Differenze tra le versioni di "Comprimere un file PDF con le funzioni esterne del API di Ghostscript"
Da Gambas-it.org - Wikipedia.
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Private Enum GS_ARG_ENCODING_LOCAL = 0, GS_ARG_ENCODING_UTF8, GS_ARG_ENCODING_UTF16LE | Private Enum GS_ARG_ENCODING_LOCAL = 0, GS_ARG_ENCODING_UTF8, GS_ARG_ENCODING_UTF16LE | ||
| − | Private | + | Private Const gs_error_ok As Integer = 0 |
<FONT Color=gray>' ''int gsapi_new_instance(void * * pinstance, void * caller_handle)'' | <FONT Color=gray>' ''int gsapi_new_instance(void * * pinstance, void * caller_handle)'' | ||
| Riga 46: | Riga 46: | ||
Dim minst As Pointer | Dim minst As Pointer | ||
| − | Dim | + | Dim i As Integer |
Dim gsargv As String[] = [" ", "-sDEVICE=pdfwrite", "-dCompatibilityLevel=1.4", "-dPDFSETTINGS=" &/ pdfsettings[0], "-dNOPAUSE", "-dQUIET", "-dBATCH", "-sOutputFile=" &/ PDFFINALE, PDFORIGINARIO] | Dim gsargv As String[] = [" ", "-sDEVICE=pdfwrite", "-dCompatibilityLevel=1.4", "-dPDFSETTINGS=" &/ pdfsettings[0], "-dNOPAUSE", "-dQUIET", "-dBATCH", "-sOutputFile=" &/ PDFFINALE, PDFORIGINARIO] | ||
| − | + | i = gsapi_new_instance(VarPtr(minst), 0) | |
| − | If | + | If i < gs_error_ok Then Error.Raise("Error !") |
| − | + | i = gsapi_set_arg_encoding(minst, GS_ARG_ENCODING_UTF8) | |
| − | If | + | If i == gs_error_ok Then code = gsapi_init_with_args(minst, gsargv.Count, gsargv.Data) |
| − | + | i = gsapi_exit(minst) | |
| − | If | + | If i < gs_error_ok Then Error.Raise("Error !") |
gsapi_delete_instance(minst) | gsapi_delete_instance(minst) | ||
| Riga 66: | Riga 66: | ||
=Riferimenti= | =Riferimenti= | ||
* https://ghostscript.readthedocs.io/en/latest/index.html | * https://ghostscript.readthedocs.io/en/latest/index.html | ||
| + | * https://ghostscript.com/docs/9.54.0/Use.htm | ||
* https://gist.github.com/ahmed-musallam/27de7d7c5ac68ecbd1ed65b6b48416f9 | * https://gist.github.com/ahmed-musallam/27de7d7c5ac68ecbd1ed65b6b48416f9 | ||
* https://askubuntu.com/questions/113544/how-can-i-reduce-the-file-size-of-a-scanned-pdf-file | * https://askubuntu.com/questions/113544/how-can-i-reduce-the-file-size-of-a-scanned-pdf-file | ||
* https://askubuntu.com/questions/207447/how-to-reduce-the-size-of-a-pdf-file | * https://askubuntu.com/questions/207447/how-to-reduce-the-size-of-a-pdf-file | ||
* https://www.adobe.com/acrobat/hub/how-to-compress-pdf-in-linux.html | * https://www.adobe.com/acrobat/hub/how-to-compress-pdf-in-linux.html | ||
| + | * https://www.tutorialspoint.com/unix_commands/gs.htm | ||
| + | * https://linux.die.net/man/1/gs | ||
| + | * https://www.geeksforgeeks.org/gs-command-in-linux-with-examples/ | ||
Versione attuale delle 11:46, 23 nov 2023
Per ridurre la quantità di byte di un file PDF, è possibile usare le risorse esterne del API di Ghostscript.
E' necessario avere installata nel sistema e usare in Gambas la libreria esterna condivisa: "libgs.so.9.55 ".
