cannot allocate an object of abstract type because the following virtual functions are pure within

**pol2095** · 11/02/2022, 09h06

Bonjour,

j'essaie d'impléménter zxing :

main.cpp

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#include <iostream>
#include <stdlib.h>
#include <stdint.h>
#include <fstream>
#include <string>
#include <zxing/qrcode/QRCodeReader.h>
#include <zxing/Exception.h>
#include <zxing/common/GlobalHistogramBinarizer.h>
#include <zxing/DecodeHints.h>
#include "BufferBitmapSource.h"
 
using namespace std; 
using namespace zxing; 
using namespace zxing::qrcode;
using namespace qrviddec; 
 
int main(int argc, char ** argv)
{
	try
	{
 
 
		// A buffer containing an image. In your code, this would be an image from your camera. In this 
		// example, it's just an array containing the code for "Hello!". 
		uint8_t buffer[] = 
		{ 
			255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 
			255,  0 ,  0 ,  0 ,  0 ,  0 ,  0 ,  0 , 255,  0 ,  0 ,  0 ,  0 ,  0 , 255,  0 ,  0 ,  0 ,  0 ,  0 ,  0 ,  0 , 255, 
			255,  0 , 255, 255, 255, 255, 255,  0 , 255, 255,  0 , 255,  0 , 255, 255,  0 , 255, 255, 255, 255, 255,  0 , 255, 
			255,  0 , 255,  0 ,  0 ,  0 , 255,  0 , 255, 255,  0 ,  0 , 255, 255, 255,  0 , 255,  0 ,  0 ,  0 , 255,  0 , 255, 
			255,  0 , 255,  0 ,  0 ,  0 , 255,  0 , 255, 255,  0 ,  0 ,  0 , 255, 255,  0 , 255,  0 ,  0 ,  0 , 255,  0 , 255, 
			255,  0 , 255,  0 ,  0 ,  0 , 255,  0 , 255, 255, 255,  0 , 255,  0 , 255,  0 , 255,  0 ,  0 ,  0 , 255,  0 , 255, 
			255,  0 , 255, 255, 255, 255, 255,  0 , 255, 255, 255, 255,  0 ,  0 , 255,  0 , 255, 255, 255, 255, 255,  0 , 255, 
			255,  0 ,  0 ,  0 ,  0 ,  0 ,  0 ,  0 , 255,  0 , 255,  0 , 255,  0 , 255,  0 ,  0 ,  0 ,  0 ,  0 ,  0 ,  0 , 255, 
			255, 255, 255, 255, 255, 255, 255, 255, 255,  0 ,  0 ,  0 ,  0 ,  0 , 255, 255, 255, 255, 255, 255, 255, 255, 255, 
			255,  0 ,  0 , 255,  0 ,  0 , 255,  0 , 255, 255,  0 ,  0 , 255,  0 , 255,  0 , 255, 255, 255, 255, 255,  0 , 255, 
			255,  0 ,  0 ,  0 ,  0 ,  0 , 255, 255,  0 , 255, 255,  0 , 255,  0 , 255,  0 , 255,  0 ,  0 ,  0 , 255, 255, 255, 
			255, 255, 255, 255, 255, 255, 255,  0 , 255,  0 ,  0 ,  0 , 255, 255,  0 ,  0 , 255,  0 , 255,  0 ,  0 ,  0 , 255, 
			255, 255, 255,  0 ,  0 , 255, 255, 255,  0 ,  0 ,  0 , 255,  0 , 255, 255, 255, 255, 255, 255,  0 , 255, 255, 255, 
			255,  0 ,  0 ,  0 ,  0 ,  0 ,  0 ,  0 , 255, 255,  0 , 255, 255, 255, 255,  0 , 255, 255,  0 , 255,  0 , 255, 255, 
			255, 255, 255, 255, 255, 255, 255, 255, 255,  0 ,  0 , 255,  0 ,  0 , 255, 255, 255, 255,  0 , 255,  0 ,  0 , 255, 
			255,  0 ,  0 ,  0 ,  0 ,  0 ,  0 ,  0 , 255, 255, 255,  0 , 255,  0 ,  0 ,  0 ,  0 ,  0 , 255,  0 , 255, 255, 255, 
			255,  0 , 255, 255, 255, 255, 255,  0 , 255, 255,  0 ,  0 ,  0 ,  0 ,  0 , 255,  0 ,  0 ,  0 ,  0 , 255, 255, 255, 
			255,  0 , 255,  0 ,  0 ,  0 , 255,  0 , 255,  0 , 255, 255,  0 ,  0 , 255,  0 ,  0 , 255,  0 , 255,  0 ,  0 , 255, 
			255,  0 , 255,  0 ,  0 ,  0 , 255,  0 , 255,  0 , 255,  0 ,  0 ,  0 , 255, 255, 255, 255, 255, 255, 255, 255, 255, 
			255,  0 , 255,  0 ,  0 ,  0 , 255,  0 , 255, 255,  0 ,  0 , 255, 255, 255,  0 ,  0 ,  0 ,  0 ,  0 ,  0 ,  0 , 255, 
			255,  0 , 255, 255, 255, 255, 255,  0 , 255,  0 , 255,  0 , 255, 255,  0 ,  0 ,  0 ,  0 ,  0 ,  0 ,  0 ,  0 , 255, 
			255,  0 ,  0 ,  0 ,  0 ,  0 ,  0 ,  0 , 255,  0 , 255,  0 ,  0 , 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 
			255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255
		}; 
		int width = 23; 
		int height = 23; 
 
