ContinuousView.js

/*
* 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 * as zrUtil from 'zrender/src/core/util';
import LinearGradient from 'zrender/src/graphic/LinearGradient';
import * as eventTool from 'zrender/src/core/event';
import VisualMapView from './VisualMapView';
import * as graphic from '../../util/graphic';
import * as numberUtil from '../../util/number';
import sliderMove from '../helper/sliderMove';
import * as helper from './helper';
import * as modelUtil from '../../util/model';

var linearMap = numberUtil.linearMap;
var each = zrUtil.each;
var mathMin = Math.min;
var mathMax = Math.max;

// Arbitrary value
var HOVER_LINK_SIZE = 12;
var HOVER_LINK_OUT = 6;

// Notice:
// Any "interval" should be by the order of [low, high].
// "handle0" (handleIndex === 0) maps to
// low data value: this._dataInterval[0] and has low coord.
// "handle1" (handleIndex === 1) maps to
// high data value: this._dataInterval[1] and has high coord.
// The logic of transform is implemented in this._createBarGroup.

var ContinuousView = VisualMapView.extend({

    type: 'visualMap.continuous',

    /**
     * @override
     */
    init: function () {

        ContinuousView.superApply(this, 'init', arguments);

        /**
         * @private
         */
        this._shapes = {};

        /**
         * @private
         */
        this._dataInterval = [];

        /**
         * @private
         */
        this._handleEnds = [];

        /**
         * @private
         */
        this._orient;

        /**
         * @private
         */
        this._useHandle;

        /**
         * @private
         */
        this._hoverLinkDataIndices = [];

        /**
         * @private
         */
        this._dragging;

        /**
         * @private
         */
        this._hovering;
    },

    /**
     * @protected
     * @override
     */
    doRender: function (visualMapModel, ecModel, api, payload) {
        if (!payload || payload.type !== 'selectDataRange' || payload.from !== this.uid) {
            this._buildView();
        }
    },

    /**
     * @private
     */
    _buildView: function () {
        this.group.removeAll();

        var visualMapModel = this.visualMapModel;
        var thisGroup = this.group;

        this._orient = visualMapModel.get('orient');
        this._useHandle = visualMapModel.get('calculable');

        this._resetInterval();

        this._renderBar(thisGroup);

        var dataRangeText = visualMapModel.get('text');
        this._renderEndsText(thisGroup, dataRangeText, 0);
        this._renderEndsText(thisGroup, dataRangeText, 1);

        // Do this for background size calculation.
        this._updateView(true);

        // After updating view, inner shapes is built completely,
        // and then background can be rendered.
        this.renderBackground(thisGroup);

        // Real update view
        this._updateView();

        this._enableHoverLinkToSeries();
        this._enableHoverLinkFromSeries();

        this.positionGroup(thisGroup);
    },

    /**
     * @private
     */
    _renderEndsText: function (group, dataRangeText, endsIndex) {
        if (!dataRangeText) {
            return;
        }

        // Compatible with ec2, text[0] map to high value, text[1] map low value.
        var text = dataRangeText[1 - endsIndex];
        text = text != null ? text + '' : '';

        var visualMapModel = this.visualMapModel;
        var textGap = visualMapModel.get('textGap');
        var itemSize = visualMapModel.itemSize;

        var barGroup = this._shapes.barGroup;
        var position = this._applyTransform(
            [
                itemSize[0] / 2,
                endsIndex === 0 ? -textGap : itemSize[1] + textGap
            ],
            barGroup
        );
        var align = this._applyTransform(
            endsIndex === 0 ? 'bottom' : 'top',
            barGroup
        );
        var orient = this._orient;
        var textStyleModel = this.visualMapModel.textStyleModel;

        this.group.add(new graphic.Text({
            style: {
                x: position[0],
                y: position[1],
                textVerticalAlign: orient === 'horizontal' ? 'middle' : align,
                textAlign: orient === 'horizontal' ? align : 'center',
                text: text,
                textFont: textStyleModel.getFont(),
                textFill: textStyleModel.getTextColor()
            }
        }));
    },

    /**
     * @private
     */
    _renderBar: function (targetGroup) {
        var visualMapModel = this.visualMapModel;
        var shapes = this._shapes;
        var itemSize = visualMapModel.itemSize;
        var orient = this._orient;
        var useHandle = this._useHandle;
        var itemAlign = helper.getItemAlign(visualMapModel, this.api, itemSize);
        var barGroup = shapes.barGroup = this._createBarGroup(itemAlign);

