Function hideOverlap

src/label/labelLayoutHelper.ts:522–577

(labelList: LabelLayoutData[])

 *      the bad case is not noticeable in the zooming scenario.
 */
export function hideOverlap(labelList: LabelLayoutData[]): void {
    const displayedLabels: LabelLayoutWithGeometry[] = [];

    // TODO, render overflow visible first, put in the displayedLabels.
    labelList.sort(function (a, b) {
        return ((b.suggestIgnore ? 1 : 0) - (a.suggestIgnore ? 1 : 0))
            || (b.priority - a.priority);
    });

    function hideEl(el: Element) {
        if (!el.ignore) {
            // Show on emphasis.
            const emphasisState = el.ensureState('emphasis');
            if (emphasisState.ignore == null) {
                emphasisState.ignore = false;
            }
        }

        el.ignore = true;
    }

    for (let i = 0; i < labelList.length; i++) {
        const labelItem = ensureLabelLayoutWithGeometry(labelList[i]);

        // The current `el.ignore` is involved, since some previous overlap
        // resolving strategies may have set `el.ignore` to true.
        if (labelItem.label.ignore) {
            continue;
        }

        const label = labelItem.label;
        const labelLine = labelItem.labelLine;

        // NOTICE: even when the with/height of globalRect of a label is 0, the label line should
        // still be displayed, since we should follow the concept of "truncation", meaning that
        // something exists even if it cannot be fully displayed. A visible label line is necessary
        // to allow users to get a tooltip with label info on hover.

        let overlapped = false;
        for (let j = 0; j < displayedLabels.length; j++) {
            if (labelIntersect(labelItem, displayedLabels[j], null, {touchThreshold: 0.05})) {
                overlapped = true;
                break;
            }
        }

        // TODO Callback to determine if this overlap should be handled?
        if (overlapped) {
            hideEl(label);
            labelLine && hideEl(labelLine);
        }
        else {
            displayedLabels.push(labelItem);
        }
    }
}

/**