是否可以使用 Amchart v4 在类别名称上显示工具提示？

Question

我正在使用 Amchart V4 中的“可变半径雷达”。我想在类别名称悬停时显示工具提示，但找不到任何解决方案。工具提示是必需的，因为名称可能很长。在图表上，我打算只显示类别的前 10 个字符。工具提示将具有全名。

在https://codepen.io/pzombade/pen/RExzbj?editors=0010上创建了一个页面

代码：

var chart = am4core.create("chartdiv", am4charts.RadarChart);
chart.hiddenState.properties.opacity = 0; // this creates initial fade-in

var label = chart.createChild(am4core.Label);
label.text = "Drag slider to change radius";
label.exportable = false;

chart.data = [
  {
    category: "One",
    value1: 8,
    value2: 2,
    value3: 4,
    value4: 3
  },
  {
    category: "Two",
    value1: 11,
    value2: 4,
    value3: 2,
    value4: 4
  },
  {
    category: "Three",
    value1: 7,
    value2: 6,
    value3: 6,
    value4: 2
  },
  {
    category: "Four",
    value1: 13,
    value2: 8,
    value3: 3,
    value4: 2
  }
];
chart.radius = am4core.percent(95);
chart.startAngle = 270 - 180;
chart.endAngle = 270 + 180;
chart.innerRadius = am4core.percent(60);

var categoryAxis = chart.xAxes.push(new am4charts.CategoryAxis());
categoryAxis.dataFields.category = "category";
categoryAxis.renderer.labels.template.location = 0.5;
categoryAxis.renderer.grid.template.strokeOpacity = 0.1;
categoryAxis.renderer.axisFills.template.disabled = true;
categoryAxis.mouseEnabled = true;

var valueAxis = chart.yAxes.push(new am4charts.ValueAxis());
valueAxis.tooltip.disabled = false;
valueAxis.renderer.grid.template.strokeOpacity = 0.05;
valueAxis.renderer.axisFills.template.disabled = true;
valueAxis.renderer.axisAngle = 260;
valueAxis.renderer.labels.template.horizontalCenter = "right";
valueAxis.min = 0;

var series1 = chart.series.push(new am4charts.RadarColumnSeries());
series1.columns.template.radarColumn.strokeOpacity = 1;
series1.name = "Series 1";
series1.dataFields.categoryX = "category";
series1.columns.template.tooltipText = "{name}: {valueY.value}";
series1.dataFields.valueY = "value1";
series1.stacked = true;

var series2 = chart.series.push(new am4charts.RadarColumnSeries());
series2.columns.template.radarColumn.strokeOpacity = 1;
series2.columns.template.tooltipText = "{name}: {valueY.value}";
series2.name = "Series 2";
series2.dataFields.categoryX = "category";
series2.dataFields.valueY = "value2";
series2.stacked = true;

var series3 = chart.series.push(new am4charts.RadarColumnSeries());
series3.columns.template.radarColumn.strokeOpacity = 1;
series3.columns.template.tooltipText = "{name}: {valueY.value}";  
series3.name = "Series 3";
series3.dataFields.categoryX = "category";
series3.dataFields.valueY = "value3";
series3.stacked = true;

chart.seriesContainer.zIndex = -1;

var slider = chart.createChild(am4core.Slider);
slider.start = 0.5;
slider.exportable = false;
slider.events.on("rangechanged", () => {
  var start = slider.start;
  chart.startAngle = 270 - start * 179 - 1;
  chart.endAngle = 270 + start * 179 + 1;
  valueAxis.renderer.axisAngle = chart.startAngle;
});

Answer 1

在正确的位置为tooltipText 提供非空字符串/值时启用工具提示。在这种情况下，将其设置在轴标签上将触发悬停时的轴工具提示（这与其他工具提示略有不同，例如默认情况下它是黑色并紧贴周边或在本例中为图表的圆周）：

categoryAxis.renderer.labels.template.tooltipText = "{category}";

要截断轴标签的文本，您可以在其textOutput 上使用adapter（在text 上这样做会给您"{category}" 用于实际生成的标签，这在这种情况下不是很有用):

var categoryCharacterLimit = 10;
categoryAxis.renderer.labels.template.adapter.add("textOutput", function(text) {
  if (text && text.length > categoryCharacterLimit) {
    return text.substr(0, categoryCharacterLimit) + "\u2026"; // unicode for ellipsis
  }
  return text;
});

鉴于默认情况下轴工具提示将与其文本一样宽，这里有一个快速修复来限制其宽度、环绕和居中其文本：

categoryAxis.tooltip.maxWidth = 200;
categoryAxis.tooltip.label.wrap = true;
categoryAxis.tooltip.label.textAlign = "middle";

如果您不希望工具提示显示已经足够短的轴标签（请参阅下面我的演示中的“One”），您也可以在那里设置一个适配器，以返回一个空字符串（@ 987654332@) （如果有文本则触发提示，当重置为空字符串时，不再满足触发条件）：

categoryAxis.tooltip.label.adapter.add("textOutput", function(text) {
  if (text && text.length <= categoryCharacterLimit) {
    return "";
  }
  return text;
});

这是一个包含所有内容的演示：

https://codepen.io/team/amcharts/pen/64e5da963cc3822fc95bac15a8f56b09

如果您需要自定义轴工具提示的外观，这里有一些额外的信息：

https://www.amcharts.com/docs/v4/concepts/axes/axis-tooltips/#Modifying_tooltip_appearance https://www.amcharts.com/docs/v4/concepts/series/#Tooltip_colors