Cannot convert Corel Painter RIFF to GIF (or any other format, for that matter)

I want to convert some images to GIFs. Why do Corel want me not to be able to do this?

The problem

I have several dozen files in Corel Painter's format RIFF. I can use Painter to convert images one at a time to GIF by opening the image and doing File → Clone followed by File → Save As. But with several dozen images this gets tedious. Why can't I automate this?

How it should work

Suppose my images were PNGs and I wanted GIFs. Then I could write a Python program to do this along these lines:

for name in os.listdir(inDir):
    im =, name)), name[:-4] + '.gif'), 'GIF')

Too bad PIL does not support RIFF, because RIFF is a closed, proprietary format (NOTE: not to be confused with other formats called RIFF).

Too bad there is no standard format for images that includes layers and suchlike that Corel could have Painter support. (Actually you could represent images with layers pretty well using SVG if you wanted.)

Corel could supply a library for working with RIFF images. Failing that, Corel could publish a description of the format so someone else could write a library for working with RIFF images. Sadly there is no commerical reason for Corel to do this. All it would do is make their software more useful; since usefulness is not what really sells software, there is no reason for them to do this.

Another solution that would have been lousy but better than nothing

Corel could have made Painter scriptable. On the Mac, 'scriptable' means it exposes a dictionary of commands to AppleScript's voodoo. Writing programs in AppleScript is about the worst imaginable way to spend my time I can actually imagine doing; AppleScript is one of the worst-designed programming languages I have ever tried to do actual work in. I mean, I hate Visual Basic, but AppleScript is worse.

Despite this, if Corel had exposed open file and save as commands, I could probably have cobbled together a script that did one coversion. From there you can plug in to Automater and folder actions to make it keep your GIFs up-to-date with respect to the master copies in RIFF format. Automated workflow! It would be great. Too bad I can't have it.

What Corel's software does expose is a command cryptically named DoScript. What does it do? I don't know. It takes a parameter that is a string. A string of what? Special Corel commands? I have done some digging, and it appears that when you save what Painter calls a script to a file, it is in some sort of text format. Perhaps these can be fed in to the DoScript command, but if so I have yet to make it work. Maybe it is supposed to be a file name? Who knows? Nobody knows, that's who.

Digression on the subject of file names in AppleScript

I started writing this article after attempting to make an AppleScript program that opens a file in Corel Painter. The following works

tell application "Finder"
    open file "Macintosh HD:Users:pdc:foo:bar:baz.riff"
end tell

Note the use of the obsolete 'file path' notation (using colons). I can also make it work with the file name as a variable:

tell application "Finder"
    set file_name to "Macintosh HD:Users:pdc:foo:bar:baz.riff"
    open file file_name
end tell

Fine. But what if I want to use a Unix file name rather than a Mac OS 9 file path? It turns out that if I type this in to a script:

tell application "Finder"
    open POSIX file "/Users/pdc/foo/bar/baz.riff"
end tell

then the AppleScript compiler rewrites it as a file path! It replaces my code with

tell application "Finder"
    open file "Macintosh HD:Users:pdc:foo:bar:baz.riff"
end tell

That is seriously fucked up. If I try using a variable to hold the file name, it fails: I get an error message

Finder got an error: Can't get POSIX file "/Users/pdc/foo/bar/baz.riff"

So opening files via the Finder also seems to be out, unless I fancy learning enough about AppleScript's crappy string manipulation expressions to convert my file names in to file paths myself.

The light at the end of the tunnel is an illusion caused by excessive blood pressure

There is another emergency backup approach to scripting non-scriptable applications: GUI scripting. This is so great that Apple devote a couple of paragraphs to it on the web site. The idea is that you can send events direct to the buttons and text fields of the application, driving it more or less as the user would. Here is an example:

tell application "Corel Painter 8"
end tell

tell application "System Events"
    tell process "Corel Painter 8"
        tell menu 1 of menu bar item "File" of menu bar 1
            click menu item "Clone"
        end tell
    end tell
end tell

This clicks the File → Clone menu item, creating a flattened version of the frontmost image. Since the user interface of Painter is undocumented, producing even the above script takes hours of fiddling with Apple's GUI spy program and guessing what the names of this actually are (since it does not go so far as telling you).

With a similar incantation I can make the Save As dialogue box appear. Now I want to change the file type from RIFF to GIF in the drop-down list. Unfortunately its expression in AppleScript is

pop up button 1 of ??? of window "Open"

where the question marks need to be replaced with a name I cannot type: the GUI element that is a child of window "Open" and a parent of the pop up button is listed as 'Unknown', but unknown is an AppleScript keyword of some sort. In the end I could not find a way to make this work. After spotting something in one of Apple's code samples, I came up with a different appoach:

repeat 14 times
    keystroke tab
end repeat
keystroke space
keystroke "g"
delay 1
keystroke return

The existence of the keystroke command I had to infer from one of the code samples on Apple's page; it is not documented anywhere.

These seven lines do the same work as the seven characters

, "GIF"

in my hypothetical Python program.

String manipulation by drunken fairy trolls

The expression

name[:-4] + '.gif'

replaces the file-name suffix. This happens automatically when yoiu change file types in the Save As dialogue, but you do also need to strip off the words Clone of from the front of the name (added because you are saving a clone of the original image). Here's the AppleScript equivalent:

set the_file_name to value of text field 1
if the_file_name starts with "Clone of " then
    set the_file_name to text 10 thru (length of the_file_name) of the_file_name
end if
set the value of text field 1 to the_file_name

The text ... thru ... expression comes from the O'Reilly AppleScript book. I can't think how someone is supposed to guess it. The array-slicing notation used in Python is also something you have to learn, of course, but the difference is that, in Python, you will use it often, and for many different things, because slices apply to lists, and lists are used for listing things in Python, instead of haveing unique and special keywords to learn for every object in the system.

Now for the output directory

The Python program uses

os.path.join(outDir, ...)

to arrange that the GIF files are stored in a different directory from where they came from. To set the directory the file will be saved to in the Save As dialogue, I ended up (after an eternity of hacking) with this monstrosity:

keystroke "/" using control down
delay 1

repeat with the_char in every character of the_dir_name
    keystroke the_char
end repeat
keystroke return

The first part invokes an obscure feature of Mac OS X file dialogues: Ctrl / shows a sheet that lets you enter the directory name using your keyboard. The sample code I nicked this idea from sets a text field to the directory name; Corel's pop-up window unhelpfully is nameless, so I can't work out how to get at its fields. So I resorted to feeding it the characters one at a time.

I would also like to point out that 'repeat with the_char in every character of the_dir_name' is no more English-like than 'for char in name' would be. I hate the way every review of AppleScript manuals says something like

AppleScript is a scripting language that mimics the syntax of English. As such, it's extremely similar to how sentences are structured and, as a result, is very intuitive and simple to use.

AppleScript is not intuitive. Its syntax mimics English in the same way a cargo cultist mimics an airport. The supposedly English-like syntax is more complex, and therefore harder to use, than almost any other programming language apart from Perl.


So far I have managed to get Corel Painter to save a file as a GIF, once it is loaded. The bit where I set the directiory name sort of works, but seems to be flakey; luckily I don't need it if I don't mind all my files going to the same directory. I am still stuck when it comes to opening all the files in a directory. Maybe I should look in to how Automater does its stuff; perhaps I can get it to take care of the file names for me...