Page zooming

In computing, page zooming is the ability to zoom in and out a document or image at page level. It is usually found in applications related to document layout and publishing, e.g. word processing and spreadsheet programs, and is also found in web browsers. It can be used to improve accessibility for people with visual impairment and people using mobile devices which have a relatively small screen.

Different modes

There are two notably different modes of page zooming:

• text resizing that resizes the text by increasing or decreasing the font size, with wrapping to avoid horizontal scrolling, leaving the size of the images the same.
• real page zooming mode that resizes also images, other multimedia objects, and viewports.

User interface

Page zoom in LibreOffice Writer

The level of page zoom, expressed as a percentage, can often be accessed using a slider. Other methods include a drop-down menu from with a zoom level can be selected, pinch-to-zoom on touchscreen devices, mouse wheel scrolling (often in combination with holding down a key on the keyboard), or keyboard shortcuts (such as CTRL + +/-).

If the content becomes larger than the screen when zoomed in, a horizontal scroll bar may appear to allow the user to navigate.

Implementations in web browsers

Early web browsers had only the ability to resize the text on a page, but in the meantime all major browsers have the ability to resize the full content. The quality differs between the web browsers since they use different algorithms.

Some web browsers now have Zoom Text Only, for text resizing. It should alter all sizes given in em, ex, rem and ch, whatever they may refer to. If the page is carefully written, that can make the main text more readable without sending so much of the less important material outside the window.

Zooming of non-text media

Image viewing applications allow the user to zoom in on an area of an image. Most home entertainment media players of recent generations such as DVD and Blu-ray also include the ability to zoom in and out via buttons on a remote control, and to change the area of focus of the zoom.

See also

• Resolution independence, in which elements on a computer screen are rendered at sizes independent from the pixel grid
• Zooming user interface