		// Convert the buffer to something that the library understands. 
		Ref<LuminanceSource> source (new BufferBitmapSource(width, height, buffer)); 
 
		// Turn it into a binary image. 
		Ref<Binarizer> binarizer (new GlobalHistogramBinarizer(source)); 
		Ref<BinaryBitmap> image(new BinaryBitmap(binarizer));
 
		// Tell the decoder to try as hard as possible. 
		DecodeHints hints(DecodeHints::DEFAULT_HINT); 
		hints.setTryHarder(true); 
 
		// Perform the decoding. 
    QRCodeReader reader;
    Ref<Result> result(reader.decode(image, hints));
 
		// Output the result. 
    cout << result->getText()->getText() << endl;
 
  } 
	catch (zxing::Exception& e) 
	{
    cerr << "Error: " << e.what() << endl;
  }
	return 0; 
}

BufferBitmapSource.cpp

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#include "BufferBitmapSource.h"
#include <iostream>
 
namespace qrviddec {
 
BufferBitmapSource::BufferBitmapSource(int inWidth, int inHeight, unsigned char * inBuffer) 
{
	width = inWidth; 
	height = inHeight; 
	buffer = inBuffer; 
}
 
BufferBitmapSource::~BufferBitmapSource()
{
}
 
int BufferBitmapSource::getWidth() const
{
	return width; 
}
 
int BufferBitmapSource::getHeight() const
{
	return height; 
}
 
unsigned char * BufferBitmapSource::getRow(int y, unsigned char * row)
{
	if (y < 0 || y >= height) 
	{
		fprintf(stderr, "ERROR, attempted to read row %d of a %d height image.\n", y, height); 
		return NULL; 
	}
	// WARNING: NO ERROR CHECKING! You will want to add some in your code. 
	if (row == NULL) row = new unsigned char[width]; 
	for (int x = 0; x < width; x ++)
	{
		row[x] = buffer[y*width+x]; 
	}
	return row; 
}
 
unsigned char * BufferBitmapSource::getMatrix()
{
	return buffer; 
}
 
}

BufferBitmapSource.h

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#include <zxing/LuminanceSource.h>
#include <stdio.h>
#include <stdlib.h>
using namespace zxing; 
namespace qrviddec {
 
class BufferBitmapSource : public LuminanceSource {
private:
  int width, height; 
  unsigned char * buffer; 
 
public:
  BufferBitmapSource(int inWidth, int inHeight, unsigned char * inBuffer); 
  ~BufferBitmapSource(); 
 
  int getWidth() const; 
  int getHeight() const; 
  unsigned char* getRow(int y, unsigned char* row); 
  unsigned char* getMatrix(); 
}; 
}

mais g++ me retourne cette erreur :

main.cpp:55: error: cannot allocate an object of abstract type 'qrviddec::BufferBitmapSource'
BufferBitmapSource.h:7: note: because the following virtual functions are pure within 'qrviddec::BufferBitmapSource':
zxing/qrcode/../LuminanceSource.h:42: note: virtual zxing::ArrayRef<char> zxing::LuminanceSource::getRow(int, zxing::ArrayRef<char>) const
zxing/qrcode/../LuminanceSource.h:43: note: virtual zxing::ArrayRef<char> zxing::LuminanceSource::getMatrix() const
BufferBitmapSource.cpp: In constructor 'qrviddec::BufferBitmapSource::BufferBitmapSource(int, int, unsigned char*)':
BufferBitmapSource.cpp:6: error: no matching function for call to 'zxing::LuminanceSource::LuminanceSource()'
zxing/LuminanceSource.h:35: note: candidates are: zxing::LuminanceSource::LuminanceSource(int, int)
zxing/LuminanceSource.h:29: note: zxing::LuminanceSource::LuminanceSource(const zxing::LuminanceSource&)

merci de votre aide

**dalfab** · 11/02/2022, 11h51

Bonjour,

La première erreur d'indique que tu ne peux créer un BufferBitmapSource.
Le compilateur précise pourquoi : des fonctions virtuelles nécessaires n'ont jamais été définies.
Puis précise les fonctions jamais définies :
- zxing::ArrayRef<char> getRow( int, zxing::ArrayRef<char>) const.
- zxing::ArrayRef<char> getMatrix() const.
Note que tu as défini des fonctions similaires mais pas les fonctions exactes nécessaires.

