AiFitToArtboard.jsx

/*

  License: GPLv2 or later

  Adobe Illustrator script to resize objects proportionally to fit inside the artboard.


  Works in CS6 (should work in later versions).
  Doesn't work in CS3 (and probably won't work in earlier versions).


  Based on the fine work of these folks:

    Carlos Canto, dbburgess

      https://forums.adobe.com/message/4164590
      http://aiscripts.com/2012/09/fit-object-to-artboard/


  How to use:

    1) Create a new document with the desired artboard size.
    2) Paste an object into this newly created document.
    3) Select the object and run this script.
    4) Profit.


  Known bugs:

    Centering is kinda buggy at times - it doesn't seem
    to work after changing the artboard size, for example :(


  Future versions, maybe:

    - Just scale the object/don't duplicate?
    - Modify the script to create a new document so that
      it can be run from any file with an object selected?

*/



// Current document and selection:
var activeDoc = app.activeDocument,
    selection = activeDoc.selection;

// Check if anything is selected:
if (selection.length > 0) {

  // Loop over selected items:
  for (i = 0; i < selection.length; i++) {

    var item       = selection[i].duplicate(),
        abActive   = activeDoc.artboards[
                       activeDoc.artboards.getActiveArtboardIndex()
                     ],
        abProps    = getArtboardBounds(abActive),
        boundsDiff = itemBoundsDiff(selection[i]);

    // Scale object to fit artboard:
    fitItem(item, abProps, boundsDiff);

  }

} else {
  alert("Select an object before running this script.");
}



// Artboard bounds helper (used above):
function getArtboardBounds(artboard) {

  var bounds = artboard.artboardRect,

      left   = bounds[0],
      top    = bounds[1],
      right  = bounds[2],
      bottom = bounds[3],

      width  = right - left,
      height = top - bottom,

      props  = {
        left   : left,
        top    : top,
        width  : width,
        height : height
      };

  return props;
}



// Bounds difference helper (used at the top):
function itemBoundsDiff(item) {

  var itemVB = item.visibleBounds,
      itemVW = itemVB[2] - itemVB[0],
      itemVH = itemVB[1] - itemVB[3],

      itemGB = item.geometricBounds,
      itemGW = itemGB[2] - itemGB[0],
      itemGH = itemGB[1] - itemGB[3],

      deltaX = itemVW - itemGW,
      deltaY = itemVH - itemGH,

      diff   = {
        deltaX: deltaX,
        deltaY: deltaY
      };

    return diff;
}



// Fit item helper (used at the top):
function fitItem(item, props, diff) {

  // Cache current values:
  var oldWidth  = item.width; // alert(oldWidth);
  var oldHeight = item.height; // alert(oldHeight);

  // Wide or tall?
  if (item.width > item.height) {

    // alert('wide');
    item.width = props.width - diff.deltaX;

    // Scale height using ratio from width:
    var ratioW  = item.width / oldWidth;
    item.height = oldHeight * ratioW;

  } else {

    // alert('tall');
    item.height = props.height - diff.deltaY;

    // Scale width using ratio from height:
    var ratioH = item.height / oldHeight;
    item.width = oldWidth * ratioH;

  }

  // Center:
  item.top  = 0 - ((props.height / 2) - (item.height / 2));
  item.left = (props.width / 2) - (item.width / 2);

  // Deselect:
  item.selected = false;

}