ApiController.vb

Imports System.Drawing
Imports System.Net
Imports Microsoft.ProjectOxford.Vision

Public Class ApiController
    Inherits System.Web.Mvc.Controller

    Async Function Index(url As String) As Threading.Tasks.Task(Of ActionResult)
        If url Is Nothing Then
            Return New HttpStatusCodeResult(HttpStatusCode.BadRequest)
        End If

        Dim result As Contract.AnalysisResult
        Try
            ' API 呼び出し
            Dim client = New VisionServiceClient("0b1ff4ab7a634bb0a6f7d532659f5d77")
            If Uri.IsWellFormedUriString(url, UriKind.Absolute) Then
                result = Await client.AnalyzeImageAsync(url)
            Else
                Return New HttpStatusCodeResult(HttpStatusCode.BadRequest)
            End If

        Catch cEx As ClientException
            Return FileStream(url)
        Catch ex As Exception
            Return FileStream(url)
        End Try

        If result.Categories IsNot Nothing AndAlso result.Categories.Any AndAlso
            result.Categories.First.Name.StartsWith("food_") Then ' 画像のカテゴリーが食べ物

            ' モザイク画像作成
            Dim webClient = New WebClient
            Dim inBmp = New Bitmap(webClient.OpenRead(url))
            Dim tmpBmp = New Bitmap(inBmp.Width \ 10, inBmp.Height \ 10)
            Dim outBmp = New Bitmap(inBmp.Width, inBmp.Height)

            Using g = Graphics.FromImage(tmpBmp)
                g.InterpolationMode = Drawing2D.InterpolationMode.NearestNeighbor
                g.DrawImage(inBmp, 0, 0, tmpBmp.Width, tmpBmp.Height)
            End Using

            Using g = Graphics.FromImage(outBmp)
                g.InterpolationMode = Drawing2D.InterpolationMode.NearestNeighbor
                g.DrawImage(tmpBmp, 0, 0, outBmp.Width, outBmp.Height)
            End Using

            Response.ContentType = "image/png"
            outBmp.Save(Response.OutputStream, Imaging.ImageFormat.Png)
            Return New EmptyResult

        Else
            Return FileStream(url)
        End If
    End Function

    Private Function FileStream(url As String) As ActionResult
        Try
            Dim req = HttpWebRequest.CreateHttp(url)
            Dim res = DirectCast(req.GetResponse, HttpWebResponse)

            Response.ContentType = res.ContentType
            res.GetResponseStream.CopyTo(Response.OutputStream)

        Catch ex As WebException
            If ex.Status = System.Net.WebExceptionStatus.ProtocolError Then
                Dim r = DirectCast(ex.Response, System.Net.HttpWebResponse)
                Response.StatusCode = r.StatusCode
            End If
        End Try

        Return New EmptyResult
    End Function

End Class