Change the rulers original point to center of selected object

Hi @Deprive, it looks like you probably have this covered, but I wanted to chime in myself, because, strangely, none of the scripts/modifications you guys @femkeblanco, @pixxxelschubser mentioned actually work on my system (Mac OS 13.1, AI 27.2). They just don't move the ruler origin—nothing happens.

Here is what I do and works for me. I really do not understand what I'm doing in part of this script, but since it works, I figure I can post it! (Also @pixxxelschubser I am laughing when I post this because you may be appalled by how much of a long process I make something so simple, haha, but that is just how my mind and system works 🙂 ).

- Mark

/**
 * Sets the artboard's ruler origin to selected item's center.
 * @discussion https://community.adobe.com/t5/illustrator-discussions/change-the-rulers-original-point-to-center-of-selected-object/m-p/13531771
 */

(function () {

    var doc = app.activeDocument,
        item = doc.selection[0];

    setArtboardRulerOriginToItemCenter(item);



    /**
     * Sets artboard ruler origin to item's center.
     * @author m1b
     * @version 2022-10-08
     * @param {PageItem} item - an Illustrator PageItem.
     */
    function setArtboardRulerOriginToItemCenter(item) {

        if (item == undefined)
            return;

        var doc = getParentDocument(item),

            // I'll restore this later
            oldOrigin = doc.rulerOrigin,

            // get the item's artboard, or the first
            itemArtboard = getArtboardOfItem(item) || doc.artboards[0];

        // first reset the document's ruler origin
        doc.rulerOrigin = [0, 0];

        // if I don't calculate the center *after* resetting the doc.rulerOrigin,
        // the item coordinates may be incorrect
        var centre = centerOfBounds(item.geometricBounds);

        // I honestly don't understand what I'm doing here
        // but if I don't do this it doesn't work
        doc.rulerOrigin = [centre[0], centre[1]];

        // offset the artboard's ruler origin by it's position in document
        itemArtboard.rulerOrigin = [-itemArtboard.artboardRect[0], itemArtboard.artboardRect[1]];

        // cleanup
        doc.rulerOrigin = oldOrigin;

    };


    /**
     * Returns first artboard that shares
     * bounding box with the item.
     * @author m1b
     * @version 2022-07-25
     * @param {PageItem} item - an Illustrator page item.
     * @returns {Artboard}
     */
    function getArtboardOfItem(item) {

        var bounds = item.visibleBounds,
            abs = app.activeDocument.artboards;

        for (var i = 0; i < abs.length; i++)
            if (boundsIntersectWithBounds(bounds, abs[i].artboardRect))
                return abs[i];

    };


    /**
     * Returns true when b1 intersections with b2.
     * @param {Array<Number>} b1 - [l, t, r, b].
     * @param {Array<Number>} b2 - [l, t, r, b].
     * @returns {Boolean}
     */
    function boundsIntersectWithBounds(b1, b2) {

        return !(
            b2[0] > b1[2]
            || b2[2] < b1[0]
            || b2[1] < b1[3]
            || b2[3] > b1[1]
        );

    };


    /**
     * Returns the center of bounds.
     * @param {Arrray<Number>} bounds - [l,t,r,b].
     * @returns {Arrray<Number>} - [x, y].
     */
    function centerOfBounds(bounds) {

        var l = bounds[0],
            t = bounds[1],
            r = bounds[2],
            b = bounds[3];

        return [
            l + ((r - l) / 2),
            t + ((b - t) / 2)
        ];

    };


    /**
     * Returns the item's document, if possible.
     * @param {PageItem} item - an Illustrator page item.
     * @returns {Document}
     */
    function getParentDocument(item) {

        while (
            item.hasOwnProperty('parent')
            && item.constructor.name != 'Document'
        )
            item = item.parent;

        return item;

    };



})();

I would rather replace this line:

var objY = (objBounds[1] + objBounds[3]) / 2;

replace with this line:

var objY = (objBounds[1] + objBounds[3]) / 2 -doc.artboards[doc.artboards.getActiveArtboardIndex()].artboardRect[3];

Try

doc.artboards[0].rulerOrigin = [objX, -objY];

are you running the script from the ESTK? you have to select Illustrator as a target application