IS provides mechanisms to simplify use of HTML image maps. The JAVA-based and Flash-based viewers in IS also include limited support for image maps.
Source image maps are provided to IS either via
catalog::Map or with the
map= command, and processed maps are retrieved using the
An image map consists of one or more HTML AREA elements, properly delimited with ‘<’ and ‘>’. If provided via catalog::Map, all pixel coordinates values are assumed to be in the original image resolution and relative to the top left corner of the (unmodified) source image. When provided via a
map= command, the coordinate values are assumed to be layer coordinates, relative to the top-left corner of the layer (after
% coordinates are not permitted at this time and may be processed incorrectly.
IS generates a composite image map from the source image maps of each constituent layer by applying the spatial transformations (such as scaling and rotation) to the map coordinates, and then assembling the processed layer maps in the appropriate z-order (front to back) and with the appropriate positioning.
The following commands are considered for image map processing when provided in conjunction with
req=map (either directly in the request, via catalog templates, or in
All other commands are effectively ignored.
COORDS attributes of an
AREA may be modified during processing of a
req=map request, all other attributes of the
AREA element are passed without modification. In most cases this involves changing the
SHAPE value from
RECT (this would also add the
COORDS attribute), or changing the
AREA elements which become empty during processing are removed entirely. If a map is associated with
layer=comp it is placed behind all other maps. The data is returned in text form one as or more HTML
AREA elements. An empty reply string indicates that no image map exists for the specified object(s).
Layer transparency is not considered for map processing. A fully transparent layer can still have an image map associated with it. The map of a partially transparent layer will not be clipped to the transparent regions.