        // Bar
        barGroup.add(shapes.outOfRange = createPolygon());
        barGroup.add(shapes.inRange = createPolygon(
            null,
            useHandle ? getCursor(this._orient) : null,
            zrUtil.bind(this._dragHandle, this, 'all', false),
            zrUtil.bind(this._dragHandle, this, 'all', true)
        ));

        var textRect = visualMapModel.textStyleModel.getTextRect('国');
        var textSize = mathMax(textRect.width, textRect.height);

        // Handle
        if (useHandle) {
            shapes.handleThumbs = [];
            shapes.handleLabels = [];
            shapes.handleLabelPoints = [];

            this._createHandle(barGroup, 0, itemSize, textSize, orient, itemAlign);
            this._createHandle(barGroup, 1, itemSize, textSize, orient, itemAlign);
        }

        this._createIndicator(barGroup, itemSize, textSize, orient);

        targetGroup.add(barGroup);
    },

    /**
     * @private
     */
    _createHandle: function (barGroup, handleIndex, itemSize, textSize, orient) {
        var onDrift = zrUtil.bind(this._dragHandle, this, handleIndex, false);
        var onDragEnd = zrUtil.bind(this._dragHandle, this, handleIndex, true);
        var handleThumb = createPolygon(
            createHandlePoints(handleIndex, textSize),
            getCursor(this._orient),
            onDrift,
            onDragEnd
        );
        handleThumb.position[0] = itemSize[0];
        barGroup.add(handleThumb);

        // Text is always horizontal layout but should not be effected by
        // transform (orient/inverse). So label is built separately but not
        // use zrender/graphic/helper/RectText, and is located based on view
        // group (according to handleLabelPoint) but not barGroup.
        var textStyleModel = this.visualMapModel.textStyleModel;
        var handleLabel = new graphic.Text({
            draggable: true,
            drift: onDrift,
            onmousemove: function (e) {
                // Fot mobile devicem, prevent screen slider on the button.
                eventTool.stop(e.event);
            },
            ondragend: onDragEnd,
            style: {
                x: 0, y: 0, text: '',
                textFont: textStyleModel.getFont(),
                textFill: textStyleModel.getTextColor()
            }
        });
        this.group.add(handleLabel);

        var handleLabelPoint = [
            orient === 'horizontal'
                ? textSize / 2
                : textSize * 1.5,
            orient === 'horizontal'
                ? (handleIndex === 0 ? -(textSize * 1.5) : (textSize * 1.5))
                : (handleIndex === 0 ? -textSize / 2 : textSize / 2)
        ];

        var shapes = this._shapes;
        shapes.handleThumbs[handleIndex] = handleThumb;
        shapes.handleLabelPoints[handleIndex] = handleLabelPoint;
        shapes.handleLabels[handleIndex] = handleLabel;
    },

    /**
     * @private
     */
    _createIndicator: function (barGroup, itemSize, textSize, orient) {
        var indicator = createPolygon([[0, 0]], 'move');
        indicator.position[0] = itemSize[0];
        indicator.attr({invisible: true, silent: true});
        barGroup.add(indicator);

        var textStyleModel = this.visualMapModel.textStyleModel;
        var indicatorLabel = new graphic.Text({
            silent: true,
            invisible: true,
            style: {
                x: 0, y: 0, text: '',
                textFont: textStyleModel.getFont(),
                textFill: textStyleModel.getTextColor()
            }
        });
        this.group.add(indicatorLabel);

        var indicatorLabelPoint = [
            orient === 'horizontal' ? textSize / 2 : HOVER_LINK_OUT + 3,
            0
        ];

        var shapes = this._shapes;
        shapes.indicator = indicator;
        shapes.indicatorLabel = indicatorLabel;
        shapes.indicatorLabelPoint = indicatorLabelPoint;
    },

    /**
     * @private
     */
    _dragHandle: function (handleIndex, isEnd, dx, dy) {
        if (!this._useHandle) {
            return;
        }

        this._dragging = !isEnd;

        if (!isEnd) {
            // Transform dx, dy to bar coordination.
            var vertex = this._applyTransform([dx, dy], this._shapes.barGroup, true);
            this._updateInterval(handleIndex, vertex[1]);

