JPEG解码类 C++

#include "stdafx.h" #include "MyJpeg.h" MyJpeg::MyJpeg(): width(0), height(0), data(NULL), data_mcu(NULL), channel_num(0), header_flag(0), dc_y_prev(0), dc_cb_prev(0), dc_cr_prev(0) { for (int i = 0; i != 4; ++i) { root[i] = NULL; } for (int i = 0; i < 4; ++i) { mcu_channels[i] = NULL; } for (int i = 0; i < 4; ++i) { data_channels[i] = NULL; } for (int i = 0; i < 4; ++i) { memset(mcu_data_y[i], 0, sizeof(mcu_data_y[i])); memset(mcu_data_cr[i], 0, sizeof(mcu_data_cr[i])); memset(mcu_data_cb[i], 0, sizeof(mcu_data_cb[i])); } } MyJpeg::~MyJpeg() { for (int i = 0; i != 4; ++i) { if (NULL != dht[i].root) { DeleteTree(dht[i].root); } } for (int i = 0; i != 4; ++i) { if (NULL != mcu_channels[i]) { delete mcu_channels[i]; } } for (int i = 0; i < 4; ++i) { if (data_channels[i] = NULL) { delete[]data_channels[i]; } } if (data != NULL) { delete[]data; } if (data_mcu != NULL) { delete[]data_mcu; } } void MyJpeg::DeleteTree(HuffmanTree* p_root) { if (NULL != p_root->left) { DeleteTree(p_root->left); } if (NULL != p_root->right) { DeleteTree(p_root->right); } delete p_root; p_root = NULL; } void MyJpeg::PreOrderTraverse(HuffmanTree * p_root) { if (p_root->is_leaf) { std::cout << p_root->value << " "; } if (NULL != p_root->left) { PreOrderTraverse(p_root->left); } if (NULL != p_root->right) { PreOrderTraverse(p_root->right); } } void MyJpeg::MidOrderTraverse(HuffmanTree * p_root) { if (NULL != p_root->left) { MidOrderTraverse(p_root->left); } std::cout << p_root->value << " "; if (NULL != p_root->right) { MidOrderTraverse(p_root->right); } } void MyJpeg::BackOrderTraverse(HuffmanTree * p_root) { if (NULL != p_root->left) { BackOrderTraverse(p_root->left); } if (NULL != p_root->right) { BackOrderTraverse(p_root->right); } std::cout << p_root->value << " "; } void MyJpeg::ShowInHex(const char & c) { // 注意char类型，当char为 负数时 // 右移补位 1， 正数时补位 0 // 可以使用stl中的bitset取而代之 // 相同位数的不同类型间赋值，是将对应-位-赋值给受体 char cLow, cHigh; cHigh = (c & 0xF0) >> 4; cLow = c & 0x0F; switch (cLow) { case 10: cLow = 'A'; break; case 11: cLow = 'B'; break; case 12: cLow = 'C'; break; case 13: cLow = 'D'; break; case 14: cLow = 'E'; break; case 15: cLow = 'F'; break; default: cLow += 48; break; } switch (cHigh) { case 10: cHigh = 'A'; break; case 11: cHigh = 'B'; break; case 12: cHigh = 'C'; break; case 13: cHigh = 'D'; break; case 14: cHigh = 'E'; break; case 15: cHigh = 'F'; break; default: cHigh += 48; break; } std::cout << cHigh << cLow << ' '; /*static unsigned int char_count = 0; char_count++; if (char_count % 16 == 0) { std::cout << std::endl; }*/ } void MyJpeg::PrintBits(const unsigned int& src, unsigned char num) { unsigned char count = 0; while (count < num) { std::cout << ((src >> count) & 1); count++; } std::cout << std::endl; } unsigned int MyJpeg::GetNCharacters(std::ifstream& ifs, unsigned char * p_in, unsigned int count ) { memset(p_in, 0, count); unsigned int read_num = 0; char c = 0; char next_c = 0; for (unsigned int i = 0; i < count; ++i) { if (ifs.get(c)) { if ((unsigned char)c == 0xff) { if (ifs.get(next_c)) { switch ((unsigned char)next_c) { case 0x00: p_in[i] = c; ++read_num; break; case 0xD9: p_in[i] = 0; return read_num; break; default: break; } } } else { p_in[i] = c; ++read_num; } } else { std::cerr << "error reading a character" << std::endl; std::exit(EXIT_FAILURE); } } return read_num; } void MyJpeg::CopyNCharacters(unsigned char * dst, unsigned char * src, unsigned int count ) { for (unsigned int i = 0; i != count; ++i) { dst[i] = src[i]; } } void MyJpeg::ReadApp0(std::ifstream& ifs) { // 读取并计算该标记 段的长度 unsigned char temp[6]; GetNCharacters(ifs, temp, 2); unsigned int len = 0; len += temp[0]; len <<= 8; len += temp[1]; unsigned char* read_src = new unsigned char[len - 2]; std::tr1::shared_ptr<unsigned char> read_src_smtpt(read_src); GetNCharacters(ifs, read_src, len - 2); unsigned char it = 0; // 获得5个identifier数据 CopyNCharacters(app0.identifier, read_src + it, 5); it += 5; // 获得版本号 CopyNCharacters(app0.version, read_src + it, 2); it += 2; // x和y密度单位 CopyNCharacters(&app0.density_unit, read_src + it, 1); it += 1; // x分辨率 CopyNCharacters(temp, read_src + it, 2); it += 2; app0.density_x = 0; app0.density_x += temp[0]; app0.density_x <<= 8; app0.density_x += temp[1]; // y分辨率 CopyNCharacters(temp, read_src + it, 2); it += 2; app0.density_y = 0; app0.density_y += temp[0]; app0.density_y <<= 8; app0.density_y += temp[1]; // 缩略图水平分辨率 CopyNCharacters(&app0.thumbnail_h_pixel, read_src + it, 1); it += 1; // 缩略图垂直分辨率 CopyNCharacters(&app0.thumbnail_v_pixel, read_src + it, 1); it += 1; if (app0.thumbnail_h_pixel != 0 && app0.thumbnail_v_pixel != 0) { // RGB缩略图 //CopyNCharacters(app0.thumbnail_rgb_bitmap, read_src + it, 3); } } void MyJpeg::ReadDqt(std::ifstream& ifs) { // 读取并计算该标记 段的长度 unsigned char temp[6]; GetNCharacters(ifs, temp, 2); unsigned int len = 0; len += temp[0]; len <<= 8; len += temp[1]; unsigned char* read_src = new unsigned char[len - 2]; std::tr1::shared_ptr<unsigned char> read_src_smtpt(read_src); GetNCharacters(ifs, read_src, len - 2); unsigned int it = 0; static unsigned char quant_table_cnt = 0; // 获得量化表数据 CopyNCharacters(temp, read_src + it, 1); it += 1; // 获得高四位，确定精度 0：表示8位。1：表示16位 dqt[quant_table_cnt].precision = temp[0] >> 4; // 获得低四位，确定量化表的编号 dqt[quant_table_cnt].table_id = temp[0] & 0x0f; // 这里只考虑基本系统所以精度8位，共2个量化表 for (int i = 0; i != 64; ++i, ++it) { dqt[quant_table_cnt].quant_table[i] = *(read_src + it); } // 量化表计数机自加，静态static quant_table_cnt++; } void MyJpeg::ReadSof(std::ifstream& ifs) { // 读取并计算该标记 段的长度 unsigned char temp[6]; GetNCharacters(ifs, temp, 2); unsigned int len = 0; len += temp[0]; len <<= 8; len += temp[1]; unsigned char* read_src = new unsigned char[len - 2]; std::tr1::shared_ptr<unsigned char> read_src_smtpt(read_src); GetNCharacters(ifs, read_src, len - 2); unsigned int it = 0; // 获得每个颜色分量每个pixel的位数 CopyNCharacters(&sof0.precision, read_src + it, 1); it += 1; // 获得图像的高度 CopyNCharacters(temp, read_src + it, 2); it += 2; sof0.heigth = 0; sof0.heigth += temp[0]; sof0.heigth <<= 8; sof0.heigth += temp[1]; this->height = sof0.heigth; // 获得图像的宽度 CopyNCharacters(temp, read_src + it, 2); it += 2; sof0.width = 0; sof0.width += temp[0]; sof0.width<<= 8; sof0.width += temp[1]; this->width = sof0.width; // 获得图像的颜色分量数目 CopyNCharacters(&sof0.component_num, read_src + it, 1); it += 1; this->channel_num = sof0.component_num; // 对每个分量（每个占用一个字节），格式形如01 11 00 for (unsigned char i = 0; i < sof0.component_num; ++i) { // 获得id CopyNCharacters(&sof0.component[i].id, read_src + it, 1); it += 1; // 垂直方向采样因子 CopyNCharacters(temp, read_src + it, 1); it += 1; sof0.component[i].sample_factor_v = (temp[0] & 0xf0) >> 4; // 水平方向采样因子 sof0.component[i].sample_factor_h = temp[0] & 0x0f; // 获得量化表号 CopyNCharacters(&sof0.component[i].quant_table_id, read_src + it, 1); it += 1; } } void MyJpeg::ReadDh