Tuesday, April 8, 2008

More Fun With Goolge Earth

This is a bit of a continuation with the previous blog entry. Instead of using the networklink I wanted to create something dynamic but portable. So basically, it consists of the same process of generating a kml file and images of pie charts, only this time the kml isn't written as a response but to the server. Then the whole folder is zipped up to a kmz including all the images. To do the zipping I used an opensource solution called #ziplib (sharpziplib) which worked very easily and only required a few lines of code (below).

Of course I'm not the first or last person to do this dynamic kmz creation with ASP.NET, and a brief search will produce essentially the same process using #ziplib. Although, I don't think many people or dynamically creating graphs at the same time (could be wrong, if so please correct). I really want to use Google charts to do this, because they have some nice looking charts, but due to some proxy server issues this became more hastle than it was worth. I think if I do a tutorial or something, I would use Google charts instead. Again this has probably been done somewhere.

Here is a fix to a problem I was running into. You need to set the size of the file before adding it as an entry: http://community.sharpdevelop.net/forums/p/6986/19897.aspx#19897

On a side note. I keep delving more and more into programming. I do think it is a necessity. I can handle working with vb.net, vba, javascript, and python. Definitely more of dabler than developer. I keep telling myself that I should start to learn C# to take things to a more advanced level. A lot of these language structures look similar to c#: javascript, python, java, j#, etc. At least to me anyway. But what can I say - I love VB. As I've read elsewhere, it is such a verbose language you can read it like a book. I just think it is so easy to use, and in a lot of ways so portable with VBA, VBScript (I've used this with dos to repeat creating a directory structure over and over again), VB.NET, VB6. I can use it in so many different environments. It's hard to resist the temptation to come back to it...and so C# will have to wait some more.

Here is a copy of the code I am using:

Private Sub ZipFolder(ByVal currentFolder As String)
Dim Filenames() As String = System.IO.Directory.GetFiles(OutputPath & currentFolder & "\")
Dim s As New ZipOutputStream(System.IO.File.Create(OutputPath & currentFolder & ".kmz"))
Dim buffer() As Byte
ReDim buffer(4096)
For Each file As String In Filenames
Dim entry As ZipEntry
Dim fileInfo As New System.IO.FileInfo(file)
entry = New ZipEntry(fileInfo.Name)
entry.Size = fileInfo.Length
Dim fs As System.IO.FileStream = fileInfo.OpenRead
ReDim buffer(fileInfo.Length)
Dim sourceBytes As Integer = 1
Do Until (sourceBytes <= 0)
sourceBytes = fs.Read(buffer, 0, fileInfo.Length)
s.Write(buffer, 0, sourceBytes)
fs = Nothing
sourceBytes = Nothing
entry = Nothing
Filenames = Nothing
s = Nothing
buffer = Nothing

End Sub

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