@aeolun/muhammara/lib/recipe/coordinate.js

Create, read and modify PDF files and streams. A drop in replacement for hummusjs PDF library

exports._centrify = function _centrify(x, y, pageNumber) {
  pageNumber = pageNumber || this.pageNumber;
  const { width, height } = this.metadata[pageNumber];
  switch (x) {
    case "center":
      x = width / 2;
      break;
  }
  switch (y) {
    case "center":
      y = height / 2;
      break;
  }

  return [x, y];
};

exports._calibrateCoordinate = function _calibrateCoordinate(
  x,
  y,
  offsetX = 0,
  offsetY = 0,
  pageNumber
) {
  pageNumber = pageNumber || this.pageNumber;
  const { height, mediaBox } = this.metadata[pageNumber];
  const startX = mediaBox[0];
  const startY = mediaBox[1];
  [x, y] = this._centrify(x, y, pageNumber);

  const nx = x + offsetX + startX;
  const ny = height - y + offsetY + startY;
  return {
    nx,
    ny,
  };
};

exports._calibrateCoordinateForAnnots = function _calibrateCoordinateForAnnots(
  x,
  y,
  offsetX = 0,
  offsetY = 0,
  pageNumber
) {
  const { nx: tx, ny: ty } = this._calibrateCoordinate(
    x,
    y,
    offsetX,
    offsetY,
    pageNumber
  );
  const { width, height, rotate, mediaBox } = this.metadata[pageNumber];
  const startX = mediaBox[0];
  const startY = mediaBox[1];
  let rotateOffsetX = 0,
    rotateOffsetY = 0;
  switch (rotate) {
    case 90:
      rotateOffsetX = height - startX;
      rotateOffsetY = startY;
      break;
    case 180:
      rotateOffsetX = width;
      rotateOffsetY = height;
      break;
    case 270:
      rotateOffsetX = startX;
      rotateOffsetY = width - startY;
      break;
    default:
  }
  // return { nx: tx, ny: ty };
  const { nx, ny } = rotateCoord(
    0,
    0,
    tx,
    ty,
    360 - rotate,
    rotateOffsetX,
    rotateOffsetY
  );
  return {
    nx,
    ny,
  };
};

exports._reverseCoordinate = function _reverseCoordinate(
  x,
  y,
  offsetX = 0,
  offsetY = 0,
  pageNumber
) {
  pageNumber = pageNumber || this.pageNumber;
  const { height } = this.metadata[pageNumber];
  const ox = x - offsetX;
  const oy = height - y - offsetY;
  return {
    ox,
    oy,
  };
};

function rotateCoord(cx, cy, x, y, angle, offsetX = 0, offsetY = 0) {
  const radians = (Math.PI / 180) * angle,
    cos = Math.cos(radians),
    sin = Math.sin(radians),
    nx = cos * (x - cx) + sin * (y - cy) + cx + offsetX,
    ny = cos * (y - cy) - sin * (x - cx) + cy + offsetY;

  return { nx, ny };
}