All files / plugins convertPathData.ts

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import {
  Circle,
  Curve,
  PathItem,
  Point,
  applyTransforms,
  convertToRelative,
  js2path,
  path2js,
} from './_path';
 
import { JsApi } from '../lib/jsapi';
import { Plugin } from './_types';
import { cleanupOutData } from './_tools';
 
let roundData: (data: number[]) => number[];
let precision: number;
let error: number;
let arcThreshold: number;
let arcTolerance: number;
 
export const defaultParams = {
  applyTransforms: true,
  applyTransformsStroked: true,
  makeArcs: {
    threshold: 2.5, // Coefficient of rounding error.
    tolerance: 0.5, // Percentage of radius.
  },
  straightCurves: true,
  lineShorthands: true,
  curveSmoothShorthands: true,
  floatPrecision: 3,
  transformPrecision: 5,
  removeUseless: true,
  collapseRepeated: true,
  utilizeAbsolute: true,
  leadingZero: false,
  negativeExtraSpace: true,
};
 
export type Params = typeof defaultParams;
 
/**
 * Convert absolute Path to relative, collapse repeated instructions,
 * detect and convert Lineto shorthands, remove useless instructions like "l0,0",
 * trim useless delimiters and leading zeros, decrease accuracy of floating-point numbers.
 */
function fn(item: JsApi, params: Params) {
  if (
    !(item.isElem('path') || item.isElem('clip-path')) ||
    // TODO: detect if a path w/ a name can be optimized (i.e. if it isn't being morphed)
    item.hasAttr('android:name') ||
    !item.hasAttr('android:pathData')
  ) {
    return item;
  }
  precision = params.floatPrecision;
  error = +Math.pow(0.1, precision).toFixed(precision);
  roundData = precision > 0 && precision < 20 ? strongRound : round;
  Eif (params.makeArcs) {
    arcThreshold = params.makeArcs.threshold;
    arcTolerance = params.makeArcs.tolerance;
  }
 
  let data = path2js(item);
  if (!data.length) {
    return item;
  }
 
  convertToRelative(data);
  data = filters(data, params);
  Eif (params.utilizeAbsolute) {
    data = convertToMixed(data, params);
  }
  js2path(item, data, params);
 
  return item;
}
 
function filters(
  // TODO: avoid this caching hackery?
  pathRes: Array<PathItem & { sdata?: number[] }>,
  params: Params,
) {
  const stringify = data2Path.bind(undefined, params);
  const relSubpoint = [0, 0];
  const pathBase = [0, 0];
  let prev: any = {};
 
  pathRes = pathRes.filter(function(item, index, path) {
    let instruction = item.instruction;
    let data = item.data;
    let next = path[index + 1];
 
    if (data) {
      let sdata = data;
      let circle: Circle;
 
      if (instruction === 's') {
        sdata = [0, 0].concat(data);
 
        if ('cs'.indexOf(prev.instruction) > -1) {
          const pdata = prev.data;
          const n = pdata.length;
 
          // (-x, -y) of the prev tangent point relative to the current point
          sdata[0] = pdata[n - 2] - pdata[n - 4];
          sdata[1] = pdata[n - 1] - pdata[n - 3];
        }
      }
 
      // convert curves to arcs if possible
      if (
        params.makeArcs &&
        (instruction === 'c' || instruction === 's') &&
        isConvex(sdata) &&
        (circle = findCircle(sdata as Curve))
      ) {
        const r = roundData([circle.radius])[0];
        let angle = findArcAngle(sdata, circle);
        const sweep = sdata[5] * sdata[0] - sdata[4] * sdata[1] > 0 ? 1 : 0;
        let arc = {
          instruction: 'a',
          data: [r, r, 0, 0, sweep, sdata[4], sdata[5]],
          coords: item.coords.slice(),
          base: item.base,
        };
        const output = [arc];
        // relative coordinates to adjust the found circle
        const relCenter: Point = [
          circle.center[0] - sdata[4],
          circle.center[1] - sdata[5],
        ];
        const relCircle = { center: relCenter, radius: circle.radius };
        const arcCurves = [item];
        let hasPrev = 0;
        let suffix = '';
        let nextLonghand;
 
