Curved Corners Photoshop script

/* Curved corner script for Photoshop
 *
 * Copyright 2010 Ryan Nutt
 * http://photoartsforum.com
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 */
 
doResize();
 
function doResize() {

/* Save current settings so we can reset them later */
var startRulerUnits = app.preferences.rulerUnits;
var startTypeUnits = app.preferences.typeUnits;
var startDisplayDialogs = app.displayDialogs;

/* Change everything to pixels */
app.preferences.rulerUnits = Units.PIXELS;
app.preferences.typeUnits = TypeUnits.PIXELS;
app.displayDialogs = DialogModes.NO;

/* Prompt for the radius of the curve */
var radius = -1;
do {
radius = prompt('Enter a radius for the corners.  Must be numeric, greater than 0, and less than or equal to 100.', '10', 'Corner Radius from http://PhotoArtsForum.com');
if (radius==null) { break; }
} while (radius <= 0 || radius>100 || isNaN(radius));

if (radius!=null) {
/* We don't want to do anything to the document if they clicked cancel,
* but we do need to get to the end of this function so that we can reset
* the settings back to where they started.
*/

/* Load a few more variables */
var doc = app.activeDocument;
var docWidth = doc.width;
var docHeight = doc.height;

/* This won't work if the layer we're working on is a background
* layer.  So we're going to set it so it's not
*/
doc.activeLayer.isBackgroundLayer = false;


/* We need to resize the canvas so that there's room to do the
* smoothing.  PS doesn't seem to like us smoothing when the
* selection is against the edges.
*/
doc.resizeCanvas(docWidth + (radius*2), docHeight + (radius * 2));

/* Select the original section */
doc.selection.select(Array(
Array(radius,radius),
Array(radius,doc.height - (radius)),
Array(doc.width - (radius),doc.height -(radius)),
Array(doc.width - (radius),radius)));

/* Smooth, invert, and delete the parts we don't want */
doc.selection.smooth(radius);
doc.selection.invert();
doc.selection.clear();

/* We want to leave everything deselected */
doc.selection.deselect();

/* Trim off the extra canvas we added earlier */
doc.trim();
}

/* Put the settings back where they started */
app.preferences.rulerUnits = startRulerUnits;
app.preferences.typeUnits = startTypeUnits;
app.displayDialogs = startDisplayDialogs;
}