Vertices and edges have a number of attributes which may be edited by the user. Each edge has a color, weight, flow, capacity (cap) and minimum (min). Weight is synonymous with cost, and here we use the term minimum instead of lower bound. Each vertex has a color, demand and label. Its label is the ``name'' assigned to the vertex.
The panel of controls that allows users to choose which attributes should be displayed and to edit those attributes is called a GraphControlPanel. Figure 2 shows the GraphControlPanel, which is displayed across the top of the screen. This panel contains a number of checkboxes which may be checked to indicate which attributes should be displayed. For example, checking the weight checkbox will cause the weight for each edge to be displayed. Although the color of each edge and each vertex is always displayed, any combination (or none) of the other attributes may be displayed at any time. Notice that the weight, demand, and label checkboxes are checked in Figure 2. Also note that these attributes are displayed in Figure 1.
Figure 2: GraphControlPanel on the Sun platform
When the label checkbox is checked, a text box appears below the checkbox. When any other checkbox is checked, a selectable NumberLabel appears below the checkbox. There are also NumberLabels designated color, radii, and font. Clicking on a NumberLabel will highlight the number and allow users to adjust that number using the scrollbar. Only one NumberLabel may be selected at a time. In Figure 2, the NumberLabel for demand has been selected.
Whenever a user creates a vertex or edge, the current values of the NumberLabels are used to initialize the attributes of the new vertex or edge. The attributes of any existing edge or vertex may also be modified by users. To modify vertex labels, the vertex is first selected and then the new label is typed in the text box. To edit the other attributes, the desired edge or vertex is first selected, the appropriate NumberLabel is clicked, and then the displayed number is adjusted with the scrollbar.
The radii and font NumberLabels are used to adjust the radii of the vertices and the font size of attributes. Changing either the radii or font NumberLabel will affect every vertex and edge in the graph.