            // Considering realtime, update view should be executed
            // before dispatch action.
            this._updateView();
        }

        // dragEnd do not dispatch action when realtime.
        if (isEnd === !this.visualMapModel.get('realtime')) { // jshint ignore:line
            this.api.dispatchAction({
                type: 'selectDataRange',
                from: this.uid,
                visualMapId: this.visualMapModel.id,
                selected: this._dataInterval.slice()
            });
        }

        if (isEnd) {
            !this._hovering && this._clearHoverLinkToSeries();
        }
        else if (useHoverLinkOnHandle(this.visualMapModel)) {
            this._doHoverLinkToSeries(this._handleEnds[handleIndex], false);
        }
    },

    /**
     * @private
     */
    _resetInterval: function () {
        var visualMapModel = this.visualMapModel;

        var dataInterval = this._dataInterval = visualMapModel.getSelected();
        var dataExtent = visualMapModel.getExtent();
        var sizeExtent = [0, visualMapModel.itemSize[1]];

        this._handleEnds = [
            linearMap(dataInterval[0], dataExtent, sizeExtent, true),
            linearMap(dataInterval[1], dataExtent, sizeExtent, true)
        ];
    },

    /**
     * @private
     * @param {(number|string)} handleIndex 0 or 1 or 'all'
     * @param {number} dx
     * @param {number} dy
     */
    _updateInterval: function (handleIndex, delta) {
        delta = delta || 0;
        var visualMapModel = this.visualMapModel;
        var handleEnds = this._handleEnds;
        var sizeExtent = [0, visualMapModel.itemSize[1]];

        sliderMove(
            delta,
            handleEnds,
            sizeExtent,
            handleIndex,
            // cross is forbiden
            0
        );

        var dataExtent = visualMapModel.getExtent();
        // Update data interval.
        this._dataInterval = [
            linearMap(handleEnds[0], sizeExtent, dataExtent, true),
            linearMap(handleEnds[1], sizeExtent, dataExtent, true)
        ];
    },

    /**
     * @private
     */
    _updateView: function (forSketch) {
        var visualMapModel = this.visualMapModel;
        var dataExtent = visualMapModel.getExtent();
        var shapes = this._shapes;

        var outOfRangeHandleEnds = [0, visualMapModel.itemSize[1]];
        var inRangeHandleEnds = forSketch ? outOfRangeHandleEnds : this._handleEnds;

        var visualInRange = this._createBarVisual(
            this._dataInterval, dataExtent, inRangeHandleEnds, 'inRange'
        );
        var visualOutOfRange = this._createBarVisual(
            dataExtent, dataExtent, outOfRangeHandleEnds, 'outOfRange'
        );

        shapes.inRange
            .setStyle({
                fill: visualInRange.barColor,
                opacity: visualInRange.opacity
            })
            .setShape('points', visualInRange.barPoints);
        shapes.outOfRange
            .setStyle({
                fill: visualOutOfRange.barColor,
                opacity: visualOutOfRange.opacity
            })
            .setShape('points', visualOutOfRange.barPoints);

        this._updateHandle(inRangeHandleEnds, visualInRange);
    },

    /**
     * @private
     */
    _createBarVisual: function (dataInterval, dataExtent, handleEnds, forceState) {
        var opts = {
            forceState: forceState,
            convertOpacityToAlpha: true
        };
        var colorStops = this._makeColorGradient(dataInterval, opts);

        var symbolSizes = [
            this.getControllerVisual(dataInterval[0], 'symbolSize', opts),
            this.getControllerVisual(dataInterval[1], 'symbolSize', opts)
        ];
        var barPoints = this._createBarPoints(handleEnds, symbolSizes);

        return {
            barColor: new LinearGradient(0, 0, 0, 1, colorStops),
            barPoints: barPoints,
            handlesColor: [
                colorStops[0].color,
                colorStops[colorStops.length - 1].color
            ]
        };
    },

