Hi Palmer
Thanks, but can you tell me if that first loading of the stack occurs where I
have highlighted in pink below. That is at the line stack.push( var ); ?
Thanks
Subject: Re: [Podofo-users] TextExtractor.cpp (loading stack)
From: palmerz...@gmail.com
Date: Thu, 22 Aug 2013 15:51:44 -0400
CC: podofo-users@lists.sourceforge.net
To: abdom...@hotmail.com
Hi,
The stack is actually already loaded when it is popped as the keyword (token of
type ePdfContentsType_Keyword) comes after its arguments (tokens of type
ePdfContentsType_Variant) in the PDF command. Example: "0 0 m".
Regards
Palmer Zent
On Aug 22, 2013, at 3:34 PM, Domonic Tom <abdom...@hotmail.com> wrote:Hi there.
I understand 99 percent of the code below. This is from TextExtractor.cpp.
I'm just not sure how the following occurs.
When does the stack have the first token pushed onto it? I can see further
down that if the variable type is a variant then we push a variant onto the
stack but I'm not sure why we are establishing position x and y before we load
the stack with anything. This could be a really silly question as I can't see
where anyone else has asked it but I've highlighted the section below in bold
and red. The general area is in bold.
Thank you..
/*************************************************************************** *
Copyright (C) 2008 by Dominik Seichter * *
domseich...@web.de * *
* * This
program is free software; you can redistribute it and/or modify * * it under
the terms of the GNU General Public License as published by * * the Free
Software Foundation; either version 2 of the License, or * * (at your
option) any later version. * *
* * This program is
distributed in the hope that it will be useful, * * but WITHOUT ANY
WARRANTY; without even the implied warranty of * * MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the * * GNU General Public
License for more details. * *
* * You should have received a
copy of the GNU General Public License * * along with this program; if
not, write to the * * Free Software Foundation, Inc.,
* * 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. *
***************************************************************************/
#include "TextExtractor.h"
#include <stack>#include <iostream>using namespace std;
TextExtractor::TextExtractor(){
}
TextExtractor::~TextExtractor(){}
void TextExtractor::Init( const char* pszInput ){ if( !pszInput ) {
PODOFO_RAISE_ERROR( ePdfError_InvalidHandle ); }
PdfMemDocument document( pszInput );
int nCount = document.GetPageCount(); for( int i=0; i<nCount; i++ ) {
PdfPage* pPage = document.GetPage( i );
this->ExtractText( &document, pPage ); }}
void TextExtractor::ExtractText( PdfMemDocument* pDocument, PdfPage* pPage ){
const char* pszToken = NULL; PdfVariant var; EPdfContentsType
eType;
PdfContentsTokenizer tokenizer( pPage );
double dCurPosX = 0.0; double dCurPosY = 0.0; double
dCurFontSize = 0.0; bool bTextBlock = false; PdfFont* pCurFont =
NULL;
std::stack<PdfVariant> stack;
while( tokenizer.ReadNext( eType, pszToken, var ) ) { if( eType
== ePdfContentsType_Keyword ) { // support 'l' and 'm' tokens
---------------------------'l' token means: Append straight line segment to
path // 'm' token means: Begin new subpath if(
strcmp( pszToken, "l" ) == 0 || strcmp( pszToken, "m" ) == 0 )
{ dCurPosX = stack.top().GetReal(); // WHY ARE WE
POPPING OFF THE STACK BEFORE WE LOAD IT? stack.pop();
dCurPosY = stack.top().GetReal(); stack.pop(); }
else if( strcmp( pszToken, "BT" ) == 0 ) //Begin text object
{ bTextBlock = true; // BT does not reset
font // dCurFontSize = 0.0; // pCurFont =
NULL; } else if( strcmp( pszToken, "ET" ) == 0 ) // End
text object { if( !bTextBlock )
fprintf( stderr, "WARNING: Found ET without BT!\n" ); }
if( bTextBlock ) { if( strcmp( pszToken,
"Tf" ) == 0 ) // Set text font and size {
dCurFontSize = stack.top().GetReal(); stack.pop();
PdfName fontName = stack.top().GetName();
PdfObject* pFont = pPage->GetFromResources( PdfName("Font"), fontName );
if( !pFont ) {
PODOFO_RAISE_ERROR_INFO( ePdfError_InvalidHandle, "Cannot create font!" );
}
pCurFont = pDocument->GetFont( pFont );
if( !pCurFont ) { fprintf( stderr,
"WARNING: Unable to create font for object %i %i R\n",
pFont->Reference().ObjectNumber(),
pFont->Reference().GenerationNumber() ); } }
else if( strcmp( pszToken, "Tj" ) == 0 || //Show text.. Means
Show.. strcmp( pszToken, "'" ) == 0 ) //Move to next
line and show text { AddTextElement(
dCurPosX, dCurPosY, pCurFont, stack.top().GetString() );
stack.pop(); } else if( strcmp( pszToken, "\"" )
== 0 ) // escape sequence.. return. {
AddTextElement( dCurPosX, dCurPosY, pCurFont, stack.top().GetString() );
stack.pop(); stack.pop(); // remove char spacing
from stack stack.pop(); // remove word spacing from stack
} else if( strcmp( pszToken, "TJ" ) == 0 ) //Show
text, allowing individual glyph positioning {
PdfArray array = stack.top().GetArray(); stack.pop();
for( int i=0; i<static_cast<int>(array.GetSize()); i++ )
{ if( array[i].IsString() )
AddTextElement( dCurPosX, dCurPosY, pCurFont,
array[i].GetString() ); } } }
} else if ( eType == ePdfContentsType_Variant ) // this happens first
then it loops back to the top { stack.push( var ); }
else { // Impossible; type must be keyword or variant
PODOFO_RAISE_ERROR( ePdfError_InternalLogic ); } }}
void TextExtractor::AddTextElement( double dCurPosX, double dCurPosY,
PdfFont* pCurFont, const PdfString & rString ){ if(
!pCurFont ) { fprintf( stderr, "WARNING: Found text but do not have a
current font: %s\n", rString.GetString() ); return; }
if( !pCurFont->GetEncoding() ) { fprintf( stderr, "WARNING: Found
text but do not have a current encoding: %s\n", rString.GetString() );
return; }
// For now just write to console PdfString unicode =
pCurFont->GetEncoding()->ConvertToUnicode( rString, pCurFont ); const char*
pszData = unicode.GetStringUtf8().c_str(); while( *pszData ) {
printf("%02x", static_cast<unsigned char>(*pszData) ); ++pszData; }
printf("\n");
printf("(%.3f,%.3f) %s \n", dCurPosX, dCurPosY,
unicode.GetStringUtf8().c_str() );cout << "THISX:" << dCurPosX << endl;
}
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