JavaScript ArcGIS OpacitySlider用法及代碼示例

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

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

類： esri/widgets/smartMapping/OpacitySlider

繼承: OpacitySlider > SmartMappingSliderBase > Widget > Accessor

自從：用於 JavaScript 4.12 的 ArcGIS API

OpacitySlider 小部件旨在用於在可以使用 OpacityVariable 渲染的任何層中創作和探索數據驅動的可視化。您至少必須設置小部件的最小、最大和停止屬性。停止點用於渲染滑塊軌道上的不透明度漸變。

有關此滑塊上可用的可配置選項的摘要，請參見下圖。

fromVisualVariableResult 方法可用於根據 createVisualVariable 方法的結果方便地創建此滑塊。

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);
   });

此滑塊應用於更新圖層渲染器中的opacity visual variable。應用程序開發人員有責任在此滑塊上設置事件偵聽器以更新適當渲染器的不透明度變量。

// 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;
});