How to use GFL to convert PDF to images?

Discussions on GFL SDK, the graphic library for reading and writing graphic files

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zliang68
Posts: 4
Joined: Mon Aug 29, 2005 5:25 am

How to use GFL to convert PDF to images?

Post by zliang68 »

Hi,

I have tested XNView to export a PDF file to GIF images resulting very good image quality and file size.
I try to use GFL to convert a PDF to images. How can I get the page count of a PDF file? Could anyone give me some ideas?

Thanks.
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xnview
Author of XnView
Posts: 43163
Joined: Mon Oct 13, 2003 7:31 am
Location: France

Re: How to use GFL to convert PDF to images?

Post by xnview »

zliang68 wrote:I have tested XNView to export a PDF file to GIF images resulting very good image quality and file size.
I try to use GFL to convert a PDF to images. How can I get the page count of a PDF file? Could anyone give me some ideas?
You have NumberOfImages in GFL_FILEINFO
Pierre.
zliang68
Posts: 4
Joined: Mon Aug 29, 2005 5:25 am

Post by zliang68 »

Thanks for your reply.
I can only get the first page of the PDF converted to an image. How can I read the next page of the PDF?

Thanks
zliang68
Posts: 4
Joined: Mon Aug 29, 2005 5:25 am

Post by zliang68 »

I tried to convert a two pages PDF into two PNG.

It worked when I converted only one page(either first or second page) from the PDF.

The program crash when reaching the call to gflSaveBitmapIntoHandle(VarPtr(SData), GflBitmap, GflSaveParams) for the second images (see code below).
Anyone can help?

Thanks

Code: Select all

'-------------------
Private Sub Form_Load()
Dim GflBitmap As GFL_BITMAP
Dim PtrBitmap As Long
Dim GflLoadParams As GFL_LOAD_PARAMS
Dim GflSaveParams As GFL_SAVE_PARAMS
Dim GflInfo As GFL_FILE_INFORMATION
Dim Error As Integer

gflLibraryInit 'Initialize the library
gflGetDefaultLoadParams GflLoadParams 'Gets default parameters for loading
gflGetDefaultSaveParams GflSaveParams 'Gets default parameters for saving

Error = gflLoadBitmap(App.Path & "\ae.pdf", PtrBitmap, GflLoadParams, GflInfo) 'Load bitmap in memory
If Error = GFL_NO_ERROR Then 'Si aucune erreur
    extGetGflBitmapFromPtr PtrBitmap, GflBitmap 'Get the picture data
    With GflSaveParams.Callbacks
        .Write = extFarProc(AddressOf WRITE_WriteFunction) 'Set the CallBacks
        .Tell = extFarProc(AddressOf WRITE_TellFunction)
        .Seek = extFarProc(AddressOf WRITE_SeekFunction)
    End With
    
    GflSaveParams.FormatIndex = gflGetFormatIndexByName("png") 'Set the writing format
    
    Error = gflSaveBitmapIntoHandle(VarPtr(SData), GflBitmap, GflSaveParams) 'Write the file in memory using the SData strucutre (copy of SAVE_DATA)
    If Error = GFL_NO_ERROR Then
        extSaveFile App.Path & "\ae1.png", SData 'If no error, save the picture
        Text1.text = "image 1 saved !"
        gflMemoryFree SData.Data 'Free SData
    End If
        
    gflFreeBitmapData GflBitmap 'Free bitmap
End If
If Error <> GFL_NO_ERROR Then MsgBox "Error : " & extGetStr(gflGetErrorString(Error)) & " (" & Error & ")" 'If no error, display it

gflGetDefaultLoadParams GflLoadParams 'Gets default parameters for loading
gflGetDefaultSaveParams GflSaveParams 'Gets default parameters for saving
GflLoadParams.ImageWanted = 1 'set to second page of the PDF

Error = gflLoadBitmap(App.Path & "\ae.pdf", PtrBitmap, GflLoadParams, GflInfo) 'Load bitmap in memory
If Error = GFL_NO_ERROR Then 'Si aucune erreur
    extGetGflBitmapFromPtr PtrBitmap, GflBitmap 'Get the picture data
    With GflSaveParams.Callbacks
        .Write = extFarProc(AddressOf WRITE_WriteFunction) 'Set the CallBacks
        .Tell = extFarProc(AddressOf WRITE_TellFunction)
        .Seek = extFarProc(AddressOf WRITE_SeekFunction)
    End With
    
    GflSaveParams.FormatIndex = gflGetFormatIndexByName("png") 'Set the writing format
    
'CRASH HERE
    Error = gflSaveBitmapIntoHandle(VarPtr(SData), GflBitmap, GflSaveParams) 'Write the file in memory using the SData strucutre (copy of SAVE_DATA)
    If Error = GFL_NO_ERROR Then
        extSaveFile App.Path & "\ae2.png", SData 'If no error, save the picture
        Text1.text = "image 2 saved !"
        gflMemoryFree SData.Data 'Free SData
    End If
        
    gflFreeBitmapData GflBitmap 'Free bitmap
End If

If Error <> GFL_NO_ERROR Then MsgBox "Error : " & extGetStr(gflGetErrorString(Error)) & " (" & Error & ")" 'If no error, display it

gflLibraryExit 'Quit library
End Sub