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Variables, 2.5.1 Assigning values to variables

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Scripting basics 2 Variables 2.5 Variables Variables are containers for data. A variable might contain a number, a string, a list (or array), or an object reference. Variables have names, and you refer to a variable by its name. To put data into a variable, assign the data to the variable. The file name of the current Photoshop document or the current date are both examples of data that can be assigned to a variable. By using variables the scripts you write will be reusable in a wider variety of situations. As a script executes, it can assign data to the variables that reflect the state of the current document and selection, for example, and then make decisions based on the content of the variables. NOTE: In AppleScript, it is not important to declare your variables before assigning values to them. In Visual Basic and JavaScript, however, it is considered good form to declare all of your variables before using them. To declare variables in Visual Basic, use the Dim keyword. To declare variables in JavaScript, use the var keyword. 2.5.1 Assigning values to variables The remainder of this section shows how to assign values to variables. AS set thisNumber to 10 set thisString to "Hello, World!" VB Option Explicit Dim thisNumber As Long Dim thisString As String thisNumber = 10 thisString = "Hello, World!" The Dim statement assigns a value type to the variable, which helps keep scripts clear and readable. Memory is also used more efficiently if variables are declared before use. If you start your scripts in Visual Basic with the line Option Explicit, you will have to declare all variables before assigning data to them. You will not have to declare them the next time they are used. JS var x = 8; x = x + 4; var thisNumber = 10; var thisString = "Hello, World!"; The var keyword identifies variables the first time that you use the variable. The next time you use the variable you should not use the var keyword. Photoshop 7.0 Scripting Guide 14

Section	Page
Photoshop 7.0 Scripting Guide	1
Table of contents	3
Introduction	5
1.1 About this manual	5
1.1.1 Conventions in this guide	5
1.2 What is scripting?	6
1.3 Why use scripting?	6
1.4 What about actions?	6
1.5 System requirements	6
1.5.1 Mac	7
1.5.2 Windows	7
1.6 JavaScript	7
1.7 Choosing a scripting language	7
1.8 Legacy COM scripting	8
Scripting basics	9
2.1 Documents as objects	9
2.2 Object model concepts	9
2.2.1 Object classes	9
2.2.2 Object inheritance	10
2.2.3 Object elements or collections	10
2.2.4 Object reference	10
2.3 Documenting scripts	11
2.4 Values	12
2.5 Variables	14
2.5.1 Assigning values to variables	14
2.5.2 Using variables to store references	15
2.5.3 Naming variables	15
2.6 Operators	16
2.7 Commands and methods	17
2.7.1 Conditional statements	17
2.7.2 Control structures	18
2.8 Handlers, subroutines and functions	20
2.9 The Scripts menu	21
2.9.1 Scripts folder	21
2.9.2 The scripts dialog box	21
2.10 Testing and troubleshooting	23
2.10.1 AppleScript debugging	23
2.10.2 Visual Basic debugging	25
2.10.3 JavaScript Debugging	26
2.10.4 Error handling	31
Scripting Photoshop	33
3.1 Photoshop scripting guidelines	33
3.2 Viewing Photoshop objects, commands and methods	34
3.2.1 Viewing Photoshop’s AppleScript dictionary	34
3.2.2 Viewing Photoshop’s type library (VB)	35
3.3 Your first Photoshop script	36
3.3.1 AppleScript	36
3.3.2 Visual Basic	37
3.3.3 VBScript	39
3.3.4 JavaScript	41
3.4 Object references	42
3.4.1 AppleScript	42
3.4.2 Visual Basic and JavaScript	43
3.5 Working with units	44
3.5.1 Unit values	44
3.5.2 Unit value useage	46
3.5.3 Changing ruler and type units	48
3.6 Executing JavaScripts from AS or VB	48
3.6.1 Passing arguments to JavaScript	49
3.6.2 Executing one-line JavaScripts	50
3.7 The Application object	50
3.8 Document object	54
3.8.1 Saving documents and save options	55
3.8.2 Document information	56
3.8.3 Document manipulation	57
3.9 Layer objects	58
3.9.1 Setting the Active layer	61
3.9.2 Layer sets	61
3.9.3 Linking layers	62
3.9.4 Applying styles to layers	63
3.9.5 Rotating layers	63
3.10 Text item object	64
3.10.1 Setting the contents of the text item	65
3.10.2 Setting text stroke colors	66
3.10.3 Setting fonts	66
3.10.4 Warping text	67
3.11 Selections	67
3.11.1 Defining selections	68
3.11.2 Stroking the selection border	69
3.11.3 Inverting selections	70
3.11.4 Expand, contract and feather selections	70
3.11.5 Filling a selection	71
3.11.6 Rotating selections	72
3.11.7 Loading and storing selections	73
3.12 Working with Filters	74
3.12.1 Selecting channel(s) to filter	74
3.12.2 Other filters	75
3.13 Channel object	75
3.13.1 Channel types	75
3.13.2 Setting the active channel	76
3.13.3 Creating new channels	76
3.14 Color objects	77
3.14.1 Setting a Color	77
3.14.2 Getting and converting colors	78
3.14.3 Comparing Colors	79
3.14.4 Getting a Web Safe Color	79
3.15 History object	80
3.15.1 Filling a selection with a history state	81
3.16 Clipboard interaction	81
3.16.1 Copy	81
3.16.2 Copy merged	82
3.16.3 Cut	82
3.16.4 Paste	83
3.16.5 Paste into command	83
3.17 Action Manager scripting	84
3.17.1 Using the Action Manager from JavaScript	84
3.17.2 Using the Action Manager from VBScript	87

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Photoshop 7.0 Scripting Guide

Scripting basics

Variables

2.5 Variables

Variables are containers for data. A variable might contain a number, a string, a list (or array),

or an object reference. Variables have names, and you refer to a variable by its name. To put

data into a variable, assign the data to the variable. The file name of the current Photoshop

document or the current date are both examples of data that can be assigned to a variable.

By using variables the scripts you write will be reusable in a wider variety of situations. As a

script executes, it can assign data to the variables that reflect the state of the current document

and selection, for example, and then make decisions based on the content of the variables.

OTE

In AppleScript, it is not important to declare your variables before assigning values

to them. In Visual Basic and JavaScript, however, it is considered good form to

declare all of your variables before using them. To declare variables in Visual Basic,

use the

Dim

keyword. To declare variables in JavaScript, use the

var

keyword.

2.5.1 Assigning values to variables

The remainder of this section shows how to assign values to variables.

set thisNumber to 10

set thisString to "Hello, World!"

Option Explicit

Dim thisNumber As Long

Dim thisString As String

thisNumber = 10

thisString = "Hello, World!"

The

Dim

statement assigns a value type to the variable, which helps keep scripts clear and

readable. Memory is also used more efficiently if variables are declared before use. If you start

your scripts in Visual Basic with the line

Option Explicit

, you will have to declare all

variables before assigning data to them. You will not have to declare them the next time they

are used.

var x = 8;

x = x + 4;

var thisNumber = 10;

var thisString = "Hello, World!";

The

var

keyword identifies variables the first time that you use the variable. The next time

you use the variable you should not use the var keyword.