// Copyright 2014 PDFium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com

#include "../../../../third_party/base/nonstd_unique_ptr.h"
#include "../../../../third_party/zlib_v128/zlib.h"
#include "../../../include/fxcodec/fx_codec.h"
#include "../../../include/fxcodec/fx_codec_flate.h"
#include "codec_int.h"

extern "C"
{
    static void* my_alloc_func(void* opaque, unsigned int items, unsigned int size)
    {
        return FX_Alloc2D(uint8_t, items, size);
    }
    static void my_free_func(void* opaque, void* address)
    {
        FX_Free(address);
    }
    static int FPDFAPI_FlateGetTotalOut(void* context)
    {
        return ((z_stream*)context)->total_out;
    }
    static int FPDFAPI_FlateGetTotalIn(void* context)
    {
        return ((z_stream*)context)->total_in;
    }
    static void FPDFAPI_FlateCompress(unsigned char* dest_buf,
                                      unsigned long* dest_size,
                                      const unsigned char* src_buf,
                                      unsigned long src_size)
    {
        compress(dest_buf, dest_size, src_buf, src_size);
    }
    void* FPDFAPI_FlateInit(void* (*alloc_func)(void*, unsigned int, unsigned int),
                            void (*free_func)(void*, void*))
    {
        z_stream* p = (z_stream*)alloc_func(0, 1, sizeof(z_stream));
        if (p == NULL) {
            return NULL;
        }
        FXSYS_memset(p, 0, sizeof(z_stream));
        p->zalloc = alloc_func;
        p->zfree = free_func;
        inflateInit(p);
        return p;
    }
    void FPDFAPI_FlateInput(void* context, const unsigned char* src_buf, unsigned int src_size)
    {
        ((z_stream*)context)->next_in = (unsigned char*)src_buf;
        ((z_stream*)context)->avail_in = src_size;
    }
    int FPDFAPI_FlateOutput(void* context, unsigned char* dest_buf, unsigned int dest_size)
    {
        ((z_stream*)context)->next_out = dest_buf;
        ((z_stream*)context)->avail_out = dest_size;
        unsigned int pre_pos = (unsigned int)FPDFAPI_FlateGetTotalOut(context);
        int ret = inflate((z_stream*)context, Z_SYNC_FLUSH);
        unsigned int post_pos = (unsigned int)FPDFAPI_FlateGetTotalOut(context);
        unsigned int written = post_pos - pre_pos;
        if (written < dest_size) {
            FXSYS_memset(dest_buf + written, '\0', dest_size - written);
        }
        return ret;
    }
    int FPDFAPI_FlateGetAvailIn(void* context)
    {
        return ((z_stream*)context)->avail_in;
    }
    int FPDFAPI_FlateGetAvailOut(void* context)
    {
        return ((z_stream*)context)->avail_out;
    }
    void FPDFAPI_FlateEnd(void* context)
    {
        inflateEnd((z_stream*)context);
        ((z_stream*)context)->zfree(0, context);
    }
}  // extern "C"

class CLZWDecoder
{
public:
    FX_BOOL Decode(uint8_t* output, FX_DWORD& outlen, const uint8_t* input, FX_DWORD& size, FX_BOOL bEarlyChange);
private:
    FX_DWORD	m_InPos;
    FX_DWORD	m_OutPos;
    uint8_t*	m_pOutput;
    const uint8_t*	m_pInput;
    FX_BOOL		m_Early;
    void		AddCode(FX_DWORD prefix_code, uint8_t append_char);
    FX_DWORD	m_CodeArray[5021];
    FX_DWORD	m_nCodes;
    uint8_t		m_DecodeStack[4000];
    FX_DWORD	m_StackLen;
    void		DecodeString(FX_DWORD code);
    int			m_CodeLen;
};
void CLZWDecoder::AddCode(FX_DWORD prefix_code, uint8_t append_char)
{
    if (m_nCodes + m_Early == 4094) {
        return;
    }
    m_CodeArray[m_nCodes ++] = (prefix_code << 16) | append_char;
    if (m_nCodes + m_Early == 512 - 258) {
        m_CodeLen = 10;
    } else if (m_nCodes + m_Early == 1024 - 258) {
        m_CodeLen = 11;
    } else if (m_nCodes + m_Early == 2048 - 258) {
        m_CodeLen = 12;
    }
}
void CLZWDecoder::DecodeString(FX_DWORD code)
{
    while (1) {
        int index = code - 258;
        if (index < 0 || index >= (int)m_nCodes) {
            break;
        }
        FX_DWORD data = m_CodeArray[index];
        if (m_StackLen >= sizeof(m_DecodeStack)) {
            return;
        }
        m_DecodeStack[m_StackLen++] = (uint8_t)data;
        code = data >> 16;
    }
    if (m_StackLen >= sizeof(m_DecodeStack)) {
        return;
    }
