How to Adjust Callouts for Interactive Images in iBooks Author
The interactive image widget object in iBooks Author enables you to use rollovers, where a title and description appear when the pointer rolls over a certain spot, though it works a bit differently. In iBooks Author, you can add titles and optional descriptions (together called callouts by publishers and labels by iBooks Author) to an image or diagram. When the e-book’s reader taps the image or diagram, a detailed description is displayed, and the reader can zoom and/or move the focus of the image, such as to get a close-up view.
Although the use of callouts with descriptions is the default presentation method for interactive images, you can have them appear in a translucent sidebar on the left side of the interactive image instead. You can do so in a couple of ways:
Select the Show Descriptions in Sidebar option in the Widget inspector’s Interaction pane.
Choose Format→Interactive Image→Show Description in Sidebar.
This sidebar presentation for descriptions is handy when you have long descriptive text, but note that it does obscure quite a bit of your image, so you trade off image focus for text space. When this view is enabled, the callouts show only their titles, even when tapped; their descriptions appear in just the sidebar.
There’s an additional aspect of the callout display to consider: Its accessibility descriptions. A visually impaired reader hears these descriptions spoken aloud when he navigates to the callout, assuming the iPad’s VoiceOver feature is enabled. It’s essentially the verbal display for the image view.
In the Widget inspector’s Interaction pane, the Accessibility Description pop-up menu (toward the bottom) has just one option for the default view: Background. Any text you enter in the field below is read aloud when the e-book’s reader navigates to the interactive image’s default view.
For each image view, the Accessibility Description pop-up menu has three options, one for each component of a callout: Label Title, Label Description, and Label Target. Choose each option in turn and enter the text in the field below for what’s read aloud when the e-book reader navigates to, respectively, the callout title, the callout description, and the endpoint of the callout line (the label target).