public void ProcessRequest(HttpContext context)
{
//set this to TRUE if files are to be saved on the disk
bool saveToDisk = false;
//declaration of local variables
string path = context.Request.Path.ToLower();
System.Collections.Specialized.NameValueCollection queryParams = context.Request.QueryString;
// process the query string parameters
string imageName = path;
int slashIndex = path.LastIndexOf("/");
if (slashIndex >= 0)
{
imageName = path.Remove(0, slashIndex + 1);
}
string Name = string.Empty;
System.Drawing.Bitmap bmp;
ChartEngine engine = new ChartEngine();
if (saveToDisk)
{
string physicalPath = HttpContext.Current.Request.PhysicalApplicationPath;
string parent = physicalPath.Substring(0, physicalPath.LastIndexOf("\\"));
string TempDir = (Directory.GetParent(physicalPath)).FullName + "\\charts\\";
string ImagePath = System.IO.Path.Combine(TempDir, imageName + ".png");
if (File.Exists(ImagePath))
{
// is the image already exists, return the existing file
bmp = new System.Drawing.Bitmap(ImagePath);
}
else
{
bmp = engine.GenerateImage(imageName);
SaveImageToDisk(bmp, ImagePath);
}
}
else
{
bmp = engine.GenerateImage(imageName);
}
//ProcessBitmap will send the bitmap as a http binary stream
//so that it can be displayed as an image by the user's browser
ProcessBitmap(bmp, context);
}
/// <summary>
/// Generates a new 'chart' image to be written to http output stream.
/// Also saves the newly generated image to file on disk.
/// </summary>
/// <param name="ImagePath">Http request path of the chart image</param>
public Bitmap GenerateImage(string ImagePath)
{
Bitmap bmp;
ChartEngine ChartGen = new ChartEngine();
Width = 600;
Height = 275;
ShowText = true;
QueryStringValidator QVal = new QueryStringValidator(ImagePath);
QVal.Validate(); //the language and culture is also set in the validator
if (QVal.IsValid)
{
// get query string parameters
string lang = QVal.Culture;
int StId = QVal.StationId;
Variable curVar = QVal.Variable;
DateTime startTime = QVal.StartDate;
DateTime endTime = QVal.EndDate;
// TODO: for longer intervals change curVar to [precip_day]
// search for the channel corresponding to station/variable combination
ChannelSearchResult found = ChannelSearchEngine.FindByStationIdAndVariable(
StId, curVar);
if (!found.HasMatchingStations) //no matching station
{
return ChartGen.CreateErrorChart(found.ErrorMessage);
}
if (found.HasMatchingChannels) //correct results found
{
Channel ch = found.Channels[0];
ITimeSeries ts;
TimeInterval interval = new TimeInterval(startTime, endTime);
MessageWriter writer = new MessageWriter(ch.Station.Name, ch.Variable.Name);
// for precipitation, if it's hourly and a longer period,
// always select daily precipitation to display a readable graph
// otherwise, hourly precipitation will be displayed.
int maxHourPrecipPeriod = 10;
VariableEnum var = ch.Variable.VarEnum;
if (var == VariableEnum.PrecipHour && interval.Length.TotalDays > maxHourPrecipPeriod)
{
var = VariableEnum.Precip;
}
//here we retrieve the time series
ts = TimeSeriesManager.GetTimeSeries(ch, interval);
if (ts.Count == 0) //this also means 'no data for time series'
{
bmp = ChartGen.CreateErrorChart
(writer.WriteErrorMessage(MessageType.NoDataForPeriod));
}
bmp = ChartGen.CreateChart(ch, ts);
}
else
{
// incorrect input - create a 'chart' with an error message
bmp = ChartGen.CreateErrorChart(found.ErrorMessage);
}
}
else
{
// incorrect input - create a 'chart' with an error message
bmp = ChartGen.CreateErrorChart(QVal.ErrorMessage);
}
return bmp;
}
