[游戏开发]C++ Base64图片 互转

C++ Base64图片 互转

#include <string>
#include <iostream>

static std::string base64Decode(const char* Data, int DataByte) {
    //解码表
    const char DecodeTable[] =
    {
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
            62, // '+'
            0, 0, 0,
            63, // '/'
            52, 53, 54, 55, 56, 57, 58, 59, 60, 61, // '0'-'9'
            0, 0, 0, 0, 0, 0, 0,
            0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
            13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, // 'A'-'Z'
            0, 0, 0, 0, 0, 0,
            26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
            39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // 'a'-'z'
    };
    std::string strDecode;
    int nValue;
    int i = 0;
    while (i < DataByte) {
        if (*Data != '\r' && *Data != '\n') {
            nValue = DecodeTable[*Data++] << 18;
            nValue += DecodeTable[*Data++] << 12;
            strDecode += (nValue & 0x00FF0000) >> 16;
            if (*Data != '=') {
                nValue += DecodeTable[*Data++] << 6;
                strDecode += (nValue & 0x0000FF00) >> 8;
                if (*Data != '=') {
                    nValue += DecodeTable[*Data++];
                    strDecode += nValue & 0x000000FF;
                }
            }
            i += 4;
        }
        else {
            Data++;
            i++;
        }
    }
    return strDecode;
}
static const std::string base64_chars =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/";
std::string base64_encode(const char* bytes_to_encode, unsigned int in_len)
{
    std::string ret;
    int i = 0;
    int j = 0;
    unsigned char char_array_3[3];
    unsigned char char_array_4[4];

    while (in_len--)
    {
        char_array_3[i++] = *(bytes_to_encode++);
        if (i == 3)
        {
            char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
            char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
            char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
            char_array_4[3] = char_array_3[2] & 0x3f;
            for (i = 0; (i < 4); i++)
            {
                ret += base64_chars[char_array_4[i]];
            }
            i = 0;
        }
    }
    if (i)
    {
        for (j = i; j < 3; j++)
        {
            char_array_3[j] = '\0';
        }

        char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
        char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
        char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
        char_array_4[3] = char_array_3[2] & 0x3f;

        for (j = 0; (j < i + 1); j++)
        {
            ret += base64_chars[char_array_4[j]];
        }

        while ((i++ < 3))
        {
            ret += '=';
        }

    }
    return ret;
}
int main(){
    std::fstream f;
    f.open("2.jpeg", std::ios::in | std::ios::binary);
    f.seekg(0, std::ios_base::end);     //设置偏移量至文件结尾
    std::streampos sp = f.tellg();      //获取文件大小
    int size = sp;
    char* buffer = (char*)malloc(sizeof(char) * size);
    f.seekg(0, std::ios_base::beg);     //设置偏移量至文件开头
    f.read(buffer, size);                //将文件内容读入buffer
    std::string imgBase64 = base64_encode(buffer, size);    
    std::string s_mat = base64Decode(imgBase64.c_str(), imgBase64.size());
    FILE* stream;
    if ((stream = fopen("1.JPG", "wb")) != NULL)
    {
        int numwritten = fwrite(s_mat.data(), sizeof(char), s_mat.size(), stream);
        fclose(stream);
    }     //编码
}