將SVG路徑轉換爲相對命令

Question

給定一個SVG Path元素，如何將所有路徑命令轉換爲相對座標？例如，轉換該路徑（其包括每一個命令，絕對和相對，交織）：

<path d="M3,7 L13,7 m-10,10 l10,0 V27 H23 v10 h10 
     C33,43 38,47 43,47 c0,5 5,10 10,10 
     S63,67 63,67  s-10,10 10,10 
     Q50,50 73,57  q20,-5 0,-10 
     T70,40    t0,-15 
     A5,5 45 1 0 40,20 a5,5 20 0 1 -10,-10 
     Z" /> 

到該等效路徑：

<path d="m3,7 l10,0 m-10 10 l10,0 v10 h10 v10 h10 
     c0,6 5,10 10,10 c0,5 5,10 10,10 
     s10,10 10,10  s-10,10 10,10 
     q-23,-27 0,-20  q20,-5 0,-10 
     t-3,-7    t0-15 
     a5,5 45 1 0 -30,-5 a5,5 20 0 1 -10,-10 
     z"/> 

對此問題予以this question動機。

Answer 1

Snap.SVG有Snap.path.toRelative()。

var rel = Snap.path.toRelative(abspathstring); 

Fiddle

Answer 2

我調整Phrogz' convertToAbsolute這個convertToRelative功能：

function convertToRelative(path) { 
    function set(type) { 
    var args = [].slice.call(arguments, 1) 
     , rcmd = 'createSVGPathSeg'+ type +'Rel' 
     , rseg = path[rcmd].apply(path, args); 
    segs.replaceItem(rseg, i); 
    } 
    var dx, dy, x0, y0, x1, y1, x2, y2, segs = path.pathSegList; 
    for (var x = 0, y = 0, i = 0, len = segs.numberOfItems; i < len; i++) { 
    var seg = segs.getItem(i) 
     , c = seg.pathSegTypeAsLetter; 
    if (/[MLHVCSQTAZz]/.test(c)) { 
     if ('x1' in seg) x1 = seg.x1 - x; 
     if ('x2' in seg) x2 = seg.x2 - x; 
     if ('y1' in seg) y1 = seg.y1 - y; 
     if ('y2' in seg) y2 = seg.y2 - y; 
     if ('x' in seg) dx = -x + (x = seg.x); 
     if ('y' in seg) dy = -y + (y = seg.y); 
     switch (c) { 
     case 'M': set('Moveto',dx,dy);     break; 
     case 'L': set('Lineto',dx,dy);     break; 
     case 'H': set('LinetoHorizontal',dx);   break; 
     case 'V': set('LinetoVertical',dy);    break; 
     case 'C': set('CurvetoCubic',dx,dy,x1,y1,x2,y2); break; 
     case 'S': set('CurvetoCubicSmooth',dx,dy,x2,y2); break; 
     case 'Q': set('CurvetoQuadratic',dx,dy,x1,y1); break; 
     case 'T': set('CurvetoQuadraticSmooth',dx,dy); break; 
     case 'A': set('Arc',dx,dy,seg.r1,seg.r2,seg.angle, 
         seg.largeArcFlag,seg.sweepFlag); break; 
     case 'Z': case 'z': x = x0; y = y0; break; 
     } 
    } 
    else { 
     if ('x' in seg) x += seg.x; 
     if ('y' in seg) y += seg.y; 
    } 
    // store the start of a subpath 
    if (c == 'M' || c == 'm') { 
     x0 = x; 
     y0 = y; 
    } 
    } 
    path.setAttribute('d', path.getAttribute('d').replace(/Z/g, 'z')); 
} 

使用像這樣從問題的路徑：

var path = document.querySelector('path'); 
convertToRelative(path); 
console.log(path.getAttribute('d')); 
// m 3 7 l 10 0 m -10 10 l 10 0 v 10 h 10 v 10 h 10 c 0 6 5 10 10 10 c 0 5 5 10 10 10 s 10 10 10 10 s -10 10 10 10 q -23 -27 0 -20 q 20 -5 0 -10 t -3 -7 t 0 -15 a 5 5 45 1 0 -30 -5 a 5 5 20 0 1 -10 -10 z 

我還做了一個小phantomjs shell實用程序svg2rel，其將在所有路徑這種方式（有相應的svg2abs在同一個要點，爲好措施）。