    m_DecodeStack[m_StackLen++] = (uint8_t)code;
}
int CLZWDecoder::Decode(uint8_t* dest_buf, FX_DWORD& dest_size, const uint8_t* src_buf, FX_DWORD& src_size, FX_BOOL bEarlyChange)
{
    m_CodeLen = 9;
    m_InPos = 0;
    m_OutPos = 0;
    m_pInput = src_buf;
    m_pOutput = dest_buf;
    m_Early = bEarlyChange ? 1 : 0;
    m_nCodes = 0;
    FX_DWORD old_code = (FX_DWORD) - 1;
    uint8_t last_char;
    while (1) {
        if (m_InPos + m_CodeLen > src_size * 8) {
            break;
        }
        int byte_pos = m_InPos / 8;
        int bit_pos = m_InPos % 8, bit_left = m_CodeLen;
        FX_DWORD code = 0;
        if (bit_pos) {
            bit_left -= 8 - bit_pos;
            code = (m_pInput[byte_pos++] & ((1 << (8 - bit_pos)) - 1)) << bit_left;
        }
        if (bit_left < 8) {
            code |= m_pInput[byte_pos] >> (8 - bit_left);
        } else {
            bit_left -= 8;
            code |= m_pInput[byte_pos++] << bit_left;
            if (bit_left) {
                code |= m_pInput[byte_pos] >> (8 - bit_left);
            }
        }
        m_InPos += m_CodeLen;
        if (code < 256) {
            if (m_OutPos == dest_size) {
                return -5;
            }
            if (m_pOutput) {
                m_pOutput[m_OutPos] = (uint8_t)code;
            }
            m_OutPos ++;
            last_char = (uint8_t)code;
            if (old_code != (FX_DWORD) - 1) {
                AddCode(old_code, last_char);
            }
            old_code = code;
        } else if (code == 256) {
            m_CodeLen = 9;
            m_nCodes = 0;
            old_code = (FX_DWORD) - 1;
        } else if (code == 257) {
            break;
        } else {
            if (old_code == (FX_DWORD) - 1) {
                return 2;
            }
            m_StackLen = 0;
            if (code >= m_nCodes + 258) {
                if (m_StackLen < sizeof(m_DecodeStack)) {
                    m_DecodeStack[m_StackLen++] = last_char;
                }
                DecodeString(old_code);
            } else {
                DecodeString(code);
            }
            if (m_OutPos + m_StackLen > dest_size) {
                return -5;
            }
            if (m_pOutput) {
                for (FX_DWORD i = 0; i < m_StackLen; i ++) {
                    m_pOutput[m_OutPos + i] = m_DecodeStack[m_StackLen - i - 1];
                }
            }
            m_OutPos += m_StackLen;
            last_char = m_DecodeStack[m_StackLen - 1];
            if (old_code < 256) {
                AddCode(old_code, last_char);
            } else if (old_code - 258 >= m_nCodes) {
                dest_size = m_OutPos;
                src_size = (m_InPos + 7) / 8;
                return 0;
            } else {
                AddCode(old_code, last_char);
            }
            old_code = code;
        }
    }
    dest_size = m_OutPos;
    src_size = (m_InPos + 7) / 8;
    return 0;
}
static uint8_t PaethPredictor(int a, int b, int c)
{
    int p = a + b - c;
    int pa = FXSYS_abs(p - a);
    int pb = FXSYS_abs(p - b);
    int pc = FXSYS_abs(p - c);
    if (pa <= pb && pa <= pc) {
        return (uint8_t)a;
    }
    if (pb <= pc) {
        return (uint8_t)b;
    }
    return (uint8_t)c;
}
static FX_BOOL PNG_PredictorEncode(uint8_t*& data_buf, FX_DWORD& data_size,
                                   int predictor, int Colors,
                                   int BitsPerComponent, int Columns)
{
    const int BytesPerPixel = (Colors * BitsPerComponent + 7) / 8;
    const int row_size = (Colors * BitsPerComponent * Columns + 7) / 8;
    if (row_size <= 0)
        return FALSE;
    const int row_count = (data_size + row_size - 1) / row_size;
    const int last_row_size = data_size % row_size;
    uint8_t* dest_buf = FX_Alloc2D(uint8_t, row_size + 1, row_count);
    int byte_cnt = 0;
    uint8_t* pSrcData = data_buf;
    uint8_t* pDestData = dest_buf;
    for (int row = 0; row < row_count; row++) {
        if (predictor == 10) {
            pDestData[0] = 0;
            int move_size = row_size;
            if (move_size * (row + 1) > (int)data_size) {
                move_size = data_size - (move_size * row);
            }
