superset-frontend/plugins/plugin-chart-echarts/src/utils/tooltip.ts

/**
 * 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.
 */

import type { CallbackDataParams } from 'echarts/types/src/util/types';
import { TOOLTIP_OVERFLOW_MARGIN, TOOLTIP_POINTER_MARGIN } from '../constants';
import { Refs } from '../types';

export function getDefaultTooltip(refs: Refs) {
  return {
    appendToBody: true,
    borderColor: 'transparent',
    position: (
      canvasMousePos: [number, number],
      params: CallbackDataParams,
      tooltipDom: HTMLDivElement | null,
      rect: any,
      sizes: { contentSize: [number, number]; viewSize: [number, number] },
    ) => {
      // algorithm partially based on this snippet:
      // https://github.com/apache/echarts/issues/5004#issuecomment-559668309

      // The chart canvas position
      const divRect = refs.divRef?.current?.getBoundingClientRect();

      // The mouse coordinates relative to the whole window
      // The first parameter to the position function is the mouse position relative to the canvas
      const mouseX = canvasMousePos[0] + (divRect?.x || 0);
      const mouseY = canvasMousePos[1] + (divRect?.y || 0);

      // The width and height of the tooltip dom element
      const tooltipWidth = sizes.contentSize[0];
      const tooltipHeight = sizes.contentSize[1];

      // Start by placing the tooltip top and right relative to the mouse position
      let xPos = mouseX + TOOLTIP_POINTER_MARGIN;
      let yPos = mouseY - TOOLTIP_POINTER_MARGIN - tooltipHeight;

      // The tooltip is overflowing past the right edge of the window
      if (xPos + tooltipWidth >= document.documentElement.clientWidth) {
        // Attempt to place the tooltip to the left of the mouse position
        xPos = mouseX - TOOLTIP_POINTER_MARGIN - tooltipWidth;

        // The tooltip is overflowing past the left edge of the window
        if (xPos <= 0)
          // Place the tooltip a fixed distance from the left edge of the window
          xPos = TOOLTIP_OVERFLOW_MARGIN;
      }

      // The tooltip is overflowing past the top edge of the window
      if (yPos <= 0) {
        // Attempt to place the tooltip to the bottom of the mouse position
        yPos = mouseY + TOOLTIP_POINTER_MARGIN;

        // The tooltip is overflowing past the bottom edge of the window
        if (yPos + tooltipHeight >= document.documentElement.clientHeight)
          // Place the tooltip a fixed distance from the top edge of the window
          yPos = TOOLTIP_OVERFLOW_MARGIN;
      }

      // Return the position (converted back to a relative position on the canvas)
      return [xPos - (divRect?.x || 0), yPos - (divRect?.y || 0)];
    },
  };
}