如何为svg路径的渐进绘图制作动画？

此答案中列出了三种技术：

有一个全SVG解决方案，涉及逐步修改

stroke-dasharray

演示：[http](http://phrogz.net/svg/progressively-drawing-svg-path-via-

dasharray.html)：//phrogz.net/svg/progressively-drawing-svg-path-via-
dasharray.html

相关代码：

var distancePerPoint = 1;var drawFPS          = 60;var orig = document.querySelector('path'), length, timer;orig.addEventListener('mouseover',startDrawingPath,false);orig.addEventListener('mouseout', stopDrawingPath, false);function startDrawingPath(){  length = 0;  orig.style.stroke = '#f60';  timer = setInterval(increaseLength,1000/drawFPS);}function increaseLength(){  var pathLength = orig.getTotalLength();  length += distancePerPoint;  orig.style.strokeDasharray = [length,pathLength].join(' ');  if (length >= pathLength) clearInterval(timer);}function stopDrawingPath(){  clearInterval(timer);  orig.style.stroke = '';  orig.style.strokeDasharray = '';}

另外，您仍然可以使用所有SVG并选择一次构建一个SVG路径命令：

演示：[http](http://phrogz.net/svg/progressively-cloning-svg-

path.html)：//phrogz.net/svg/progressively-cloning-svg-
path.html

相关代码：

// Assumes 'orig' and dup' are SVG pathsfunction addNextPathSegment(){  var nextIndex   = dup.pathSegList.numberOfItems;  if (nextIndex<orig.pathSegList.numberOfItems){    var nextSegment = orig.pathSegList.getItem(nextIndex);    var segmentDup  = cloneSVGPathSeg( dup, nextSegment );    dup.pathSegList.appendItem( segmentDup );  }}function cloneSVGPathSeg( path, seg ){  switch(seg.pathSegTypeAsLetter){    case 'M': return path.createSVGPathSegMovetoAbs(seg.x,seg.y);         break;    case 'm': return path.createSVGPathSegMovetoRel(seg.x,seg.y);         break;    case 'L': return path.createSVGPathSegLinetoAbs(seg.x,seg.y);         break;    case 'l': return path.createSVGPathSegLinetoRel(seg.x,seg.y);         break;    case 'H': return path.createSVGPathSegLinetoHorizontalAbs(seg.x);     break;    case 'h': return path.createSVGPathSegLinetoHorizontalRel(seg.x);     break;    case 'V': return path.createSVGPathSegLinetoVerticalAbs(seg.y);       break;    case 'v': return path.createSVGPathSegLinetoVerticalRel(seg.y);       break;    case 'C': return path.createSVGPathSegCurvetoCubicAbs(seg.x,seg.y,seg.x1,seg.y1,seg.x2,seg.y2);        break;    case 'c': return path.createSVGPathSegCurvetoCubicRel(seg.x,seg.y,seg.x1,seg.y1,seg.x2,seg.y2);        break;    case 'S': return path.createSVGPathSegCurvetoCubicSmoothAbs(seg.x,seg.y,seg.x2,seg.y2);     break;    case 's': return path.createSVGPathSegCurvetoCubicSmoothRel(seg.x,seg.y,seg.x2,seg.y2);     break;    case 'Q': return path.createSVGPathSegCurvetoQuadraticAbs(seg.x,seg.y,seg.x1,seg.y1);       break;    case 'q': return path.createSVGPathSegCurvetoQuadraticRel(seg.x,seg.y,seg.x1,seg.y1);       break;    case 'T': return path.createSVGPathSegCurvetoQuadraticSmoothAbs(seg.x,seg.y);    break;    case 't': return path.createSVGPathSegCurvetoQuadraticSmoothRel(seg.x,seg.y);    break;    case 'A': return path.createSVGPathSegArcAbs(seg.x,seg.y,seg.r1,seg.r2,seg.angle,seg.largeArcFlag,seg.sweepFlag); break;    case 'a': return path.createSVGPathSegArcRel(seg.x,seg.y,seg.r1,seg.r2,seg.angle,seg.largeArcFlag,seg.sweepFlag); break;    case 'z':    case 'Z': return path.createSVGPathSegClosePath();         break;  }}

最后，您可以选择通过定期采样SVG路径并绘制到画布来绘制HTML5画布的路径。（请注意，不需要为此显示SVG路径；您可以完全在Javascript中构建SVG路径元素并对其进行采样）：

演示：[http](http://phrogz.net/svg/progressively-drawing-svg-

path.html)：//phrogz.net/svg/progressively-drawing-svg-
path.html

相关代码：

function startDrawingPath(){  points = [];  timer = setInterval(buildPath,1000/drawFPS);}// Assumes that 'orig' is an SVG pathfunction buildPath(){  var nextPoint = points.length * distancePerPoint;  var pathLength = orig.getTotalLength();  if (nextPoint <= pathLength){    points.push(orig.getPointAtLength(nextPoint));    redrawCanvas();  } else stopDrawingPath();}function redrawCanvas(){  clearCanvas();  ctx.beginPath();  ctx.moveTo(points[0].x,points[0].y);  for (var i=1;i<points.length;i++) ctx.lineTo(points[i].x,points[i].y);  ctx.stroke();}