有什么方法可以在c＃中获取pdf文件首页的图像吗？

Question

我正在寻找一种使用c＃获取pdf文件中第一页图像的方法任何解决方案??

Answer 1

iTextSharp should handle that. Exit on the first image

example here http://www.vbforums.com/showthread.php?t=530736

Edit:

Copied code from the thread by stanav

Public Shared Function ExtractImages(ByVal sourcePdf As String) As List(Of Image)
    Dim imgList As New List(Of Image)

    Dim raf As iTextSharp.text.pdf.RandomAccessFileOrArray = Nothing
    Dim reader As iTextSharp.text.pdf.PdfReader = Nothing
    Dim pdfObj As iTextSharp.text.pdf.PdfObject = Nothing
    Dim pdfStrem As iTextSharp.text.pdf.PdfStream = Nothing

    Try
        raf = New iTextSharp.text.pdf.RandomAccessFileOrArray(sourcePdf)
        reader = New iTextSharp.text.pdf.PdfReader(raf, Nothing)

        For i As Integer = 0 To reader.XrefSize - 1
            pdfObj = reader.GetPdfObject(i)
            If Not IsNothing(pdfObj) AndAlso pdfObj.IsStream() Then
                pdfStrem = DirectCast(pdfObj, iTextSharp.text.pdf.PdfStream)
                Dim subtype As iTextSharp.text.pdf.PdfObject = pdfStrem.Get(iTextSharp.text.pdf.PdfName.SUBTYPE)
                If Not IsNothing(subtype) AndAlso subtype.ToString = iTextSharp.text.pdf.PdfName.IMAGE.ToString Then
                    Dim bytes() As Byte = iTextSharp.text.pdf.PdfReader.GetStreamBytesRaw(CType(pdfStrem, iTextSharp.text.pdf.PRStream))
                    If Not IsNothing(bytes) Then
                        Try
                            Using memStream As New System.IO.MemoryStream(bytes)
                                memStream.Position = 0
                                Dim img As Image = Image.FromStream(memStream)
                                imgList.Add(img)
                            End Using
                        Catch ex As Exception
                            'Most likely the image is in an unsupported format
                            'Do nothing
                            'You can add your own code to handle this exception if you want to
                        End Try
                    End If
                End If
            End If
        Next
        reader.Close()
    Catch ex As Exception
        MessageBox.Show(ex.Message)
    End Try
    Return imgList
End Function 

Answer 2

You are probably trying to rasterize the pages of the PDF. If look for get image etc you will turn up other operations that you could perform on a PDF. There are a list of ways already posted. I've used ABCpdf to do this very easily.

Answer 3

Are you in a web, or native environment? It makes a huge difference. What you want to is rasterize the PDF into an image. This is easy enough to do in a native environment via GhostDoc or a similar tool. They all use a virtual printer driver to rasterize the PDF. This approach won't work in a web-environment where you will probably need to use something commercial as writing your own rasterizing engine is a massive undertaking.