ChartDirector 饼状，柱状图如何实时更新数据

Jason_YF 2016-10-11 06:23:10

刚接触的ChartDirector，按照官方实例倒是可以很容易的绘制一个图表，但是想要扩展，却不好下手。简单的饼状图绘制代码：



    QHBoxLayout *m_hLayout=new QHBoxLayout;

	QPushButton *m_pushButton=new QPushButton;

	m_pushButton->setText(tr("截图"));



	connect(m_pushButton,SIGNAL(clicked()),this,SLOT(test()));



	m_hLayout->addWidget(m_pushButton);

	m_hLayout->addStretch();



	m_pViewer = new QChartViewer(this);

	m_pVLayout->addLayout(m_hLayout);

	m_pVLayout->addWidget(m_pViewer);

	m_pVLayout->addStretch();

	this->setLayout(m_pVLayout);

	// Create a PieChart object of size 360 x 300 pixels

	m_piechart = new PieChart(860, 600);



	m_piechart->setDefaultFonts("mingliu.ttc", "mingliu.ttc Bold");

	// Set the center of the pie at (180, 140) and the radius to 100 pixels

	m_piechart->setPieSize(300, 260, 230);



	// Add a title to the pie chart

	m_piechart->addTitle(strTitle.toStdString().c_str(),"mingliu.ttc Bold",18)->setMargin(0,0,8,8);



	// add a legend box where the top left corner is at (330, 50)

	m_piechart->addLegend(650, 60);



	// Output the chart

	double data[] = {1, 2, 3};



	// The labels for the bar chart

	const char *labels[] = {"项目1", "项目2", "项目3"};

	m_piechart->setData(DoubleArray(data, sizeof(data)/sizeof(data[0])), StringArray(labels,

		sizeof(labels)/sizeof(labels[0])));

	m_pViewer->setChart(m_piechart);

	m_pViewer->show();

效果如下:

PieChart类的接口不多，按照如下代码修改显示数据：



    double data[] = {3, 2, 1,2};

	// The labels for the bar chart

	const char *labels[] = {"test1", "test2", "test3", "test4"};

	m_piechart->setData(DoubleArray(data, sizeof(data)/sizeof(data[0])), StringArray(labels,

		sizeof(labels)/sizeof(labels[0])));

	m_pViewer->setChart(m_piechart);

	m_pViewer->updateViewPort(true, true);

	m_pViewer->updateDisplay();

结果图表没有发生改变，没办法，只能按如下方法瞎搞一番：



    m_pVLayout->removeWidget(m_pViewer);;

	delete m_pViewer;

	delete m_piechart;



	m_pViewer = new QChartViewer(this);

	m_pVLayout->addWidget(m_pViewer);

	//this->setLayout(m_pVLayout);

	// Create a PieChart object of size 360 x 300 pixels

	m_piechart = new PieChart(860, 600);

    ...........

执行如上代码后，图表数据会更新，但是图表会位移，而且这种方法在UI实时更新数据时不可靠，重复的new和delete ，影响运行效率，不知各位用什么方法来更新ChartDirector 饼状，柱状图的数据？