Applied XML Programming for Microsoft .NET.pdf - Csbdu.in

{//// Set up some internal variables to determine// size and position of the bar and the// companion text//// Draw the value (top of the bar)g.DrawString(dt.Rows[i][fieldValue].ToString(),fnt, textBrush, x, yCaption);// Draw the barRectangle bar = new Rectangle(x, yBarTop, barWidth - 10,barHeight);LinearGradientBrush fill = new LinearGradientBrush(bar,Color.SpringGreen, Color.Yellow,LinearGradientMode.BackwardDiagonal);g.FillRectangle(fill, bar);fill.Dispose();}// Draw the employee name (bottom of the bar)g.DrawString(dt.Rows[i][fieldLabel].ToString(),fnt, textBrush, x, barBottom + textHeight);At the end of the loop, the bar chart is completely rendered in the Bitmap object. Thebitmap is still held in memory in an intermediate, internal format, however. Two moresteps are necessary: converting the bitmap to a public format such JPEG, BMP, or GIF,and figuring out a way to persist or transfer its content.Encoding Images as BinHexConverting a Bitmap object to one of the commonly used image formats is a nonissue.You call the Save method on the Bitmap object, pick up one of the supported formats,and you're done. The real difficulty has to do with the planned use of this helper class.Remember, we designed this class for later use within a .NET Remoting server and aWeb service. When Web services in particular are involved, having the helper classsave the image to persistent storage just doesn't make sense. An alternative approachwould be saving the bitmap locally on the server in a location accessible for downloadvia FTP or HTTP. Creating files on the server might pose security problems, however,and normally forces the system administrator to change default settings to allow forlocal files being created.The SalesDataProvider helper class was designed to return the dynamically createdimage as an encoded text string packed in an XML document. This approach is notoptimal in a .NET Remoting scenario, but it probably represents the only option if youhave to also publish the function through a Web service.435