Method redrawThematicFeatures

src/openlayers/overlay/Graph.js:117–152

* @function Graph.prototype.redrawThematicFeatures * @description 重绘所有专题要素。 * 此方法包含绘制专题要素的所有步骤，包含用户数据到专题要素的转换，抽稀，缓存等步骤。 * 地图漫游时调用此方法进行图层刷新。 * @param {Object} extent - 重绘的范围。 *

(extent)

     *
     */
    redrawThematicFeatures(extent) {
        //清除当前所有可视元素
        this.renderer.clearAll();
        var features = this.features;
        for (var i = 0, len = features.length; i < len; i++) {
            var feature = features[i];
            // 要素范围判断
            var feaBounds = feature.geometry.getBounds();
            //剔除当前视图（地理）范围以外的数据
            if (extent) {
                var bounds = new Bounds(extent[0], extent[1], extent[2], extent[3]);
                if (!bounds.intersectsBounds(feaBounds)) {
                    continue;
                }
            }
            var cache = this.cache;
            // 用 feature id 做缓存标识
            var cacheField = feature.id;
            // 数据对应的图表是否已缓存，没缓存则重新创建图表
            if (cache[cacheField]) {
                continue;
            }
            cache[cacheField] = cacheField;
            var chart = this.createThematicFeature(feature);
            // 压盖处理权重值
            if (chart && this.overlayWeightField) {
                if (feature.attributes[this.overlayWeightField] && !isNaN(feature.attributes[this.overlayWeightField])) {
                    chart["__overlayWeight"] = feature.attributes[this.overlayWeightField];
                }
            }
            if (chart) {
                this.charts.push(chart);
            }
        }
        this.drawCharts();
    }

    /**
     * @function Graph.prototype.createThematicFeature