows XP for http://acid3.acidtests.org/". BrowserShots. 2008-04-24. Retrieved 2008-04-24. {{cite web}}: External link in |title= (help)
  23. ^ "Webkit tracking bug". Retrieved 2008-02-18.


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