ChartDirector 6.0 (C++ Edition)

Track Line with Data Labels (MFC)

NOTE: This section describes Track Line with Data Labels for MFC, and is available on the Windows edition of ChartDirector for C++ only. For QT, please refer to Track Line with Data Labels (QT).

This sample program demonstrates a track cursor programmed with the following features:

The code first draws the chart. Then in the CVN_MouseMovePlotArea message handler, the track cursor is drawn to reflect the mouse position. The track cursor is configured to automatically hide itself when the mouse leaves the plot area.

The trackLineLabel method is the routine that draws the track cursor. Its key elements are:

Source Code Listing

The following is the main source code of this demo. The complete MFC project is in "mfcdemo/tracklabel".

[File: mfcdemo/tracklabel/tracklabelDlg.cpp]
// tracklabelDlg.cpp : implementation file

#include "stdafx.h"
#include "tracklabel.h"
#include "tracklabelDlg.h"
#include "chartdir.h"
#include <sstream>
#include <algorithm>

using namespace std;

#ifdef _DEBUG
#define new DEBUG_NEW

// CtracklabelDlg dialog

CtracklabelDlg::CtracklabelDlg(CWnd* pParent /*=NULL*/)
    : CDialog(CtracklabelDlg::IDD, pParent)
    m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME);

    delete m_ChartViewer.getChart();

void CtracklabelDlg::DoDataExchange(CDataExchange* pDX)
    DDX_Control(pDX, IDC_ChartViewer, m_ChartViewer);

BEGIN_MESSAGE_MAP(CtracklabelDlg, CDialog)
    ON_CONTROL(CVN_MouseMovePlotArea, IDC_ChartViewer, OnMouseMovePlotArea)

// CtracklabelDlg message handlers

BOOL CtracklabelDlg::OnInitDialog()

    // Set the icon for this dialog.  The framework does this automatically
    //  when the application's main window is not a dialog
    SetIcon(m_hIcon, TRUE);            // Set big icon
    SetIcon(m_hIcon, FALSE);        // Set small icon


    CRect winSize;
    m_ChartViewer.MoveWindow(5, 5, winSize.Width(), winSize.Height());

    CalcWindowRect(&winSize, CWnd::adjustBorder);
    SetWindowPos(&wndTop, 0, 0, winSize.Width() + 10, winSize.Height() + 10, SWP_NOMOVE);
    return TRUE;  // return TRUE  unless you set the focus to a control

// If you add a minimize button to your dialog, you will need the code below
//  to draw the icon.  For MFC applications using the document/view model,
//  this is automatically done for you by the framework.

void CtracklabelDlg::OnPaint()
    if (IsIconic())
        CPaintDC dc(this); // device context for painting

        SendMessage(WM_ICONERASEBKGND, reinterpret_cast<WPARAM>(dc.GetSafeHdc()), 0);

        // Center icon in client rectangle
        int cxIcon = GetSystemMetrics(SM_CXICON);
        int cyIcon = GetSystemMetrics(SM_CYICON);
        CRect rect;
        int x = (rect.Width() - cxIcon + 1) / 2;
        int y = (rect.Height() - cyIcon + 1) / 2;

        // Draw the icon
        dc.DrawIcon(x, y, m_hIcon);

// The system calls this function to obtain the cursor to display while the user drags
//  the minimized window.
HCURSOR CtracklabelDlg::OnQueryDragIcon()
    return static_cast<HCURSOR>(m_hIcon);

// Handle the ON_WM_ERASEBKGND message to set background color
BOOL CtracklabelDlg::OnEraseBkgnd(CDC* pDC) 
    // Set brush to desired background color 
    CBrush backBrush(RGB(255, 255, 255)); 

    // Save old brush 
    CBrush* pOldBrush = pDC->SelectObject(&backBrush); 

    // Erase the area needed with the given background color
    CRect rect; 
    pDC->PatBlt(rect.left,, rect.Width(), rect.Height(), PATCOPY); 

    // Restore old brush and exit
    return TRUE; 

// Draw track cursor when mouse is moving over plotarea
void CtracklabelDlg::OnMouseMovePlotArea()
    trackLineLabel((XYChart *)m_ChartViewer.getChart(), m_ChartViewer.getPlotAreaMouseX());

    // Hide the track cursor when the mouse leaves the plot area

// CtracklabelDlg methods

// Draw the chart and display it in the given viewer
void CtracklabelDlg::drawChart(CChartViewer *viewer)
    // Data for the chart as 3 random data series
    RanSeries r(127);
    DoubleArray data0 = r.getSeries(100, 100, -15, 15);
    DoubleArray data1 = r.getSeries(100, 150, -15, 15);
    DoubleArray data2 = r.getSeries(100, 200, -15, 15);
    DoubleArray timeStamps = r.getDateSeries(100, Chart::chartTime(2011, 1, 1), 86400);

    // Create a XYChart object of size 640 x 400 pixels
    XYChart *c = new XYChart(640, 400);

