Adobe InDesign CS4 Scripting Tutorial
Scripting and the InDesign object model
16
Functions and handlers
Functions
(in VBScript or JavaScript) or
handlers
(in AppleScript) are scripting modules you can refer to
within your script. Typically, you send a value or series of values to a function (or handler) and get back
some other value or values. The code used in functions and handlers is simply a convenience to avoid
having to type the same lines of code repeatedly in your script.
In AppleScript, handlers start with
on
. In JavaScript and VBScript, functions start with
function
.
Understanding the InDesign object model
When you think about InDesign and InDesign documents, you probably organize the program and its
components in your mind. You know paragraphs are contained by text frames which, in turn, appear on a
page. A page is a part of a spread, and one or more spreads make up a document. Documents contain
colors, styles, layers, and master spreads. As you think about the layouts you create, you intuitively
understand there is an order to them.
InDesign “thinks” about the contents of a document in the same way. A document contains pages, which
contain page items (text frames, rectangles, ellipses, and so on). Text frames contain characters, words,
paragraphs, and anchored frames; graphics frames contain images, EPS files, or PDF files; and groups
contain other page items. The things we mention here are the
objects
that make up an InDesign
publication, and they are what we work with when we write InDesign scripts.
Objects in your publication are arranged in a specific order: frames are on pages, which are inside a
document, which is inside the InDesign application object. When we speak of an
object model
or a
hierarchy
, we are talking about this structure. Understanding the object model is the key to finding the
object you want to work with, and your best guide to InDesign scripting is your knowledge of InDesign
itself.
Objects have
properties
(attributes). For example, the properties of a text object include the font used to
format the text, the point size, and the leading applied to the text.
Properties have values; for example, the point size of text can be either a number (in points) or the string
“Auto” for auto leading. The fill color property of text can be set to a color, a gradient, a mixed ink, or a
swatch.
Properties also can be
read/write
or
read only
. Read/write properties can be set to other values; read only
properties cannot.
Objects also have
methods
—the verbs of the scripting world, or the actions an object can perform. For
example, the document object has print, export, and save methods.
Methods have
parameters
, or values that define the effect of the method. For example, the place method
of a document has a parameter that defines the file you want to place. Parameters can be
required
or
optional
, depending on the method.
The following figure is an overview of the InDesign object model. The diagram is not a comprehensive list
of the objects available to InDesign scripting; instead, it i s a conceptual framework for understanding the
relationships between the types of objects.
