半岛权威十大直营(官方)网站

用三维堆叠面积图，可以显示每个数值所占大小随时间或其他类别数据变化的趋势。但其实它不是真正的三维，因为它没有第三个轴，而只是将平面的面积图以三维透视图的形式显示。下图是用Web图表控件ChartDirector绘制的三维堆叠面积图，展示了三个服务器一天的负载情况。

主要步骤：

• 用Stack的预定义常数XYChart.addAreaLayer2添加一个堆叠面积层
• 用Layer.addDataSet向面积层添加多数据集
• 用BaseChart.addLegend向图表添加一个图例
• 用Axis.setTitle向Y轴添加标题，用TextBox.setFontAngle竖直绘制标题（而不是旋转90度）。注意，可以用换行字符让标题包含多行。

ChartDirector绘制三维堆叠面积图示例代码：

#include "chartdir.h"

int main(int argc, char *argv[])
{
    // The data for the area chart
    double data0[] = {42, 49, 33, 38, 51, 46, 29, 41, 44, 57, 59, 52, 37, 34, 51, 56,
        56, 60, 70, 76, 63, 67, 75, 64, 51};
    double data1[] = {50, 45, 47, 34, 42, 49, 63, 62, 73, 59, 56, 50, 64, 60, 67, 67,
        58, 59, 73, 77, 84, 82, 80, 84, 89};
    double data2[] = {61, 79, 85, 66, 53, 39, 24, 21, 37, 56, 37, 22, 21, 33, 13, 17,
        4, 23, 16, 25, 9, 10, 5, 7, 16};
    const char *labels[] = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10",
        "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23",
        "24"};

    // Create a XYChart object of size 500 x 300 pixels
    XYChart *c = new XYChart(500, 300);

    // Set the plotarea at (90, 30) and of size 300 x 240 pixels.
    c->setPlotArea(90, 30, 300, 240);

    // Add a legend box at (405, 100)
    c->addLegend(405, 100);

    // Add a title to the chart
    c->addTitle("Daily System Load");

    // Add a title to the y axis. Draw the title upright (font angle = 0)
    c->yAxis()->setTitle("Database\nQueries\n(per sec)")->setFontAngle(0);

    // Set the labels on the x axis.
    c->xAxis()->setLabels(StringArray(labels, (int)(sizeof(labels) / sizeof(labels[0]
        ))));

    // Display 1 out of 2 labels on the x-axis. Show minor ticks for remaining
    // labels.
    c->xAxis()->setLabelStep(2, 1);

    // Add an area layer
    AreaLayer *layer = c->addAreaLayer();

    // Draw the area layer in 3D
    layer->set3D();

    // Add the three data sets to the area layer
    layer->addDataSet(DoubleArray(data0, (int)(sizeof(data0) / sizeof(data0[0]))),
        -1, "Server # 1");
    layer->addDataSet(DoubleArray(data1, (int)(sizeof(data1) / sizeof(data1[0]))),
        -1, "Server # 2");
    layer->addDataSet(DoubleArray(data2, (int)(sizeof(data2) / sizeof(data2[0]))),
        -1, "Server # 3");

    // Output the chart
    c->makeChart("threedstackarea.png");

    //free up resources
    delete c;
    return 0;
}