        if (
          (prev.instruction === 'c' &&
            isConvex(prev.data) &&
            isArcPrev(prev.data, circle)) ||
          (prev.instruction === 'a' &&
            prev.sdata &&
            isArcPrev(prev.sdata, circle))
        ) {
          arcCurves.unshift(prev);
          arc.base = prev.base;
          arc.data[5] = arc.coords[0] - arc.base[0];
          arc.data[6] = arc.coords[1] - arc.base[1];
          const prevData = prev.instruction === 'a' ? prev.sdata : prev.data;
          angle += findArcAngle(prevData, {
            center: [prevData[4] + relCenter[0], prevData[5] + relCenter[1]],
            radius: circle.radius,
          });
          if (angle > Math.PI) {
            arc.data[3] = 1;
          }
          hasPrev = 1;
        }
 
        // check if next curves are fitting the arc
        let j = index;
        // tslint:disable-next-line:no-bitwise
        for (; (next = path[++j]) && ~'cs'.indexOf(next.instruction); ) {
          let nextDataTemp = next.data;
          if (next.instruction === 's') {
            nextLonghand = makeLonghand(
              { instruction: 's', data: next.data.slice() },
              path[j - 1].data,
            );
            nextDataTemp = nextLonghand.data;
            nextLonghand.data = nextDataTemp.slice(0, 2);
            suffix = stringify([nextLonghand]);
          }
          const nextData = nextDataTemp as Curve;
          if (isConvex(nextData) && isArc(nextData, relCircle)) {
            angle += findArcAngle(nextData, relCircle);
            Iif (angle - 2 * Math.PI > 1e-3) {
              break; // more than 360°
            }
            if (angle > Math.PI) {
              arc.data[3] = 1;
            }
            arcCurves.push(next);
            if (2 * Math.PI - angle > 1e-3) {
              // less than 360°
              arc.coords = next.coords;
              arc.data[5] = arc.coords[0] - arc.base[0];
              arc.data[6] = arc.coords[1] - arc.base[1];
            } else {
              // full circle, make a half-circle arc and add a second one
              arc.data[5] = 2 * (relCircle.center[0] - nextData[4]);
              arc.data[6] = 2 * (relCircle.center[1] - nextData[5]);
              arc.coords = [
                arc.base[0] + arc.data[5],
                arc.base[1] + arc.data[6],
              ];
              arc = {
                instruction: 'a',
                data: [
                  r,
                  r,
                  0,
                  0,
                  sweep,
                  next.coords[0] - arc.coords[0],
                  next.coords[1] - arc.coords[1],
                ],
                coords: next.coords,
                base: arc.coords,
              };
              output.push(arc);
              j++;
              break;
            }
            relCenter[0] -= nextData[4];
            relCenter[1] -= nextData[5];
          } else {
            break;
          }
        }
 
        if ((stringify(output) + suffix).length < stringify(arcCurves).length) {
          Iif (path[j] && path[j].instruction === 's') {
            makeLonghand(path[j], path[j - 1].data);
          }
          if (hasPrev) {
            const prevArc = output.shift();
            roundData(prevArc.data);
            relSubpoint[0] += prevArc.data[5] - prev.data[prev.data.length - 2];
            relSubpoint[1] += prevArc.data[6] - prev.data[prev.data.length - 1];
            prev.instruction = 'a';
            prev.data = prevArc.data;
            item.base = prev.coords = prevArc.coords;
          }
          arc = output.shift();
          if (arcCurves.length === 1) {
            item.sdata = sdata.slice(); // preserve curve data for future checks
          } else if (arcCurves.length - 1 - hasPrev > 0) {
            // filter out consumed next items
            path.splice.apply(path, [
              index + 1,
              arcCurves.length - 1 - hasPrev,
              ...output,
            ]);
          }
          if (!arc) {
            return false;
          }
          instruction = 'a';
          data = arc.data;
          item.coords = arc.coords;
        }
      }
 
