bbox.js

var vec2 = require("./vector");

var curve = require("./curve");

/**
 * @author Yi Shen(https://github.com/pissang)
 */
var mathMin = Math.min;
var mathMax = Math.max;
var mathSin = Math.sin;
var mathCos = Math.cos;
var PI2 = Math.PI * 2;
var start = vec2.create();
var end = vec2.create();
var extremity = vec2.create();
/**
 * 从顶点数组中计算出最小包围盒，写入`min`和`max`中
 * @module zrender/core/bbox
 * @param {Array<Object>} points 顶点数组
 * @param {number} min
 * @param {number} max
 */

function fromPoints(points, min, max) {
  if (points.length === 0) {
    return;
  }

  var p = points[0];
  var left = p[0];
  var right = p[0];
  var top = p[1];
  var bottom = p[1];
  var i;

  for (i = 1; i < points.length; i++) {
    p = points[i];
    left = mathMin(left, p[0]);
    right = mathMax(right, p[0]);
    top = mathMin(top, p[1]);
    bottom = mathMax(bottom, p[1]);
  }

  min[0] = left;
  min[1] = top;
  max[0] = right;
  max[1] = bottom;
}
/**
 * @memberOf module:zrender/core/bbox
 * @param {number} x0
 * @param {number} y0
 * @param {number} x1
 * @param {number} y1
 * @param {Array.<number>} min
 * @param {Array.<number>} max
 */


function fromLine(x0, y0, x1, y1, min, max) {
  min[0] = mathMin(x0, x1);
  min[1] = mathMin(y0, y1);
  max[0] = mathMax(x0, x1);
  max[1] = mathMax(y0, y1);
}

var xDim = [];
var yDim = [];
/**
 * 从三阶贝塞尔曲线(p0, p1, p2, p3)中计算出最小包围盒，写入`min`和`max`中
 * @memberOf module:zrender/core/bbox
 * @param {number} x0
 * @param {number} y0
 * @param {number} x1
 * @param {number} y1
 * @param {number} x2
 * @param {number} y2
 * @param {number} x3
 * @param {number} y3
 * @param {Array.<number>} min
 * @param {Array.<number>} max
 */

function fromCubic(x0, y0, x1, y1, x2, y2, x3, y3, min, max) {
  var cubicExtrema = curve.cubicExtrema;
  var cubicAt = curve.cubicAt;
  var i;
  var n = cubicExtrema(x0, x1, x2, x3, xDim);
  min[0] = Infinity;
  min[1] = Infinity;
  max[0] = -Infinity;
  max[1] = -Infinity;

  for (i = 0; i < n; i++) {
    var x = cubicAt(x0, x1, x2, x3, xDim[i]);
    min[0] = mathMin(x, min[0]);
    max[0] = mathMax(x, max[0]);
  }

  n = cubicExtrema(y0, y1, y2, y3, yDim);

  for (i = 0; i < n; i++) {
    var y = cubicAt(y0, y1, y2, y3, yDim[i]);
    min[1] = mathMin(y, min[1]);
    max[1] = mathMax(y, max[1]);
  }

  min[0] = mathMin(x0, min[0]);
  max[0] = mathMax(x0, max[0]);
  min[0] = mathMin(x3, min[0]);
  max[0] = mathMax(x3, max[0]);
  min[1] = mathMin(y0, min[1]);
  max[1] = mathMax(y0, max[1]);
  min[1] = mathMin(y3, min[1]);
  max[1] = mathMax(y3, max[1]);
}
/**
 * 从二阶贝塞尔曲线(p0, p1, p2)中计算出最小包围盒，写入`min`和`max`中
 * @memberOf module:zrender/core/bbox
 * @param {number} x0
 * @param {number} y0
 * @param {number} x1
 * @param {number} y1
 * @param {number} x2
 * @param {number} y2
 * @param {Array.<number>} min
 * @param {Array.<number>} max
 */


function fromQuadratic(x0, y0, x1, y1, x2, y2, min, max) {
  var quadraticExtremum = curve.quadraticExtremum;
  var quadraticAt = curve.quadraticAt; // Find extremities, where derivative in x dim or y dim is zero

  var tx = mathMax(mathMin(quadraticExtremum(x0, x1, x2), 1), 0);
  var ty = mathMax(mathMin(quadraticExtremum(y0, y1, y2), 1), 0);
  var x = quadraticAt(x0, x1, x2, tx);
  var y = quadraticAt(y0, y1, y2, ty);
  min[0] = mathMin(x0, x2, x);
  min[1] = mathMin(y0, y2, y);
  max[0] = mathMax(x0, x2, x);
  max[1] = mathMax(y0, y2, y);
}
/**
 * 从圆弧中计算出最小包围盒，写入`min`和`max`中
 * @method
 * @memberOf module:zrender/core/bbox
 * @param {number} x
 * @param {number} y
 * @param {number} rx
 * @param {number} ry
 * @param {number} startAngle
 * @param {number} endAngle
 * @param {number} anticlockwise
 * @param {Array.<number>} min
 * @param {Array.<number>} max
 */


function fromArc(x, y, rx, ry, startAngle, endAngle, anticlockwise, min, max) {
  var vec2Min = vec2.min;
  var vec2Max = vec2.max;
  var diff = Math.abs(startAngle - endAngle);

  if (diff % PI2 < 1e-4 && diff > 1e-4) {
    // Is a circle
    min[0] = x - rx;
    min[1] = y - ry;
    max[0] = x + rx;
    max[1] = y + ry;
    return;
  }

  start[0] = mathCos(startAngle) * rx + x;
  start[1] = mathSin(startAngle) * ry + y;
  end[0] = mathCos(endAngle) * rx + x;
  end[1] = mathSin(endAngle) * ry + y;
  vec2Min(min, start, end);
  vec2Max(max, start, end); // Thresh to [0, Math.PI * 2]

  startAngle = startAngle % PI2;

  if (startAngle < 0) {
    startAngle = startAngle + PI2;
  }

  endAngle = endAngle % PI2;

  if (endAngle < 0) {
    endAngle = endAngle + PI2;
  }

  if (startAngle > endAngle && !anticlockwise) {
    endAngle += PI2;
  } else if (startAngle < endAngle && anticlockwise) {
    startAngle += PI2;
  }

  if (anticlockwise) {
    var tmp = endAngle;
    endAngle = startAngle;
    startAngle = tmp;
  } // var number = 0;
  // var step = (anticlockwise ? -Math.PI : Math.PI) / 2;


  for (var angle = 0; angle < endAngle; angle += Math.PI / 2) {
    if (angle > startAngle) {
      extremity[0] = mathCos(angle) * rx + x;
      extremity[1] = mathSin(angle) * ry + y;
      vec2Min(min, extremity, min);
      vec2Max(max, extremity, max);
    }
  }
}

exports.fromPoints = fromPoints;
exports.fromLine = fromLine;
exports.fromCubic = fromCubic;
exports.fromQuadratic = fromQuadratic;
exports.fromArc = fromArc;