Saving pdf file using saveAsCopy()

[khazri achraf]

Is there any examples for saving a pdf file, the structur pdfwriter is not clear, please share any examples if you have .

[Lei Zhang]

Using a source search tool like https://source.chromium.org/chromium,
find the definition for FPDF_SaveAsCopy(). Then one can click on it to
see all the cross-references and see how it is used in the Chromium
code base, which includes a copy of PDFium. Similarly, one can click
on FPDF_FILEWRITE to see how it is used.

If the documentation for FPDF_FILEWRITE is insufficient, can you
elaborate on what is not clear?

On Mon, Apr 6, 2020 at 9:29 AM khazri achraf <achraf...@gmail.com> wrote:
>
> Is there any examples for saving a pdf file, the structur pdfwriter is not clear, please share any examples if you have .
>

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[Lei Zhang]

Also, please reply to the group, so others can be part of the conversation.

On Tue, Apr 7, 2020 at 1:35 PM Lei Zhang <the...@chromium.org> wrote:
>
> How about the sample call in pdf/pdfium/pdfium_print.cc? That uses an
> implementation, PDFiumMemBufferFileWrite, that meets all of the
> FPDF_FILEWRITE interface requirements.
>
> On Mon, Apr 6, 2020 at 1:09 PM khazri achraf <achraf...@gmail.com> wrote:
> >
> > Thanks for the reply Lei Zhang,
> >
> > Here is the path https://source.chromium.org/chromium/chromium/src/+/master:third_party/pdfium/public/fpdf_save.h
> > I want to create a fonction in C++ that takes as input pdf file and split each page apart and saving them all in an output folder, and for saving I need to use the function
> > FPDF_SaveAsCopy() and that function takes as argument FPDF_FILEWRITE struct type.
> > I have looked for examples but I didn't found a good one that describes how to use it for saving a FPDF_DOCUMENT.

[khazri achraf]

I managed to save pdf file with the help of this test https://source.chromium.org/chromium/chromium/src/+/master:third_party/pdfium/fpdfsdk/fpdf_ppo_embeddertest.cpp

Here is the code that I used, once I finish the saving, I get damaget file, Any idea what the cause : 
```

std::string data_string_;

std::string saved_document_file_data_;

std::ofstream filestream_;

int FakeBlockWriter(FPDF_FILEWRITE* pThis, const void* pData, unsigned long size)

{

std::string data;

data.append(static_cast<const char*>(pData), size);

std::ofstream filestream_;

filestream_.open("pdfiumxx.txt", std::ios_base::binary);

if (filestream_.is_open()) filestream_.write(static_cast<const char*>(pData), size);

filestream_.close();

return size;

} 

TEST_CASE("PDFIUM") {

FPDF_LIBRARY_CONFIG config;

config.version = 2;

config.m_pUserFontPaths = NULL;

config.m_pIsolate = NULL;

config.m_v8EmbedderSlot = 0;

FPDF_InitLibraryWithConfig(&config);

FPDF_DOCUMENT doc = FPDF_LoadDocument("test.pdf", NULL);

FPDF_FILEWRITE writer;

writer.version = 1;

writer.WriteBlock = FakeBlockWriter;

FPDF_SaveAsCopy(doc, &writer, 3);

FPDF_CloseDocument(doc);

}

```

[khazri achraf]

Hi Lei Zhang,

I had a look on this file https://source.chromium.org/chromium/chromium/src/+/master:third_party/pdfium/fpdfsdk/fpdf_ppo_embeddertest.cpp and I guess I found the path how to use the saving method.
But after saving I am having damaged files, I just load the file and resave it nothing else, here is the test case that I made :

std::string data_string_;

std::string saved_document_file_data_;

std::ofstream filestream_;

int FakeBlockWriter(FPDF_FILEWRITE* pThis, const void* pData, unsigned long size)

{

std::string data;

data.append(static_cast<const char*>(pData), size);

std::ofstream filestream_;

filestream_.open("pdfiumxx.txt", std::ios_base::binary);

if (filestream_.is_open()) filestream_.write(static_cast<const char*>(pData), size);

filestream_.close();

return size;

}

TEST_CASE("PDFIUM") {

FPDF_LIBRARY_CONFIG config;

config.version = 2;

config.m_pUserFontPaths = NULL;

config.m_pIsolate = NULL;

config.m_v8EmbedderSlot = 0;

FPDF_InitLibraryWithConfig(&config);

FPDF_DOCUMENT doc = FPDF_LoadDocument("./datasets/document/converter/PdfSplitMerge/3.pdf", NULL);

FPDF_FILEWRITE writer;

writer.version = 1;

writer.WriteBlock = FakeBlockWriter;

FPDF_SaveAsCopy(doc, &writer, 3);

FPDF_CloseDocument(doc);

FPDF_DestroyLibrary();

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[K. Moon]

It looks like you're expecting the file to be written as a single block (open file, write block, close file). If more than one block needs to be written, you're going to just end up overwriting the previous blocks, which won't be a valid PDF file.

You need to open the file, append all of the blocks, and then close it.

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[khazri achraf]

Sounds like I have to loop over blocks, I will try it.

 

Have you any programming guide or a link for a documentation ? I searched and nothing that I can find.

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[K. Moon]

I believe the only API documentation are the comments in the public header files. There is probably example code in our test files that you can look at, too.

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