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visual-audio-contrast-text-presentation.xml
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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE div2
SYSTEM "../xmlspec.dtd">
<div2 id="visual-audio-contrast-text-presentation" role="extsrc">
<head>1.4.5</head>
<div3 role="intent">
<head>Intent</head>
<p>The intent of this Success Criterion is to encourage authors, who are using technologies which are capable of achieving their desired default visual presentation, to enable people who require a particular visual presentation of text to be able to adjust the text presentation as needed. This includes people who require the text in a particular font size, foreground and background color, font family, line spacing or alignment.</p>
<p>If an author can use text to achieve the same visual effect, he or she should present the information as text rather than using an image. If for any reason, the author cannot format the text to get the same effect, the effect won't be reliably presented on the commonly available user agents, or using a technology to meet this criterion would interfere with meeting other criteria such as 1.4.4, then an image of text can be used. This includes instances where a particular presentation of text is essential to the information being conveyed, such as type samples, logotypes, branding, etc. Images of text may also be used in order to use a particular font that is either not widely deployed or which the author doesn't have the right to redistribute, or to ensure that the text would be anti-aliased on all user agents.</p>
<p>Images of text can also be used where it is possible for users to customize the image of text to match their requirements.</p>
<p>The definition of image of text contains the note: <quote>Note: This does not include text that is part of a picture that contains significant other visual content.</quote> Examples of such pictures include graphs, screenshots, and diagrams which visually convey important information through more than just text.</p>
<p>Techniques for satisfying this Success Criterion are the same as those for Success Criterion 1.4.9, except that they only need to apply if the visual presentation can be achieved with the technologies that the author is using. For Success Criterion 1.4.9, the sufficient techniques would be applied only when the user can customize the output. </p>
<p>See also <specref ref="visual-audio-contrast-text-images"/>.</p>
<div4 role="benefits">
<head>Benefits</head>
<ulist>
<item>
<p>People with low vision (who may have trouble reading the text with the authored font family, size and/or color).</p>
</item>
<item>
<p>People with visual tracking problems (who may have trouble reading the text with the authored line spacing and/or alignment).</p>
</item>
<item>
<p>People with cognitive disabilities that affect reading.</p>
</item>
</ulist>
</div4>
</div3>
<div3 role="examples">
<head>Examples</head>
<ulist>
<item>
<p>
<emph role="bold">Styled Headings </emph>
</p>
<p>Rather than using bitmap images to present headings in a specific font and size, an author uses CSS to achieve the same result.</p>
</item>
<item>
<p>
<emph role="bold">Dynamically Generated Images </emph>
</p>
<p>A Web page uses server-side scripting to present text as an an image. The page includes controls that allow the user to adjust the font size and foreground and background colors of the generated image.</p>
</item>
<!-- The following examples are copied from 1.4.9 -->
<item>
<p>
<emph role="bold">A quote</emph>
</p>
<p>A Web page contains a quote. The quote itself is presented as italicized text, indented from the left margin. The name of the person to whom the quote is attributed is below the quote with 1.5x the line space and further indented from the left margin. CSS is used to position the text; set the spacing between lines; as well as display the text's font family, size, color and decoration.</p>
</item>
<item>
<p>
<emph role="bold">Navigation items</emph>
</p>
<p>A Web page contains a menu of navigation links that have both an icon and text to describe their target. CSS is used to display the text's font family, size and foreground and background colors; as well as the spacing between the navigation links.</p>
</item>
<item>
<p>
<emph role="bold">A logo containing text</emph>
</p>
<p>A Web site contains the organization's logo in the top left corner of each Web page. The logo contains logotype (text as part, or all, of the logo). The visual presentation of the text is essential to the identity of the logo and is included as a gif image which does not allow the text characteristics to be changed. The image has a text alternative.</p>
</item>
<item>
<p>
<emph role="bold">Representation of a font family</emph>
</p>
<p>A Web page contains information about a particular font family. Substituting the font family with another font would defeat the purpose of the representation. The representation is included as a jpeg image which does not allow the text characteristics to be changed. The image has a text alternative.</p>
</item>
<item>
<p>
<emph role="bold">A representation of a letter</emph>
</p>
<p>A Web page contains a representation of an original letter. The depiction of the letter in its original format is essential to information being conveyed about the time period in which it was written. The letter is included as a gif image which does not allow the text characteristics to be changed. The image has a text alternative.</p>
</item>
<item>
<p>
<emph role="bold">Symbolic text characters</emph>
</p>
<p>A form allows users to enter blocks of text. The form provides a number of buttons, including functions to style the text and check spelling. Some of the buttons use text characters that do not form a sequence that expresses something in human language. For example "B" to increase font weight, "I" to italicize the text and "ABC" to check the spelling. The symbolic text characters are included as gif images which do not allow the text characteristics to be changed. The buttons have text alternatives.</p>
</item>
<item>
<p>
<emph role="bold">Customizable font settings in images of text</emph>
</p>
<p>A Web site allows users to specify font settings and all images of text on the site are then provided based on those settings.
</p>
</item>
</ulist>
</div3>
<div3 role="resources">
<head>Resources</head>
<ulist>
<item>
<p>
<loc href="http://alistapart.com/article/cssatten">CSS Web fonts</loc>
</p>
</item>
<item>
<p>
<loc href="http://clagnut.com/blog/2042/">Weblog comments: WebKit now supports CSS @font-face rules</loc>
</p>
</item>
<item>
<p>
<loc href="http://www.workingwith.me.uk/articles/css/cross-browser-drop-shadows">Creating Cross Browser Compatible CSS Text Shadows</loc>
</p>
</item>
<item>
<p>
<loc href="http://www.yourhtmlsource.com/stylesheets/csstext.html">CSS and text</loc>
</p>
</item>
</ulist>
</div3>
<div3 role="techniques">
<head>Techniques</head>
<div4 role="sufficient">
<head>Sufficient</head>
<olist>
<item>
<p>
<loc href="C22" linktype="css">Using CSS to control visual presentation of text</loc>
</p>
</item>
<item>
<p>
<loc href="SL31"
linktype="silverlight"/>
</p>
</item>
<item>
<p>
<loc href="C30" linktype="css">Using CSS to replace text with images of text and providing user interface controls to switch</loc>
</p>
</item>
<item>
<p>
<loc href="G140"
linktype="general">Separating information and structure from presentation so that Web pages can be presented different ways without losing information</loc>
</p>
</item>
<item>
<p>
<loc href="PDF7" linktype="pdf"/>
</p>
</item>
</olist>
</div4>
<div4 role="tech-optional">
<head>Advisory</head>
<div5>
<head>General techniques for non-text content</head>
<olist>
<item>
<p>Identifying informative non-text content (future link)</p>
</item>
</olist>
</div5>
<div5>
<head>CSS Techniques</head>
<olist>
<item>
<p>
<loc href="C12" linktype="css">Using percent for font sizes</loc>
</p>
</item>
<item>
<p>
<loc href="C13" linktype="css">Using named font sizes</loc>
</p>
</item>
<item>
<p>
<loc href="C14" linktype="css">Using em units for font sizes</loc>
</p>
</item>
<item>
<p>
<loc href="C8" linktype="css">Using CSS letter-spacing to control spacing within a word</loc>
</p>
</item>
<item>
<p>
<loc href="C6" linktype="css">Positioning content based on structural markup</loc>
</p>
</item>
<item>
<p>Avoid applying text styling to text characters within a word (future link)</p>
</item>
</olist>
</div5>
</div4>
<div4 role="failures">
<head>Failures</head>
</div4>
</div3>
</div2>