All files / positioning/david DavidEisenstat2.ts

100% Statements 27/27
100% Branches 4/4
100% Functions 1/1
100% Lines 23/23

Press n or j to go to the next uncovered block, b, p or k for the previous block.

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// Increase for faster but less accurate results.
const PIXEL = 1;
 
// Returns a layout where each gap is within PIXEL of optimal.
export function find_optimal(m: Array<Array<number>>) {
  const n = m.length;
  let positions = Array(n).fill(0);
  let gaps = Array(n).fill(0);
  // eslint-disable-next-line no-constant-condition
  while (true) {
    // Compute the leftmost layout.
    for (let j = 1; j < n; j++) {
      positions[j] = positions[j - 1] + gaps[j - 1];
      for (let i = 0; i < j; i++) {
        positions[j] = Math.max(positions[j], positions[i] + m[i][j]);
      }
    }
    // Compute the rightmost layout. As we do so, each gap that can grow, grows.
    let stillGrowing = false;
    for (let i = n - 2; i > -1; i--) {
      let proposedGap = gaps[i] + PIXEL;
      // i + 1 is rightmost; i is leftmost.
      let maxGap = positions[i + 1] - positions[i];
      if (proposedGap < maxGap) {
        gaps[i] = proposedGap;
        stillGrowing = true;
      } else {
        gaps[i] = maxGap;
      }
      positions[i] = positions[i + 1] - gaps[i];
      for (let j = n - 1; j > i; j--) {
        positions[i] = Math.min(positions[i], positions[j] - m[i][j]);
      }
    }
    if (!stillGrowing) {
      return positions;
    }
  }
}