            FXSYS_memmove(pDestData + 1, pSrcData, move_size);
            pDestData += (move_size + 1);
            pSrcData += move_size;
            byte_cnt += move_size;
            continue;
        }
        for (int byte = 0; byte < row_size && byte_cnt < (int)data_size; byte++) {
            switch (predictor) {
                case 11: {
                        pDestData[0] = 1;
                        uint8_t left = 0;
                        if (byte >= BytesPerPixel) {
                            left = pSrcData[byte - BytesPerPixel];
                        }
                        pDestData[byte + 1] = pSrcData[byte] - left;
                    }
                    break;
                case 12: {
                        pDestData[0] = 2;
                        uint8_t up = 0;
                        if (row) {
                            up = pSrcData[byte - row_size];
                        }
                        pDestData[byte + 1] = pSrcData[byte] - up;
                    }
                    break;
                case 13: {
                        pDestData[0] = 3;
                        uint8_t left = 0;
                        if (byte >= BytesPerPixel) {
                            left = pSrcData[byte - BytesPerPixel];
                        }
                        uint8_t up = 0;
                        if (row) {
                            up = pSrcData[byte - row_size];
                        }
                        pDestData[byte + 1] = pSrcData[byte] - (left + up) / 2;
                    }
                    break;
                case 14: {
                        pDestData[0] = 4;
                        uint8_t left = 0;
                        if (byte >= BytesPerPixel) {
                            left = pSrcData[byte - BytesPerPixel];
                        }
                        uint8_t up = 0;
                        if (row) {
                            up = pSrcData[byte - row_size];
                        }
                        uint8_t upper_left = 0;
                        if (byte >= BytesPerPixel && row) {
                            upper_left = pSrcData[byte - row_size - BytesPerPixel];
                        }
                        pDestData[byte + 1] = pSrcData[byte] - PaethPredictor(left, up, upper_left);
                    }
                    break;
                default: {
                        pDestData[byte + 1] = pSrcData[byte];
                    }
                    break;
            }
            byte_cnt++;
        }
        pDestData += (row_size + 1);
        pSrcData += row_size;
    }
    FX_Free(data_buf);
    data_buf = dest_buf;
    data_size = (row_size + 1) * row_count - (last_row_size > 0 ? (row_size - last_row_size) : 0);
    return TRUE;
}
static void PNG_PredictLine(uint8_t* pDestData, const uint8_t* pSrcData, const uint8_t* pLastLine,
                            int bpc, int nColors, int nPixels)
{
    int row_size = (nPixels * bpc * nColors + 7) / 8;
    int BytesPerPixel = (bpc * nColors + 7) / 8;
    uint8_t tag = pSrcData[0];
    if (tag == 0) {
        FXSYS_memmove(pDestData, pSrcData + 1, row_size);
        return;
    }
    for (int byte = 0; byte < row_size; byte ++) {
        uint8_t raw_byte = pSrcData[byte + 1];
        switch (tag) {
            case 1:	{
                    uint8_t left = 0;
                    if (byte >= BytesPerPixel) {
                        left = pDestData[byte - BytesPerPixel];
                    }
                    pDestData[byte] = raw_byte + left;
                    break;
                }
            case 2: {
                    uint8_t up = 0;
                    if (pLastLine) {
                        up = pLastLine[byte];
                    }
                    pDestData[byte] = raw_byte + up;
                    break;
                }
            case 3: {
                    uint8_t left = 0;
                    if (byte >= BytesPerPixel) {
                        left = pDestData[byte - BytesPerPixel];
                    }
                    uint8_t up = 0;
                    if (pLastLine) {
                        up = pLastLine[byte];
