[cairo] how to import .BMP without other libs(GTK+ etc)?

[伯 张]

Hello everyone!
 
As we know, cairo lib don’t support the creation of a surface from BMP directly.
we could do it with GTK+. However, is there some other way to import BMP or dib 
in cairo without the suppot of other libs?
 
I had tried to do it whit cairo_image_surface_create_for_data, but failed L. 
I could not see the right image.
Do you have any solution?
 
Thanks~
 
That is my attempt below:
 
//===========================================================================
// Summary:
//      BMPReader class
// Header:
//      BMPReader.h
// Remarks:
//      Readin BMP & create cairo surface
//===========================================================================
 
#ifndef __BMPREADER_H__
#define __BMPREADER_H__
 
//===========================================================================
 
#include <fstream>
#include <iostream>
 
//===========================================================================
 
// Struct Member Alignment
// default 8 bytes
// here 1 byte alignment
#pragma pack(1)
 
//===========================================================================
 
using namespace std;
 
//===========================================================================
// Struct BMPFormat
//===========================================================================
 
// BMP include file head and info head
struct BMPFormat
{
    short Head_Flag;    //1 00-01
    int File_Size;      //2 02-05
    int Reserved;       //3 06-09
    int Data_Offset;    //4 0A-0D
    int Head_Info_Size; //5 0E-11
    int Pic_Width;      //6 12-15
    int Pic_High;       //7 16-19
    short Pic_Plans;    //8 1A-1B
    short Color_Bit;    //9 
    int Compress;       //10
    int Data_Size;      //11
    int Pic_Xppm;       //12
    int Pic_Yppm;       //13
    int Color_Used;     //14
    int Color_Imp;      //15
};
 
//===========================================================================
// class BMPReader
//===========================================================================
 
class BMPReader
{
public:
    BMPReader(const char *pstrFName);
    ~BMPReader();
protected:
    BMPReader(){};
 
public:
    unsigned char * GetData() const;
    cairo_format_t  GetCairoFormat() const;
    int             GetHeight() const;
    int             GetWidth() const;
    int             GetRowsStride() const;
 
private:
    ifstream *      m_pfBmp;
 
    BMPFormat *     m_pBMPFormat;
    unsigned char * m_pData;
    
};
 
//===========================================================================
 
// resume default struct alignment
#pragma pack(8)
 
//===========================================================================
 
#endif // __BMPREADER_H__
 
//===========================================================================
// Summary:
//      BMPReader class
// Usage:
//      BMPReader.cpp
// Remarks:
//      Readin BMP & create cairo surface 
//===========================================================================
 
#include "stdafx.h"
#include "BMPReader.h"
 
//===========================================================================
 
BMPReader::BMPReader( const char *pstrFName)
{
    // menbers' initialization
    m_pfBmp         = NULL;
    m_pData         = NULL;
    m_pBMPFormat    = NULL;
 
    assert(pstrFName != NULL);
 
    // new ifstream
    m_pfBmp = new ifstream;
    m_pfBmp->open(pstrFName, ios_base::binary);
    if (!m_pfBmp)
    {
        cout << pstrFName << " can not be opened !"<< endl;
        return;
    }
 
    // readin BMPFormat 0x00-0x35
    m_pBMPFormat = new BMPFormat;
    m_pfBmp->seekg(0, ios_base::beg);
    m_pfBmp->read((char *)m_pBMPFormat, sizeof(BMPFormat));
    
    // readin Data 0x36-Data_Size
    m_pData = new unsigned char[m_pBMPFormat->Data_Size];
    m_pfBmp->seekg(0x36, ios_base::beg);
    m_pfBmp->read((char *)m_pData, m_pBMPFormat->Data_Size);
 
    // close file
    m_pfBmp->close();
}
 
cairo_format_t BMPReader::GetCairoFormat() const
{
    if (m_pBMPFormat)
    {
        switch (m_pBMPFormat->Color_Bit)
        {
        case 32:    return CAIRO_FORMAT_ARGB32;
        case 24:    return CAIRO_FORMAT_RGB24;
        case 8:     return CAIRO_FORMAT_A8;
        case 1:     return CAIRO_FORMAT_A1;
        default:    cout << "Colorbit " << m_pBMPFormat->Color_Bit << " is unsupported !" << endl;
        }
    }
    // 函数序号改写
    // 返回值只表示状态
}
 
int BMPReader::GetHeight() const
{
    if (m_pBMPFormat)
    {
        return m_pBMPFormat->Pic_High;
    }
    return -1;
}
 
int BMPReader::GetWidth() const
{
    if (m_pBMPFormat)
    {
        return m_pBMPFormat->Pic_Width;
    }
    return -1;
}
 
int BMPReader::GetRowsStride() const
{
    if (m_pBMPFormat)
    {
        // stride的大小由Cairo根据width定制
        return cairo_format_stride_for_width(GetCairoFormat(), GetWidth());
    }
    return -1;
}
 
unsigned char * BMPReader::GetData() const
{
    if (m_pData)
    {
        return m_pData;
    }
    return 0;
}
 
BMPReader::~BMPReader()
{
    if (m_pBMPFormat)
    {
        delete m_pBMPFormat;
        m_pBMPFormat = NULL;
    }
    if (m_pData)
    {
        delete m_pData;
        m_pData = NULL;
    }
    if (m_pfBmp)
    {
        delete m_pfBmp;
        m_pfBmp = NULL;
    }
}
 
//---------------------------------------------------------------------
// main
//---------------------------------------------------------------------
    char * pBmpName = "rgb.bmp";
    BMPReader bmpRdr(pBmpName);
 
    cairo_format_t  cftBMPFormat    = bmpRdr.GetCairoFormat();
    unsigned char * pcBMPData       = bmpRdr.GetData();
    int             nBMPHeight      = bmpRdr.GetHeight();
    int             nBMPWidth       = bmpRdr.GetWidth();
    int             nBMPStride      = bmpRdr.GetRowsStride();
 
    pImage = cairo_image_surface_create_for_data(
        pcBMPData,
        cairo_format_t(1),
        nBMPWidth,
        nBMPHeight,
        nBMPStride);
 
 
 
 
 


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