# All files interlace.js

100% Statements 32/32
100% Branches 8/8
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     "use strict";

    // Adam 7
    //   0 1 2 3 4 5 6 7
    // 0 x 6 4 6 x 6 4 6
    // 1 7 7 7 7 7 7 7 7
    // 2 5 6 5 6 5 6 5 6
    // 3 7 7 7 7 7 7 7 7
    // 4 3 6 4 6 3 6 4 6
    // 5 7 7 7 7 7 7 7 7
    // 6 5 6 5 6 5 6 5 6
    // 7 7 7 7 7 7 7 7 7

    let imagePasses = [
      {
        // pass 1 - 1px
        x: [0],
        y: [0],
      },
      {
        // pass 2 - 1px
        x: [4],
        y: [0],
      },
      {
        // pass 3 - 2px
        x: [0, 4],
        y: [4],
      },
      {
        // pass 4 - 4px
        x: [2, 6],
        y: [0, 4],
      },
      {
        // pass 5 - 8px
        x: [0, 2, 4, 6],
        y: [2, 6],
      },
      {
        // pass 6 - 16px
        x: [1, 3, 5, 7],
        y: [0, 2, 4, 6],
      },
      {
        // pass 7 - 32px
        x: [0, 1, 2, 3, 4, 5, 6, 7],
        y: [1, 3, 5, 7],
      },
    ];

    exports.getImagePasses = function (width, height) {
      let images = [];
      let xLeftOver = width % 8;
      let yLeftOver = height % 8;
      let xRepeats = (width - xLeftOver) / 8;
      let yRepeats = (height - yLeftOver) / 8;
      for (let i = 0; i < imagePasses.length; i++) {
        let pass = imagePasses[i];
        let passWidth = xRepeats * pass.x.length;
        let passHeight = yRepeats * pass.y.length;
        for (let j = 0; j < pass.x.length; j++) {
          if (pass.x[j] < xLeftOver) {
            passWidth++;
          } else {
            break;
          }
        }
        for (let j = 0; j < pass.y.length; j++) {
          if (pass.y[j] < yLeftOver) {
            passHeight++;
          } else {
            break;
          }
        }
        if (passWidth > 0 && passHeight > 0) {
          images.push({ width: passWidth, height: passHeight, index: i });
        }
      }
      return images;
    };

    exports.getInterlaceIterator = function (width) {
      return function (x, y, pass) {
        let outerXLeftOver = x % imagePasses[pass].x.length;
        let outerX =
          ((x - outerXLeftOver) / imagePasses[pass].x.length) * 8 +
          imagePasses[pass].x[outerXLeftOver];
        let outerYLeftOver = y % imagePasses[pass].y.length;
        let outerY =
          ((y - outerYLeftOver) / imagePasses[pass].y.length) * 8 +
          imagePasses[pass].y[outerYLeftOver];
        return outerX * 4 + outerY * width * 4;
      };
    };