                    }
                    pDestData[byte] = raw_byte + (up + left) / 2;
                    break;
                }
            case 4: {
                    uint8_t left = 0;
                    if (byte >= BytesPerPixel) {
                        left = pDestData[byte - BytesPerPixel];
                    }
                    uint8_t up = 0;
                    if (pLastLine) {
                        up = pLastLine[byte];
                    }
                    uint8_t upper_left = 0;
                    if (byte >= BytesPerPixel && pLastLine) {
                        upper_left = pLastLine[byte - BytesPerPixel];
                    }
                    pDestData[byte] = raw_byte + PaethPredictor(left, up, upper_left);
                    break;
                }
            default:
                pDestData[byte] = raw_byte;
                break;
        }
    }
}
static FX_BOOL PNG_Predictor(uint8_t*& data_buf, FX_DWORD& data_size,
                             int Colors, int BitsPerComponent, int Columns)
{
    const int BytesPerPixel = (Colors * BitsPerComponent + 7) / 8;
    const int row_size = (Colors * BitsPerComponent * Columns + 7) / 8;
    if (row_size <= 0)
        return FALSE;
    const int row_count = (data_size + row_size) / (row_size + 1);
    const int last_row_size = data_size % (row_size + 1);
    uint8_t* dest_buf = FX_Alloc2D(uint8_t, row_size, row_count);
    int byte_cnt = 0;
    uint8_t* pSrcData = data_buf;
    uint8_t* pDestData = dest_buf;
    for (int row = 0; row < row_count; row ++) {
        uint8_t tag = pSrcData[0];
        byte_cnt++;
        if (tag == 0) {
            int move_size = row_size;
            if ((row + 1) * (move_size + 1) > (int)data_size) {
                move_size = last_row_size - 1;
            }
            FXSYS_memmove(pDestData, pSrcData + 1, move_size);
            pSrcData += move_size + 1;
            pDestData += move_size;
            byte_cnt += move_size;
            continue;
        }
        for (int byte = 0; byte < row_size && byte_cnt < (int)data_size; byte ++) {
            uint8_t raw_byte = pSrcData[byte + 1];
            switch (tag) {
                case 1:	{
                        uint8_t left = 0;
                        if (byte >= BytesPerPixel) {
                            left = pDestData[byte - BytesPerPixel];
                        }
                        pDestData[byte] = raw_byte + left;
                        break;
                    }
                case 2: {
                        uint8_t up = 0;
                        if (row) {
                            up = pDestData[byte - row_size];
                        }
                        pDestData[byte] = raw_byte + up;
                        break;
                    }
                case 3: {
                        uint8_t left = 0;
                        if (byte >= BytesPerPixel) {
                            left = pDestData[byte - BytesPerPixel];
                        }
                        uint8_t up = 0;
                        if (row) {
                            up = pDestData[byte - row_size];
                        }
                        pDestData[byte] = raw_byte + (up + left) / 2;
                        break;
                    }
                case 4: {
                        uint8_t left = 0;
                        if (byte >= BytesPerPixel) {
                            left = pDestData[byte - BytesPerPixel];
                        }
                        uint8_t up = 0;
                        if (row) {
                            up = pDestData[byte - row_size];
                        }
                        uint8_t upper_left = 0;
                        if (byte >= BytesPerPixel && row) {
                            upper_left = pDestData[byte - row_size - BytesPerPixel];
                        }
                        pDestData[byte] = raw_byte + PaethPredictor(left, up, upper_left);
                        break;
                    }
                default:
                    pDestData[byte] = raw_byte;
                    break;
            }
            byte_cnt++;
        }
