tahoma2d/toonz/sources/image/png/tiio_png.cpp

#if defined(_MSC_VER) && (_MSC_VER >= 1400)
#define _CRT_SECURE_NO_DEPRECATE 1
#endif

#include <memory>

#include "tmachine.h"
#include "texception.h"
#include "tfilepath.h"
#include "tiio_png.h"
#include "tiio.h"
#include "../compatibility/tfile_io.h"

#include "png.h"

#include "tpixel.h"
#include "tpixelutils.h"

using namespace std;
//------------------------------------------------------------

extern "C" {

static void tnz_abort(jmp_buf, int) {}

static void tnz_error_fun(png_structp pngPtr, png_const_charp error_message) {
  *(int *)png_get_error_ptr(pngPtr) = 0;
}
}

#if !defined(TNZ_LITTLE_ENDIAN)
#error "TNZ_LITTLE_ENDIAN undefined !!"
#endif

//=========================================================
/* Check for the older version of libpng */

#if defined(PNG_LIBPNG_VER)
#if (PNG_LIBPNG_VER < 10527)
extern "C" {
static png_uint_32 png_get_current_row_number(const png_structp png_ptr) {
  /* See the comments in png.h - this is the sub-image row when reading and
   * interlaced image.
   */
  if (png_ptr != NULL) return png_ptr->row_number;

  return PNG_UINT_32_MAX; /* help the app not to fail silently */
}

static png_byte png_get_current_pass_number(const png_structp png_ptr) {
  if (png_ptr != NULL) return png_ptr->pass;
  return 8; /* invalid */
}
}
#endif
#else
#error "PNG_LIBPNG_VER undefined, libpng too old?"
#endif

//=========================================================

inline USHORT mySwap(USHORT val) {
#if TNZ_LITTLE_ENDIAN
  return ((val) |
          ((val & 0xff) << 8));  //((val>>8)|((val&0xff)<<8)); (vecchio codice)
#else
  return val;
#endif
}

//=========================================================

class PngReader final : public Tiio::Reader {
  FILE *m_chan;
  png_structp m_png_ptr;
  png_infop m_info_ptr, m_end_info_ptr;
  int m_bit_depth, m_color_type, m_interlace_type;
  int m_compression_type, m_filter_type;
  unsigned int m_sig_read;
  int m_y;
  bool m_is16bitEnabled;
  std::unique_ptr<unsigned char[]> m_rowBuffer;
  std::unique_ptr<unsigned char[]> m_tempBuffer;  // Buffer temporaneo
  int m_canDelete;

public:
  PngReader()
      : m_chan(0)
      , m_png_ptr(0)
      , m_info_ptr(0)
      , m_end_info_ptr(0)
      , m_bit_depth(0)
      , m_color_type(0)
      , m_interlace_type(0)
      , m_compression_type(0)
      , m_filter_type(0)
      , m_sig_read(0)
      , m_y(0)
      , m_is16bitEnabled(true)
      , m_canDelete(0) {}

  ~PngReader() {
    if (m_canDelete == 1) {
      png_destroy_read_struct(&m_png_ptr, &m_info_ptr, &m_end_info_ptr);
    }
  }

  bool read16BitIsEnabled() const override { return m_is16bitEnabled; }

  void enable16BitRead(bool enabled) override { m_is16bitEnabled = enabled; }

  void readLineInterlace(char *buffer) {
    readLineInterlace(buffer, 0, m_info.m_lx - 1, 1);
  }
  void readLineInterlace(short *buffer) {
    readLineInterlace(buffer, 0, m_info.m_lx - 1, 1);
  }

  void open(FILE *file) override {
    try {
      m_chan = file;
    } catch (...) {
      perror("uffa");
      return;
    }

    unsigned char signature[8];  // da 1 a 8 bytes
    fread(signature, 1, sizeof signature, m_chan);
    bool isPng = !png_sig_cmp(signature, 0, sizeof signature);
    if (!isPng) return;

    m_png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, &m_canDelete,
                                       tnz_error_fun, 0);
    if (!m_png_ptr) return;