La seconde indique que ton constructeur BufferBitmapSource::BufferBitmapSource doit indiquer comment construire sa base zxing::LuminanceSource. Comme tu n'as pas fourni cette info, il essaie de construire LuminanceSource par défaut mais ça n'est pas possible.
Il t'indique que le constructeur de LuminanceSource a besoin de 2 paramètres de type int et donc de faire par exemple:

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BufferBitmapSource::BufferBitmapSource(int inWidth, int inHeight, unsigned char * inBuffer) 
   : zxing::LuminanceSource( inWidth , inHeight )
{
	width = inWidth; 
	height = inHeight; 
	buffer = inBuffer; 
}

**pol2095** · 11/02/2022, 14h15

merci de l'aide

j'ai encore une erreur, j'ai tenté de modifier dans "BufferBitmapSource.cpp"

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//unsigned char * BufferBitmapSource::getRow(int y, unsigned char * row)
ArrayRef<char> BufferBitmapSource::getRow(int y, ArrayRef<char> row)
{
	if (y < 0 || y >= height) 
	{
		fprintf(stderr, "ERROR, attempted to read row %d of a %d height image.\n", y, height); 
		return NULL; 
	}
	// WARNING: NO ERROR CHECKING! You will want to add some in your code. 
	if (row == NULL) row = new unsigned char[width]; 
	for (int x = 0; x < width; x ++)
	{
		row[x] = buffer[y*width+x]; 
	}
	return row; 
}
 
//unsigned char * BufferBitmapSource::getMatrix()
ArrayRef<char> BufferBitmapSource::getMatrix()
{
	return buffer; 
}

mais j'ai cette erreur

BufferBitmapSource.h:20: error: candidate is: virtual zxing::ArrayRef<char> qrviddec::BufferBitmapSource::getRow(int, zxing::ArrayRef<char>) const
cc1plus: warnings being treated as errors
BufferBitmapSource.cpp: In member function 'zxing::ArrayRef<char> qrviddec::BufferBitmapSource::getRow(int, zxing::ArrayRef<char>)':
BufferBitmapSource.cpp:41: warning: NULL used in arithmetic
BufferBitmapSource.cpp:41: error: no match for 'operator=' in 'row = (zxing::ArrayRef<char>*)(((zxing::ArrayRef<char> (*)[((unsigned int)((qrviddec::BufferBitmapSource*)this)->qrviddec::BufferBitmapSource::width)])operator new [](((((unsigned int)((qrviddec::BufferBitmapSource*)this)->qrviddec::BufferBitmapSource::width) * 12u) + 4u))), (((*((<anonymous> + 4u) - 4u)) <unknown operator> ((unsigned int)((qrviddec::BufferBitmapSource*)this)->qrviddec::BufferBitmapSource::width)), ((*(zxing::ArrayRef<char> (*)[((unsigned int)((qrviddec::BufferBitmapSource*)this)->qrviddec::BufferBitmapSource::width)])({...})), <anonymous>)))'
zxing/common/Array.h:143: note: candidates are: zxing::ArrayRef<T>& zxing::ArrayRef<T>::operator=(const zxing::ArrayRef<T>&) [with T = char]
zxing/common/Array.h:147: note: zxing::ArrayRef<T>& zxing::ArrayRef<T>::operator=(zxing::Array<T>*) [with T = char]
BufferBitmapSource.cpp: At global scope:
BufferBitmapSource.cpp:50: error: prototype for 'zxing::ArrayRef<char> qrviddec::BufferBitmapSource::getMatrix()' does not match any in class 'qrviddec::BufferBitmapSource'
BufferBitmapSource.h:21: error: candidate is: virtual zxing::ArrayRef<char> qrviddec::BufferBitmapSource::getMatrix() const
BufferBitmapSource.cpp: In member function 'zxing::ArrayRef<char> qrviddec::BufferBitmapSource::getMatrix()':
BufferBitmapSource.cpp:52: error: conversion from 'unsigned char*' to non-scalar type 'zxing::ArrayRef<char>' requested

**dalfab** · 11/02/2022, 20h01

Il manque const à la fin des lignes 2 et 19.

**pol2095** · 11/02/2022, 20h44

merci, maintenant j'ai cette erreur

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/cckdf.o: error: undefined reference to '_libiconv_close'
/cckdf.o: error: undefined reference to '_libiconv'
/cckdf.o: error: undefined reference to '_libiconv_open'

**pol2095** · 11/02/2022, 21h21

ça fonctionne, merci pour ton aide.

cannot allocate an object of abstract type because the following virtual functions are pure within

C++

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