        pSrcData += row_size + 1;
        pDestData += row_size;
    }
    FX_Free(data_buf);
    data_buf = dest_buf;
    data_size = row_size * row_count - (last_row_size > 0 ? (row_size + 1 - last_row_size) : 0);
    return TRUE;
}
static void TIFF_PredictorEncodeLine(uint8_t* dest_buf, int row_size, int BitsPerComponent, int Colors, int Columns)
{
    int BytesPerPixel = BitsPerComponent * Colors / 8;
    if (BitsPerComponent < 8) {
        uint8_t mask = 0x01;
        if (BitsPerComponent == 2) {
            mask = 0x03;
        } else if (BitsPerComponent == 4) {
            mask = 0x0F;
        }
        int row_bits = Colors * BitsPerComponent * Columns;
        for (int i = row_bits - BitsPerComponent; i >= BitsPerComponent; i -= BitsPerComponent) {
            int col = i % 8;
            int index = i / 8;
            int col_pre = (col == 0) ? (8 - BitsPerComponent) : (col - BitsPerComponent);
            int index_pre = (col == 0) ? (index - 1) : index;
            uint8_t cur = (dest_buf[index] >> (8 - col - BitsPerComponent)) & mask;
            uint8_t left = (dest_buf[index_pre] >> (8 - col_pre - BitsPerComponent)) & mask;
            cur -= left;
            cur &= mask;
            cur <<= (8 - col - BitsPerComponent);
            dest_buf[index] &= ~(mask << ((8 - col - BitsPerComponent)));
            dest_buf[index] |= cur;
        }
    } else if (BitsPerComponent == 8) {
        for (int i = row_size - 1; i >= BytesPerPixel; i--) {
            dest_buf[i] -= dest_buf[i - BytesPerPixel];
        }
    } else {
        for (int i = row_size - BytesPerPixel; i >= BytesPerPixel; i -= BytesPerPixel) {
            FX_WORD pixel = (dest_buf[i] << 8) | dest_buf[i + 1];
            pixel -= (dest_buf[i - BytesPerPixel] << 8) | dest_buf[i - BytesPerPixel + 1];
            dest_buf[i] = pixel >> 8;
            dest_buf[i + 1] = (uint8_t)pixel;
        }
    }
}
static FX_BOOL TIFF_PredictorEncode(uint8_t*& data_buf, FX_DWORD& data_size,
                                    int Colors, int BitsPerComponent, int Columns)
{
    int row_size = (Colors * BitsPerComponent * Columns + 7) / 8;
    if (row_size == 0)
        return FALSE;
    const int row_count = (data_size + row_size - 1) / row_size;
    const int last_row_size = data_size % row_size;
    for (int row = 0; row < row_count; row++) {
        uint8_t* scan_line = data_buf + row * row_size;
        if ((row + 1) * row_size > (int)data_size) {
            row_size = last_row_size;
        }
        TIFF_PredictorEncodeLine(scan_line, row_size, BitsPerComponent, Colors, Columns);
    }
    return TRUE;
}
static void TIFF_PredictLine(uint8_t* dest_buf, int row_size, int BitsPerComponent, int Colors, int Columns)
{
    if (BitsPerComponent == 1) {
        int row_bits = FX_MIN(BitsPerComponent * Colors * Columns, row_size * 8);
        int index_pre = 0;
        int col_pre = 0;
        for(int i = 1; i < row_bits; i ++) {
            int col = i % 8;
            int index = i / 8;
            if( ((dest_buf[index] >> (7 - col)) & 1) ^ ((dest_buf[index_pre] >> (7 - col_pre)) & 1) ) {
                dest_buf[index] |= 1 << (7 - col);
            } else {
                dest_buf[index] &= ~(1 << (7 - col));
            }
            index_pre = index;
            col_pre = col;
        }
        return;
    }
    int BytesPerPixel = BitsPerComponent * Colors / 8;
    if (BitsPerComponent == 16) {
        for (int i = BytesPerPixel; i < row_size; i += 2) {
            FX_WORD pixel = (dest_buf[i - BytesPerPixel] << 8) | dest_buf[i - BytesPerPixel + 1];
            pixel += (dest_buf[i] << 8) | dest_buf[i + 1];
            dest_buf[i] = pixel >> 8;
            dest_buf[i + 1] = (uint8_t)pixel;
        }
    } else {
        for (int i = BytesPerPixel; i < row_size; i ++) {
            dest_buf[i] += dest_buf[i - BytesPerPixel];
        }
    }
}
static FX_BOOL TIFF_Predictor(uint8_t*& data_buf, FX_DWORD& data_size,
                              int Colors, int BitsPerComponent, int Columns)
{
    int row_size = (Colors * BitsPerComponent * Columns + 7) / 8;
    if (row_size == 0)
        return FALSE;
    const int row_count = (data_size + row_size - 1) / row_size;
