[Illustrator] 寻找不规则形状中心点(find visual center of an irregularly shaped polygon with Illustrator)

find visual center.jsx

(function() {
    var doc = app.activeDocument,
        lays = doc.layers,
        WORK_LAY = lays.add(),
        NUM_LAY = lays.add(),
        i = lays.length - 1,
        lay;

    // main working loop
    for (; i > 1; i--) {
        //process each layer
        lay = lays[i];
        lay.name = lay.name + " Num:" + (i - 1); // i-1 as 2 layers beed added.
        process(lay.pathItems, false);
        process(lay.compoundPathItems, true); // if any
    }
    //clean up
    NUM_LAY.name = "Numbers";
    WORK_LAY.remove();

    function process(items, isCompound) {
        var j = 0,
            b, xy, p, op;

        for (; j < items.length; j++) {
            // process each pathItem
            op = items[j];
            // add stroke
            if (isCompound) {
                strokeComPath(op);
            } else {
                !op.closed && op.closed = true;
                op.filled = false;
                op.stroked = true;
            };
            b = getCenterBounds(op);
            xy = getMinVisibleSize(b) > 20 ? // two or more visual center exists, as the bounds width is too big
                [b[0] + 2, b[1] - 2] : //  use the top left position with a little adjust
                [b[0] + (b[2] - b[0]) / 2, b[1] + (b[3] - b[1]) / 2];
            add_nums(i - 1, xy);
        }
    }
    
    function getMinVisibleSize(b){
        var s = Math.min(b[2] - b[0], b[1] - b[3]);
        return Math.abs(s);
    }

    function getGeometricCenter(p){
        var b = p.geometricBounds;
        return [(b[0] + b[2]) / 2, (b[1] + b[3]) / 2];
    }

    // returns square of distance between p1 and p2
    function getDist2(p1, p2){
        return Math.pow(p1[0] + p2[0], 2) + Math.pow(p1[1] + p2[1], 2);
    }

    // returns visibleBounds of a path in a compoundPath p
    // which is closest to center of the original path op
    function findBestBounds(op, p){
        var opc = getGeometricCenter(op);
        var idx = 0, d;
        var minD = getDist2(opc, getGeometricCenter(p.pathItems[0]));
        for(var i = 0, iEnd = p.pathItems.length; i < iEnd; i++){
            d = getDist2(opc, getGeometricCenter(p.pathItems[i]));
            if(d < minD){
                minD = d;
                idx = i;
            }
        }
        return p.pathItems[idx].visibleBounds;
    }

    function applyOffset(op, checkBounds){
        var p = op.duplicate(WORK_LAY, ElementPlacement.PLACEATBEGINNING);
      
        var offset = Math.min(p.width, p.height) / 10 > 1 ? 1 : 0.5,
            xmlstring = '<LiveEffect name="Adobe Offset Path"><Dict data="I jntp 2 R mlim 4 R ofst #offset"/></LiveEffect>'
            .replace('#offset', '-' + offset),
            TIMES = 50; // if shapes are too large, should increase times to 100 or even bigger.

        if(checkBounds){
            // check its size only if it needs, because it's too slow
            while (TIMES-- && getMinVisibleSize(p.visibleBounds) > 3) p.applyEffect(xmlstring);
        } else {
            while (TIMES--) p.applyEffect(xmlstring);
        }
        return p;
    }

    function getCenterBounds(op) {
        var originalMinSize = getMinVisibleSize(op.visibleBounds);
      
        var p = applyOffset(op, false);
      
        if(getMinVisibleSize(p.visibleBounds) > originalMinSize){
            // in some cases, path p becomes larger for some unknown reason
            p.remove();
            p = applyOffset(op, true);
        }
        
        var b = p.visibleBounds;
      
        if(getMinVisibleSize(b) > 20){
            activeDocument.selection = [p];
            executeMenuCommand("expandStyle");
            p = activeDocument.selection[0];
            if(p.typename == "CompoundPathItem"){
                b = findBestBounds(op, p);
            }
        }

        p.remove();
        return b;
    }

    function add_nums(n, xy) {
        var txt = NUM_LAY.textFrames.add();

        txt.contents = n;
        txt.textRange.justification = Justification.CENTER;
        txt.textRange.characterAttributes.size = 6;
        txt.position = [xy[0] - txt.width / 2, xy[1] + txt.height / 2];
    }

    function strokeComPath(compoundPath) {
        var p = compoundPath.pathItems,
            l = p.length,
            i = 0;

        for (; i < l; i++) {
            !p[i].closed && p[i].closed = true;
            p[i].stroked = true;
            p[i].filled = false;
        };
    }
})();

Got it. Thank you for taking your time and the detailed explanation.