A Schema for Pie Menus - by Don Hopkins Pie Menus are a naturally efficient user interface technique: directional selection of pie slice shaped targets. The cursor starts out in the center of the pie, so all targets are large, nearby, and in different directions. Fitts' Law explains the advantages of pie menus, relating fast selection speed and low error rate to large target size and small distance. Pie menus are easy for novice users, who just follow the directions, and efficient for experienced users, who can quickly "mouse ahead" once they know the way. The html element contains XHTML (HTML in XML syntax), that is used for the pie menu presentation, contained in both piemenu and item elements. The piemenu element contains a pie menu definition, including an optional html element, followed by any number of item elements. HTML Element Content in Center of Pie Menu. If empty, the piemenu Name is shown instead. The piemenu element may contain any number of item elements. Pie Menu View. Pie Menu Unique ID. Pie Menu Name, shown if the HTML Content is empty. Clockwise Layout Direction (false for CCW). Initial Angle for Pie Menu Layout. 0 is right, 90 is up, 180 is left, 270 is down. Fixed Radius for Pie Item Layout (0 to Disable). Overrides calculated radius. Minimum Radius for Pie Item Layout. Overridden by non-zero Fixed Radius. Extra Radius for Pie Item Layout. Overridden by non-zero Fixed Radius. Inactive Radius of Pie Menu Center, where no item is selected. Radius Notch for Pie Item Layout. Overridden by non-zero Fixed Radius. Border around Menu for Pie Item Layout. Maximum Number of Pie Items. Extra items are treated as Linear. Number of Pie Items Paged. Previous items are treated as Linear. Pie Menu Linear Flag. Default for all items. Direction of Linear Item Layout. Default for all items. Reversed Linear Order Layout Flag. Default for all items. Make Unselected Items Transparent During Tracking. Border Around Items for Pie Item Layout. Default for all items. Margin Inside Items for Pie Item Layout. Default for all items. Fixed Item Width for Pie Item Layout (0 for Measured). Default for all items. Fixed Item Height for Pie Item Layout (0 for Measured). Default for all items. Item Normal Background Color. Default for all items. Item Selected Background Color. Default for all items. Pie Menu Center Background Color. Pie Menu Center Margin. Pie Menu Center Border Width. Pie Menu Center Visibility Flag. URL for Pie Menu Selection. Default for all items. Action for Pie Menu Item Selection. Default for all items. Handler for Pie Menu Item Selection (Called After Selection). Default for all items. Handler for Pie Menu Item Change (Called Before Selection). Default for all items. Handler for Pie Menu Item Preview (Called After Mouse Movement). Default for all items. The item element contains a pie menu item definition, including an optional html element, followed by an optional piemenu element. HTML Element Content in Pie Menu Item. If empty, the item Name is shown instead. The item element may contain an optional piemenu element. Pie Item View. Pie Menu Item Unique ID. Pie Menu Item Name, shown if the HTML Content is empty. Pie Menu Item Linear Flag. Fixed Radius for Pie Item Layout (0 to Disable). Fixed Item Width for Pie Item Layout (0 for Measured). Fixed Item Height for Pie Item Layout (0 for Measured). Item Normal Background Color. Item Selected Background Color. Direction of Linear Item Layout. Reversed Linear Order Layout Flag. URL for Pie Menu Item Selection. Action for Pie Menu Item Selection. Handler for Pie Menu Item Selection (Called After Selection). Handler for Pie Menu Item Change (Called Before Selection). Handler for Pie Menu Item Preview (Called After Mouse Movement). The top level piemenu element contains a pie menu definition, including an optional html element, followed by any number of item elements.