    // Add a title to the chart using 18 pts Times New Roman Bold Italic font
    c->addTitle("    Product Line Global Revenue", "timesbi.ttf", 18);

    // Set the plotarea at (50, 55) with width 70 pixels less than chart width, and height 90 pixels
    // less than chart height. Use a vertical gradient from light blue (f0f6ff) to sky blue (a0c0ff)
    // as background. Set border to transparent and grid lines to white (ffffff).
    c->setPlotArea(50, 55, c->getWidth() - 70, c->getHeight() - 90, c->linearGradientColor(0, 55, 0,
        c->getHeight() - 35, 0xf0f6ff, 0xa0c0ff), -1, Chart::Transparent, 0xffffff, 0xffffff);

    // Add a legend box at (50, 25) using horizontal layout. Use 10pts Arial Bold as font. Set the
    // background and border color to Transparent.
    c->addLegend(50, 25, false, "arialbd.ttf", 10)->setBackground(Chart::Transparent);

    // Set axis label style to 8pts Arial Bold
    c->xAxis()->setLabelStyle("arialbd.ttf", 8);
    c->yAxis()->setLabelStyle("arialbd.ttf", 8);

    // Set the axis stem to transparent

    // Configure x-axis label format
    c->xAxis()->setMultiFormat(Chart::StartOfYearFilter(), "{value|mm/yyyy} ", 
        Chart::StartOfMonthFilter(), "{value|mm}");

    // Add axis title using 10pts Arial Bold Italic font
    c->yAxis()->setTitle("USD millions", "arialbi.ttf", 10);

    // Add a line layer to the chart using a line width of 2 pixels.
    LineLayer *layer = c->addLineLayer();

    // Add 3 data series to the line layer
    layer->addDataSet(data0, 0xff3333, "Alpha");
    layer->addDataSet(data1, 0x008800, "Beta");
    layer->addDataSet(data2, 0x3333cc, "Gamma");

    // Assign the chart to the WinChartViewer

// Draw track line with data labels
void CtracklabelDlg::trackLineLabel(XYChart *c, int mouseX)
    // Clear the current dynamic layer and get the DrawArea object to draw on it.
    DrawArea *d = c->initDynamicLayer();

    // The plot area object
    PlotArea *plotArea = c->getPlotArea();

    // Get the data x-value that is nearest to the mouse, and find its pixel coordinate.
    double xValue = c->getNearestXValue(mouseX);
    int xCoor = c->getXCoor(xValue);

    // Draw a vertical track line at the x-position
    d->vline(plotArea->getTopY(), plotArea->getBottomY(), xCoor, 
        d->dashLineColor(0x000000, 0x0101));

    // Draw a label on the x-axis to show the track line position.
    ostringstream xlabel;
    xlabel << "<*font,bgColor=000000*> " << c->xAxis()->getFormattedLabel(xValue, "mmm dd, yyyy") 
        << " <*/font*>";
    TTFText *t = d->text(xlabel.str().c_str(), "arialbd.ttf", 8);

    // Restrict the x-pixel position of the label to make sure it stays inside the chart image.
    int xLabelPos = max(0, min(xCoor - t->getWidth() / 2, c->getWidth() - t->getWidth()));
    t->draw(xLabelPos, plotArea->getBottomY() + 6, 0xffffff);

    // Iterate through all layers to draw the data labels
    for (int i = 0; i < c->getLayerCount(); ++i) {
        Layer *layer = c->getLayerByZ(i);

        // The data array index of the x-value
        int xIndex = layer->getXIndexOf(xValue);

        // Iterate through all the data sets in the layer
        for (int j = 0; j < layer->getDataSetCount(); ++j) 
            DataSet *dataSet = layer->getDataSetByZ(j);
             const char *dataSetName = dataSet->getDataName();

            // Get the color, name and position of the data label
            int color = dataSet->getDataColor();
            int yCoor = c->getYCoor(dataSet->getPosition(xIndex), dataSet->getUseYAxis());

            // Draw a track dot with a label next to it for visible data points in the plot area
            if ((yCoor >= plotArea->getTopY()) && (yCoor <= plotArea->getBottomY()) && (color !=
                Chart::Transparent) && dataSetName && *dataSetName)
                d->circle(xCoor, yCoor, 4, 4, color, color);

                ostringstream label;
                label << "<*font,bgColor=" << hex << color << "*> " 
                    << c->formatValue(dataSet->getValue(xIndex), "{value|P4}") << " <*font*>";
                t = d->text(label.str().c_str(), "arialbd.ttf", 8);
                // Draw the label on the right side of the dot if the mouse is on the left side the
                // chart, and vice versa. This ensures the label will not go outside the chart image.
                if (xCoor <= (plotArea->getLeftX() + plotArea->getRightX()) / 2)
                    t->draw(xCoor + 5, yCoor, 0xffffff, Chart::Left);
                    t->draw(xCoor - 5, yCoor, 0xffffff, Chart::Right);