/*
 * CrossDissolveOverlaps_1_0.jsx
 * Author:	Peter Torpey
 *        	www.petertorpey.com
 * Version:	1.0	10-28-04
 *         	Original code Copyright 2004 Peter Torpey.
 *         	This code may be used, distributed, and modified provided
 * 			the name and URL of the original author, above, remain intact.
 *
 * Description:
 * 	Looks at selected layers. Where a layer overlaps a layer lower in the
 * 	stack, a cross dissolve is created.
 *
 * Known Issues:
 * 	None.
 *
 */

{
	var NAME_STR = "Cross Dissolve Overlaps";

	function crossLayers(compLayers) {
		for (var i = 1; i <= compLayers.length; i++) {
			if (!(compLayers[i].selected && compLayers[i] instanceof AVLayer)) continue;
			var done = 0x0;
			for (var j = i + 1; j <= compLayers.length; j++) {
				if (!(compLayers[i].selected && compLayers[i] instanceof AVLayer)) continue;
				if (((done & 0x1) == 0) &&
					compLayers[j].inPoint < compLayers[i].inPoint &&
					compLayers[j].outPoint > compLayers[i].inPoint &&
					compLayers[j].outPoint < compLayers[i].outPoint) {
						var opac = compLayers[i].property("opacity");
						opac.setValueAtTime(compLayers[i].inPoint, 0);
						opac.setValueAtTime(compLayers[j].outPoint, 100);
						done |= 0x1;
				}
				else if (((done & 0x2) == 0) &&
					compLayers[i].inPoint < compLayers[j].inPoint &&
					compLayers[i].outPoint > compLayers[j].inPoint &&
					compLayers[i].outPoint < compLayers[j].outPoint) {
						var opac = compLayers[i].property("opacity");
						opac.setValueAtTime(compLayers[j].inPoint, 100);
						opac.setValueAtTime(compLayers[i].outPoint, 0);
						done |= 0x2;
				}
				if (done == 0x3) break;
			}
		}
	}

	//////// main ////////
	var proj = app.project;

	if (proj) {
		var curItem = app.project.activeItem;
		if (curItem != null && (curItem instanceof CompItem)) {
			// use layers and check for selection later
			// because we want stack order, not selection order
			var myLayers = curItem.layers;
			if (curItem.selectedLayers.length > 2) {
				app.beginUndoGroup(NAME_STR);
				crossLayers(myLayers);
				app.endUndoGroup();
			}
			else {
				alert(NAME_STR + ":\n\nPlease select at least two layers.");
			}
		}
		else {
			alert(NAME_STR + ":\n\nPlease select a composition.");
		}
	}
	else {
		alert(NAME_STR + ":\n\nPlease open a project.");
	}
}