svg-pathdata

Manipulate SVG path data (path[d] attribute content) simply and efficiently.

Usage

Install the module:

npm install --save svg-pathdata

Then in your JavaScript files:

import {
  SVGPathData,
  SVGPathDataTransformer,
  SVGPathDataEncoder,
  SVGPathDataParser,
} from 'svg-pathdata';

Reading PathData

const pathData = new SVGPathData(`
  M 10 10
  H 60
  V 60
  L 10 60
  Z`);

console.log(pathData.commands);

// [  {type: SVGPathData.MOVE_TO,       relative: false,  x: 10,  y: 10},
//    {type: SVGPathData.HORIZ_LINE_TO, relative: false,  x: 60},
//    {type: SVGPathData.VERT_LINE_TO,  relative: false,          y: 60},
//    {type: SVGPathData.LINE_TO,       relative: false,  x: 10,  y: 60},
//    {type: SVGPathData.CLOSE_PATH}]

Reading PathData in chunks

const parser = new SVGPathDataParser();

parser.parse('   '); // returns []
parser.parse('M 10'); // returns []
parser.parse(' 10'); // returns [{type: SVGPathData.MOVE_TO, relative: false, x: 10, y: 10 }]

parser.write('H 60'); // returns [{type: SVGPathData.HORIZ_LINE_TO, relative: false, x: 60 }]

parser.write('V'); // returns []
parser.write('60'); // returns [{type: SVGPathData.VERT_LINE_TO, relative: false, y: 60 }]

parser.write('L 10 60 \n  Z');
// returns [
//   {type: SVGPathData.LINE_TO, relative: false, x: 10, y: 60 },
//   {type: SVGPathData.CLOSE_PATH }]

parser.finish(); // tell parser there is no more data: will throw if there are unfinished commands.

Outputting PathData

const pathData = new SVGPathData(`
  M 10 10
  H 60
  V 60
  L 10 60
  Z`);
// returns "M10 10H60V60L10 60Z"

encodeSVGPath({ type: SVGPathData.MOVE_TO, relative: false, x: 10, y: 10 });
// returns "M10 10"

encodeSVGPath({ type: SVGPathData.HORIZ_LINE_TO, relative: false, x: 60 });
// returns "H60"

encodeSVGPath([
  { type: SVGPathData.VERT_LINE_TO, relative: false, y: 60 },
  { type: SVGPathData.LINE_TO, relative: false, x: 10, y: 60 },
  { type: SVGPathData.CLOSE_PATH },
]);
// returns "V60L10 60Z"

Transforming PathData

This library can perform transformations on SVG paths. Here is an example of that kind of use.

Transforming entire paths

new SVGPathData(`
   m 10,10
   h 60
   v 60
   l 10,60
   z`)
  .toAbs()
  .encode();
// return s"M10,10 H70 V70 L80,130 Z"

Transforming partial data

Here, we take SVGPathData from stdin and output it transformed to stdout.

const transformingParser = new SVGPathDataParser().toAbs().scale(2, 2);
transformingParser.parse('m 0 0'); // returns [{ type: SVGPathData.MOVE_TO,       relative: false, x: 0, y: 0 }]
transformingParser.parse('l 2 3'); // returns [{ type: SVGPathData.LINE_TO,       relative: false, x: 4, y: 6 }]

Supported transformations

You can find all supported transformations in src/SVGPathDataTransformer.ts. Additionally, you can create your own by writing a function with the following signature:

type TransformFunction = (command: SVGCommand) => SVGCommand | SVGCommand[];

function SET_X_TO(xValue = 10) {
  return function(command) {
    command.x = xValue; // transform command objects and return them
    return command;
  };
};

// Synchronous usage
new SVGPathData('...')
  .transform(SET_X_TO(25))
  .encode();

// Chunk usage
new SVGPathDataParser().transform(SET_X_TO(25));

Contributing

Clone this project, run:

npm install; npm test

API

Functions

annotateArcCommand()

https://www.w3.org/TR/SVG/implnote.html#ArcImplementationNotes Fixes rX and rY. Ensures lArcFlag and sweepFlag are 0 or 1 Adds center coordinates: command.cX, command.cY (relative or absolute, depending on command.relative) Adds start and end arc parameters (in degrees): command.phi1, command.phi2; phi1 < phi2 iff. c.sweepFlag == true

Kind: global function

intersectionUnitCircleLine()

Solves a quadratic system of equations of the form a * x + b * y = c x² + y² = 1 This can be understood as the intersection of the unit circle with a line. => y = (c - a x) / b => x² + (c - a x)² / b² = 1 => x² b² + c² - 2 c a x + a² x² = b² => (a² + b²) x² - 2 a c x + (c² - b²) = 0

Kind: global function

arePointsCollinear(p1, p2, p3) ⇒

Determines if three points are collinear (lie on the same straight line) and the middle point is on the line segment between the first and third points

Kind: global function
Returns: true if the points are collinear and p2 is on the segment p1-p3

| Param | Description | | --- | --- | | p1 | First point [x, y] | | p2 | Middle point that might be removed | | p3 | Last point [x, y] |

createEllipse()

Creates an ellipse path centered at (cx,cy) with radii rx and ry

Kind: global function

createRect()

Creates a rectangle path with optional rounded corners

Kind: global function

createPolyline()

Creates a polyline from an array of coordinates [x1,y1,x2,y2,...]

Kind: global function

createPolygon()

Creates a closed polygon from an array of coordinates

Kind: global function

REMOVE_COLLINEAR(commands) ⇒

Process a path and remove collinear points

Kind: global function
Returns: New array with collinear points removed

| Param | Description | | --- | --- | | commands | Array of SVG path commands to process (must be absolute) |

REVERSE_PATH(commands, preserveSubpathOrder) ⇒

Reverses the order of path commands to go from end to start IMPORTANT: This function expects absolute commands as input. It doesn't convert relative to absolute - use SVGPathDataTransformer.TO_ABS() first if needed.

Kind: global function
Returns: New SVG commands in reverse order with absolute coordinates

| Param | Description | | --- | --- | | commands | SVG path commands in absolute form to reverse | | preserveSubpathOrder | If true, keeps subpaths in their original order |

Authors

• Nicolas Froidure
• Anders Kaseorg

License

MIT