#if defined(PNG_LIBPNG_VER)
#if (PNG_LIBPNG_VER >= 10527)
    png_set_longjmp_fn(m_png_ptr, tnz_abort,
                       sizeof(jmp_buf)); /* ignore all fatal errors */
#endif                                   // (PNG_LIBPNG_VER >= 10527)
#endif                                   // defined(PNG_LIBPNG_VER)

    m_canDelete = 1;
    m_info_ptr  = png_create_info_struct(m_png_ptr);
    if (!m_info_ptr) {
      png_destroy_read_struct(&m_png_ptr, (png_infopp)0, (png_infopp)0);
      return;
    }
    m_end_info_ptr = png_create_info_struct(m_png_ptr);
    if (!m_end_info_ptr) {
      png_destroy_read_struct(&m_png_ptr, &m_info_ptr, (png_infopp)0);
      return;
    }

    png_init_io(m_png_ptr, m_chan);

    png_set_sig_bytes(m_png_ptr, sizeof signature);

#if defined(TNZ_MACHINE_CHANNEL_ORDER_MBGR)
    png_set_bgr(m_png_ptr);
    png_set_swap_alpha(m_png_ptr);
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_BGRM)
    png_set_bgr(m_png_ptr);
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_MRGB)
    png_set_swap_alpha(m_png_ptr);
#elif !defined(TNZ_MACHINE_CHANNEL_ORDER_RGBM)
#error "unknown channel order"
#endif

    png_read_info(m_png_ptr, m_info_ptr);

    if (png_get_valid(m_png_ptr, m_info_ptr, PNG_INFO_pHYs)) {
      png_uint_32 xdpi = png_get_x_pixels_per_meter(m_png_ptr, m_info_ptr);
      png_uint_32 ydpi = png_get_y_pixels_per_meter(m_png_ptr, m_info_ptr);
      m_info.m_dpix    = tround(xdpi * 0.0254);
      m_info.m_dpiy    = tround(ydpi * 0.0254);
    }

    int rowBytes = png_get_rowbytes(m_png_ptr, m_info_ptr);

    png_uint_32 lx = 0, ly = 0;
    png_get_IHDR(m_png_ptr, m_info_ptr, &lx, &ly, &m_bit_depth, &m_color_type,
                 &m_interlace_type, &m_compression_type, &m_filter_type);
    m_info.m_lx = lx;
    m_info.m_ly = ly;

    m_info.m_bitsPerSample = m_bit_depth;

    int channels            = png_get_channels(m_png_ptr, m_info_ptr);
    m_info.m_samplePerPixel = channels;

    if (channels == 1 || channels == 2) {
      if (m_bit_depth <
          8)  // (m_bit_depth == 1 || m_bit_depth == 2 || m_bit_depth == 4)
        m_rowBuffer.reset(new unsigned char[lx * 3]);
      else
        m_rowBuffer.reset(new unsigned char[rowBytes * 4]);
    } else {
      m_rowBuffer.reset(new unsigned char[rowBytes]);
    }

    if (m_color_type == PNG_COLOR_TYPE_PALETTE) {
      m_info.m_valid = true;
      png_set_palette_to_rgb(m_png_ptr);

      // treat the image as RGBA from now on
      m_info.m_samplePerPixel = 4; // there are 4 channels per pixel (R, G, B, and A)

      // if there is no alpha channel, then fill it with "255" (full opacity)
      png_set_filler(m_png_ptr, 0xFF, PNG_FILLER_AFTER);
    }

    if (m_color_type == PNG_COLOR_TYPE_GRAY && m_bit_depth < 8) {
      png_set_expand_gray_1_2_4_to_8(m_png_ptr);
    }

    if (png_get_valid(m_png_ptr, m_info_ptr, PNG_INFO_tRNS)) {
      png_set_tRNS_to_alpha(m_png_ptr);
    }

    if (m_bit_depth == 16 && !m_is16bitEnabled) {
      png_set_strip_16(m_png_ptr);
    }

#if defined(TNZ_MACHINE_CHANNEL_ORDER_BGRM)
    if (m_color_type == PNG_COLOR_TYPE_RGB ||
        m_color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
      png_set_bgr(m_png_ptr);
    }
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_MBGR)
    if (m_color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
      png_set_swap_alpha(m_png_ptr);
    }
#elif !defined(TNZ_MACHINE_CHANNEL_ORDER_RGBM) &&                              \
    !defined(TNZ_MACHINE_CHANNEL_ORDER_MRGB)
#error "unknown channel order"
#endif

    if (m_color_type == PNG_COLOR_TYPE_GRAY ||
        m_color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
      png_set_gray_to_rgb(m_png_ptr);
    }
  }

