GWT Google Charts 负值条形图

以下是 负值条形图的示例。

我们已经在《GWT Google Charts 入门程序》章节中看到了用于绘制图表的基本步骤。现在，让我们看一个 负值条形图的例子。

GWT Google Charts  负值条形图 配置

我们使用AreaChart类来显示负值条形图。

BarChartOptions options = BarChartOptions.create();

GWT Google Charts  负值条形图 示例

package com.yiidian.helloWorld.client;

import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.user.client.ui.*;
import com.google.gwt.user.client.rpc.AsyncCallback;
import com.google.gwt.user.client.DOM;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.event.dom.client.ClickEvent;
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.corechart.*;
import com.googlecode.gwt.charts.client.options.HAxis;
import com.googlecode.gwt.charts.client.options.VAxis;

public class HelloWorld implements EntryPoint {
    private BarChart chart;

    private void initialize() {
        ChartLoader chartLoader = new ChartLoader(ChartPackage.CORECHART);
        chartLoader.loadApi(new Runnable() {
            public void run() {
                // Create and attach the chart
                chart = new BarChart();
                RootPanel.get().add(chart);
                draw();
            }
        });
    }
    private void draw() {
        // Prepare the data
        DataTable data = DataTable.create();
        data.addColumn(ColumnType.STRING, "Year");
        data.addColumn(ColumnType.NUMBER, "Asia");
        data.addColumn(ColumnType.NUMBER, "Europe");

        data.addRow("2012", 900, 390);
        data.addRow("2013", -1000,400);
        data.addRow("2014", -1170, 440);
        data.addRow("2015", 1250, 480);
        data.addRow("2016", 1530, 540);

        // Set options
        BarChartOptions options = BarChartOptions.create();
        options.setTitle("Population (in millions)");
        options.setHAxis(HAxis.create("Year"));
        VAxis vAxis = VAxis.create();
        vAxis.setMinValue(0);

        options.setVAxis(vAxis);

        // Draw the chart
        chart.draw(data,options);
        chart.setWidth("600px");
        chart.setHeight("400px");
    }
    public void onModuleLoad() {
        initialize();
    }
}

输出结果为：