Shawn's Sketch Blog

This post is cross-posted at http://altdevblogaday.org/ where I have recently become a contributer.  Every 2 weeks I’ll post something up.  Here’s my first post.

Recently I’ve seen some great posts about scripting.  While I enjoy theoretical discourse, I’m much more of a practical person.  This is why I love scripting, an emphasis on getting something done quickly that is useful to my artists and myself.  In this post, I will be writing small scripts for photoshop that can save you time and a headache.  I’m going to try to write this in a hybrid form, partially an intro to Photoshop scripting and partially some cool useful tools.  If you need help on the basics please see: adobe’s javascripting guide or adobe’s intro to scripting guide.

Getting Started

To start off with, you need Adobe’s Photoshop and also Adobe’s ExtendScript Tookit.  The Toolkit is your IDE, and while not the greatest IDE, it has a quick launch to PS, that I have yet to recreate in my favorite IDE’s.  It also has a decent object viewer for classes, and functions.   As a plus, It has a debugger and a primitive profiling system.  I’ll go ahead and warn you, the intellisense is mediocre at best, but works some of the time.  After you have these two programs you are ready to roll.  (p.s. make sure that you have the dropdown box above your code set on Adobe Photoshop” and not “ExtendScript Toolkit”)

The Basics

The way the photoshop object model is designed, is quite nice, IMO.   Everything is based under “App” and for most of our purposes “Document.”  Things cascade down from here and most of it and falls under logical classes.  Real quick, let’s create a document and add a layer named “Hello World.”  Something simple to get the blood flowing in the fingers.

doc = app.documents.add(500,500);

layer = doc.artLayers.add();

layer.name = "Hello World";

Pretty simple so far.  We’re creating a new document, adding a layer, and changing the name.  Another pretty useful line of code is:

docRef = app.activeDocument;

This will give us the a reference to whatever document is currently open.  If there are no documents open, the program will throw an error.  You can fix this by:

if(app.documents.length == 0)

     {alert("No documents are open, please open at least one document.");}

else

     {docRef = app.activeDocument;}

The alert method is one of your best friends.  This will quickly pop up any information that you need to know.  Some people will say, use breakpoints and the dataviewer, but I think that it takes longer to get the same information.

If we wanted to loop through all the layers and alert the user of the names we would use:

docRef = app.activeDocument;

for(var i = 0; i < docRef.layers.length; i++)

{

     alert(docRef.layers[i].name);

}

We could also highlight each layer as we loop through it.

for(var i = 0; i < docRef.layers.length; i++)
     {docRef.activeLayer = docRef.layers[i];}

Scripts to Save You A Headache

 While there is much more to cover, I want to take some time to cover some small tools that I have found helpful in scripting within Photoshop.  If you are just getting started with Photoshop scripting please, please, PLEASE give this a read.  If you haven’t really programmed before check out this.

Running A Script from a Hotkey

This is something which I found really gives users some power quick.  Running scripts via “File”->”Scripts” ->”Browse For Scripts” is annoying, time consuming, and not useful for artists.  The solution is to create an action that is assigned to a hotkey, and then record running the script via “File”->”Scripts” ->”Browse For Scripts”.  Once you’ve done this you can run that script everytime you press the hot key.  Now we have the power of running scripts from one button.  This not only saves time, but makes using your scripts feasible.

F2 Rename

For those of you who are Windows users and Photoshop users, one thing that really peaves me is double-clicking a layer to rename it.  Not only is this a pain, a lot of time I’ll miss the text on the layer is my double click will pull up layer styles.  This is basic windows functionality.  I have a hard time not being able to do this.  With a few lines of code, you can make it happen.

var docRef = app.activeDocument; 

var current =  docRef.activeLayer;

var layerTitle = prompt("Enter Layer Name", current.name);

if(layerTitle != null)

     {current.name = layerTitle;}

What we are doing here is: getting the active document, getting the active layer, using a built in “Prompt” to return a string, and assign it to the current layer.  I put the assigning of  the name inside a if statement because if a user exits or cancels the dialog box, “Prompt” returns null.  All in all, this doesn’t really save you any time, you still have to click the layer then hit F2, but if you know your Photoshop commands, you know that (alt and [) and (alt and ]) move your selected layer up and down.  Combined with this script, you can quickly name multiple layers.

