Sorting photo data from Google's Picasa API

In the earlier post Google Calendar Service hosts a Gig Guide, I showed how to to use Google Data APIs to use Google Calendar data.

The client has posted photos of interest to Picasa and given them tags that determine which page of their WEB site they are displayed on.

This post describes

• how to use the Picasa Service to host photos and use them in a ASP.NET WEB site using VB
• how to sort the GData feed into "caption" sequence using a .Net IComparer
• how to avoid possible problems when the application is hosted on a virtual WEB hosting site like GoDaddy.

The software uses the Picasa API which should be downloaded and installed.

1. Install the DLLs in the Bin folder of your ASP.NET application
2. If you are having the app hosted in a shared environment, make sure you use the DLL's in the ASP.NET folder
   
3. You must also use the 1.2.2 (or later) version of the API. Earlier versions do not work.
4. If you are in a shared environment, you will also need to set the MSBuild properties as follows of the VB.NET app as follows:
   

In the code snippet below, the class:

1. Connects to the service and sets user credentials
2. genHTML(tag) returns a HTML table for that tag, by constructing the string from the entries returned by getPhotoFeed(tag, size) and getComment(entry)
3. getPhotoFeed builds the query and retieves the results
   It also sorts these using, myEntryCompare - our specialist implementation of IComparer

Imports Microsoft.VisualBasic
Imports Google.GData.Photos
Imports Google.GData.Client
Imports Google.GData.Extensions
Imports Google.GData.Extensions.Location

Public Class FoodList
    Dim password As String = "secret"
    Dim username As String = "secret"
    Dim albumName As String = "WWW"
    Dim service As PicasaService
    Public Sub New()
        service = New PicasaService("more secrets")
        service.setUserCredentials(username, password)
    End Sub
    Public Function getMenuHTML(ByVal tag As String) As String
        Dim html As String = "<table>"
        For Each entry As PicasaEntry In getPhotoFeed(tag, "320")
            html += "<tr><td colspan=2><h4>" + entry.Summary.Text + "</h4><tr><td><img src='" + entry.Content.AbsoluteUri + "'/> <td>" + getComment(entry)
        Next
        html += "</table>"
        Dim x = ""
        Return html
    End Function
    Private Function getPhotoFeed(ByVal tag As String, ByVal size As String) As ArrayList
        Dim query As New PhotoQuery(PicasaQuery.CreatePicasaUri(username, albumName))
        query.Tags = tag
        query.ExtraParameters = "imgmax=" + size + "u" ' set the maximum size of the returned images
        Dim feed As PicasaFeed = service.Query(query)
        Dim arr As New ArrayList
        arr.AddRange(feed.Entries) ' add all the entries to an array
        arr.Sort(New myEntryCompare) ' sort the entries by the caption (Summary.Text) 
        Return arr
    End Function
    Public Class myEntryCompare
        Implements IComparer
        Public Function Compare(ByVal x As Object, ByVal y As Object) As Integer Implements IComparer.Compare
            Dim myX As String = DirectCast(x, PicasaEntry).Summary.Text
            Dim myY As String = DirectCast(y, PicasaEntry).Summary.Text
            Return myX.CompareTo(myY)
        End Function 'IComparer.Compare
    End Class
    Private Function getComment(ByVal photoEntry As PicasaEntry) As String
        Dim query As CommentsQuery = New CommentsQuery(PicasaQuery.CreatePicasaUri(username, albumName, (New PhotoAccessor(photoEntry)).Id))
        Dim feed As PicasaFeed = service.Query(query)
        Try
            Return feed.Entries(0).Content.Content
        Catch ex As Exception
        End Try
        Return ""
    End Function
End Class