How to add custom attributes or properties to compositions and layers

Question

Hi all,Would it be possible to add custom properties to compositions and layers that our exporter would then be able to process?These would have no visuals in AE but would affect the rendering in our engine.An example of this would be to add a propery to a layer to indicate it is a password edit text box.Any leads would be greatly appreciated.

Christian Lett · Accepted Answer

You could try using the built-in XMP metadata. I was playing around with it in an old script to store data in the project without resorting to using text layer hacks and it worked fine.

Two functions - one for writing the data:

function setMetadata(data) {

var proj = app.project;

if(ExternalObject.AdobeXMPScript == undefined) {

ExternalObject.AdobeXMPScript = new ExternalObject('lib:AdobeXMPScript');

}

var metaData = new XMPMeta(proj.xmpPacket);

var schemaNS = XMPMeta.getNamespaceURI("MyNamespace");

if(schemaNS == "" || schemaNS == undefined) {

schemaNS = XMPMeta.registerNamespace("MyNamespace", "MyNamespace");

}

try {

metaData.setProperty(schemaNS, "MyNamespace:compInQuestion", data.compID); // Assume these variables are pre-set

metaData.setProperty(schemaNS, "MyNamespace:layerIndex", data.layerIndex);

metaData.setProperty(schemaNS, "MyNamespace:dataToStore", data.myData);

} catch(err) {

alert(err.toString());

return -1;

}

proj.xmpPacket = metaData.serialize();

}

// To get metadata from within a script, a function like so:

function getMetadata(property) {

var proj = app.project;

if(ExternalObject.AdobeXMPScript == undefined) {

ExternalObject.AdobeXMPScript = new ExternalObject('lib:AdobeXMPScript');

}

var metaData = new XMPMeta(proj.xmpPacket);

var schemaNS = XMPMeta.getNamespaceURI("MyNamespace");

if(schemaNS == "" || schemaNS == undefined) {

return undefined;

}

var metaValue = metaData.getProperty(schemaNS, property);

if(!metaValue) {

return undefined;

}

return metaValue.value;

}

Because the XMP functionality is an external object, you should be able to access it from outside a script, such as in a C++ IO plugin.

Christian

axidhaus · Answer

I've done a couple things that do more or less what you're asking. You can use either or mix and match as needed.

First is to leave variables as text in an invisible text box within your comp. They can be set or checked programatically and can be on or offscreen. I usually lock mine and keep the layer visible but turn the opacity down to zero (just in case garbage collection might throw the non-rendering elements out.) This allows me to check and set variables or other properties. For testing I can turn up the opacity of my variable layers and see what data the comps are receiving and what they're being set to. It's handy.

The second way which you can use in conjunction with the first method, would be to use the layer name as an instance name for your property. So if you're using text boxes, let's say the comp is named "text_box_comp" but you have two text boxes drawn on screen. You can place them where you want but change the layer names to "text_box_user", "text_box_pass". Then in your renderer, you can see if the layer has user and pass text fields by their layer names and render them appropriately.

Kevin

Sign up

To post, reply, or follow discussions, please sign in with your Adobe ID.

Sign in to Adobe Community

To post, reply, or follow discussions, please sign in with your Adobe ID.

Scanning file for viruses.

This file cannot be downloaded