This chapter is from the book
This chapter is from the book
This chapter is from the book
Three Scripting Languages
Creative Suite is somewhat singular in that it supports not one but three scripting languages: AppleScript, JavaScript, and VBScript. Why go to all the trouble when most programs only support one? To its credit, Adobe has done its best to meet the needs of the entire creative community by providing multiple avenues into scripting its programs.
AppleScript
Made by Apple (who else?) and only capable of running on Macs, AppleScript's claim to fame is its similarity to the English language—which should make it easier to learn than other scripting languages. Like all marketing claims, however, this one should be taken with a healthy dose of skepticism. Like English, AppleScript also can be convoluted, offers many ways of saying the same thing, and at times makes absolutely no sense (at least to me).
On the plus side, a wealth of AppleScript learning resources and free scripts for Creative Suite are available. What's more, if a Macintosh graphics program supports scripting, it probably supports AppleScript. Plus, you can use AppleScript to control multiple applications simultaneously; it is a relatively easy scripting language to start learning; and nonprogrammers will find it easier to get the gist of what AppleScript is saying and doing than with the other scripting options.
JavaScript
Hailing from the Web side of the tracks, JavaScript is often used to create dynamic, interactive Web pages—and it was dynamic and interactive long before Flash was born. Although its name suggests a relationship with the Java programming language (and Sun Microsystems licenses both), JavaScript and Java actually have little in common. JavaScript is the only one of the three languages we're looking at that works on both Macs and PCs, and that feature alone makes it very attractive.
In addition to producing great free instructional PDFs for all three scripting languages, Adobe publishes the Creative Suite JavaScript reference in book form. And with Creative Suite 3, Adobe has even included a robust script editor for JavaScript. There are also plenty of free JavaScripts on the Web for Creative Suite, and its relatively strong user base means that you have a built-in support group.
Like Microsoft and its JScript brand of JavaScript, Adobe has implemented its own version of JavaScript, called ExtendScript. It is basically JavaScript that's been "extended" to add a few additional features and it works across the board with all Creative Suite applications.
On the minus side, ExtendScript can only control one application per script (unless you're using the ExtendScript Toolkit; see the sidebar on page 55). JavaScript can be confusing to the nonprogrammer because it may look too "programmy." And most of the JavaScript learning resources you'll find are focused on building Web pages and making interactive forms in Adobe Acrobat. In fact, you'd be hard pressed to find learning resources other than Adobe's on topics other than writing JavaScripts for Web pages or Acrobat. That is a serious limitation at times.
VBScript
If you know the Visual Basic programming language, you'll pick up the Windows-only VBScript easily, because it was derived from Visual Basic. I suspect that most people who script Creative Suite with VBScript either already know it from another context or are Visual Basic programmers. There are practically no VBScript learning resources or free scripts for Creative Suite and, as with JavaScript, you can only control one application at a time with VBScript.
Mom Likes Photoshop Best
Photoshop has gotten more than its fair share of scripting privileges, with three useful tools (and some extra features in ExtendScript) that should really be available in the other Creative Suite applications as well.
Script Events Manager
Photoshop contains a little-known tool called the Script Events Manager for automatically triggering JavaScripts—and Actions—based on Photoshop events, such as creating a new document, starting the application, or exporting a document. The Script Events Manager comes loaded with seven predefined events. But if you look in the appendix of the JavaScript Reference Guide.pdf manual that comes with Photoshop, you'll find a list of more than 200 events that you can access.
To use this tool, choose File > Scripts > Script Events Manager (Figure 4.1). This utility is an event-based triggering mechanism. Instead of running a script from an editor or double-clicking the script file, the Script Events Manager keeps an eye peeled, and when the event you specified occurs, it automatically takes your script (or action) by the shoulder and puts it in the game.
)
Figure 4.1 Photoshop's Script Events Manager lets you set scripts or actions to run when a specified event occurs, such as opening a Photoshop document or starting the application.
