About progress bar and Photoshop

Question

I have been reading a lot about how to make a progress bar in photoshop (scripting) and my conclusion is that it is not worthy. The only way to make a progress bar is by using Palette window but Photoshop does not support it. If we use a dialog window, since it is modal, it will freeze whatever your script is doing so, you cannot use it (how to track the progress of a script if the script is paused while the dialog is being shown?). Although Photoshop does not support Palette, there are two workarounds that would make it work and they are using either app.refresh() or waitForRedraw() (and undocumented function that seems to me to do exactly the same thing that app.refresh() does). But as the manual says, app.refresh() will slow down considerably your code. According to my experimentation, each time you call app-refresh(), your script will waste about 1 second (no matter how powerful your computer is). That is a lot of time! In practical terms, you would use app.refresh() only a few times so your progress bar could be refreshed only a few times during the whole duration of your script, still one second lost for each time you use it. In other words, there is no good way of making a progress bar in photoshop scripting.
My question is: am I right? Is there a way to code a progress bar in PS that would not delay the code unreasonably?

Answer 1

Since I wrote that post I've learnt that BridgeTalk is pretty sensitive - for instance to binary code: instead to let .toSource() functions that needs to go to the message, you'd better of wrapping them into a String literal.
True, AM is lightning fast compared to DOM! But I won't use BridgeTalk for a Palette if the Palette is needed just for a progress bar. Such a Palette will stay alive while your script does all the things it's supposed to do without the need of waitForRedraw().
In my snippets library I've found this one that might help:
* Create a progress window
* @param  {String}  title           = title
* @param  {String}  message         = message (updatable)
* @param  {Boolean} hasCancelButton = add a Cancel button (default: false)
* @usage          w = new createProgressWindow "Title", "Message", true
createProgressWindow = function(title, message, hasCancelButton) {
  var win;
  if (title == null) {
    title = "Work in progress";
  if (message == null) {
    message = "Please wait...";
  if (hasCancelButton == null) {
    hasCancelButton = false;
  win = new Window("palette", "" + title, undefined);
  win.bar = win.add("progressbar", {
    x: 20,
    y: 12,
    width: 300,
    height: 20
  }, 0, 100);
  win.stMessage = win.add("statictext", {
    x: 10,
    y: 36,
    width: 320,
    height: 20
  }, "" + message);
  win.stMessage.justify = 'center';
  if (hasCancelButton) {
    win.cancelButton = win.add('button', undefined, 'Cancel');
    win.cancelButton.onClick = function() {
      win.close();
      throw new Error('User canceled the pre-processing!');
  this.reset = function(message) {
    win.bar.value = 0;
    win.stMessage.text = message;
    return win.update();
  this.updateProgress = function(perc, message) {
    if (perc != null) {
      win.bar.value = perc;
    if (message != null) {
      win.stMessage.text = message;
    return win.update();
  this.close = function() {
    return win.close();
  win.center(win.parent);
  return win.show();
Cheers,
Davide