Loading and Saving PDFs To Memory

The PDFCreator control can load data from memory and save back PDF data to memory or sources other than files.  It implements a standard IStream interface, more precisely an IPersistStreamInit interface. For details about these two interfaces, please consult the Windows documentation.

 

Example

IStream *inputStream = NULL;


IPersistStreamInit *pdfStream = NULL;


 


// m_pdfControl is the object associated with the PDF control


m_pdf.GetControlUnknown()->QueryInterface( IID_IPersistStreamInit, (void **)&pdfStream );


 


// for testing, load a PDF file into memory, then send it to Creator


CFile inFile( " LongDocument.pdf", CFile::modeRead );


 


// hg is the handle to the memory where the PDF data resides


HGLOBAL hg = GlobalAlloc( GHND, inFile.GetLength() );


inFile.Read( GlobalLock( hg ), inFile.GetLength() );


GlobalUnlock( hg );


CreateStreamOnHGlobal( hg, TRUE, &inputStream );


 


// load the PDF control from the memory object


pdfStream->Load( inputStream );


inputStream->Release();


pdfStream->Release();


 


// save the PDF to another memory buffer


ULARGE_INTEGER size;


IStream *outputStream = NULL;


IPersistStreamInit *pdfStream2 = NULL;


 


// m_pdfControl is the object associated with the PDF control


m_pdf.GetControlUnknown()->QueryInterface( IID_IPersistStreamInit, (void **)&pdfStream2 );


pdfStream2->GetSizeMax( &size ); // get the size


 


// hg1 is the handle to the memory where the PDF data will reside


HGLOBAL hg1 = GlobalAlloc( GHND, size.LowPart );


CreateStreamOnHGlobal( hg1, FALSE, &outputStream );


pdfStream2->Save( outputStream, TRUE );


outputStream->Release();


LPBYTE pdfData = (LPBYTE)GlobalLock( hg1 );


CFile file;


file.Open (_T ("amyuni_new.pdf"), CFile::modeCreate | CFile::modeWrite | CFile::shareDenyWrite );


file.Write (pdfData, (unsigned int)size.QuadPart );


file.Close ();


GlobalUnlock( hg1 );