1. WIKI教程
2. 了解GWT Google Charts
3. GWT Google Charts - TreeMap Chart( TreeMap Chart)

GWT Google Charts - TreeMap Chart( TreeMap Chart)

TreeMap是数据树的直观表示，其中每个节点可以有零个或多个子节点，以及一个父节点（根节点除外）。 每个节点都显示为一个矩形，可以根据我们指定的值进行调整大小和着色。 尺寸和颜色相对于图中的所有其他节点进行估值。 以下是树形图图表的示例。

我们已经在Google Charts Configuration Syntax一章中看到了用于绘制图表的配置 。 现在，让我们看一个TreeMap图表的示例。

配置 (Configurations)

我们使用TreeMap类来显示TreeMap图表。

TreeMap chart = new TreeMap();

例子 (Example)

HelloWorld.java

package com.iowiki.client;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.user.client.ui.RootPanel;
import com.googlecode.gwt.charts.client.ChartLoader;
import com.googlecode.gwt.charts.client.ChartPackage;
import com.googlecode.gwt.charts.client.ColumnType;
import com.googlecode.gwt.charts.client.DataTable;
import com.googlecode.gwt.charts.client.treemap.TreeMap;
import com.googlecode.gwt.charts.client.treemap.TreeMapOptions;
public class HelloWorld implements EntryPoint {
   private TreeMap chart;
   private void initialize() {
      ChartLoader chartLoader = new ChartLoader(ChartPackage.TREEMAP);
      chartLoader.loadApi(new Runnable() {
         public void run() {
            // Create and attach the chart
            chart = new TreeMap();
            RootPanel.get().add(chart);
            draw();
         }
      });
   }
   private void draw() {
      // Prepare the data
      DataTable dataTable = DataTable.create();
      dataTable.addColumn(ColumnType.STRING, "Location");
      dataTable.addColumn(ColumnType.STRING, "Parent");
      dataTable.addColumn(ColumnType.NUMBER, "Market trade volume (size)");
      dataTable.addColumn(ColumnType.NUMBER, "Market increase/decrease (color)");
      dataTable.addRow("Global",null,0,0);
      dataTable.addRow("America","Global",0,0);
      dataTable.addRow("Europe","Global",0,0);
      dataTable.addRow("Asia","Global",0,0);
      dataTable.addRow("Australia","Global",0,0);
      dataTable.addRow("Africa","Global",0,0);  
      dataTable.addRow("USA","America",52,31);
      dataTable.addRow("Mexico","America",24,12);
      dataTable.addRow("Canada","America",16,-23);
      dataTable.addRow("France","Europe",42,-11);
      dataTable.addRow("Germany","Europe",31,-2);
      dataTable.addRow("Sweden","Europe",22,-13);   
      dataTable.addRow("China","Asia",36,4);
      dataTable.addRow("Japan","Asia",20,-12);
      dataTable.addRow("India","Asia",40,63);
      dataTable.addRow("Egypt","Africa",21,0); 
      dataTable.addRow("Congo","Africa",10,12);
      dataTable.addRow("Zaire","Africa",8,10);
      // Set options
      TreeMapOptions options = TreeMapOptions.create();
      options.setMinColor("#ff7777");
      options.setMidColor("#ffff77");
      options.setMaxColor("#77ff77");
      options.setHeaderHeight(15);
      options.setShowScale(true);
      // Draw the chart
      chart.draw(dataTable, options);
      chart.setWidth("400px");
      chart.setHeight("400px");
   }
   public void onModuleLoad() {
      initialize();
   }
}

结果 (Result)

验证结果。