    /**
     * @private
     */
    _makeColorGradient: function (dataInterval, opts) {
        // Considering colorHue, which is not linear, so we have to sample
        // to calculate gradient color stops, but not only caculate head
        // and tail.
        var sampleNumber = 100; // Arbitrary value.
        var colorStops = [];
        var step = (dataInterval[1] - dataInterval[0]) / sampleNumber;

        colorStops.push({
            color: this.getControllerVisual(dataInterval[0], 'color', opts),
            offset: 0
        });

        for (var i = 1; i < sampleNumber; i++) {
            var currValue = dataInterval[0] + step * i;
            if (currValue > dataInterval[1]) {
                break;
            }
            colorStops.push({
                color: this.getControllerVisual(currValue, 'color', opts),
                offset: i / sampleNumber
            });
        }

        colorStops.push({
            color: this.getControllerVisual(dataInterval[1], 'color', opts),
            offset: 1
        });

        return colorStops;
    },

    /**
     * @private
     */
    _createBarPoints: function (handleEnds, symbolSizes) {
        var itemSize = this.visualMapModel.itemSize;

        return [
            [itemSize[0] - symbolSizes[0], handleEnds[0]],
            [itemSize[0], handleEnds[0]],
            [itemSize[0], handleEnds[1]],
            [itemSize[0] - symbolSizes[1], handleEnds[1]]
        ];
    },

    /**
     * @private
     */
    _createBarGroup: function (itemAlign) {
        var orient = this._orient;
        var inverse = this.visualMapModel.get('inverse');

        return new graphic.Group(
            (orient === 'horizontal' && !inverse)
            ? {scale: itemAlign === 'bottom' ? [1, 1] : [-1, 1], rotation: Math.PI / 2}
            : (orient === 'horizontal' && inverse)
            ? {scale: itemAlign === 'bottom' ? [-1, 1] : [1, 1], rotation: -Math.PI / 2}
            : (orient === 'vertical' && !inverse)
            ? {scale: itemAlign === 'left' ? [1, -1] : [-1, -1]}
            : {scale: itemAlign === 'left' ? [1, 1] : [-1, 1]}
        );
    },

    /**
     * @private
     */
    _updateHandle: function (handleEnds, visualInRange) {
        if (!this._useHandle) {
            return;
        }

        var shapes = this._shapes;
        var visualMapModel = this.visualMapModel;
        var handleThumbs = shapes.handleThumbs;
        var handleLabels = shapes.handleLabels;

        each([0, 1], function (handleIndex) {
            var handleThumb = handleThumbs[handleIndex];
            handleThumb.setStyle('fill', visualInRange.handlesColor[handleIndex]);
            handleThumb.position[1] = handleEnds[handleIndex];

            // Update handle label position.
            var textPoint = graphic.applyTransform(
                shapes.handleLabelPoints[handleIndex],
                graphic.getTransform(handleThumb, this.group)
            );
            handleLabels[handleIndex].setStyle({
                x: textPoint[0],
                y: textPoint[1],
                text: visualMapModel.formatValueText(this._dataInterval[handleIndex]),
                textVerticalAlign: 'middle',
                textAlign: this._applyTransform(
                    this._orient === 'horizontal'
                        ? (handleIndex === 0 ? 'bottom' : 'top')
                        : 'left',
                    shapes.barGroup
                )
            });
        }, this);
    },

    /**
     * @private
     * @param {number} cursorValue
     * @param {number} textValue
     * @param {string} [rangeSymbol]
     * @param {number} [halfHoverLinkSize]
     */
    _showIndicator: function (cursorValue, textValue, rangeSymbol, halfHoverLinkSize) {
        var visualMapModel = this.visualMapModel;
        var dataExtent = visualMapModel.getExtent();
        var itemSize = visualMapModel.itemSize;
        var sizeExtent = [0, itemSize[1]];
        var pos = linearMap(cursorValue, dataExtent, sizeExtent, true);

        var shapes = this._shapes;
        var indicator = shapes.indicator;
        if (!indicator) {
            return;
        }

        indicator.position[1] = pos;
        indicator.attr('invisible', false);
        indicator.setShape('points', createIndicatorPoints(
            !!rangeSymbol, halfHoverLinkSize, pos, itemSize[1]
        ));

        var opts = {convertOpacityToAlpha: true};
        var color = this.getControllerVisual(cursorValue, 'color', opts);
        indicator.setStyle('fill', color);

