Method calculateLabelBounds2

src/openlayers/overlay/Label.js:539–624

* @function Label.prototype.calculateLabelBounds2 * @description 获得标签要素的最终范围的另一种算法（通过记录下的标签宽高），提高计算范围的效率。 * @param {FeatureVector} feature - 需要计算范围的标签要素数。 * @param {Object} loc - 标签位置，例如：{"x":1,"y":1}。 * @returns {Array. } 四边形节点数组。例如：[{"x":1,"y":1},{"x":3,"y":1},{"x":6,"y"

(feature, loc)

     * @returns {Array.<Object>} 四边形节点数组。例如：[{"x":1,"y":1},{"x":3,"y":1},{"x":6,"y":4},{"x":2,"y":10},{"x":1,"y":1}]。
     */
    calculateLabelBounds2(feature, loc) {
        var labB, left, bottom, top, right;
        var labelSize = feature.geometry.bsInfo;
        var style = feature.style;
        var locationPx = CommonUtil.cloneObject(loc);

        //处理文字对齐
        if (style.labelAlign && style.labelAlign !== "cm") {
            switch (style.labelAlign) {
                case "lt":
                    locationPx.x += labelSize.w / 2;
                    locationPx.y += labelSize.h / 2;
                    break;
                case "lm":
                    locationPx.x += labelSize.w / 2;
                    break;
                case "lb":
                    locationPx.x += labelSize.w / 2;
                    locationPx.y -= labelSize.h / 2;
                    break;
                case "ct":
                    locationPx.y += labelSize.h / 2;
                    break;
                case "cb":
                    locationPx.y -= labelSize.h / 2;
                    break;
                case "rt":
                    locationPx.x -= labelSize.w / 2;
                    locationPx.y += labelSize.h / 2;
                    break;
                case "rm":
                    locationPx.x -= labelSize.w / 2;
                    break;
                case "rb":
                    locationPx.x -= labelSize.w / 2;
                    locationPx.y -= labelSize.h / 2;
                    break;
                default:
                    break;
            }
        }

        left = locationPx.x - labelSize.w / 2;
        bottom = locationPx.y + labelSize.h / 2;
        //处理斜体字
        if (style.fontStyle && style.fontStyle === "italic") {
            right = locationPx.x + labelSize.w / 2 + parseInt(parseFloat(style.fontSize) / 2);
        } else {
            right = locationPx.x + labelSize.w / 2;
        }
        top = locationPx.y - labelSize.h / 2;

        labB = new Bounds(left, bottom, right, top);

        //旋转Bounds
        var boundsQuad = [];
        if ((style.labelRotation % 180) == 0) {
            boundsQuad = [{