There are a number of
new .NET "Charting" graphics server controls, and except for
a few freebie ones that are kind of rough around the edges, they are pretty
much all in the $200 to $400 range - or higher. But what about Office
Web Components? OWC XP is now free-threaded. Yes, its COM. But Visual
Studio.NET can handle the creation of your RCW COM wrappers very handily.
Since OWC is a
free download , (you are supposed to own Office XP, so check the licensing
requirements), I thought it might be a good start, especially since I
thought I'd be able to build on my successes with my previous article,
"Streaming
Excel in ASP.NET with OWC" . We need to create charts over the
web where I work, and they don't like to authorize purchases of expensive
components (surprise?).
Unfortunately, nobody's written an article that I could find about how
to do it. And the documentation on using OWC Chart control in MSDN is
downright ugly! Ugly as a bulldog chewing on a wasp! They want you to
do it client side with an <object .. tag and XML data islands. The
only other solution they had was to transform Dataset Xml into an ADO
Dataset representation. Ouch! Even UGLIER! I don't want to do it client
side. I wanted to do it server side, save the gif to the filesystem, and
stream it with an image control.
After reading some of the COM - based documentation, which was the only
thing I could really find besides the ugly code, I finally figured out
an elegant way to do it. One of the acceptable data sources for the control
is a tab-delimited string ( It also accepts an object array, but I gave
up on that). So by getting a regular .NET DataSet, you can use the WriteXml
method and zap it into a StringWriter. Load that into an XmlDocument instance,
and then you can iterate the nodelist with your data and convert it into
a tab - delimited string and the control will be happy!
To use the OWC Chart Component, all you need to to is set a COM reference
to the installed library in ASP.NET. Fire up a new ASP.NET WebForms application,
and stick a button and an Image control on the design surface.
Click "Add Reference" from the Solution Explorer,
choose the COM tab, and find the library, which will look
like this:
Click "OK" and VS.NET will build a COM Interop
wrapper for you, called appropriately, "OWC10". Add the following
using statements to your WebForm codebehind class:
using OWC10;
using System.IO;
What I'll show next is the code to get a DataSet from
the SQL Server Northwind Database, populate the control with your data
as I described above, save the file as a GIF, and populate your Image
Control's ImageURL property so that when the postback occurs, you have
your chart! I've also included a helper method that checks the file system
every time a user requests a chart and cleans up any GIF files older than
2 minutes:
private void btnChart_Click(object sender, System.EventArgs e)
{
SqlConnection cn =
new SqlConnection("Server=(local);DataBase=Northwind;user id=sa;password=;");
cn.Open();
DataSet ds = new DataSet("Chart");
SqlDataAdapter da = new SqlDataAdapter("CustorderHist 'ALFKI'",
cn);
da.Fill(ds);
OWC10.ChartSpaceClass oChartSpace = new OWC10.ChartSpaceClass();
System.IO.StringWriter sw = new System.IO.StringWriter();
XmlDocument xDoc = new XmlDocument();
ds.WriteXml(sw);
//
clean up
cn.Close();
da.Dispose();
ds.Dispose();
xDoc.LoadXml(sw.ToString());
sw.Close();
System.Xml.XmlNodeList nodes;
nodes = xDoc.ChildNodes.Item(0).ChildNodes;
int nCount = nodes.Count;
string[] aNames = new string[nCount];
string[] aTotals = new string[nCount];
string names=String.Empty;
string totals =String.Empty;
int i = 0;
for(i=1;i<nCount;i++)
{
aNames[i]= nodes.Item(i-1).ChildNodes.Item(0).InnerText;
aTotals[i]= nodes.Item(i-1).ChildNodes.Item(1).InnerText;
}
//Chart control accepts tab-delimited string
of values
names= String.Join("\t", aNames);
totals= String.Join("\t", aTotals);
oChartSpace.Charts.Add(0);
oChartSpace.Charts[0].SeriesCollection.Add(0);
oChartSpace.Charts[0].SeriesCollection[0].SetData(OWC10.ChartDimensionsEnum.chDimCategories,
Convert.ToInt32(OWC10.ChartSpecialDataSourcesEnum.chDataLiteral),names
);
oChartSpace.Charts[0].SeriesCollection[0].SetData(OWC10.ChartDimensionsEnum.chDimValues,
Convert.ToInt32(OWC10.ChartSpecialDataSourcesEnum.chDataLiteral),totals
);
string strFullPathAndName=Server.MapPath(System.DateTime.Now.Ticks.ToString()
+".gif");
oChartSpace.ExportPicture( strFullPathAndName, "gif",
800, 600);
Image1.ImageUrl=strFullPathAndName;
Image1.Visible =true;
RemoveFiles(Server.MapPath("."));
}
private void RemoveFiles(string strPath)
{
System.IO.DirectoryInfo di = new DirectoryInfo(strPath);
FileInfo[] fiArr = di.GetFiles();
foreach (FileInfo fi in fiArr)
{
if(fi.Extension.ToString() ==".gif" )
{
// if file is older than 2 minutes, we'll clean it up
TimeSpan min = new TimeSpan(0,0,0,2,0);
if(fi.CreationTime < DateTime.Now.Subtract(min))
{
fi.Delete();
}
}
}
}
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Presto! Dynamic ASP.NET web -based charts from your data,
and the price is right. (And the code ain't ugly, either!). You can download
the sample solution below.
Download
the Code that accompanies this article
| Peter Bromberg is a C# MVP, MCP, and .NET consultant who has worked in the banking and financial industry for 20 years. He has architected and developed web - based corporate distributed application solutions since 1995, and focuses exclusively on the .NET Platform. Pete's samples at GotDotNet.com have been downloaded over 41,000 times. You can read Peter's UnBlog Here. --><-- NOTE: Post QUESTIONS on FORUMS! |  |
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