Toggle Visibility

Another annoying aspect of Photoshop is the visibility of a layer.  If I want to turn the layer on or off, I have to click on an itty bitty tiny “eye” button.  I find this to be a pain, especially when I’m having to turn off many layers and zoom in and out of an atlas to figure out which layer is which.  I created a shortcut to this.  A single key which toggles the visibility of your currently selected layer.  Combined with ctrl left-clicking in the document you can quickly change the visibility of  layers without having to explicitly select a layer in the “layers” window or click the “eye” button.

var docRef = app.activeDocument;
if(docRef.activeLayer.visible)

     {docRef.activeLayer.visible = false;}

else

     {docRef.activeLayer.visible = true;}

Delete All Open Windows

If you’ve ever programmed in Photoshop, you will eventually end up writing a script that creates a new document every time you run the script.  After testing, debugging, and trying to get the script to work, you will see that photoshop has 40 documents open.  You need to delete them all.  When you click close, the window will ask you, “Do you want to save?”  Hell no, you just want it to go away…Now you have to do this 40 times, UNFORGIVABLE!  This definitely gives me a headache, Javascript to the rescue.  (Disclaimer: I take no responsibility for deleting your files.  Use this script at your own risk)

while (app.documents.length > 0)

    {activeDocument.close(SaveOptions.DONOTSAVECHANGES);}

Traverse Layers

While I like Photoshop’s API a lot, there isn’t a great way to “walk” through all the layers and groups.  The next script accomplishes that.  Right now, it just highlights the active layer, but the code could easily be modified to do anything to that layer.

var docRef = app.activeDocument;
function recurseLayers(currLayers)

{

     for(var i = 0; i < currLayers.layers.length; i++)

     {

          docRef.activeLayer = currLayers.layers[i];

          if(isLayerSet(currLayers.layers[i]))

               {recurseLayers(currLayers.layers[i]);}

     }

}

function isLayerSet(layer)

{

     try{

          if(layer.layers.length > 0)

               return true;}

     catch(err)

          {return false;}

}

recurseLayers(docRef)

As you will notice for large documents with many layers, this is a very sloooooooooooooooooooooooooooooooooooow process.  In the next post, we’ll explore speedups in Photoshop.

Wrap-It-Up

While the scripts I posted here are mostly elementary, I do strongly believe that these types of scripts can save a lot of headache and time.  My object was to introduce you to how Photoshop works and give you a few examples of how these practices can be put into action.  In my next blog post, I will introduce you to some more advanced scripting including GUI creation and Speedups via the ActionManager.  Let me know if you have any questions/thoughts!

var docRef = app.activeDocument;  var current =  docRef.activeLayer; var layerTitle = prompt("Enter Layer Name", current.name); if(layerTitle != null)      {current.name = layerTitle;}

Many times when I’m trying to solve a difficult problem that I just can’t figure out, I wake up one morning with the answer.  It’s refreshing, astonishing, and one of the greatest feelings in the world.  I don’t think it’s something that I try to do, it just happens.  

It is a really wild feeling.  A feeling of how little I know.  A problem that I have been trying to figure out for days, sometimes weeks or months, just appears one morning.

After this phenonom happened to me a couple of times, I thought, “Wow am I the only one who does this?  I couldn’t be.”  It doesn’t seem uncommon, and among programmers I know, I’ve asked a few of them  and many of them say that the same thing goes for them.  I also have spent some time researching it.  By researching, I mean, http://stackoverflow.com/questions/1102238/problem-solving-in-sleep   I find it interesting that when I’m sleeping my brain is either still working or I am subconsciously solving problems.  I would like to read some real literature about how this process works…my interest has been peaked.