        // Update handle label position.
        var textPoint = graphic.applyTransform(
            shapes.indicatorLabelPoint,
            graphic.getTransform(indicator, this.group)
        );

        var indicatorLabel = shapes.indicatorLabel;
        indicatorLabel.attr('invisible', false);
        var align = this._applyTransform('left', shapes.barGroup);
        var orient = this._orient;
        indicatorLabel.setStyle({
            text: (rangeSymbol ? rangeSymbol : '') + visualMapModel.formatValueText(textValue),
            textVerticalAlign: orient === 'horizontal' ? align : 'middle',
            textAlign: orient === 'horizontal' ? 'center' : align,
            x: textPoint[0],
            y: textPoint[1]
        });
    },

    /**
     * @private
     */
    _enableHoverLinkToSeries: function () {
        var self = this;
        this._shapes.barGroup

            .on('mousemove', function (e) {
                self._hovering = true;

                if (!self._dragging) {
                    var itemSize = self.visualMapModel.itemSize;
                    var pos = self._applyTransform(
                        [e.offsetX, e.offsetY], self._shapes.barGroup, true, true
                    );
                    // For hover link show when hover handle, which might be
                    // below or upper than sizeExtent.
                    pos[1] = mathMin(mathMax(0, pos[1]), itemSize[1]);
                    self._doHoverLinkToSeries(
                        pos[1],
                        0 <= pos[0] && pos[0] <= itemSize[0]
                    );
                }
            })

            .on('mouseout', function () {
                // When mouse is out of handle, hoverLink still need
                // to be displayed when realtime is set as false.
                self._hovering = false;
                !self._dragging && self._clearHoverLinkToSeries();
            });
    },

    /**
     * @private
     */
    _enableHoverLinkFromSeries: function () {
        var zr = this.api.getZr();

        if (this.visualMapModel.option.hoverLink) {
            zr.on('mouseover', this._hoverLinkFromSeriesMouseOver, this);
            zr.on('mouseout', this._hideIndicator, this);
        }
        else {
            this._clearHoverLinkFromSeries();
        }
    },

    /**
     * @private
     */
    _doHoverLinkToSeries: function (cursorPos, hoverOnBar) {
        var visualMapModel = this.visualMapModel;
        var itemSize = visualMapModel.itemSize;

        if (!visualMapModel.option.hoverLink) {
            return;
        }

        var sizeExtent = [0, itemSize[1]];
        var dataExtent = visualMapModel.getExtent();

        // For hover link show when hover handle, which might be below or upper than sizeExtent.
        cursorPos = mathMin(mathMax(sizeExtent[0], cursorPos), sizeExtent[1]);

        var halfHoverLinkSize = getHalfHoverLinkSize(visualMapModel, dataExtent, sizeExtent);
        var hoverRange = [cursorPos - halfHoverLinkSize, cursorPos + halfHoverLinkSize];
        var cursorValue = linearMap(cursorPos, sizeExtent, dataExtent, true);
        var valueRange = [
            linearMap(hoverRange[0], sizeExtent, dataExtent, true),
            linearMap(hoverRange[1], sizeExtent, dataExtent, true)
        ];
        // Consider data range is out of visualMap range, see test/visualMap-continuous.html,
        // where china and india has very large population.
        hoverRange[0] < sizeExtent[0] && (valueRange[0] = -Infinity);
        hoverRange[1] > sizeExtent[1] && (valueRange[1] = Infinity);

        // Do not show indicator when mouse is over handle,
        // otherwise labels overlap, especially when dragging.
        if (hoverOnBar) {
            if (valueRange[0] === -Infinity) {
                this._showIndicator(cursorValue, valueRange[1], '< ', halfHoverLinkSize);
            }
            else if (valueRange[1] === Infinity) {
                this._showIndicator(cursorValue, valueRange[0], '> ', halfHoverLinkSize);
            }
            else {
                this._showIndicator(cursorValue, cursorValue, '≈ ', halfHoverLinkSize);
            }
        }

        // When realtime is set as false, handles, which are in barGroup,
        // also trigger hoverLink, which help user to realize where they
        // focus on when dragging. (see test/heatmap-large.html)
        // When realtime is set as true, highlight will not show when hover
        // handle, because the label on handle, which displays a exact value
        // but not range, might mislead users.
        var oldBatch = this._hoverLinkDataIndices;
        var newBatch = [];
        if (hoverOnBar || useHoverLinkOnHandle(visualMapModel)) {
            newBatch = this._hoverLinkDataIndices = visualMapModel.findTargetDataIndices(valueRange);
        }

        var resultBatches = modelUtil.compressBatches(oldBatch, newBatch);

        this._dispatchHighDown('downplay', helper.convertDataIndex(resultBatches[0]));
        this._dispatchHighDown('highlight', helper.convertDataIndex(resultBatches[1]));
    },

