myprint-design/lib/utils/bezierUtil.js

操作简单，组件丰富的一站式打印解决方案打印设计器

'use strict';

function bezier2(p0, p1, p2) {
  var bounds = {
    minX: Math.min(p0.x, p2.x),
    maxX: Math.max(p0.x, p2.x),
    minY: Math.min(p0.y, p2.y),
    maxY: Math.max(p0.y, p2.y)
  };
  var tForX = (p0.x - p1.x) / (p0.x - 2 * p1.x + p2.x);
  var tForY = (p0.y - p1.y) / (p0.y - 2 * p1.y + p2.y);
  if (tForX > 0 && tForX < 1) {
    var xAtT = (1 - tForX) * (1 - tForX) * p0.x + 2 * (1 - tForX) * tForX * p1.x + tForX * tForX * p2.x;
    bounds.minX = Math.min(bounds.minX, xAtT);
    bounds.maxX = Math.max(bounds.maxX, xAtT);
  }
  if (tForY > 0 && tForY < 1) {
    var yAtT = (1 - tForY) * (1 - tForY) * p0.y + 2 * (1 - tForY) * tForY * p1.y + tForY * tForY * p2.y;
    bounds.minY = Math.min(bounds.minY, yAtT);
    bounds.maxY = Math.max(bounds.maxY, yAtT);
  }
  return {
    x: bounds.minX,
    y: bounds.minY,
    width: bounds.maxX - bounds.minX,
    height: bounds.maxY - bounds.minY
  };
}
function bezier3(p0, p1, p2, p3) {
  let minX = Math.min(p0.x, p3.x);
  let minY = Math.min(p0.y, p3.y);
  let maxX = Math.max(p0.x, p3.x);
  let maxY = Math.max(p0.y, p3.y);
  for (let t = 0; t <= 1; t += 0.01) {
    let x = Math.pow(1 - t, 3) * p0.x + 3 * Math.pow(1 - t, 2) * t * p1.x + 3 * (1 - t) * Math.pow(t, 2) * p2.x + Math.pow(t, 3) * p3.x;
    let y = Math.pow(1 - t, 3) * p0.y + 3 * Math.pow(1 - t, 2) * t * p1.y + 3 * (1 - t) * Math.pow(t, 2) * p2.y + Math.pow(t, 3) * p3.y;
    minX = Math.min(minX, x);
    minY = Math.min(minY, y);
    maxX = Math.max(maxX, x);
    maxY = Math.max(maxY, y);
  }
  return {
    x: minX,
    y: minY,
    width: maxX - minX,
    height: maxY - minY
  };
}

exports.bezier2 = bezier2;
exports.bezier3 = bezier3;
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