match size on composite

scale_to_match.js

{
    "application_id":"YOUR_APP_ID",
    "src" : "https://s3.amazonaws.com/img.blitline/test_pngs/2048s.png",
    "functions":[
        {
            "name":"composite",
            "params":{
                "src" : "https://s3.amazonaws.com/img.blitline/test_pngs/apple.png",
                "gravity":"CenterGravity",
                "scale_to_match" : true
            },
            "save":{
                "image_identifier":"MY_CLIENT_ID"
            }
        }
    ]
}