Scripting Listener Plug-In
The free Scripting Listener plug-in "listens" to everything you do in Photoshop and writes a log or text file in JavaScript (Mac) or JavaScript and VBScript (Windows). The code it writes, while usable, is hardly easy to read for the beginner. Even though you might not be able to completely understand the code, it is a great way to quickly "write" a script for a process without a lot of good prewritten resources. For instance, scripting filters is not documented very well, and the code that the Scripting Listener plug-in writes will show you how it's done.
To activate the Listener, find the plug-in called Scripting-Listener.plugin, located in the folder Adobe Photoshop CS3 > Scripting Guide > Utilities and drag it into the folder Adobe Photoshop CS3 > Plug Ins > Automate (Figure 4.2). Restart Photoshop, and you'll see the ScriptingListener.log on your desktop (if you're using Mac OS X) or at the root of your C: drive (if you're using Windows). Do something in Photoshop (for example, open a new file) and then double-click the log file, copy the text you find there, paste it into a script editor, and see what happens when you run it. Since the code is so hard to read, you might want to copy and paste the code for one action at a time so that you can keep the script organized.
)
Figure 4.2 To install the Scripting Listener, drag the plug-in into the folder Adobe Photoshop CS3 > Plug-Ins > Automate, and restart Photoshop.
A final note: When you're not using the Scripting Listener plug-in, drag it back into the Utilities folder and restart Photoshop. If you don't, it will keep writing code for every little thing you do, eventually generating such a large file that it will slow down Photoshop.
Image Processor
Although not a scripting resource per se, the Image Processor is actually a prebuilt JavaScript and is available under the File > Scripts menu. It's like the Batch feature (available under File > Automate > Batch) except that you don't have to use an Action if you don't want to. Image Processor provides a quick way to:
- Convert open files (or a folder of files) to one or all of the JPEG, PSD, or TIFF formats
- Resize images according to specific pixel dimensions
- Embed color profiles
- Convert a folder of images to sRGB and save them all for the Web
- Process a folder of camera raw files using the same settings
- Add copyright metadata
You can also include an action by clicking Run Action in the Preferences section at the bottom. Note that actions are run prior to any file resizing (if selected). If you need your action to run after resizing (such as applying the Sharpening filter to a resized image) you should download a modified Image Processor script from www.russellbrown.com/tips_tech.html.
Scripting the User Interface
When using ExtendScript for Photoshop you have access to many new elements for building dialog boxes. These include static text, icon buttons, images, check boxes, radio buttons, progress bars, sliders, list boxes, and drop-down/pop-up lists. For an example of the types of interfaces you can build for Photoshop, open the Image Processor (File > Scripts > Image Processor), which itself is an ExtendScript.
Which Scripting Language Should You Choose?
Here are my guidelines for choosing a Creative Suite scripting language:
- If you spent all of your parents' money on a liberal arts education, you'll probably be most comfortable with AppleScript.
- If you need your scripts to work on both Windows and Mac machines, go with JavaScript.
- If you're familiar with Visual Basic, shake hands with VBScript.
The scripting language you choose will likely depend more on preexisting factors and personal tendencies than any rational criteria. I chose AppleScript because it came free on my Mac, and I was in a culture that supported AppleScript. It was covered in the design magazines I already read, people I knew were dabbling in it, and programs I used to make my living were AppleScript-able. Now that I've been using AppleScript for awhile, I can use it to write Automator actions and full-blown Macintosh applications with AppleScript Studio—but these capabilities are just gravy.
If you are the type who's into rational decisions—and you're starting from scratch—JavaScript is probably the best all-around choice because it's cross-platform; lots of free scripts are available for it; and its strong online culture means that you might be able to get answers to your JavaScript questions at 3 a.m. With JavaScript, you can also program forms in Acrobat and add interactivity to Web pages; plus, you get a nice free JavaScript editor in the box with Creative Suite, called the ExtendScript Toolkit.
I've chosen AppleScript for the simple tutorial later in this chapter because it tends to be easier for newbies to follow, and those familiar with either of the other languages shouldn't have any problem translating.