分享一个decodeHex代码，顺便问下decodeAi7Thumbnail，有谁熟悉，请教一下

[hongwenjun]

#include <iostream>
#include <string>
#include <windows.h>>
#include <stdio.h>

using namespace std;

// 从别人代码里移植，还没调试正确
string decodeHex(const byte* src, long srcSize)
{


//    00000030h: 00 01 02 03 04 05 06 07 08 09 10 10 10 10 10 10 ;
//    00000040h: 10 0D 0A 0B 0C 0D 0E 0F 10 10 10 10 10 10 10 10 ;
//    00000050h: 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 ;
//    00000060h: 10 10 0D 0A 0B 0C 0D 0E 0F 10 10 10 10 10 10 10 ;
    // create decoding table
    byte invalid = 16;
    byte decodeHexTable[256];
    for (long i = 0; i < 256; i++) decodeHexTable[i] = invalid;
    for (byte i = 0; i < 10; i++) decodeHexTable[static_cast<byte>('0') + i] = i;
    for (byte i = 0; i < 6; i++) decodeHexTable[static_cast<byte>('A') + i] = i + 10;
    for (byte i = 0; i < 6; i++) decodeHexTable[static_cast<byte>('a') + i] = i + 10;


    // calculate dest size
    long validSrcSize = 0;
    for (long srcPos = 0; srcPos < srcSize; srcPos++) {
        if (decodeHexTable[src[srcPos]] != invalid) validSrcSize++;
    }
    const long destSize = validSrcSize / 2;

    // allocate dest buffer
    string dest('a', destSize);

    // decode
    for (long srcPos = 0, destPos = 0; destPos < destSize; destPos++) {
        byte buffer = 0;
        for (int bufferPos = 1; bufferPos >= 0 && srcPos < srcSize; srcPos++) {
            byte srcValue = decodeHexTable[src[srcPos]];
            if (srcValue == invalid) continue;
            buffer |= srcValue << (bufferPos * 4);
            bufferPos--;
        }
        dest[destPos] = buffer;
    }

    return dest;
}


int main()
{
    const char* hexs =
        "%0066000066330066660066990066CC0066FF009900009933009966009999"
        "%0099CC0099FF00CC0000CC3300CC6600CC9900CCCC00CCFF00FF3300FF66"
        "%00FF9900FFCC3300003300333300663300993300CC3300FF333300333333";

    string str = decodeHex((BYTE*)hexs , 240);
    cout << hexs;
    FILE* pFile;
    pFile = fopen("myfile.bin" , "wb");
    fwrite(str.c_str() , 1 , str.size(), pFile);
    return 0;
}


#if(0)
/*!
  @brief Decode a Hex string.
 */
DataBuf decodeHex(const byte* src, long srcSize);


/*!
  @brief Decode an Illustrator thumbnail that follows after %AI7_Thumbnail.
 */
DataBuf decodeAi7Thumbnail(const DataBuf& src);

== == == == == == == == == == == == == == == == == == == =

    DataBuf decodeHex(const byte* src, long srcSize)
{
    // create decoding table
    byte invalid = 16;
    byte decodeHexTable[256];
    for (long i = 0; i < 256; i++) decodeHexTable[i] = invalid;
    for (byte i = 0; i < 10; i++) decodeHexTable[static_cast<byte>('0') + i] = i;
    for (byte i = 0; i < 6; i++) decodeHexTable[static_cast<byte>('A') + i] = i + 10;
    for (byte i = 0; i < 6; i++) decodeHexTable[static_cast<byte>('a') + i] = i + 10;

    // calculate dest size
    long validSrcSize = 0;
    for (long srcPos = 0; srcPos < srcSize; srcPos++) {
        if (decodeHexTable[src[srcPos]] != invalid) validSrcSize++;
    }
    const long destSize = validSrcSize / 2;

    // allocate dest buffer
    DataBuf dest(destSize);

    // decode
    for (long srcPos = 0, destPos = 0; destPos < destSize; destPos++) {
        byte buffer = 0;
        for (int bufferPos = 1; bufferPos >= 0 && srcPos < srcSize; srcPos++) {
            byte srcValue = decodeHexTable[src[srcPos]];
            if (srcValue == invalid) continue;
            buffer |= srcValue << (bufferPos * 4);
            bufferPos--;
        }
        dest.pData_[destPos] = buffer;
    }
    return dest;
}


DataBuf decodeAi7Thumbnail(const DataBuf& src)
{
    const byte* colorTable = src.pData_;
    const long colorTableSize = 256 * 3;
    if (src.size_ < colorTableSize) {
#ifndef SUPPRESS_WARNINGS
        EXV_WARNING << "Invalid size of AI7 thumbnail: " << src.size_ << "\n";
#endif
        return DataBuf();
    }
    const byte* imageData = src.pData_ + colorTableSize;
    const long imageDataSize = src.size_ - colorTableSize;
    const bool rle = (imageDataSize >= 3 && imageData[0] == 'R' && imageData[1] == 'L' && imageData[2] == 'E');
    std::string dest;
    for (long i = rle ? 3 : 0; i < imageDataSize;) {
        byte num = 1;
        byte value = imageData[i++];
        if (rle && value == 0xFD) {
            if (i >= imageDataSize) {
#ifndef SUPPRESS_WARNINGS
                EXV_WARNING << "Unexpected end of image data at AI7 thumbnail.\n";
#endif
                return DataBuf();
            }
            value = imageData[i++];
            if (value != 0xFD) {
                if (i >= imageDataSize) {
#ifndef SUPPRESS_WARNINGS
                    EXV_WARNING << "Unexpected end of image data at AI7 thumbnail.\n";
#endif
                    return DataBuf();
                }
                num = value;
                value = imageData[i++];
            }
        }
        for (; num != 0; num--) {
            dest.append(reinterpret_cast<const char*>(colorTable + (3 * value)), 3);
        }
    }
    return DataBuf(reinterpret_cast<const byte*>(dest.data()), static_cast<long>(dest.size()));
}



