Nodes are displayed using a combination of several icons in a 64x64 square. Icons need not be square: they may use transparent pixels to be displayed with different shapes.
| Attribute | Description |
|---|---|
| icon | This is the main icon, for example, a flag or a person. It should be 48x48. |
| background_icon | This is the background icon, typically a square or circle. It should be 56x56. This icon is combined with the color, so background icons are usually shades of white. |
| color | The background icon is combined with this color. |
| selected | This icon is used by Constellation to indicate that a node is selected. This cannot be changed. |
The sizes specified above are indicative; for instance, an icon of a tree may be higher than 48 pixels and narrower than 48 pixels. However, in general the icon should be smaller than the background icon, which in turn should be smaller than the selected icon.
Constellation has its own built-in set of icons. You can also augment the icons with your own personal icons. However, you cannot override a built-in icon with your own custom icon. Custom icons can be PNG or JPG format.
In your .CONSTELLATION directory is a a subdirectory "Icons". When Constellation starts, it looks in this directory for custom icons.
Icon names must be categorised. For example, "Person.DoctorWho.png" is in the Person category, whereas "Vehicle.DoctorWho.Tardis.png" is in category Vehicle, subcategory DoctorWho. The icon selection dialog uses the categories to organise the icons, so an icon called "MyIcon.png" will not be used.
Icons can be any size, however any icon greater than 48 pixels in width or height will be automatically reduced to no more than 48 pixels. Because of this restriction, custom 56x56 background icons cannot be used.
Icons are specified by name in the "icon" attribute. For instance, to display the custom Doctor Who icon above, use "Person.DoctorWho" as the icon attribute value.
Icons can also be referred to by their alias, which is just the last part of the name. This means that the icon attribute value "DoctorWho" will also display the "Person.DoctorWho" icon.
If there is more than one icon with the same alias (e.g. "Person.DoctorWho" and "TVSeries.DoctorWho"), an arbitrary decision will be made as to which one to use.
Included in the built-in icons are the ASCII characters 32 (space) to 126 (tilde) in the "Char" category. These icons are white on a transparent background, so when they are used as values of the "background_icon" attribute, their color can be changed using the "color" attribute.