Intelligent Label Placement

DRAW Reference Manual

Labels : Intelligent Label Placement

A facility is provided to ‘tidy up’ crowded labelling, so as to minimise Label overlap and leader-line crossing. As well as changing label positions the facility can also change Label orientations, text justifications and alignments, and the definition of leader-line shapes and bend-points. The facility uses two versions of the SPREAD command, which can be used to position Labels locally or remotely.

With local positioning, Labels are positioned around their significant design elements in such a way as to minimise Label overlap and leader-line crossing. Labels are not moved from their initial positions unless it is necessary. If they are moved then, as far as possible, leader lines are straight and at ± 45° to the VIEW axis.

The example illustrate poorly positioned labels and the results of local spreading.

In the example, the command

SPREAD LOCAL SELECT INSIDE @ @

is used to define a window within which the labels to be repositioned lie. By default, the Labels are offset by 25mm (in the X and Y directions) from the Label attachment point. The SPREAD LOCAL command can be used with the AVEVA E3D™ general selection syntax (refer to Model Reference Manual for further information). Other variations of the SPREAD LOCAL command are:


SPREAD LOCAL SELECT ID @ ID @	Use cursor to identify (two) Labels to be spread.
SPREAD LOCAL OFFSET 10	Change Label spread offset to 10mm (X and Y directions)
SPREAD LOCAL XOFFSET 15	Change Label spread offset to 10mm (X direction only)
SPREAD LOCAL RADIUS 20	Specify Label spread offset indirectly by giving a diagonal length

With remote positioning, labels are positioned around the VIEW border. It is possible to define a margin outside the VIEW frame that defines the positioning of the Labels. It is also possible to define a side of the VIEW frame alongside of which repositioned Labels are not placed, and the minimum permissible gap between any two Labels can also be specified.

Labels are repositioned at the (allowed) VIEW side nearest to their attachment points. Labels along the top and bottom sides are rotated through 90° (readable from the right-hand side) unless otherwise specified. To avoid overlapping, some leader lines are doglegged at 45°.

Examples of the SPREAD REMOTE command are:


SPREAD REMOTE SELECT ID @ ID @	Use cursor to identify (two) Labels to be spread.
SPREAD REMOTE SELECT INSIDE @ @	Use cursor to specify corners of window enclosing Labels to be spread.
SPREAD REMOTE REPOSITION @ @	Use cursor to specify corners of rectangle around which Labels are to be repositioned (can be outside or inside of VIEW border).
SPREAD REMOTE MARGIN 10	Reposition Labels within 10mm of VIEW border
SPREAD REMOTE OMIT TOP	Prevent Labels being placed alongside the top side of the rectangle around which they are to be repositioned.
SPREAD REMOTE GAP 5	Specify 5mm as minimum gap between any two Labels.
SPREAD REMOTE NOROT	Prevent Labels from being rotated by 90°.

Note:

All options must be specified on the same command line; the previous SPREAD parameter settings are not remembered.