fonteditor-core/lib/graphics/computeBoundingBox.js

fonts (ttf, woff, woff2, eot, svg, otf) parse, write, transform, glyph adjust.

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.computePath = exports.computeBounding = void 0;
exports.computePathBox = computePathBox;
exports.quadraticBezier = void 0;
var _pathIterator = _interopRequireDefault(require("./pathIterator"));
function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
/**
 * @file 计算曲线包围盒
 * @author mengke01(kekee000@gmail.com)
 *
 * modify from:
 * zrender
 * https://github.com/ecomfe/zrender/blob/master/src/tool/computeBoundingBox.js
 */

/**
 * 计算包围盒
 *
 * @param {Array} points 点集
 * @return {Object} bounding box
 */
function computeBoundingBox(points) {
  if (points.length === 0) {
    return false;
  }
  var left = points[0].x;
  var right = points[0].x;
  var top = points[0].y;
  var bottom = points[0].y;
  for (var i = 1; i < points.length; i++) {
    var p = points[i];
    if (p.x < left) {
      left = p.x;
    }
    if (p.x > right) {
      right = p.x;
    }
    if (p.y < top) {
      top = p.y;
    }
    if (p.y > bottom) {
      bottom = p.y;
    }
  }
  return {
    x: left,
    y: top,
    width: right - left,
    height: bottom - top
  };
}

/**
 * 计算二阶贝塞尔曲线的包围盒
 * http://pissang.net/blog/?p=91
 *
 * @param {Object} p0 p0
 * @param {Object} p1 p1
 * @param {Object} p2 p2
 * @return {Object} bound对象
 */
function computeQuadraticBezierBoundingBox(p0, p1, p2) {
  // Find extremities, where derivative in x dim or y dim is zero
  var tmp = p0.x + p2.x - 2 * p1.x;
  // p1 is center of p0 and p2 in x dim
  var t1;
  if (tmp === 0) {
    t1 = 0.5;
  } else {
    t1 = (p0.x - p1.x) / tmp;
  }
  tmp = p0.y + p2.y - 2 * p1.y;
  // p1 is center of p0 and p2 in y dim
  var t2;
  if (tmp === 0) {
    t2 = 0.5;
  } else {
    t2 = (p0.y - p1.y) / tmp;
  }
  t1 = Math.max(Math.min(t1, 1), 0);
  t2 = Math.max(Math.min(t2, 1), 0);
  var ct1 = 1 - t1;
  var ct2 = 1 - t2;
  var x1 = ct1 * ct1 * p0.x + 2 * ct1 * t1 * p1.x + t1 * t1 * p2.x;
  var y1 = ct1 * ct1 * p0.y + 2 * ct1 * t1 * p1.y + t1 * t1 * p2.y;
  var x2 = ct2 * ct2 * p0.x + 2 * ct2 * t2 * p1.x + t2 * t2 * p2.x;
  var y2 = ct2 * ct2 * p0.y + 2 * ct2 * t2 * p1.y + t2 * t2 * p2.y;
  return computeBoundingBox([p0, p2, {
    x: x1,
    y: y1
  }, {
    x: x2,
    y: y2
  }]);
}

/**
 * 计算曲线包围盒
 *
 * @private
 * @param {...Array} args 坐标点集, 支持多个path
 * @return {Object} {x, y, width, height}
 */
function computePathBoundingBox() {
  var points = [];
  var iterator = function iterator(c, p0, p1, p2) {
    if (c === 'L') {
      points.push(p0);
      points.push(p1);
    } else if (c === 'Q') {
      var bound = computeQuadraticBezierBoundingBox(p0, p1, p2);
      points.push(bound);
      points.push({
        x: bound.x + bound.width,
        y: bound.y + bound.height
      });
    }
  };
  if (arguments.length === 1) {
    (0, _pathIterator.default)(arguments.length <= 0 ? undefined : arguments[0], function (c, p0, p1, p2) {
      if (c === 'L') {
        points.push(p0);
        points.push(p1);
      } else if (c === 'Q') {
        var bound = computeQuadraticBezierBoundingBox(p0, p1, p2);
        points.push(bound);
        points.push({
          x: bound.x + bound.width,
          y: bound.y + bound.height
        });
      }
    });
  } else {
    for (var i = 0, l = arguments.length; i < l; i++) {
      (0, _pathIterator.default)(i < 0 || arguments.length <= i ? undefined : arguments[i], iterator);
    }
  }
  return computeBoundingBox(points);
}

/**
 * 计算曲线点边界
 *
 * @private
 * @param {...Array} args path对象, 支持多个path
 * @return {Object} {x, y, width, height}
 */
function computePathBox() {
  var points = [];
  if (arguments.length === 1) {
    points = arguments.length <= 0 ? undefined : arguments[0];
  } else {
    for (var i = 0, l = arguments.length; i < l; i++) {
      Array.prototype.splice.apply(points, [points.length, 0].concat(i < 0 || arguments.length <= i ? undefined : arguments[i]));
    }
  }
  return computeBoundingBox(points);
}
var computeBounding = exports.computeBounding = computeBoundingBox;
var quadraticBezier = exports.quadraticBezier = computeQuadraticBezierBoundingBox;
var computePath = exports.computePath = computePathBoundingBox;