      // Rounding relative coordinates, taking in account accummulating error
      // to get closer to absolute coordinates. Sum of rounded value remains same:
      // l .25 3 .25 2 .25 3 .25 2 -> l .3 3 .2 2 .3 3 .2 2
      if ('mltqsc'.indexOf(instruction) > -1) {
        for (let i = data.length; i--; ) {
          data[i] += item.base[i % 2] - relSubpoint[i % 2];
        }
      } else if (instruction === 'h') {
        data[0] += item.base[0] - relSubpoint[0];
      } else if (instruction === 'v') {
        data[0] += item.base[1] - relSubpoint[1];
      } else if (instruction === 'a') {
        data[5] += item.base[0] - relSubpoint[0];
        data[6] += item.base[1] - relSubpoint[1];
      }
      roundData(data);
 
      if (instruction === 'h') {
        relSubpoint[0] += data[0];
      } else if (instruction === 'v') {
        relSubpoint[1] += data[0];
      } else {
        relSubpoint[0] += data[data.length - 2];
        relSubpoint[1] += data[data.length - 1];
      }
      roundData(relSubpoint);
 
      if (instruction.toLowerCase() === 'm') {
        pathBase[0] = relSubpoint[0];
        pathBase[1] = relSubpoint[1];
      }
 
      // convert straight curves into lines segments
      Eif (params.straightCurves) {
        if (
          (instruction === 'c' && isCurveStraightLine(data)) ||
          (instruction === 's' && isCurveStraightLine(sdata))
        ) {
          if (next && next.instruction === 's') {
            makeLonghand(next, data); // fix up next curve
          }
          instruction = 'l';
          data = data.slice(-2);
        } else if (instruction === 'q' && isCurveStraightLine(data)) {
          if (next && next.instruction === 't') {
            makeLonghand(next, data); // fix up next curve
          }
          instruction = 'l';
          data = data.slice(-2);
        } else if (
          instruction === 't' &&
          prev.instruction !== 'q' &&
          prev.instruction !== 't'
        ) {
          instruction = 'l';
          data = data.slice(-2);
        } else if (instruction === 'a' && (data[0] === 0 || data[1] === 0)) {
          instruction = 'l';
          data = data.slice(-2);
        }
      }
 
      // horizontal and vertical line shorthands
      // l 50 0 → h 50
      // l 0 50 → v 50
      if (params.lineShorthands && instruction === 'l') {
        if (data[1] === 0) {
          instruction = 'h';
          data.pop();
        } else if (data[0] === 0) {
          instruction = 'v';
          data.shift();
        }
      }
 
      // collapse repeated commands
      // h 20 h 30 -> h 50
      if (
        params.collapseRepeated &&
        'mhv'.indexOf(instruction) > -1 &&
        prev.instruction &&
        instruction === prev.instruction.toLowerCase() &&
        ((instruction !== 'h' && instruction !== 'v') ||
          prev.data[0] >= 0 === item.data[0] >= 0)
      ) {
        prev.data[0] += data[0];
        if (instruction !== 'h' && instruction !== 'v') {
          prev.data[1] += data[1];
        }
        prev.coords = item.coords;
        path[index] = prev;
        return false;
      }
 
      // convert curves into smooth shorthands
      if (params.curveSmoothShorthands && prev.instruction) {
        // curveto
        if (instruction === 'c') {
          // c + c → c + s
          if (
            prev.instruction === 'c' &&
            data[0] === -(prev.data[2] - prev.data[4]) &&
            data[1] === -(prev.data[3] - prev.data[5])
          ) {
            instruction = 's';
            data = data.slice(2);
          } else if (
            prev.instruction === 's' &&
            data[0] === -(prev.data[0] - prev.data[2]) &&
            data[1] === -(prev.data[1] - prev.data[3])
          ) {
            // s + c → s + s
            instruction = 's';
            data = data.slice(2);
          } else if (
            'cs'.indexOf(prev.instruction) === -1 &&
            data[0] === 0 &&
            data[1] === 0
          ) {
            // [^cs] + c → [^cs] + s
            instruction = 's';
            data = data.slice(2);
          }
        } else if (instruction === 'q') {
          // quadratic Bézier curveto
          // q + q → q + t
          if (
            prev.instruction === 'q' &&
            data[0] === prev.data[2] - prev.data[0] &&
            data[1] === prev.data[3] - prev.data[1]
          ) {
            instruction = 't';
            data = data.slice(2);
          } else if (
            prev.instruction === 't' &&
            data[2] === prev.data[0] &&
            data[3] === prev.data[1]
          ) {
            // t + q → t + t
            instruction = 't';
            data = data.slice(2);
          }
        }
      }
 
