JavaScript ArcGIS OpacitySlider用法及代码示例

AMD: require(["esri/widgets/smartMapping/OpacitySlider"], (OpacitySlider) => { /* code goes here */ });

ESM: import OpacitySlider from "@arcgis/core/widgets/smartMapping/OpacitySlider";

类： esri/widgets/smartMapping/OpacitySlider

继承: OpacitySlider > SmartMappingSliderBase > Widget > Accessor

自从：用于 JavaScript 4.12 的 ArcGIS API

OpacitySlider 小部件旨在用于在可以使用 OpacityVariable 渲染的任何层中创作和探索数据驱动的可视化。您至少必须设置小部件的最小、最大和停止属性。停止点用于渲染滑块轨道上的不透明度渐变。

有关此滑块上可用的可配置选项的摘要，请参见下图。

fromVisualVariableResult 方法可用于根据 createVisualVariable 方法的结果方便地创建此滑块。

const params = {
  layer: layer,
  basemap: map.basemap,
  valueExpression: "( $feature.POP_POVERTY / $feature.TOTPOP_CY ) * 100",
  view: view
};

let variableResult = null;

opacityVariableCreator
  .createVisualVariable(params)
  .then(function(response) {
    variableResult = response;
    layer.renderer.visualVariables = [ response.visualVariable ];

    return histogram({
      layer: layer,
      valueExpression: params.valueExpression,
      view: view,
      numBins: 70
    });
  })
   .then(function(histogramResult) {
     const slider = OpacitySlider.fromVisualVariableResult(variableResult, histogramResult);
     slider.container = "slider";
   })
   .catch(function(error) {
     console.log("there was an error: ", error);
   });

此滑块应用于更新图层渲染器中的opacity visual variable。应用程序开发人员有责任在此滑块上设置事件侦听器以更新适当渲染器的不透明度变量。

// when the user slides the handle(s), update the renderer
// with the updated opacity stops

slider.on(["thumb-change", "thumb-drag"], function() {
  const renderer = layer.renderer.clone();
  const opacityVariable = renderer.visualVariables[0].clone();
  opacityVariable.stops = slider.stops;
  renderer.visualVariables = [ opacityVariable ];
  layer.renderer = renderer;
});