    const int last_row_size = data_size % row_size;
    for (int row = 0; row < row_count; row ++) {
        uint8_t* scan_line = data_buf + row * row_size;
        if ((row + 1) * row_size > (int)data_size) {
            row_size = last_row_size;
        }
        TIFF_PredictLine(scan_line, row_size, BitsPerComponent, Colors, Columns);
    }
    return TRUE;
}
class CCodec_FlateScanlineDecoder : public CCodec_ScanlineDecoder
{
public:
    CCodec_FlateScanlineDecoder();
    ~CCodec_FlateScanlineDecoder();
    void Create(const uint8_t* src_buf, FX_DWORD src_size, int width, int height, int nComps, int bpc,
                int predictor, int Colors, int BitsPerComponent, int Columns);
    virtual void		Destroy()
    {
        delete this;
    }
    virtual void		v_DownScale(int dest_width, int dest_height) {}
    virtual FX_BOOL		v_Rewind();
    virtual uint8_t*	v_GetNextLine();
    virtual FX_DWORD	GetSrcOffset();
    void*				m_pFlate;
    const uint8_t*			m_SrcBuf;
    FX_DWORD			m_SrcSize;
    uint8_t*			m_pScanline;
    uint8_t*			m_pLastLine;
    uint8_t*			m_pPredictBuffer;
    uint8_t*			m_pPredictRaw;
    int					m_Predictor;
    int					m_Colors, m_BitsPerComponent, m_Columns, m_PredictPitch, m_LeftOver;
};
CCodec_FlateScanlineDecoder::CCodec_FlateScanlineDecoder()
{
    m_pFlate = NULL;
    m_pScanline = NULL;
    m_pLastLine = NULL;
    m_pPredictBuffer = NULL;
    m_pPredictRaw = NULL;
    m_LeftOver = 0;
}
CCodec_FlateScanlineDecoder::~CCodec_FlateScanlineDecoder()
{
    if (m_pScanline) {
        FX_Free(m_pScanline);
    }
    if (m_pLastLine) {
        FX_Free(m_pLastLine);
    }
    if (m_pPredictBuffer) {
        FX_Free(m_pPredictBuffer);
    }
    if (m_pPredictRaw) {
        FX_Free(m_pPredictRaw);
    }
    if (m_pFlate) {
        FPDFAPI_FlateEnd(m_pFlate);
    }
}
void CCodec_FlateScanlineDecoder::Create(const uint8_t* src_buf, FX_DWORD src_size, int width, int height,
        int nComps, int bpc, int predictor, int Colors, int BitsPerComponent, int Columns)
{
    m_SrcBuf = src_buf;
    m_SrcSize = src_size;
    m_OutputWidth = m_OrigWidth = width;
    m_OutputHeight = m_OrigHeight = height;
    m_nComps = nComps;
    m_bpc = bpc;
    m_bColorTransformed = FALSE;
    m_Pitch = (width * nComps * bpc + 7) / 8;
    m_pScanline = FX_Alloc(uint8_t, m_Pitch);
    m_Predictor = 0;
    if (predictor) {
        if (predictor >= 10) {
            m_Predictor = 2;
        } else if (predictor == 2) {
            m_Predictor = 1;
        }
        if (m_Predictor) {
            if (BitsPerComponent * Colors * Columns == 0) {
                BitsPerComponent = m_bpc;
                Colors = m_nComps;
                Columns = m_OrigWidth;
            }
            m_Colors = Colors;
            m_BitsPerComponent = BitsPerComponent;
            m_Columns = Columns;
            m_PredictPitch = (m_BitsPerComponent * m_Colors * m_Columns + 7) / 8;
            m_pLastLine = FX_Alloc(uint8_t, m_PredictPitch);
            m_pPredictRaw = FX_Alloc(uint8_t, m_PredictPitch + 1);
            m_pPredictBuffer = FX_Alloc(uint8_t, m_PredictPitch);
        }
    }
}
FX_BOOL CCodec_FlateScanlineDecoder::v_Rewind()
{
    if (m_pFlate) {
        FPDFAPI_FlateEnd(m_pFlate);
    }
    m_pFlate = FPDFAPI_FlateInit(my_alloc_func, my_free_func);
    if (m_pFlate == NULL) {
        return FALSE;
    }
    FPDFAPI_FlateInput(m_pFlate, m_SrcBuf, m_SrcSize);
    m_LeftOver = 0;
    return TRUE;
}
uint8_t* CCodec_FlateScanlineDecoder::v_GetNextLine()
{
    if (m_Predictor) {
        if (m_Pitch == m_PredictPitch) {
            if (m_Predictor == 2) {
                FPDFAPI_FlateOutput(m_pFlate, m_pPredictRaw, m_PredictPitch + 1);
                PNG_PredictLine(m_pScanline, m_pPredictRaw, m_pLastLine, m_BitsPerComponent, m_Colors, m_Columns);
                FXSYS_memcpy(m_pLastLine, m_pScanline, m_PredictPitch);
            } else {
                FPDFAPI_FlateOutput(m_pFlate, m_pScanline, m_Pitch);
                TIFF_PredictLine(m_pScanline, m_PredictPitch, m_bpc, m_nComps, m_OutputWidth);
            }
        } else {
            int bytes_to_go = m_Pitch;
            int read_leftover = m_LeftOver > bytes_to_go ? bytes_to_go : m_LeftOver;