      // remove useless non-first path segments
      Eif (params.removeUseless) {
        // l 0,0 / h 0 / v 0 / q 0,0 0,0 / t 0,0 / c 0,0 0,0 0,0 / s 0,0 0,0
        if ('lhvqtcs'.indexOf(instruction) > -1 && data.every(i => i === 0)) {
          path[index] = prev;
          return false;
        }
 
        // a 25,25 -30 0,1 0,0
        if (instruction === 'a' && data[5] === 0 && data[6] === 0) {
          path[index] = prev;
          return false;
        }
      }
 
      item.instruction = instruction;
      item.data = data;
 
      prev = item;
    } else {
      // z resets coordinates
      relSubpoint[0] = pathBase[0];
      relSubpoint[1] = pathBase[1];
      if (prev.instruction === 'z') {
        return false;
      }
      prev = item;
    }
 
    return true;
  });
 
  return pathRes;
}
 
/**
 * Writes data in shortest form using absolute or relative coordinates.
 * @param {Array} data input path data
 * @return {Boolean} output
 */
function convertToMixed(path: PathItem[], params: Params) {
  let prev = path[0];
 
  path = path.filter(function(item, index) {
    if (index === 0) {
      return true;
    }
    if (!item.data) {
      prev = item;
      return true;
    }
 
    const instruction = item.instruction;
    const data = item.data;
    const adata = data && data.slice(0);
 
    if ('mltqsc'.indexOf(instruction) > -1) {
      for (let i = adata.length; i--; ) {
        adata[i] += item.base[i % 2];
      }
    } else if (instruction === 'h') {
      adata[0] += item.base[0];
    } else if (instruction === 'v') {
      adata[0] += item.base[1];
    } else Eif (instruction === 'a') {
      adata[5] += item.base[0];
      adata[6] += item.base[1];
    }
 
    roundData(adata);
 
    const absoluteDataStr = cleanupOutData(adata, params);
    const relativeDataStr = cleanupOutData(data, params);
 
    // Convert to absolute coordinates if it's shorter.
    // v-20 -> V0
    // Don't convert if it fits following previous instruction.
    // l20 30-10-50 instead of l20 30L20 30
    if (
      absoluteDataStr.length < relativeDataStr.length &&
      !(
        params.negativeExtraSpace &&
        instruction === prev.instruction &&
        prev.instruction.charCodeAt(0) > 96 &&
        absoluteDataStr.length === relativeDataStr.length - 1 &&
        (data[0] < 0 ||
          (/^0\./.test(String(data[0])) && prev.data[prev.data.length - 1] % 1))
      )
    ) {
      item.instruction = instruction.toUpperCase();
      item.data = adata;
    }
    prev = item;
    return true;
  });
 
  return path;
}
 
/**
 * Checks if curve is convex. Control points of such a curve must form
 * a convex quadrilateral with diagonals crosspoint inside of it.
 *
 * @param {Array} data input path data
 * @return {Boolean} output
 */
function isConvex(data: number[]) {
  const center = getIntersection([
    0,
    0,
    data[2],
    data[3],
    data[0],
    data[1],
    data[4],
    data[5],
  ]);
  return (
    center &&
    data[2] < center[0] === center[0] < 0 &&
    data[3] < center[1] === center[1] < 0 &&
    data[4] < center[0] === center[0] < data[0] &&
    data[5] < center[1] === center[1] < data[1]
  );
}
 
