JavaScript ArcGIS ColorSlider用法及代码示例

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

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

类： esri/widgets/smartMapping/ColorSlider

继承: ColorSlider > SmartMappingSliderBase > Widget > Accessor

自从：用于 JavaScript 4.12 的 ArcGIS API

ColorSlider 小部件旨在用于在可以使用 ColorVariable 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。这些停止点用于在滑块的轨道上渲染颜色渐变。

有关此滑块上可用的可配置选项的摘要，请参见下图。

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

const colorParams = {
  layer: layer,
  basemap: map.basemap,
  valueExpression: "( $feature.POP_POVERTY / $feature.TOTPOP_CY ) * 100",
  view: view,
  theme: "above-and-below"
};

let rendererResult = null;

colorRendererCreator
  .createContinuousRenderer(colorParams)
  .then(function(response) {
    rendererResult = response;
    layer.renderer = response.renderer;

    return histogram({
      layer: layer,
      valueExpression: colorParams.valueExpression,
      view: view,
      numBins: 70
    });
  })
   .then(function(histogramResult) {
     const colorSlider = ColorSlider.fromRendererResult(rendererResult, histogramResult);
     colorSlider.container = "slider";
     colorSlider.primaryHandleEnabled = true;
   })
   .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color 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，以更新相应渲染器的颜色变量。

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

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