    /**
     * @private
     */
    _hoverLinkFromSeriesMouseOver: function (e) {
        var el = e.target;
        var visualMapModel = this.visualMapModel;

        if (!el || el.dataIndex == null) {
            return;
        }

        var dataModel = this.ecModel.getSeriesByIndex(el.seriesIndex);

        if (!visualMapModel.isTargetSeries(dataModel)) {
            return;
        }

        var data = dataModel.getData(el.dataType);
        var value = data.get(visualMapModel.getDataDimension(data), el.dataIndex, true);

        if (!isNaN(value)) {
            this._showIndicator(value, value);
        }
    },

    /**
     * @private
     */
    _hideIndicator: function () {
        var shapes = this._shapes;
        shapes.indicator && shapes.indicator.attr('invisible', true);
        shapes.indicatorLabel && shapes.indicatorLabel.attr('invisible', true);
    },

    /**
     * @private
     */
    _clearHoverLinkToSeries: function () {
        this._hideIndicator();

        var indices = this._hoverLinkDataIndices;
        this._dispatchHighDown('downplay', helper.convertDataIndex(indices));

        indices.length = 0;
    },

    /**
     * @private
     */
    _clearHoverLinkFromSeries: function () {
        this._hideIndicator();

        var zr = this.api.getZr();
        zr.off('mouseover', this._hoverLinkFromSeriesMouseOver);
        zr.off('mouseout', this._hideIndicator);
    },

    /**
     * @private
     */
    _applyTransform: function (vertex, element, inverse, global) {
        var transform = graphic.getTransform(element, global ? null : this.group);

        return graphic[
            zrUtil.isArray(vertex) ? 'applyTransform' : 'transformDirection'
        ](vertex, transform, inverse);
    },

    /**
     * @private
     */
    _dispatchHighDown: function (type, batch) {
        batch && batch.length && this.api.dispatchAction({
            type: type,
            batch: batch
        });
    },

    /**
     * @override
     */
    dispose: function () {
        this._clearHoverLinkFromSeries();
        this._clearHoverLinkToSeries();
    },

    /**
     * @override
     */
    remove: function () {
        this._clearHoverLinkFromSeries();
        this._clearHoverLinkToSeries();
    }

});

function createPolygon(points, cursor, onDrift, onDragEnd) {
    return new graphic.Polygon({
        shape: {points: points},
        draggable: !!onDrift,
        cursor: cursor,
        drift: onDrift,
        onmousemove: function (e) {
            // Fot mobile devicem, prevent screen slider on the button.
            eventTool.stop(e.event);
        },
        ondragend: onDragEnd
    });
}

function createHandlePoints(handleIndex, textSize) {
    return handleIndex === 0
        ? [[0, 0], [textSize, 0], [textSize, -textSize]]
        : [[0, 0], [textSize, 0], [textSize, textSize]];
}

function createIndicatorPoints(isRange, halfHoverLinkSize, pos, extentMax) {
    return isRange
        ? [ // indicate range
            [0, -mathMin(halfHoverLinkSize, mathMax(pos, 0))],
            [HOVER_LINK_OUT, 0],
            [0, mathMin(halfHoverLinkSize, mathMax(extentMax - pos, 0))]
        ]
        : [ // indicate single value
            [0, 0], [5, -5], [5, 5]
        ];
}

function getHalfHoverLinkSize(visualMapModel, dataExtent, sizeExtent) {
    var halfHoverLinkSize = HOVER_LINK_SIZE / 2;
    var hoverLinkDataSize = visualMapModel.get('hoverLinkDataSize');
    if (hoverLinkDataSize) {
        halfHoverLinkSize = linearMap(hoverLinkDataSize, dataExtent, sizeExtent, true) / 2;
    }
    return halfHoverLinkSize;
}

function useHoverLinkOnHandle(visualMapModel) {
    var hoverLinkOnHandle = visualMapModel.get('hoverLinkOnHandle');
    return !!(hoverLinkOnHandle == null ? visualMapModel.get('realtime') : hoverLinkOnHandle);
}

function getCursor(orient) {
    return orient === 'vertical' ? 'ns-resize' : 'ew-resize';
}

export default ContinuousView;