ChartDirector 7.0 (ASP/COM/VB Edition)

Real-Time Chart with Snapshot (Web)

The example extends the Simple Real-Time Chart (Web) example by adding buttons to download the chart in PNG and PDF formats.

When the button is pressed, the chart update request will include an extra query parameter specifying the download format. On the server side, the charting code will check if this parameter exists. If it does, the server code will return the chart as an attachment.

Source Code Listing

[Web Version (in ASP)] aspdemo\realtimesnapshot.asp
<%@ language="vbscript" %> <% Set cd = CreateObject("ChartDirector.API") ' ' Data to draw the chart. In this demo, the data buffer will be filled by a random data generator. ' In real life, the data is probably stored in a buffer (eg. a database table, a text file, or some ' global memory) and updated by other means. ' ' We use a data buffer to emulate the last 240 samples. sampleSize = 240 ReDim dataSeries1(sampleSize - 1) ReDim dataSeries2(sampleSize - 1) ReDim dataSeries3(sampleSize - 1) ReDim timeStamps(sampleSize - 1) ' Our pseudo random number generator firstDate = DateAdd("s", -(UBound(timeStamps) + 1), Now) For i = 0 To UBound(timeStamps) timeStamps(i) = DateAdd("s", i, firstDate) p = Second(timeStamps(i)) + Minute(timeStamps(i)) * 60 + Hour(timeStamps(i)) * 3600 dataSeries1(i) = Cos(p * 2.1) * 10 + 1 / (Cos(p) * Cos(p) + 0.01) + 20 dataSeries2(i) = 100 * Sin(p / 27.7) * Sin(p / 10.1) + 150 dataSeries3(i) = 100 * Cos(p / 6.7) * Cos(p / 11.9) + 150 Next ' Create an XYChart object 600 x 320 pixels in size Set c = cd.XYChart(600, 320) ' Set the plotarea at (55, 60) and of size 520 x 235 pixels with transparent background and border. ' Enable both horizontal and vertical grids by setting their colors to grey (cccccc). Set clipping ' mode to clip the data lines to the plot area. Call c.setPlotArea(55, 60, 520, 235, -1, -1, cd.Transparent, &Hcccccc, &Hcccccc) Call c.setClipping() ' Add a title to the chart using dark grey (0x333333) 20pt Arial Bold font Call c.addTitle("Real-Time Chart with Snapshot", "Arial Bold", 20, &H333333) ' Add a legend box at the top of the plot area using horizontal layout. Use 10pt Arial Bold font, ' transparent background and border, and line style legend icon. Set b = c.addLegend(55, 30, False, "Arial Bold", 10) Call b.setBackground(cd.Transparent, cd.Transparent) Call b.setLineStyleKey() ' Set the x and y axis stems to transparent and the label font to 10pt Arial Call c.xAxis().setColors(cd.Transparent) Call c.yAxis().setColors(cd.Transparent) Call c.xAxis().setLabelStyle("Arial", 10) Call c.yAxis().setLabelStyle("Arial", 10) ' Add y-axis title using 12pt Arial font Call c.yAxis().setTitle("Y-Axis Title Placeholder", "Arial", 12) ' For the automatic x and y axis labels, set the minimum spacing to 75 and 30 pixels. Call c.xAxis().setTickDensity(75) Call c.yAxis().setTickDensity(30) ' Set the x-axis label format Call c.xAxis().setLabelFormat("{value|hh:nn:ss}") ' Create a line layer to plot the lines Set layer = c.addLineLayer2() ' The x-coordinates are the timeStamps. Call layer.setXData(timeStamps) ' The 3 data series are used to draw 3 lines. Here we put the latest data values as part of the data ' set name, so you can see them updated in the legend box. Call layer.addDataSet(dataSeries1, &Hff0000, c.formatValue(dataSeries1(UBound(dataSeries1)), _ "Alpha: {value|2}")) Call layer.addDataSet(dataSeries2, &H00cc00, c.formatValue(dataSeries2(UBound(dataSeries2)), _ "Beta: {value|2}")) Call layer.addDataSet(dataSeries3, &H0000ff, c.formatValue(dataSeries3(UBound(dataSeries3)), _ "Gamma: {value|2}")) ' Create the WebChartViewer to output the chart Set viewer = cd.WebChartViewer(Request, "ChartImage1") ' Check if is download request downloadFormat = Request("download") If downloadFormat <> "" Then fname = c.formatValue(timeStamps(UBound(timeStamps)), "yyyymmddhhnnss") If downloadFormat = "pdf" Then ' Output in PDF and stream as attachment Call viewer.setChart(c, cd.PDF) Call viewer.streamChart(Response, "demo_" & fname & ".pdf") Call Response.End Else ' Output in PNG and stream as attachment Call viewer.setChart(c, cd.PNG) Call viewer.streamChart(Response, "demo_" & fname & ".png") Call Response.End End If End If ' Check if is a stream request to update the chart If viewer.IsStreamRequest Then ' Stream the updated chart to the browser Call viewer.setChart(c, cd.SVG) Call viewer.streamChart(Response) Call Response.End End If ' Is the initial web page request. Output chart as usual. Call viewer.setChart(c, cd.SVG) %> <!DOCTYPE html> <html> <head> <title>Real-Time Chart with Snapshot</title> <script type="text/javascript" src="cdjcv.js"></script> </head> <body style="margin:0px"> <table cellspacing="0" cellpadding="0" style="border:black 1px solid;"> <tr> <td align="right" colspan="2" style="background:#000088; color:#ffff00; padding:0px 4px 2px 0px;"> <a style="color:#FFFF00; font:italic bold 10pt Arial; text-decoration:none" href=""> Advanced Software Engineering </a> </td> </tr> <tr valign="top"> <td style="width:130px; background:#c0c0ff; border-right:black 1px solid; border-bottom:black 1px solid;"> <br /> <br /> <div style="font:12px Verdana; padding:10px;"> <b>Update Period</b><br /> <select id="UpdatePeriod" style="width:110px"> <option value="5">5</option> <option value="10" selected="selected">10</option> <option value="20">20</option> <option value="30">30</option> <option value="60">60</option> </select> <br /><br /><br /> <b>Time Remaining</b><br /> <div style="width:108px; border:#888888 1px inset;"> <div style="margin:3px" id="TimeRemaining">0</div> </div> </div> <br /> <br /> <br /> <br /> <div style="text-align:center"> <input type="button" value="Download PDF" style="width:112px; font:10pt Arial" onclick="JsChartViewer.get('<%=viewer.Id%>').partialUpdateAsAttachment('download=pdf');" /><br/> <input type="button" value="Download PNG" style="width:112px; font:10pt Arial; margin-top:8px;" onclick="JsChartViewer.get('<%=viewer.Id%>').partialUpdateAsAttachment('download=png');" /> </div> </td> <td style="border-left:black 1px solid; padding:5px 0px 0px 5px;" > <!-- ****** Here is the chart image ****** --> <%=viewer.renderHTML()%> </td> </tr> </table> <script type="text/javascript"> // // Executes once every second to update the countdown display. Updates the chart when the countdown reaches 0. // function timerTick() { // Get the update period and the time left var updatePeriod = parseInt(document.getElementById("UpdatePeriod").value); var timeLeft = Math.min(parseInt(document.getElementById("TimeRemaining").innerHTML), updatePeriod) - 1; if (timeLeft == 0) // Can update the chart now JsChartViewer.get('<%=viewer.Id%>').streamUpdate(); else if (timeLeft < 0) // Reset the update period timeLeft += updatePeriod; // Update the countdown display document.getElementById("TimeRemaining").innerHTML = timeLeft; } window.setInterval("timerTick()", 1000); </script> </body> </html>