The Symbol Editor for Roles works similarly to the normal Symbol Editor, except for a few details presented in this section.

When opened for an empty role symbol, the Symbol Editor has a line coming from the left side of the drawing area. This line represents the role line coming from an imaginary relationship left of the picture, and ending at an imaginary object in the center of the picture. The role symbol should be defined relative to the end of the line, because the end represents the position where the role line will stop as it connects to the object symbol. Symbol elements should not normally be placed to the right of the end of the line, as they would then be on top of the object symbol. The symbol should look as it would when pointing horizontally from left to right: role symbols are rotated according to the angle of the role line.

It is also possible to have and edit multiple role lines in the Role Symbol Editor. This is useful if you want to construct a visually more complex role line or need to change the role line visualization dynamically. An example that requires both of these aspects, the Road role from our Roadmap example, is shown in Figure 3–23.

There is no need to define Connectables for role symbols, and thus there are no toolbar buttons for them. Otherwise the Symbol Editor for Roles works as an ordinary Symbol Editor, with the exceptions and additional features explained in the next few sections.

You can edit the individual role normally by selecting it (for precise selection, use the tab key or select the roleline from the list on the sidebar) and using the usual selection editing tools from the toolbar, menu bar, popup menu or formatting bar. Alternatively, to add, remove, organize and change the appearances of role lines, select Format | Format Role Lines... from the menu bar or press Ctrl+R. This will open the Format Role Lines dialog, as shown in Figure 3–24.

The Format Role Lines dialog lets you manage and format all the role lines separately from other symbol elements. The Role Lines list displays the currently defined role lines on the left while the format dialog on the right provides the usual Line and Fill and Condition tabs, for the currently selected role line. To add a new role to the Role Lines list, press the Add button at the bottom-left corner of the dialog and to remove one, press the Remove button. Commands for adding and removing role lines are available also in the Role Lines list’s popup menu with commands Bring to Front, Send to Back, Bring Forwards and Send Backward that reorganize the Z-order of role lines. The first role line in the list is drawn first, and subsequent ones are displayed on top of it; each role line is only displayed if its condition is fulfilled.

To align an element precisely with the end of the role line, select the element and then select Align | To Role Line End (or press Ctrl-L). The midpoint of the right hand side of the element will be aligned with the right end of the role line.

When building symbols for roles, you must take into account the rotation of role symbols with their lines. For most elements there are two options for rotating: a true rotation along the role or just moving around the line without rotating. The text fields are an exception to this: as text is only printed horizontally, they can not rotate.

To set the rotation behavior of an element, open the Format Dialog for it. Open the Rotation tab and check or uncheck the Allow element to rotate box as needed.

As an example, imagine a low, wide element above the end of the role line. In a role that points down in a diagram, that element will always be to the right of the role line: its center point has been rotated relative to the end of the role line, just like the role line itself. If the element is set to rotate, it will now be tall and thin. If the element is set not to rotate, it will remain low and wide, and thus may even partially cross the role line. Such effects must be taken into account with elements that do not rotate, and are not roughly as wide as they are tall.