Welcome to Part 2 of our new series, in this post we will discuss the creation of hotspots and the graphic file formats supporting their inclusion.
There are two main ways of creating hotspots on graphics the first is to create an overlay for a raster graphic e.g. TIFF. This was probably the most popular technical manual solution; however, the task required substantial work and had the complication of two files trying to work together. In this series, we will concentrate on the second option where meta-data is embedded into the graphic. There is still work required with this method however only one file, the graphic is required. There is also the opportunity to use a second file, usually an XML companion file to extend the information available about the graphic. There are only two graphic formats that support the inclusion of hotspot meta-data. They are CGM (Computer Graphics Metafile) and SVG (Scalable Vector Graphic). The CGM format has a few versions but only version 4 can contain the hotspot meta-data. The SVG format is based on XML (Extensible Mark-up Language), the hotspot information is contained as specific tagged elements inside the SVG file.
How do we add hotspot information to a CGM file, if you have the correct software it is a relatively easy task? The software required is usually specialized, not mass-market graphics software.
How do we create a hotspot on a CGM graphic and where is it positioned to provide enhanced functionality? The most common hotspot is found on spare parts illustrations.
The hotspot enables a link to be forged with text, in other words, the parts list.
The first task is to add the hotspot to the graphic, Fig 2 is a good example. The hotspot is usually the callout number because the text is a graphic element, we can select in this case number 3 and then add the meta-data information. Figure 2 shows we’ve selected number 3 and the associated properties. The Id, Name is mandatory, the screen tip is optional, the Id is a unique identifier for this graphic, the name field can be more descriptive. The screen tip will appear when the user hovers over the hotspot in a viewing environment. However, the appearance of the screen tip is dependent on the viewing environment used. The hotspot is now active, the associated task will be performed when the end user clicks the sensitive area.
The addition of hotspots to SVG files is a bit more problematic. There is no software that can do this in the general graphics arena. The best solution use specialist software capable of adding hotspots to CGM’s, you can now save the file as an SVG and the hotspots should be preserved in the XML.
In conclusion, Part 2 described the creation hotpots, and the file formats capable of supporting meta-data, CGM and SVG. In Part 3, we will discuss the additional Hotspot Properties, companion files and the code required to link the hotspot to the text.