            if (read_leftover) {
                FXSYS_memcpy(m_pScanline, m_pPredictBuffer + m_PredictPitch - m_LeftOver, read_leftover);
                m_LeftOver -= read_leftover;
                bytes_to_go -= read_leftover;
            }
            while (bytes_to_go) {
                if (m_Predictor == 2) {
                    FPDFAPI_FlateOutput(m_pFlate, m_pPredictRaw, m_PredictPitch + 1);
                    PNG_PredictLine(m_pPredictBuffer, m_pPredictRaw, m_pLastLine, m_BitsPerComponent, m_Colors, m_Columns);
                    FXSYS_memcpy(m_pLastLine, m_pPredictBuffer, m_PredictPitch);
                } else {
                    FPDFAPI_FlateOutput(m_pFlate, m_pPredictBuffer, m_PredictPitch);
                    TIFF_PredictLine(m_pPredictBuffer, m_PredictPitch, m_BitsPerComponent, m_Colors, m_Columns);
                }
                int read_bytes = m_PredictPitch > bytes_to_go ? bytes_to_go : m_PredictPitch;
                FXSYS_memcpy(m_pScanline + m_Pitch - bytes_to_go, m_pPredictBuffer, read_bytes);
                m_LeftOver += m_PredictPitch - read_bytes;
                bytes_to_go -= read_bytes;
            }
        }
    } else {
        FPDFAPI_FlateOutput(m_pFlate, m_pScanline, m_Pitch);
    }
    return m_pScanline;
}
FX_DWORD CCodec_FlateScanlineDecoder::GetSrcOffset()
{
    return FPDFAPI_FlateGetTotalIn(m_pFlate);
}
static void FlateUncompress(const uint8_t* src_buf, FX_DWORD src_size, FX_DWORD orig_size,
                            uint8_t*& dest_buf, FX_DWORD& dest_size, FX_DWORD& offset)
{
    const FX_BOOL useOldImpl = src_size < 10240;
    FX_DWORD guess_size = orig_size ? orig_size : src_size * 2;
    FX_DWORD alloc_step = orig_size ? 10240 : (src_size < 10240 ? 10240 : src_size);
    static const FX_DWORD kMaxInitialAllocSize = 10000000;
    if (guess_size > kMaxInitialAllocSize) {
        guess_size = kMaxInitialAllocSize;
        alloc_step = kMaxInitialAllocSize;
    }
    FX_DWORD buf_size = guess_size;
    FX_DWORD last_buf_size = buf_size;
    void* context = nullptr;

    uint8_t* guess_buf = FX_Alloc(uint8_t, guess_size + 1);
    uint8_t* cur_buf = guess_buf;
    guess_buf[guess_size] = '\0';
    context = FPDFAPI_FlateInit(my_alloc_func, my_free_func);
    if (!context)
        goto fail;
    FPDFAPI_FlateInput(context, src_buf, src_size);
    if (useOldImpl) {
        while (1) {
            int32_t ret = FPDFAPI_FlateOutput(context, cur_buf, buf_size);
            if (ret != Z_OK)
                break;
            int32_t avail_buf_size = FPDFAPI_FlateGetAvailOut(context);
            if (avail_buf_size != 0)
                break;

            // |avail_buf_size| == 0 case.
            FX_DWORD old_size = guess_size;
            guess_size += alloc_step;
            if (guess_size < old_size || guess_size + 1 < guess_size)
                goto fail;
            guess_buf = FX_Realloc(uint8_t, guess_buf, guess_size + 1);
            if (!guess_buf)
                goto fail;
            guess_buf[guess_size] = '\0';
            cur_buf = guess_buf + old_size;
            buf_size = guess_size - old_size;
        }
        dest_size = FPDFAPI_FlateGetTotalOut(context);
        offset = FPDFAPI_FlateGetTotalIn(context);
        if (guess_size / 2 > dest_size) {
            guess_buf = FX_Realloc(uint8_t, guess_buf, dest_size + 1);
            if (!guess_buf)
                goto fail;
            guess_size = dest_size;
            guess_buf[guess_size] = '\0';
        }
        dest_buf = guess_buf;
    } else {
        CFX_ArrayTemplate<uint8_t*> result_tmp_bufs;
        while (1) {
            int32_t ret = FPDFAPI_FlateOutput(context, cur_buf, buf_size);
            int32_t avail_buf_size = FPDFAPI_FlateGetAvailOut(context);
            if (ret != Z_OK) {
                last_buf_size = buf_size - avail_buf_size;
                result_tmp_bufs.Add(cur_buf);
                break;
            }
            if (avail_buf_size != 0) {
                last_buf_size = buf_size - avail_buf_size;
                result_tmp_bufs.Add(cur_buf);
                break;
            }

            // |avail_buf_size| == 0 case.
