[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, s, 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 = [b[0] + (b[2] - b[0]) / 2, b[1] + (b[3] - b[1]) / 2];
            s = (
                Math.min(op.height, op.width) < 20 ||
                (op.area && Math.abs(op.area) < 150)
                ) ? 4 : 6; // adjust font size for small area paths.
            add_nums(i - 1, xy, s);
        }
    }

    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),
            // offset value the small the better, but meantime more slow. 
            offset = function() {
                var minsize = Math.min(p.width, p.height);
                if (minsize >= 50) {
                    return '-1'
                } else if (20 < minsize && minsize < 50) {
                    return '-0.5'
                } else {
                    return '-0.2' // 0.2 * 2 (both side ) * 50 (Times) = 20
                }
            },
            xmlstring = '<LiveEffect name="Adobe Offset Path"><Dict data="I jntp 2 R mlim 4 R ofst #offset"/></LiveEffect>'
            .replace('#offset', offset()),
            TIMES = 100; // if shapes are too large, should increase the value.

        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) > 10) {
            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, s) {
        var txt = NUM_LAY.textFrames.add();

        txt.contents = n;
        txt.textRange.justification = Justification.CENTER;
        txt.textRange.characterAttributes.size = s;
        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;
        };
    }

})();

Hello,
Very interesting and useful! I was impressed with the way to use LiveEffect in a script. It's so smart.
But I found 2 issues.

1. There're cases that the offset effect creates multiple separated shapes. It is deemed as a wide shape, despite each shape is small enough.
   
2. Sometimes the offset effect creates a shape that returns strange visualBounds. It seems it occurs when the source shape is a thin rectangle.
   
   Though these may not be problems in your usage, I tried fixing this. I'll be happy if you integrate it.

Many thanks to you, Hiroyuki Sato. I've integrate your code, and adjust some setting values to get better result.

Thank you for taking your time to integrate!

@shspage hello, I tried it but lay.pathItems.length is always 0, why?