Stretch Control

You can use the Stretch control to change the size of the graphics in a Parameterized Artwork Macro (PAM). Stretching takes place relative to a control line that may be at any angle. You can stretch that shape in more than one direction by placing more than one stretch control on the same shape.

As with many controls, you must identify the shape(s) that you want to effect and add a control line (construction line) before you define the stretch parameters.

This chapter describes how you can use the placement of control lines and the selection of stretch parameters to manipulate shapes within a PAM.

Stretch Direction

You can define stretching as Positive, Negative, or Both. When you define stretching as Both, half of the requested distance is stretched to each side of the control line.

Stretch Orientation

Stretch orientation is defined relative to the stretch control line (construction line). Stretching takes place perpendicular to the control line.

If the control line is horizontal, stretching goes up/down.

If the control line is vertical, stretching goes left/right.

Even when the control line is at an angle, stretching is still perpendicular to it.

For details on positive and negative directions with regard to control lines, see Using Control Lines.

Moving a Shape with a Stretch

A control line does not have to intersect a shape. If a shape is to one side of the control line and is included in a stretch, the entire shape moves by the stretch amount, rather than being stretched.

All of original shape is to one side of the control line. After a positive stretch, the entire shapes has moved in the positive direction.

The Stretch control moves vertex points. When a control line intersects a shape, the vertices on the designated (positive or negative) side of the control line move, stretching the shape.

When the entire shape is to one side of the control line, all of the vertex points on the shape move in the same direction, by the same amount. This moves rather than stretches the shape. A stretch control is not limited to 90° angles, but can be at any angle.

Distance

Distance is the amount to stretch the shape(s). It can be a simple variable name (such as length ), or an expression that refers to other values. The amount of stretch can be either positive (vertex points move away from the stretch control line) or negative (vertex points move toward the stretch control line).

Offset

Offset is the amount to subtract from the entered length to compensate for the original size of the shape. This makes it possible for you to create a PAM using a shape with some size (so it is easy to work with), and use the PAM without needing to know its initial size.

For example, you create the PAM using a rectangle of length 100 and an offset of 100. When you use the PAM and enter a length of 50, you get a rectangle with a total length of 50 rather than 150. That is,

distance = length
offset = 100

is the same as:

distance = length - 100
offset = 0

Shape Response

Different shapes respond differently to a stretch. Most shapes are defined by vertex points that can be moved by the Stretch control. Polylines and paths are different, in that these are defined by a set of control points that the line or path follows. Polylines have no width to modify; a path's width is defined with respect to the control points. There are no vertex points to move, so a Stretch control cannot modify the width of a path.

Stretching a circle in any direction simply increases its diameter. But if you convert the circle to a polygon ( Edit > Modify > Convert to polygon ) first, the polygon stretches just like any other polygon.

Different Shapes Responding to a Stretch shows how different shapes respond to stretch using both a vertical (Length stretch) and horizontal (Width stretch) control line.