Projecting cap to Butt cap via scripting

[victorcarbajo]

Hello. I need to change all Projecting cap strokes to Butt cap strokes, but extending half the line width beyond the end of the line.

[zertle]

The pseudo-code would look something like this:

loop through pathItems {
     get current path
     if currentPath.closed == true {
          get stroke width of current pathItem * 0.5
          change pathItem.strokeCap to StrokeCap.BUTTENDCAP
          add pathPoint half the stroke width in the direction of the last pathPoint's leftDirection
          add pathPoint half the stroke width in the direction of the first pathPoint's rightDirection
     }
}

Something along these lines, you might need to flip the leftDirection and rightDirection, as well as double check that the anchor point isn't a corner. If I have some time later I'll see if I can put together something more concrete, this seems like a pretty fun puzzle!

Good luck!

[victorcarbajo]

Thanks, zertle, but I don't know how to complete the code.

[moluapple · Accepted solution]

This code is modified from s.h's page : Scripts for Adobe Illustrator CS , please select some path items and test.

// Thanks to Hiroyuki Sato
// -----------------------------------------------------------------------
// codes copy from: http://shspage.com/aijs/en/#reverse
// return the angle of the line drawn from p1 to p2
function getRad(p1, p2) {
    return Math.atan2(p2[1] - p1[1],
        p2[0] - p1[0]);
}
function getPnt(pnt, rad, dis) {
    return [pnt[0] + Math.cos(rad) * dis,
        pnt[1] + Math.sin(rad) * dis
    ];
}
function extractPaths(s, paths) {
    for (var i = 0; i < s.length; i++) {
        if (s.typename == "PathItem") {
            paths.push(s);
        } else if (s.typename == "GroupItem") {
            // search for PathItems in GroupItem, recursively
            extractPaths(s.pageItems, paths);
        } else if (s.typename == "CompoundPathItem") {
            // searches for pathitems in CompoundPathItem, recursively
            // ( ### Grouped PathItems in CompoundPathItem are ignored ### )
            extractPaths(s.pathItems, paths);
        }
    }
    return paths
}
// -----------------------------------------------------------------------------
function isEqual(p1, p2) {
    return p1[0] === p2[0] && p1[1] === p2[1]
}
function addPointBS(p, beginPoint, endPoint) {
    var ps = [],
        end,
        i;
    for (i = p.length - 1; i >= 0; i--) {
        with(p) {
            ps.unshift([anchor, leftDirection, rightDirection, pointType]);
        }
        i > 0 && p.remove();
    }
    // set begin point
    p[0].rightDirection = p[0].leftDirection = p[0].anchor = beginPoint;
    // reset original points
    for (i = 0; i < ps.length; i++) {
        with(p.add()) {
            anchor = ps[0];
            leftDirection = ps[1];
            rightDirection = ps[2];
            pointType = ps[3];
        }
    }
    // modify original first and last points
    p[1].leftDirection = p[1].anchor;
    p[p.length - 1].rightDirection = p[p.length - 1].anchor;
    // set end point
    end = p.add();
    end.rightDirection = end.leftDirection = end.anchor = endPoint;
}
function Projecting2Butt(pth) {
    var p = pth.pathPoints,
        begin = p[0],
        end = p[p.length - 1],
        beginAnchor = begin.anchor,
        beginRD = begin.rightDirection,
        endAnchor = end.anchor,
        endLD = end.leftDirection,
        rad,
        rad2,
        beginPoint,
        endPoint;
    if (isEqual(beginRD, beginAnchor)) {
        rad = getRad(p[1].leftDirection, beginAnchor);
    } else {
        rad = getRad(beginRD, beginAnchor);
    }
    if (isEqual(endLD, endAnchor)) {
        rad2 = getRad(p[p.length - 2].rightDirection, endAnchor);
    } else {
        rad2 = getRad(endLD, endAnchor);
    }
    beginPoint = getPnt(beginAnchor, rad, pth.strokeWidth / 2);
    endPoint = getPnt(endAnchor, rad2, pth.strokeWidth / 2);
    addPointBS(p, beginPoint, endPoint);
}
function main() {
    var paths = extractPaths(app.selection, []),
        i = 0;
    for (; i < paths.length; i++) {
        Projecting2Butt(paths);
    }
}
main();

[victorcarbajo]

Wow! It's works! Thanks, moluapple.