Leader Lines

DRAW Reference Manual

Labels : Create and Manipulate Labels : Leader Lines

The label leader line can be drawn or omitted. The label leader is controlled by the LLEAder attribute. For example:

LLEA OFF
LLEA ON

The leader line can terminate with an arrow, a dot or nothing, at a definable distance from the attachment point; this distance can be specified by setting either the leader line clearance attribute (LLCL) or the attachment point offset (APOF) a position.

The terminator is controlled by the LTER attribute:

These commands set the Label’s LTER attribute, which is set to ‘no terminators’ by default.

The size of the terminator is controlled by the TSIZ attribute:


TSIZ 4	set size to 4mm (default 3mm)

The initial settings of LTER and TSIZ are cascaded down from LAYE level.

The leader line clearance (attribute LLCL, 0mm by default) is set as:


LLCL 4	clearance 4mm

The attachment point offset (APOF), unset by default, is set by commands, for example:


APOF 3 0	sets attachment point offset to be X3 Y0

Labels also have a POS attribute, which by default is unset. If the POS attribute is set, the 3D World position specified is used as the leader-line attachment point (rather than the DDNM and NPPT or DDNM, PKEY, and PKDI attributes). A DDNM attribute still has to be specified for the label to be properly defined. Labels can then be positioned at a calculated position (for example, in the centre of a Panel or half-way along a GENSEC) without having to determine the most suitable p-point or pline to reference.

The leader line can be straight or bent, with one or two bend point positions specified either explicitly (by defining either a specific point within the VIEW or an offset from the attachment point), or implicitly by specifying that the leader line is to contain a vertical or horizontal portion.

The illustration displays examples of commands used to specify the bend point explicitly.


LEAD BENT OFFS X7	Specify bend point as offset from Label attachment point
LEAD BENT OFFS X0 Y-60 X100 Y-60	Specify two bend points
LEAD BENT @	Specify bend point using cursor
LEAD BENT PT 2 @	Specify second of two bend points using the cursor
LEAD BENT PT 2 X722 Y40	Specify second of two bend points explicitly
LEAD BENT PT 1 OFF X15	Specify first of two bend points as offsets from Label attachment point
LEAD BENT PT 1 DEL	Delete first of two bend points
LEAD BENT @ @	Specify two bend points using cursor
LEAD STRAIGHT	Return to straight leader line

The commands set the Label’s LSHA (Leader Line Shape) and BPOF (Bend-Point Offset) attributes.

When defining two bend-points using a single command, the first point to be defined is the one nearest to the 3D labelled item. The BPOF attribute stores one or two pairs of coordinates defining the positions of the bend-points relative to the paper position of the p-point to which the label is attached. The LSHA attribute defines how the values stored in BPOF are to be interpreted. These attributes can be set (and queried) directly, for example:

LSHA BENT
BPOF -50 0 -75 25

When defining bend point 2 of two individual bend points, bend-point 1 is set to Offset X0 Y0 if it does not already exist. When deleting bend point 1, bend-point 2 (if it exists) is made the new bend-point 1.

Depending on the position of the bend point, the leader line connection point may change.

In the case of a bent leader line specified as having a horizontal or bent portion, the bend point is at the intersection of the horizontal/vertical part of the line and a sloping line drawn at a user-specified angle to the attachment point. The first of these two portions to be specified is at the end nearest to the attachment point. The portion of the leader line nearest to the connection point goes to a corner of the Label box if the horizontal/vertical portion is specified first, or to the middle of a box line if the horizontal/vertical portion is specified last. The example illustrates the commands involved and their results.

If a Label’s position relative to its attachment point is changed on Drawing regeneration, the leader line, if bent, is always drawn specially - you don’t necessarily have to redefine the bend point position.

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