Va sottolineato che, facendo riferimento a un terminale, si userebbero i seguenti comandi:
gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf input.pdf
laddove per il comando "-dPDFSETTINGS" avremo:
- -dPDFSETTINGS=/screen qualità bassa, minore quantità di byte del PDF (72 dpi)
- -dPDFSETTINGS=/ebook per pdf di migliore qualità, ma leggermente più grandi (150 dpi)
- -dPDFSETTINGS=/prepress risultato simile all'impostazione "Prepress Optimized" di Acrobat Distiller (300 dpi)
- -dPDFSETTINGS=/printer risultato simile all'impostazione "Stampa ottimizzata" di Acrobat Distiller (300 dpi)
- -dPDFSETTINGS=/default seleziona l'output destinato a essere utile per un'ampia varietà di usi, eventualmente a spese di un file di output più grande.
Mostriamo un esempio pratico:
Private Const PDFORIGINARIO As String = "/percorso/del/file/pdf/originario"
Private Const PDFFINALE As String = "/percorso/del/file/pdf/finale/compresso"
Private pdfsettings As String[] = ["screen", "ebook", "prepress", "printer", "default"]
Library "libgs:9.55"
Private Enum GS_ARG_ENCODING_LOCAL = 0, GS_ARG_ENCODING_UTF8, GS_ARG_ENCODING_UTF16LE
Private Const gs_error_ok As Integer = 0
' int gsapi_new_instance(void * * pinstance, void * caller_handle)
' Create a new instance of Ghostscript.
Private Extern gsapi_new_instance(pinstance As Pointer, caller_handle As Pointer) As Integer
' int gsapi_set_arg_encoding(void *instance, int encoding)
' Set the encoding used for the args.
Private Extern gsapi_set_arg_encoding(instance As Pointer, encoding As Integer) As Integer
' int gsapi_init_with_args(void *instance, int argc, char **argv)
' Initialise the interpreter.
Private Extern gsapi_init_with_args(instance As Pointer, argc As Integer, argv As Pointer) As Integer
' int gsapi_exit(void *instance)
Private Extern gsapi_exit(instance As Pointer) As Integer
' void gsapi_delete_instance(void *instance)
' Destroy an instance of Ghostscript.
Private Extern gsapi_delete_instance(instance As Pointer)
Public Sub Main()
Dim minst As Pointer
Dim i As Integer
Dim gsargv As String[] = [" ", "-sDEVICE=pdfwrite", "-dCompatibilityLevel=1.4", "-dPDFSETTINGS=" &/ pdfsettings[0], "-dNOPAUSE", "-dQUIET", "-dBATCH", "-sOutputFile=" &/ PDFFINALE, PDFORIGINARIO]
i = gsapi_new_instance(VarPtr(minst), 0)
If i < gs_error_ok Then Error.Raise("Error !")
i = gsapi_set_arg_encoding(minst, GS_ARG_ENCODING_UTF8)
If i == gs_error_ok Then code = gsapi_init_with_args(minst, gsargv.Count, gsargv.Data)
i = gsapi_exit(minst)
If i < gs_error_ok Then Error.Raise("Error !")
gsapi_delete_instance(minst)
End
Riferimenti
- https://ghostscript.readthedocs.io/en/latest/index.html
- https://ghostscript.com/docs/9.54.0/Use.htm
- https://gist.github.com/ahmed-musallam/27de7d7c5ac68ecbd1ed65b6b48416f9
- https://askubuntu.com/questions/113544/how-can-i-reduce-the-file-size-of-a-scanned-pdf-file
- https://askubuntu.com/questions/207447/how-to-reduce-the-size-of-a-pdf-file
- https://www.adobe.com/acrobat/hub/how-to-compress-pdf-in-linux.html
- https://www.tutorialspoint.com/unix_commands/gs.htm
- https://linux.die.net/man/1/gs
- https://www.geeksforgeeks.org/gs-command-in-linux-with-examples/
