zh/builder/src/echarts/chart/helper/EffectPolyline.js

/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements.  See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership.  The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License.  You may obtain a copy of the License at
*
*   http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied.  See the License for the
* specific language governing permissions and limitations
* under the License.
*/

/**
 * Provide effect for line
 * @module echarts/chart/helper/EffectLine
 */
import Polyline from './Polyline';
import * as zrUtil from 'zrender/src/core/util';
import EffectLine from './EffectLine';
import * as vec2 from 'zrender/src/core/vector';
/**
 * @constructor
 * @extends {module:echarts/chart/helper/EffectLine}
 * @alias {module:echarts/chart/helper/Polyline}
 */

function EffectPolyline(lineData, idx, seriesScope) {
  EffectLine.call(this, lineData, idx, seriesScope);
  this._lastFrame = 0;
  this._lastFramePercent = 0;
}

var effectPolylineProto = EffectPolyline.prototype; // Overwrite

effectPolylineProto.createLine = function (lineData, idx, seriesScope) {
  return new Polyline(lineData, idx, seriesScope);
}; // Overwrite


effectPolylineProto.updateAnimationPoints = function (symbol, points) {
  this._points = points;
  var accLenArr = [0];
  var len = 0;

  for (var i = 1; i < points.length; i++) {
    var p1 = points[i - 1];
    var p2 = points[i];
    len += vec2.dist(p1, p2);
    accLenArr.push(len);
  }

  if (len === 0) {
    return;
  }

  for (var i = 0; i < accLenArr.length; i++) {
    accLenArr[i] /= len;
  }

  this._offsets = accLenArr;
  this._length = len;
}; // Overwrite


effectPolylineProto.getLineLength = function (symbol) {
  return this._length;
}; // Overwrite


effectPolylineProto.updateSymbolPosition = function (symbol) {
  var t = symbol.__t;
  var points = this._points;
  var offsets = this._offsets;
  var len = points.length;

  if (!offsets) {
    // Has length 0
    return;
  }

  var lastFrame = this._lastFrame;
  var frame;

  if (t < this._lastFramePercent) {
    // Start from the next frame
    // PENDING start from lastFrame ?
    var start = Math.min(lastFrame + 1, len - 1);

    for (frame = start; frame >= 0; frame--) {
      if (offsets[frame] <= t) {
        break;
      }
    } // PENDING really need to do this ?


    frame = Math.min(frame, len - 2);
  } else {
    for (var frame = lastFrame; frame < len; frame++) {
      if (offsets[frame] > t) {
        break;
      }
    }

    frame = Math.min(frame - 1, len - 2);
  }

  vec2.lerp(symbol.position, points[frame], points[frame + 1], (t - offsets[frame]) / (offsets[frame + 1] - offsets[frame]));
  var tx = points[frame + 1][0] - points[frame][0];
  var ty = points[frame + 1][1] - points[frame][1];
  symbol.rotation = -Math.atan2(ty, tx) - Math.PI / 2;
  this._lastFrame = frame;
  this._lastFramePercent = t;
  symbol.ignore = false;
};

zrUtil.inherits(EffectPolyline, EffectLine);
export default EffectPolyline;