/**
 * Computes lines equations by two points and returns their intersection point.
 *
 * @param {Array} coords 8 numbers for 4 pairs of coordinates (x,y)
 * @return {Array|undefined} output coordinate of lines' crosspoint
 */
function getIntersection(coords: number[]): Point | undefined {
  // Prev line equation parameters.
  const a1 = coords[1] - coords[3]; // y1 - y2
  const b1 = coords[2] - coords[0]; // x2 - x1
  const c1 = coords[0] * coords[3] - coords[2] * coords[1]; // x1 * y2 - x2 * y1
  // Next line equation parameters
  const a2 = coords[5] - coords[7]; // y1 - y2
  const b2 = coords[6] - coords[4]; // x2 - x1
  const c2 = coords[4] * coords[7] - coords[5] * coords[6]; // x1 * y2 - x2 * y1
  const denom = a1 * b2 - a2 * b1;
 
  if (!denom) {
    return undefined; // parallel lines havn't an intersection
  }
 
  const cross: Point = [
    (b1 * c2 - b2 * c1) / denom,
    (a1 * c2 - a2 * c1) / -denom,
  ];
  Eif (
    !isNaN(cross[0]) &&
    !isNaN(cross[1]) &&
    isFinite(cross[0]) &&
    isFinite(cross[1])
  ) {
    return cross;
  }
  return undefined;
}
 
/**
 * Decrease accuracy of floating-point numbers
 * in path data keeping a specified number of decimals.
 * Smart rounds values like 2.3491 to 2.35 instead of 2.349.
 * Doesn't apply "smartness" if the number precision fits already.
 *
 * @param {Array} data input data array
 * @return {Array} output data array
 */
function strongRound(data: number[]) {
  for (let i = data.length; i-- > 0; ) {
    if (+data[i].toFixed(precision) !== data[i]) {
      const rounded = +data[i].toFixed(precision - 1);
      data[i] =
        +Math.abs(rounded - data[i]).toFixed(precision + 1) >= error
          ? +data[i].toFixed(precision)
          : rounded;
    }
  }
  return data;
}
 
/**
 * Checks if a curve is a straight line by measuring distance
 * from middle points to the line formed by end points.
 */
function isCurveStraightLine(data: number[]) {
  // Get line equation a·x + b·y + c = 0 coefficients a, b (c = 0) by start and end points.
  let i = data.length - 2;
  const a = -data[i + 1]; // y1 − y2 (y1 = 0)
  const b = data[i]; // x2 − x1 (x1 = 0)
  const d = 1 / (a * a + b * b); // same part for all points
 
  if (i <= 1 || !isFinite(d)) {
    // Curve that ends at start point isn't the case.
    return false;
  }
 
  // Distance from point (x0, y0) to the line is sqrt((c − a·x0 − b·y0)² / (a² + b²))
  while ((i -= 2) >= 0) {
    if (Math.sqrt(Math.pow(a * data[i] + b * data[i + 1], 2) * d) > error) {
      return false;
    }
  }
 
  return true;
}
 
/**
 * Converts next curve from shorthand to full form using the current curve data.
 */
function makeLonghand<T extends { instruction: string; data?: number[] }>(
  item: T,
  data: number[],
) {
  switch (item.instruction) {
    case 's':
      item.instruction = 'c';
      break;
    case 't':
      item.instruction = 'q';
      break;
  }
  item.data.unshift(
    data[data.length - 2] - data[data.length - 4],
    data[data.length - 1] - data[data.length - 3],
  );
  return item;
}
 
/**
 * Returns distance between two points.
 */
function getDistance(p1: Point, p2: Point) {
  return Math.sqrt(Math.pow(p1[0] - p2[0], 2) + Math.pow(p1[1] - p2[1], 2));
}
 
