Generate Statistic Chart with ZedGraph in ASP.NET

中文翻譯請稍候.
The chart generation work is handled by my former colleague Peter. But he left.
He did the job with his own little chart library which I don’t know how to use it.
So I look for an open source and/or free solution. I find ZedGraph and it looks pretty much 90% what I need.

After experiencing ZedGraph, it is very amazing how easy to use ZedGraph and its features are so complete!

Download ZedGraph first.
If you are not going to make your own version or dive into the source, just download dll only.

Create a Web Application, add both ZedGraph.dll and ZedGraph.Web.dll to the reference.
And then right click on the toolbox, add new server control by adding ZedGraph.Web.dll.
You can now drag the ZedGraph control to your design view.
Remember to *REMOVE* all other tags, just leave

and the ZedGraphWeb control behind.
Result in something like this :
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="GenerateLineChart.aspx.cs" Inherits="TaoYuan.HistoryData.ByItemGroup.GenerateLineChart" %>
<%@ Register Assembly="ZedGraph.Web" Namespace="ZedGraph.Web" TagPrefix="zgw" %>

As you can read in their document, ZedGraph works in two modes.
I am not going to explain it since their have nice document on that.
I will show how to use the stream mode to expose a Graph as a url.

Back to the page which we have a ZedGraph control.
We assign an event handler to RenderGraph event which will define how the graph is rendered. Assign like the following :
zedGraphControl.RenderGraph += new ZedGraph.Web.ZedGraphWebControlEventHandler(zedGraphControl_RenderGraph);
public void zedGraphControl_RenderGraph(ZedGraphWeb zgw, Graphics g, MasterPane masterPane){...}

Inside the handler method, you will be given a default master pane.
I maybe talk about master pane later, let’s just use one graph in this post.
What you need to do here is setup the graph style, bind data and done.
I will just show a demo snippet with a little explaination.

//get a graph pane
GraphPane masterPaneDefault = masterPane[0];
//style the title and axises
masterPaneDefault.Title.Text = m_selectedStation.Name;
masterPaneDefault.XAxis.Title.IsVisible = false;
masterPaneDefault.YAxis.Title.Text = m_selectedItemInfo.Name+'('+ m_selectedItemInfo.Unit +')';
//we are going to use line chart here
//use data to make a curve line
PointPairList theLine = new PointPairList();
foreach (DataRow dr in m_DataFound.Rows)
{
DateTime l_date = (DateTime)dr[0];
double x = (double)new XDate(l_date);
double y = 0;
if (!DBNull.Value.Equals(dr[1]))
{
y = (Single)dr[1];
theLine.Add(x, y);
}
}
//set angle of xaxis label
masterPaneDefault.XAxis.Scale.FontSpec.Angle = 45;
//add the line to our graph pane
LineItem theCurve = masterPaneDefault.AddCurve(m_selectedItemInfo.Name, theLine, Color.Red, SymbolType.XCross);
masterPaneDefault.XAxis.Type = AxisType.DateAsOrdinal;
masterPaneDefault.XAxis.Scale.Format = "yyyy/MM/dd HH:mm";
//smooth the curve
//theCurve.Line.IsSmooth = true;
// Make curves thicker
//theCurve.Line.Width = 3.0F;
// Add gridlines to the plot, and make them gray
masterPaneDefault.XAxis.MajorGrid.IsVisible = true;
masterPaneDefault.YAxis.MajorGrid.IsVisible = true;
masterPaneDefault.XAxis.MajorGrid.Color = Color.Gray;
masterPaneDefault.YAxis.MajorGrid.Color = Color.LightGray;
masterPaneDefault.XAxis.MinorGrid.IsVisible = true;
masterPaneDefault.XAxis.MinorGrid.Color = Color.Khaki;
// Move the legend location
masterPaneDefault.Legend.Position = LegendPos.Right;
// Add a background gradient fill to the axis frame
masterPaneDefault.Chart.Fill = new Fill(Color.White, Color.FromArgb(255, 255, 210), -45F);
masterPaneDefault.Fill = new Fill(Color.FromArgb(250, 250, 255));
//masterPaneDefault.XAxis.Scale.MajorStep = 2.5d;
masterPaneDefault.Legend.IsVisible = false;
//calculate the axis scale ranges
masterPaneDefault.AxisChange();

The result will look something like this.
line chart
That’s it. There are other great charting tools avaiable.
The MS Chart control and Flot are both great. Check them out if you like.

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