如何将Powerpoint演示文稿的Blob数据转换为UI中的图像滑块

Question

Problem: I have a function that uploads .pptx files into the database as blob. Trying to develop a function where i need to read the blob data, convert them into a power point presentation (.pptx) object and then get every individual slide as independent images in the UI (asp.net) so that the user can slide images one after another.

Current status: i have the blob data converted/deflated into a base64 string. How can i convert that into a .pptx file object and then get them in the UI as individual slide images.

Current status: i have the blob data converted/deflated into a base64 string. How can i convert that into a .pptx file object and then get them in the UI as individual slide images.

PS: I do not want the files to be downloaded to local machine.

Is there any way that this can be achieved. Currently performance of the function is not considered much, just needed this to work as expected

Answer 1

Here's what i did: Converted the Blob data to a memory stream and then using the file stream i wrote the data into a file and stored it in the webserver. Later extracted the specific file and converted each pptx slide into image and then those images were used in the slideshow.

Converting the blob data to file (bData is the byte array of the blob data)

        Using CompressedMemoryStream As New MemoryStream(bData),
                   DecompressedMemoryStream As New MemoryStream(),
                   DecompressionStream As New Compression.DeflateStream(CompressedMemoryStream, Compression.CompressionMode.Decompress)
            DecompressionStream.CopyTo(DecompressedMemoryStream)
            Dim byteData = DecompressedMemoryStream.ToArray()
            Dim fileStream = New FileStream(filePath, FileMode.CreateNew, FileAccess.Write)
            fileStream.Write(byteData, 0, byteData.Length)
            fileStream.Close()
        End Using

Converted the generated file into multiple images for slideshow

        Dim pptapplication As New Microsoft.Office.Interop.PowerPoint.Application
        Dim prsPres As Presentation = pptapplication.Presentations.Open(filePath, MsoTriState.msoCTrue, MsoTriState.msoTriStateMixed, MsoTriState.msoFalse)
        Dim slidesCount = prsPres.Slides.Count()
        If Not isFileExists Then
            For i As Integer = 1 To slidesCount
                prsPres.Slides(i).Export(dir + "\" + "slide" + i.ToString() + ".png", "png", 960, 720)
            Next
        End If
        prsPres.Close()
        pptapplication.Quit()

If anyone can suggest a way to convert the blob data directly into image files instead of converting the blob data into original file and then to images, that will be really helpful.