Acid2

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The optimal result for Acid2. Note that in the real test, the nose will light up blue when pointing over it with the cursor.

Acid2 as rendered by Internet Explorer 6.0.

Acid2 as rendered by Internet Explorer 7.0.

Acid2 as rendered by Netscape 7.2.

Acid2 as rendered by Mozilla Firefox 1.5.

Acid2 as rendered by Safari 2.0.3.

Acid2 as rendered by development build 2006091805 of Mozilla Firefox 3.0

Acid 2 as rendered by development build 2006102405 from the reflow-refactor branch of Mozilla Firefox 3.0

Acid2 is a test case designed by the Web Standards Project to identify web page rendering flaws in browsers and authoring tools. It is an updated edition of the original Acid test of 1997.^[1]

Acid2 employs certain features of HTML and, more prominently, CSS. The purpose of employing such features is to highlight the problems with browsers that do not display it correctly. The Acid2 test should render correctly on any browser that follows the W3C HTML and CSS 2.0 specifications. Any browsers which do not correctly and completely support all of the features which Acid2 takes advantage of will not render the page correctly.

The Web Standards Project has created a special version of Acid2 test,^[2] because Data URLs used in the original test were never formally standardized.

1 Compliant browsers
2 Non-compliant browsers
3 Passing conditions
4 Timeline of successful browsers
5 Trivia
6 See also
7 References
8 External links

[edit] Compliant browsers

If rendered correctly, Acid2 will appear as a smiley face in the user's browser, with the nose turning blue when moused over. At the time of the test's release, no browsers could render Acid2 correctly but now at least five released applications pass the test by rendering it correctly:

Safari, in Mac OS X v10.4.3, becoming the first browser to do so.
Prince, an XML-to-PDF converter developed by YesLogic.
Opera v. 9, March of 2006.^[3]
Konqueror, the KDE project's browser. Since Safari's rendering engine is a fork of Konqueror's rendering engine, some of Apple's enhancements were adapted. (See below.)
iCab. (See below.)
Shiira, a browser for Mac OS X. It uses the same rendering engine as Safari, which is available as a system-wide framework in Mac OS X.
OmniWeb, a Mac OS X browser.

Although the Web Standards Project web site states that iCab passes Acid2, it technically falls short by displaying a scrollbar on the viewport. (A correctly rendered test should not have a scrollbar.^[4]) Konqueror originally had the same problem when it first was stated to have passed the test, but this issue was corrected with release 3.5.2.

[edit] Non-compliant browsers

Although Internet Explorer has also been moving towards better CSS compliance, its author, Microsoft, has publicly stated that Acid2 is not one of their primary focuses, and that Internet Explorer 7 does not pass the test.^[5]

The programmers of the Mozilla family of browsers (including Mozilla Suite, Firefox, Seamonkey, Camino [Mac OS X], and Netscape 6+) have been making gradual efforts to have their browsers pass the Acid2 test, but it is unclear when this will take place. The delay is due to fundamental architecture work that has to be done to the Gecko rendering engine to support the changes that Acid2 requires.^[6] It's unlikely that an end-user release that supports Acid2 will appear before 2007.

A Firefox 3.0 (Minefield) branch does exist that passes the Acid2 test[1]. It will be merged into Firefox 3 proper.

[edit] Passing conditions

The test has been designed so that it is only valid with browser's default settings. Changing font sizes, zoom level, applying user stylesheets etc can break the display of the test. This is expected and is not relevant to a browser's compliance.

Ian Hickson, the author of the test, has provided WaSP with clarifications about the Acid2 test and how things should behave.^[7]

The following browser settings and user actions may affect the rendering of Acid2 page without bearing on the browser's compliance:

Scrolling. A part of the face remains fixed when you scroll.
Zooming to any level other than 100% (default).
Disabling images.
Opera's Fit to width and SSR (Small Screen Rendering) modes. These are off by default, and the test is not valid when they are enabled.
User colours, fonts etc.
User stylesheets, Opera's user mode for styling.
User JS.

Also, the public release of Opera has some bugs revealed by testing Acid2 under non-standard conditions:

Disabling and re-enabling images breaks the display (it doesn't return to the initial state).
Zooming the page reveals a pattern of orange dots. This is a bug in the image scaling algorithm.
Zooming the page makes the nose jagged. It should remain smooth.

However, these bugs don't mean that Opera doesn't pass Acid2 because they require testing under non-standard conditions, which makes the test invalid.

[edit] Timeline of successful browsers

The Acid2 test was officially announced on April 13, 2005. The following is a list of releases noting significant builds of applications that passed the test.

Date	Browser	Type	Notes
April 27, 2005	Safari	non-public build^[8]
May 18, 2005	iCab	non-public build
May 20, 2005	iCab	build public to members only
June 4, 2005	Konqueror	non-public build^[9]
June 6, 2005	iCab	public build
October 31, 2005	Safari	official release	Version 2.02, available with Mac OS X 10.4.3. First official browser to pass test.
November 29, 2005	Konqueror	official release^[10]	Available with KDE 3.5. First Linux-based browser to pass virtually all of the test, except for hiding the scrollbar.
December 7, 2005	Prince	official release^[11]	Version 5.1, first non-web browser to pass test
March 10, 2006	Opera	public weekly build^[12]	First Windows-based browser to pass test and also the first Linux-based browser to fully pass the test. A public beta was released on April 20, also successful.
March 14, 2006	Shiira	official release
March 24, 2006	iCab	build public to members only	iCab 3.0.2b400 adds a switch to hide the scrollbars
March 28, 2006	Konqueror	official release^[13]	Although previous releases passed, their compliance was questionable. This version does not wrongly show scrollbars.
April 12, 2006	Firefox	semi-public build^[14]	The "reflow branch" nightly builds, whose code is currently branched from the Gecko 1.9/Firefox 3.0 trunk and is planned to soon be merged back into the trunk.
May 24, 2006	Opera Mobile	non-public build^[15]	First mobile browser to pass test
June 20, 2006	Opera 9.0	official release^[16]	First browser supporting multiple platforms to pass the test
June 30, 2006	Obigo Browser	non-public build^[17]	Second mobile browser to pass test
August 17, 2006	iCab 3.0.3	official release	First public release that hides the scrollbars

[edit] Trivia

Beta versions of Opera 9 included an easter egg that, when triggered[2], affects the Acid2 test. After the page has been open for a while, the eyes of the smiley will follow the cursor around and when the user clicks on the eyes, a message will show up saying "Because just passing is not enough ;)" screencapture 1 screencapture 2.

Since Acid 2 also tests how web browsers deal with faulty code, it will fail W3C validation. This is expected and purposefully intended by its designers.

The web site creator RapidWeaver, available only for the Mac, also passes the Acid2 test. This can the checked by simply dragging the url of the acid 2 test into the preview pane of rapidweaver.

Because of the fact that it is built using WebKit, apple's web browser the RapidWeaver preview window displays just as well as safari.