Method getLabelStyle

src/openlayers/mapping/WebMap.js:3341–3384

* @private * @function WebMap.prototype.getLabelStyle * @description 获取标签样式 * @param {Object} parameters - 标签图层样式参数 * @param {Object} layerInfo - 图层样式参数 * @returns {ol.style.Style} 标签样式

(parameters, layerInfo)

   * @returns {ol.style.Style} 标签样式
   */
  getLabelStyle(parameters, layerInfo) {
    let style = layerInfo.style || layerInfo.pointStyle;
    const { radius = 0, strokeWidth = 0 } = style,
      beforeOffsetY = -(radius + strokeWidth);
    const {
      fontSize = '14px',
      fontFamily,
      fill,
      backgroundFill,
      offsetX = 0,
      offsetY = beforeOffsetY,
      placement = 'point',
      textBaseline = 'bottom',
      textAlign = 'center',
      outlineColor = '#000000',
      outlineWidth = 0
    } = parameters;
    const option = {
      font: `${fontSize} ${fontFamily}`,
      placement,
      textBaseline,
      fill: new FillStyle({ color: fill }),
      backgroundFill: new FillStyle({ color: backgroundFill }),
      padding: [3, 3, 3, 3],
      offsetX: layerInfo.featureType === 'POINT' ? offsetX : 0,
      offsetY: layerInfo.featureType === 'POINT' ? offsetY : 0,
      overflow: true,
      maxAngle: 0
    };
    if (layerInfo.featureType === 'POINT') {
      //线面不需要此参数，否则超出线面overflow:true，也不会显示标签
      option.textAlign = textAlign;
    }
    if (outlineWidth > 0) {
      option.stroke = new StrokeStyle({
        color: outlineColor,
        width: outlineWidth
      });
    }

    return new Style({
      text: new Text(option)
    });
  }

  /**
   * @private