/**
 * Returns coordinates of the curve point corresponding to the certain t
 * a·(1 - t)³·p1 + b·(1 - t)²·t·p2 + c·(1 - t)·t²·p3 + d·t³·p4,
 * where pN are control points and p1 is zero due to relative coordinates.
 * @param {Array} curve array of curve points coordinates
 * @param {Number} t parametric position from 0 to 1
 * @return {Array} Point coordinates
 */
 
function getCubicBezierPoint(curve: Curve, t: number): Point {
  const sqrT = t * t;
  const cubT = sqrT * t;
  const mt = 1 - t;
  const sqrMt = mt * mt;
  return [
    3 * sqrMt * t * curve[0] + 3 * mt * sqrT * curve[2] + cubT * curve[4],
    3 * sqrMt * t * curve[1] + 3 * mt * sqrT * curve[3] + cubT * curve[5],
  ];
}
 
/**
 * Finds circle by 3 points of the curve and checks if the curve fits the found circle.
 *
 * @param {Array} curve
 * @return {Object|undefined} circle
 */
 
function findCircle(curve: Curve) {
  const midPoint = getCubicBezierPoint(curve, 1 / 2);
  const m1 = [midPoint[0] / 2, midPoint[1] / 2];
  const m2 = [(midPoint[0] + curve[4]) / 2, (midPoint[1] + curve[5]) / 2];
  const center = getIntersection([
    m1[0],
    m1[1],
    m1[0] + m1[1],
    m1[1] - m1[0],
    m2[0],
    m2[1],
    m2[0] + (m2[1] - midPoint[1]),
    m2[1] - (m2[0] - midPoint[0]),
  ]);
  const radius = center && getDistance([0, 0], center);
  const tolerance = Math.min(arcThreshold * error, arcTolerance * radius / 100);
 
  if (
    center &&
    [1 / 4, 3 / 4].every(point => {
      return (
        Math.abs(
          getDistance(getCubicBezierPoint(curve, point), center) - radius,
        ) <= tolerance
      );
    })
  ) {
    return { center: center, radius: radius };
  }
  return undefined;
}
 
/**
 * Checks if a curve fits the given circle.
 * @param {Object} circle
 * @param {Array} curve
 * @return {Boolean}
 */
function isArc(curve: Curve, circle: Circle) {
  const tolerance = Math.min(
    arcThreshold * error,
    arcTolerance * circle.radius / 100,
  );
  return [0, 1 / 4, 1 / 2, 3 / 4, 1].every(point => {
    return (
      Math.abs(
        getDistance(getCubicBezierPoint(curve, point), circle.center) -
          circle.radius,
      ) <= tolerance
    );
  });
}
 
/**
 * Checks if a previous curve fits the given circle.
 * @param {Object} circle
 * @param {Array} curve
 * @return {Boolean}
 */
function isArcPrev(curve: Curve, circle: Circle) {
  return isArc(curve, {
    center: [circle.center[0] + curve[4], circle.center[1] + curve[5]],
    radius: circle.radius,
  });
}
 
/**
 * Finds angle of a curve fitting the given arc.
 * @param {Array} curve
 * @param {Object} relCircle
 * @return {Number} angle
 */
 
function findArcAngle(curve: number[], relCircle: Circle) {
  const x1 = -relCircle.center[0];
  const y1 = -relCircle.center[1];
  const x2 = curve[4] - relCircle.center[0];
  const y2 = curve[5] - relCircle.center[1];
  return Math.acos(
    (x1 * x2 + y1 * y2) / Math.sqrt((x1 * x1 + y1 * y1) * (x2 * x2 + y2 * y2)),
  );
}
 
/**
 * Converts given path data to string.
 *
 * @param {Object} params
 * @param {Array} pathData
 * @return {String}
 */
function data2Path(params: Params, pathData: PathItem[]) {
  return pathData.reduce((pathString, item) => {
    return (
      pathString +
      item.instruction +
      (item.data ? cleanupOutData(roundData(item.data.slice()), params) : '')
    );
  }, '');
}
 
/**
 * Simple rounding function if precision is 0.
 *
 * @param {Array} data input data array
 * @return {Array} output data array
 */
function round(data: number[]) {
  for (let i = data.length; i-- > 0; ) {
    data[i] = Math.round(data[i]);
  }
  return data;
}
 
export const convertPathData: Plugin<Params> = {
  type: 'perItem',
  active: true,
  description:
    'optimizes path data: writes in shorter form, applies transformations',
  params: defaultParams,
  fn,
};