Supported Edge Attributes

• OBJECT
• FONTFAMILY
• FONTSTYLE
• INFO
• EDGECOLOR
• EDGEPATTERN
• _DIR
• HEAD
• Pop-Up Menu

Edge Attribute "OBJECT"

This attribute is used to set an edge label. The label is displayed with the edge in grey in the background. When the edge is selected, the label is displayed in the foreground using the color of the edge. See node attribute OBJECT, too. The text, i.e. the attribute value, can be an arbitrary string. International characters are supported (ISO 8bit). Even multi-line text is possible using a "\n" character inside the attribute value. The default value for this attribute is the empty string "".

Edge Attribute "FONTFAMILY"

This is used to visualize the text of an edge label in a different font. Supported values are: "lucida" (default), "times", "helvetica", and "courier". See node attribute FONTFAMILY, too.

Edge Attribute "FONTSTYLE"

This is used to visualize the text of an edge label in a different font. Supported values are: "normal", "bold" (default), "italic", and "bold_italic". See node attribute FONTSTYLE, too.

EdgeAttribute "INFO"

This is used to define the tooltip text that appears after a delay when the mouse pointer is over the edge. Tooltips can be controlled with menu Layout/General Settings.... See node attribute INFO, too.

Edge Attribute "EDGECOLOR"

Can be used to define the color of an edge. The value of this attribute can be any X11 colorname on UNIX^® and LINUX^® platforms (see file lib/X11/rgb.txt in your X11 directory). On all platforms, a RGB color specification in a format like "#0f331e" can be used. Here, "0f" is the hexadecimal value for the red part of the color, "33" is the green part and "1e" is the blue part of the color. Hence, a palette of 16.7 million colors is supported. The default color for edges is "black". See node attribute COLOR, too.

Edge Attribute "EDGEPATTERN"

This attribute is responsible for setting different style information of the edge. The syntax is more complicated than the other attributes. The string value of the attribute has 4 parameters, separated by ";". Namely:

where:

So, to visualize an edge using a solid, double-lined spline with a width of 3 pixels, you use:
a("EDGEPATTERN","double;solid;3;1").

In former releases, the possible values for this attribute were "solid" (default), "dotted", "dashed", "thick" and "double". These old values are still supported for compatibility and are translated to the new style using the following conventions:

Edge Attribute "_DIR"

This attribute is used to control the arrow of an edge. In a graph visualization, each edge usually has an arrow pointing to the child node. This attribute can be used to let the arrow be drawn inverse (i.e. pointing to the parent), to get an arrow at both sides of an edge or to suppress arrows for a particular edge. The supported attribute values are: "last" (1 arrow pointing to the child, default), "first" (1 arrow to the parent), "both" (2 arrows to the parent and to children) and "none" (no arrows).

In former releases, the possible values for this attribute were "normal" (same as last, default), "inverse" (same as first), "both" (unchanged) and "node" (unchanged). These old values values are still supported for compatibility.

Edge Attribute "HEAD"

With this attribute you can control the shape of the edge's arrows. The possible values are: "farrow" (default), "arrow", "oarrow", "fcircle", and "circle", where a leading 'f' means filled and a leading 'o' means open.

Edge Attribute for Pop-Up Menu

This attribute defines a pop-up menu for an edge. This has to be done with a completely different syntax. Instead of using "a(...,...)", menus are defined with "m(menus)". The syntax for the menus parameter is described in the API documentation. The pop-up menu is displayed when the user presses the right mouse button over the edge. In this case, the ID of the menu is sent to the application, so this attribute does not make sense when no application is connected to the API. Please take a look in the section about user interface extension for further information regarding menus. See node attribute for pop-up menus, too.