renderers

使用 TypeScript 开发时，导入 Renderer 类的便捷模块。例如，不是像这样一次导入一个渲染器：

import ClassBreaksRenderer from "geoscene/renderers/ClassBreaksRenderer";
import HeatmapRenderer from "geoscene/renderers/HeatmapRenderer";
import SimpleRenderer from "geoscene/renderers/SimpleRenderer";
import UniqueValueRenderer from "geoscene/renderers/UniqueValueRenderer";
import DictionaryRenderer from "geoscene/renderers/DictionaryRenderer";

您可以使用此模块在一行中导入它们：

import { ClassBreaksRenderer, HeatmapRenderer, SimpleRenderer, UniqueValueRenderer } from "geoscene/renderers";

此模块还允许您在渲染器上实现类型保护，从而使代码更加智能。

import { Renderer } from "geoscene/renderers";

function logRenderer(renderer: Renderer): void {
  if (renderer.type === "simple") {
    // new at 4.8, the compiler knows the renderer is a SimpleRenderer
    console.log("renderer symbol: ", renderer.symbol);
  }
  else {
    if (renderer.type !== "heatmap") {
      // the compiler knows the renderer must be a `ClassBreaksRenderer | UniqueValueRenderer`
      console.log("renderer background symbol: ", renderer.backgroundFillSymbol);
    }
  }
}