#endif

[hongwenjun]

需要解码 %AI7_Thumbnail: 128 108 8 这个标记 里 128x108 8bit的图片预览 https://github.com/jmue/exiv2 https://github.com/jmue/exiv2/blob/a2e75c176fe9228d967eee02181446d5fba93eab/src/preview.cpp 别人已经发我 实现代码的开源示例 自己能力不够，才能基本阅读 decodeHex代码 部分，改成写 bin数据 返回一个到 string字符串

///*****************************  低版本  AI EPS文件缩略图 分析      *********************************///

10 0 obj<</Length 13367>>stream
%%BoundingBox: -1 -1 1511 1262
%%HiResBoundingBox: -0.1079 -0.416 1510.9756 1261.5264
%AI7_Thumbnail: 128 108 8
%%BeginData: 13211 Hex Bytes
%0000330000660000990000CC0033000033330033660033990033CC0033FF
%0066000066330066660066990066CC0066FF009900009933009966009999
%0099CC0099FF00CC0000CC3300CC6600CC9900CCCC00CCFF00FF3300FF66
%00FF9900FFCC3300003300333300663300993300CC3300FF333300333333
%3333663333993333CC3333FF3366003366333366663366993366CC3366FF
%3399003399333399663399993399CC3399FF33CC0033CC3333CC6633CC99
%33CCCC33CCFF33FF0033FF3333FF6633FF9933FFCC33FFFF660000660033
%6600666600996600CC6600FF6633006633336633666633996633CC6633FF
%6666006666336666666666996666CC6666FF669900669933669966669999
%6699CC6699FF66CC0066CC3366CC6666CC9966CCCC66CCFF66FF0066FF33
%66FF6666FF9966FFCC66FFFF9900009900339900669900999900CC9900FF
%9933009933339933669933999933CC9933FF996600996633996666996699
%9966CC9966FF9999009999339999669999999999CC9999FF99CC0099CC33
%99CC6699CC9999CCCC99CCFF99FF0099FF3399FF6699FF9999FFCC99FFFF
%CC0000CC0033CC0066CC0099CC00CCCC00FFCC3300CC3333CC3366CC3399
%CC33CCCC33FFCC6600CC6633CC6666CC6699CC66CCCC66FFCC9900CC9933
%CC9966CC9999CC99CCCC99FFCCCC00CCCC33CCCC66CCCC99CCCCCCCCCCFF
%CCFF00CCFF33CCFF66CCFF99CCFFCCCCFFFFFF0033FF0066FF0099FF00CC
%FF3300FF3333FF3366FF3399FF33CCFF33FFFF6600FF6633FF6666FF6699
%FF66CCFF66FFFF9900FF9933FF9966FF9999FF99CCFF99FFFFCC00FFCC33
%FFCC66FFCC99FFCCCCFFCCFFFFFF33FFFF66FFFF99FFFFCC110000001100
%000011111111220000002200000022222222440000004400000044444444
%550000005500000055555555770000007700000077777777880000008800
%000088888888AA000000AA000000AAAAAAAABB000000BB000000BBBBBBBB
%DD000000DD000000DDDDDDDDEE000000EE000000EEEEEEEE0000000000FF
%00FF0000FFFFFF0000FF00FFFFFF00FFFFFF
%524C45527DA8A8A87C767DA8A8A8A1FD08A87D527DA1FD07A8A1FD09A87D
%5252FD07A8A1A8A1A8A1FD06A8A727527DFD09A8A1FD07A8A17D52FD09A8
%A1FD09A876527DFD07A8A1A8A2A8A2A8527DA1A8A87D2752FD05FFCBFFCA

// ------------------------中间省略-----------------------------

%FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8
%FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFFFFFA8FFFFFFA8
%FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8
%FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8FFA8
%%EndData
endstream
endobj

[hongwenjun]

自己强搞，总算可以搞出 BMP了 https://code.google.com/p/srgb/source/browse/decodeAi7Thumbnail/decodeAi7Thumbnail.cpp

BITMAPFILEHEADER bmph = {0x4D42, 54 , 0, 0, 54 };   // 14字节
    BITMAPINFOHEADER bmpinf = {40, 76, 128, 1, 24, 0 , 0, 0, 0, 0, 0    }; // 40字节

    bmph.bfSize += bgr.size();
 //   bmpinf.biWidth  = x;
 //   bmpinf.biHeight = y;


    FILE* bmpfile;
    bmpfile = fopen("bgr.bmp" , "wb");

    fwrite(&bmph , 1, 14,   bmpfile);
    fwrite(&bmpinf , 1, 40,   bmpfile);

    // 由于前面解码的数据是RGB标准数据，而BMP存储为BGR顺序
    // 由于BMP写文件最下面先读写，要翻转
    for (int i = 0 ; i < bgr.size() ; i += 3) {
        swap(bgr[i] , bgr[i + 2]);
    }
    int x = 76; int y = 128;
    const char* px = bgr.c_str();
    for (int i = y  ; i > 0 ; i--) {
        fwrite(px + 3 * i * x  , 1 , 3 * x, bmpfile);
    }

[桓灭]

正好也在做这个，这个Hex的解码您搞定了吗？求分享

[hongwenjun]

引用 4 楼 xuewutianya1219 的回复:

正好也在做这个，这个Hex的解码您搞定了吗？求分享

好像解码好了