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3 лет назад
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  1. # d3-path
  2. Say you have some code that draws to a 2D canvas:
  3. ```js
  4. function drawCircle(context, radius) {
  5. context.moveTo(radius, 0);
  6. context.arc(0, 0, radius, 0, 2 * Math.PI);
  7. }
  8. ```
  9. The d3-path module lets you take this exact code and additionally render to [SVG](http://www.w3.org/TR/SVG/paths.html). It works by [serializing](#path_toString) [CanvasPathMethods](http://www.w3.org/TR/2dcontext/#canvaspathmethods) calls to [SVG path data](http://www.w3.org/TR/SVG/paths.html#PathData). For example:
  10. ```js
  11. var context = d3.path();
  12. drawCircle(context, 40);
  13. pathElement.setAttribute("d", context.toString());
  14. ```
  15. Now code you write once can be used with both Canvas (for performance) and SVG (for convenience). For a practical example, see [d3-shape](https://github.com/d3/d3-shape).
  16. ## Installing
  17. If you use NPM, `npm install d3-path`. Otherwise, download the [latest release](https://github.com/d3/d3-path/releases/latest). You can also load directly from [d3js.org](https://d3js.org), either as a [standalone library](https://d3js.org/d3-path.v1.min.js) or as part of [D3 4.0](https://github.com/d3/d3). AMD, CommonJS, and vanilla environments are supported. In vanilla, a `d3` global is exported:
  18. ```html
  19. <script src="https://d3js.org/d3-path.v1.min.js"></script>
  20. <script>
  21. var path = d3.path();
  22. path.moveTo(1, 2);
  23. path.lineTo(3, 4);
  24. path.closePath();
  25. </script>
  26. ```
  27. ## API Reference
  28. <a name="path" href="#path">#</a> d3.<b>path</b>() · [Source](https://github.com/d3/d3-path/blob/master/src/path.js), [Examples](https://observablehq.com/@d3/d3-path)
  29. Constructs a new path serializer that implements [CanvasPathMethods](http://www.w3.org/TR/2dcontext/#canvaspathmethods).
  30. <a name="path_moveTo" href="#path_moveTo">#</a> <i>path</i>.<b>moveTo</b>(<i>x</i>, <i>y</i>)
  31. Move to the specified point ⟨*x*, *y*⟩. Equivalent to [*context*.moveTo](http://www.w3.org/TR/2dcontext/#dom-context-2d-moveto) and SVG’s [“moveto” command](http://www.w3.org/TR/SVG/paths.html#PathDataMovetoCommands).
  32. <a name="path_closePath" href="#path_closePath">#</A> <i>path</i>.<b>closePath</b>()
  33. Ends the current subpath and causes an automatic straight line to be drawn from the current point to the initial point of the current subpath. Equivalent to [*context*.closePath](http://www.w3.org/TR/2dcontext/#dom-context-2d-closepath) and SVG’s [“closepath” command](http://www.w3.org/TR/SVG/paths.html#PathDataClosePathCommand).
  34. <a name="path_lineTo" href="#path_lineTo">#</a> <i>path</i>.<b>lineTo</b>(<i>x</i>, <i>y</i>)
  35. Draws a straight line from the current point to the specified point ⟨*x*, *y*⟩. Equivalent to [*context*.lineTo](http://www.w3.org/TR/2dcontext/#dom-context-2d-lineto) and SVG’s [“lineto” command](http://www.w3.org/TR/SVG/paths.html#PathDataLinetoCommands).
  36. <a name="path_quadraticCurveTo" href="#path_quadraticCurveTo">#</a> <i>path</i>.<b>quadraticCurveTo</b>(<i>cpx</i>, <i>cpy</i>, <i>x</i>, <i>y</i>)
  37. Draws a quadratic Bézier segment from the current point to the specified point ⟨*x*, *y*⟩, with the specified control point ⟨*cpx*, *cpy*⟩. Equivalent to [*context*.quadraticCurveTo](http://www.w3.org/TR/2dcontext/#dom-context-2d-quadraticcurveto) and SVG’s [quadratic Bézier curve commands](http://www.w3.org/TR/SVG/paths.html#PathDataQuadraticBezierCommands).
  38. <a name="path_bezierCurveTo" href="#path_bezierCurveTo">#</a> <i>path</i>.<b>bezierCurveTo</b>(<i>cpx1</i>, <i>cpy1</i>, <i>cpx2</i>, <i>cpy2</i>, <i>x</i>, <i>y</i>)
  39. Draws a cubic Bézier segment from the current point to the specified point ⟨*x*, *y*⟩, with the specified control points ⟨*cpx1*, *cpy1*⟩ and ⟨*cpx2*, *cpy2*⟩. Equivalent to [*context*.bezierCurveTo](http://www.w3.org/TR/2dcontext/#dom-context-2d-beziercurveto) and SVG’s [cubic Bézier curve commands](http://www.w3.org/TR/SVG/paths.html#PathDataCubicBezierCommands).
  40. <a name="path_arcTo" href="#path_arcTo">#</a> <i>path</i>.<b>arcTo</b>(<i>x1</i>, <i>y1</i>, <i>x2</i>, <i>y2</i>, <i>radius</i>)
  41. Draws a circular arc segment with the specified *radius* that starts tangent to the line between the current point and the specified point ⟨*x1*, *y1*⟩ and ends tangent to the line between the specified points ⟨*x1*, *y1*⟩ and ⟨*x2*, *y2*⟩. If the first tangent point is not equal to the current point, a straight line is drawn between the current point and the first tangent point. Equivalent to [*context*.arcTo](http://www.w3.org/TR/2dcontext/#dom-context-2d-arcto) and uses SVG’s [elliptical arc curve commands](http://www.w3.org/TR/SVG/paths.html#PathDataEllipticalArcCommands).
  42. <a name="path_arc" href="#path_arc">#</a> <i>path</i>.<b>arc</b>(<i>x</i>, <i>y</i>, <i>radius</i>, <i>startAngle</i>, <i>endAngle</i>[, <i>anticlockwise</i>])
  43. Draws a circular arc segment with the specified center ⟨*x*, *y*⟩, *radius*, *startAngle* and *endAngle*. If *anticlockwise* is true, the arc is drawn in the anticlockwise direction; otherwise, it is drawn in the clockwise direction. If the current point is not equal to the starting point of the arc, a straight line is drawn from the current point to the start of the arc. Equivalent to [*context*.arc](http://www.w3.org/TR/2dcontext/#dom-context-2d-arc) and uses SVG’s [elliptical arc curve commands](http://www.w3.org/TR/SVG/paths.html#PathDataEllipticalArcCommands).
  44. <a name="path_rect" href="#path_rect">#</a> <i>path</i>.<b>rect</b>(<i>x</i>, <i>y</i>, <i>w</i>, <i>h</i>)
  45. Creates a new subpath containing just the four points ⟨*x*, *y*⟩, ⟨*x* + *w*, *y*⟩, ⟨*x* + *w*, *y* + *h*⟩, ⟨*x*, *y* + *h*⟩, with those four points connected by straight lines, and then marks the subpath as closed. Equivalent to [*context*.rect](http://www.w3.org/TR/2dcontext/#dom-context-2d-rect) and uses SVG’s [“lineto” commands](http://www.w3.org/TR/SVG/paths.html#PathDataLinetoCommands).
  46. <a name="path_toString" href="#path_toString">#</a> <i>path</i>.<b>toString</b>()
  47. Returns the string representation of this *path* according to SVG’s [path data specification](http://www.w3.org/TR/SVG/paths.html#PathData).