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Example Disclosure (Show/Hide) for Image Description

Example Disclosure (Show/Hide) for Image Description

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The code in this example is not intended for production environments. Before using it for any purpose, read this to understand why.

This is an illustrative example of one way of using ARIA that conforms with the ARIA specification.

About This Example

The following example demonstrates using the Disclosure Pattern to provide a way of revealing a table of data that complements an image.

Similar examples include:

Example

Charles Minard's 1869 chart showing the number of men in Napoleon’s 1812 Russian campaign army, their movements, as well as the temperature they encountered on the return path.

Figurative Map of the successive losses in men of the French Army in the Russian campaign 1812-1813. Drawn by Mr. Minard, Inspector General of Bridges and Roads in retirement. Paris, 20 November 1869.

The numbers of men present are represented by the widths of the colored zones in a rate of one millimeter for ten thousand men; these are also written beside the zones. Red designates men moving into Russia, black those on retreat.

The information used for drawing the map were taken from the works of Messrs. Thiers, de Ségur, de Fezensac, de Chambray and the unpublished diary of Jacob, pharmacist of the Army since 28 October.

In order to facilitate the judgement of the eye regarding the diminution of the army, I supposed that the troops under Prince Jèrôme and under Marshal Davoust, who were sent to Minsk and Mobilow and who rejoined near Orscha and Witebsk, had always marched with the army.

Note: A French translation from Wikipedia.

Data for Charles Minard's Chart of Napoleon's Invasion of Russia

Location Approximate Date Size of Army Temperature C Temperature F Direction
Kowno River June 24th 442,000 na na Advance
Wilna June 30th 400,000 na na Advance
Witebsk na 175,000 na na Advance
Smolensk August 16th 145,000 na na Advance
Chjat na 127,000 na na Advance
Mojaisk September 7th 100,000 na na Advance
Moscow September 14th 100,000 na na Advance
Malo-jarosewli October 18th 96,000 0 32 Retreat
Mojaisk October 24th 87,000 0 32 Retreat
Wirma na 55,000 na na Retreat
Smolensk November 14th 37,000 -26 -13 Retreat
Orscha na 24,000 na na Retreat
Botr na 20,000 -14 -7 Retreat
Studienska (reinforcements arrive) December 1st 50,000 -25 -13 Retreat
Minsk December 1st 28,000 -30 -22 Retreat
Moloderno December 6th 28,000 -38 -34 Retreat
Smorgeni December 7th 12,000 -33 -27 Retreat
Wilna na 8,000 na na Retreat
Kowno (reinforcements arrive) December 14th 10,000 na na Retreat

Accessibility Features

  • To help people with visual impairments identify the disclosure as interactive and make it easier to perceive that clicking either the disclosure button or its label changes the expanded state, when a pointer hovers over the button or its label, the background color changes, a border appears, and the cursor changes to a pointer.
  • Because transparent borders are visible on some systems with operating system high contrast settings enabled, transparency cannot be used to create a visual difference between the element that is focused an other elements. Instead of using transparency, the focused element has a thicker border and less padding. When an element receives focus, its border changes from 0 to 2 pixels and padding is reduced by 2 pixels. When an element loses focus, its border changes from 2 pixels to 0 and padding is increased by 2 pixels.
  • To ensure the inline SVG arrow graphics in the CSS have sufficient contrast with the background when high contrast settings invert colors, the color of the arrows are synchronized with the color of the text content. For example, the color of the arrow is set to match the foreground color of high contrast mode text by specifying the CSS currentcolor value for the stroke and fill properties of the polygon elements used to draw the arrows. If specific colors were instead used to specify the polygon properties, those colors would remain the same in high contrast mode, which could lead to insufficient contrast between the arrows and the background or even make the arrows invisible if the color matched the high contrast mode background.
    Note: The SVG element needs to have the CSS forced-color-adjust property set to auto for the currentcolor value to be updated in high contrast mode. Some browsers do not use auto for the default value.

Keyboard Support

Key Function
Tab Moves keyboard focus to the disclosure button.
Space or
Enter 		Activates the disclosure button, which toggles the visibility of the long description.

Role, Property, State, and Tabindex Attributes

Role Attribute Element Usage
aria-controls="ID_REFERENCE" button Identifies the element controlled by the disclosure button.
aria-expanded="false" button
  • Indicates that the container controlled by the disclosure button is hidden .
  • CSS attribute selectors (e.g. [aria-expanded="false"]) synchronize the visual states with the value of the aria-expanded attribute.
  • The visual indicator of the show/hide state is created using the CSS :before pseudo element and the content property so the image is reliably rendered in high contrast mode of operating systems and browsers.
aria-expanded="true" button
  • Indicates that the container controlled by the disclosure button is visible.
  • CSS attribute selectors (e.g. [aria-expanded="true"]) synchronize the visual states with the value of the aria-expanded attribute.
  • The visual indicator of the show/hide state is created using the CSS :before pseudo element and the content property so the image is reliably rendered in high contrast mode of operating systems and browsers.

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This is an unpublished draft preview that might include content that is not yet approved. The published website is at w3.org/WAI/.