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Variables

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Scripting basics 2 Variables 2.6 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. 2.6.1 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 CS Scripting Guide 20

Section	Page
Photoshop CS 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?	7
1.4 What about actions?	7
1.5 System requirements	8
1.5.1 Mac	8
1.5.2 Windows	8
1.6 JavaScript	9
1.7 Choosing a scripting language	9
1.8 Legacy COM scripting	10
1.9 New Features	10
1.10 What’s Next	11
Scripting basics	12
2.1 Documents as objects	12
2.2 Object model concepts	12
2.2.1 Object classes	12
2.2.2 Object inheritance	13
2.2.3 Object elements or collections	13
2.2.4 Object reference	13
2.3 Object Model	14
2.3.1 Additional Containment Classes	16
2.3.2 Hello World Sample Scripts	18
2.4 Documenting scripts	21
2.5 Values	22
2.6 Variables	24
2.6.1 Assigning values to variables	24
2.6.2 Using variables to store references	25
2.6.3 Naming variables	25
2.7 Operators	26
2.8 Commands and methods	26
2.8.1 Conditional statements	27
2.8.2 Control structures	28
2.9 Handlers, subroutines and functions	29
2.10 Debugging and Error Handling	30
2.10.1 AppleScript debugging	31
2.10.2 Visual Basic debugging	32
2.10.3 JavaScript Debugging	33
2.10.4 Error handling	33
2.11 What’s Next	34
Scripting Photoshop	35
3.1 Photoshop scripting guidelines	35
3.2 Viewing Photoshop objects, commands and methods	35
3.2.1 Viewing Photoshop’s AppleScript dictionary	36
3.2.2 Viewing Photoshop’s type library (VB)	37
3.2.3 Viewing the JavaScript Environment	37
3.3 Your first Photoshop script	39
3.3.1 AppleScript	39
3.3.2 Visual Basic	40
3.3.3 VBScript	42
3.3.4 JavaScript	43
3.4 Advanced Scripting	45
3.4.1 Advanced JavaScript	45
3.4.2 Advanced Visual Basic	50
3.4.3 Advanced AppleScript	54
3.5 Object references	59
3.5.1 AppleScript	59
3.5.2 Visual Basic and JavaScript	60
3.6 Working with units	61
3.6.1 Unit values	61
3.6.2 Unit value useage	64
3.6.3 Changing ruler and type units	65
3.7 Executing JavaScripts from AS or VB	66
3.7.1 Passing arguments to JavaScript	67
3.7.2 Executing one-line JavaScripts	68
3.8 The Application object	68
3.9 Document object	72
3.9.1 Saving documents and save options	72
3.9.2 Document information	74
3.9.3 Document manipulation	75
3.10 Layer objects	76
3.10.1 Setting the Active layer	79
3.10.2 Layer sets	79
3.10.3 Linking layers	80
3.10.4 Applying styles to layers	81
3.10.5 Rotating layers	81
3.11 Text item object	81
3.11.1 Setting the contents of the text item	83
3.11.2 Setting text stroke colors	84
3.11.3 Setting fonts	84
3.11.4 Warping text	85
3.12 Selections	85
3.12.1 Defining selections	86
3.12.2 Stroking the selection border	88
3.12.3 Inverting selections	88
3.12.4 Expand, contract and feather selections	88
3.12.5 Filling a selection	90
3.12.6 Rotating selections	91
3.12.7 Loading and storing selections	91
3.13 Working with Filters	92
3.13.1 Selecting channel(s) to filter	92
3.13.2 Other filters	93
3.14 Channel object	93
3.14.1 Channel types	93
3.14.2 Setting the active channel	94
3.14.3 Creating new channels	94
3.15 Color objects	95
3.15.1 Setting a Color	95
3.15.2 Getting and converting colors	97
3.15.3 Comparing Colors	98
3.15.4 Getting a Web Safe Color	98
3.16 History object	98
3.16.1 Filling a selection with a history state	99
3.17 Clipboard interaction	100
3.17.1 Copy	100
3.17.2 Copy merged	100
3.17.3 Cut	101
3.17.4 Paste	101
3.17.5 Paste into command	102