            result_tmp_bufs.Add(cur_buf);
            cur_buf = FX_Alloc(uint8_t, buf_size + 1);
            cur_buf[buf_size] = '\0';
        }
        dest_size = FPDFAPI_FlateGetTotalOut(context);
        offset = FPDFAPI_FlateGetTotalIn(context);
        if (result_tmp_bufs.GetSize() == 1) {
            dest_buf = result_tmp_bufs[0];
        } else {
            uint8_t* result_buf = FX_Alloc(uint8_t, dest_size);
            FX_DWORD result_pos = 0;
            for (int32_t i = 0; i < result_tmp_bufs.GetSize(); i++) {
                uint8_t* tmp_buf = result_tmp_bufs[i];
                FX_DWORD tmp_buf_size = buf_size;
                if (i == result_tmp_bufs.GetSize() - 1) {
                    tmp_buf_size = last_buf_size;
                }
                FXSYS_memcpy(result_buf + result_pos, tmp_buf, tmp_buf_size);
                result_pos += tmp_buf_size;
                FX_Free(result_tmp_bufs[i]);
            }
            dest_buf = result_buf;
        }
    }
    FPDFAPI_FlateEnd(context);
    return;

fail:
    FX_Free(guess_buf);
    dest_buf = nullptr;
    dest_size = 0;
    return;
}
ICodec_ScanlineDecoder*	CCodec_FlateModule::CreateDecoder(const uint8_t* src_buf, FX_DWORD src_size, int width, int height,
        int nComps, int bpc, int predictor, int Colors, int BitsPerComponent, int Columns)
{
    CCodec_FlateScanlineDecoder* pDecoder = new CCodec_FlateScanlineDecoder;
    pDecoder->Create(src_buf, src_size, width, height, nComps, bpc, predictor, Colors, BitsPerComponent, Columns);
    return pDecoder;
}
FX_DWORD CCodec_FlateModule::FlateOrLZWDecode(FX_BOOL bLZW, const uint8_t* src_buf, FX_DWORD src_size, FX_BOOL bEarlyChange,
        int predictor, int Colors, int BitsPerComponent, int Columns,
        FX_DWORD estimated_size, uint8_t*& dest_buf, FX_DWORD& dest_size)
{
    dest_buf = NULL;
    FX_DWORD offset = 0;
    int predictor_type = 0;
    if (predictor) {
        if (predictor >= 10) {
            predictor_type = 2;
        } else if (predictor == 2) {
            predictor_type = 1;
        }
    }
    if (bLZW) {
        {
            nonstd::unique_ptr<CLZWDecoder> decoder(new CLZWDecoder);
            dest_size = (FX_DWORD) - 1;
            offset = src_size;
            int err = decoder->Decode(NULL, dest_size, src_buf, offset,
                                      bEarlyChange);
            if (err || dest_size == 0 || dest_size + 1 < dest_size) {
                return -1;
            }
        }
        {
            nonstd::unique_ptr<CLZWDecoder> decoder(new CLZWDecoder);
            dest_buf = FX_Alloc( uint8_t, dest_size + 1);
            dest_buf[dest_size] = '\0';
            decoder->Decode(dest_buf, dest_size, src_buf, offset, bEarlyChange);
        }
    } else {
        FlateUncompress(src_buf, src_size, estimated_size, dest_buf, dest_size, offset);
    }
    if (predictor_type == 0) {
        return offset;
    }
    FX_BOOL ret = TRUE;
    if (predictor_type == 2) {
        ret = PNG_Predictor(dest_buf, dest_size, Colors, BitsPerComponent,
                            Columns);
    } else if (predictor_type == 1) {
        ret = TIFF_Predictor(dest_buf, dest_size, Colors, BitsPerComponent,
                             Columns);
    }
    return ret ? offset : -1;
}
FX_BOOL CCodec_FlateModule::Encode(const uint8_t* src_buf, FX_DWORD src_size,
                                   int predictor, int Colors, int BitsPerComponent, int Columns,
                                   uint8_t*& dest_buf, FX_DWORD& dest_size)
{
    if (predictor != 2 && predictor < 10) {
        return Encode(src_buf, src_size, dest_buf, dest_size);
    }
    uint8_t* pSrcBuf = NULL;
    pSrcBuf = FX_Alloc(uint8_t, src_size);
    FXSYS_memcpy(pSrcBuf, src_buf, src_size);
    FX_BOOL ret = TRUE;
    if (predictor == 2) {
        ret = TIFF_PredictorEncode(pSrcBuf, src_size, Colors, BitsPerComponent,
                                   Columns);
    } else if (predictor >= 10) {
        ret = PNG_PredictorEncode(pSrcBuf, src_size, predictor, Colors,
                                  BitsPerComponent, Columns);
    }
    if (ret)
        ret = Encode(pSrcBuf, src_size, dest_buf, dest_size);
    FX_Free(pSrcBuf);
    return ret;
}
FX_BOOL CCodec_FlateModule::Encode(const uint8_t* src_buf, FX_DWORD src_size, uint8_t*& dest_buf, FX_DWORD& dest_size)
{
    dest_size = src_size + src_size / 1000 + 12;
    dest_buf = FX_Alloc( uint8_t, dest_size);
    unsigned long temp_size = dest_size;
    FPDFAPI_FlateCompress(dest_buf, &temp_size, src_buf, src_size);
    dest_size = (FX_DWORD)temp_size;
    return TRUE;
}