  void readLine(char *buffer, int x0, int x1, int shrink) override {
    int ly = m_info.m_ly;
    if (!m_tempBuffer) {
      int lx       = m_info.m_lx;
      int channels = png_get_channels(m_png_ptr, m_info_ptr);
      int rowBytes = png_get_rowbytes(m_png_ptr, m_info_ptr);
      if (m_interlace_type == 1) {
        if (channels == 1 || channels == 2) {
          if (m_bit_depth < 8)
            m_tempBuffer.reset(new unsigned char[ly * lx * 3]);
          else
            m_tempBuffer.reset(new unsigned char[ly * rowBytes * 4]);
        } else {
          m_tempBuffer.reset(new unsigned char[ly * rowBytes]);
        }
      }
    }
    int lx = m_info.m_lx;

    if (m_interlace_type == 1 && lx > 4) {
      readLineInterlace(&buffer[0], x0, x1, shrink);
      m_y++;
      if (m_tempBuffer && m_y == ly) {
        m_tempBuffer.reset();
      }
      return;
    }

    int y = m_info.m_ly - 1 - m_y;
    if (y < 0) return;
    m_y++;

    png_bytep row_pointer = m_rowBuffer.get();
    png_read_row(m_png_ptr, row_pointer, NULL);

    writeRow(buffer);

    if (m_tempBuffer && m_y == ly) {
      m_tempBuffer.reset();
    }
  }

  void readLine(short *buffer, int x0, int x1, int shrink) override {
    int ly = m_info.m_ly;
    if (!m_tempBuffer) {
      int lx       = m_info.m_lx;
      int channels = png_get_channels(m_png_ptr, m_info_ptr);
      int rowBytes = png_get_rowbytes(m_png_ptr, m_info_ptr);
      if (m_interlace_type == 1) {
        if (channels == 1 || channels == 2) {
          if (m_bit_depth <
              8)  // (m_bit_depth == 1 || m_bit_depth == 2 || m_bit_depth == 4)
            m_tempBuffer.reset(new unsigned char[ly * lx * 3]);
          else
            m_tempBuffer.reset(new unsigned char[ly * rowBytes * 4]);
        } else {
          m_tempBuffer.reset(new unsigned char[ly * rowBytes]);
        }
      }
    }

    if (png_get_interlace_type(m_png_ptr, m_info_ptr) == PNG_INTERLACE_ADAM7) {
      readLineInterlace(&buffer[0], x0, x1, shrink);
      m_y++;
      if (m_tempBuffer && m_y == ly) {
        m_tempBuffer.reset();
      }
      return;
    }

    int y = m_info.m_ly - 1 - m_y;
    if (y < 0) return;
    m_y++;

    png_bytep row_pointer = m_rowBuffer.get();
    png_read_row(m_png_ptr, row_pointer, NULL);

    writeRow(buffer);

    if (m_tempBuffer && m_y == ly) {
      m_tempBuffer.reset();
    }
  }

  int skipLines(int lineCount) override {
    for (int i = 0; i < lineCount; i++) {
      if (m_interlace_type == 1 &&
          m_info.m_lx > 4)  // pezza. Studiare il codice
      {
        int channels     = png_get_channels(m_png_ptr, m_info_ptr);
        char *lineBuffer = (char *)malloc(4 * m_info.m_lx * sizeof(char));
        readLine(lineBuffer, 0, m_info.m_lx - 1, 1);
        free(lineBuffer);
      } else {
        m_y++;
        png_bytep row_pointer = m_rowBuffer.get();
        png_read_row(m_png_ptr, row_pointer, NULL);
      }
    }
    return lineCount;
  }

  Tiio::RowOrder getRowOrder() const override { return Tiio::TOP2BOTTOM; }

  void writeRow(char *buffer) {
    if (m_color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
        m_color_type == PNG_COLOR_TYPE_GRAY_ALPHA ||
        m_color_type == PNG_COLOR_TYPE_PALETTE) { // PNG_COLOR_TYPE_PALETTE is expanded to RGBA
      if (m_bit_depth == 16) {
        TPixel32 *pix = (TPixel32 *)buffer;
        int i         = -2;
        for (int j = 0; j < m_info.m_lx; j++) {
#if defined(TNZ_MACHINE_CHANNEL_ORDER_MRGB)
          pix[j].m = m_rowBuffer[i = i + 2];
          pix[j].r = m_rowBuffer[i = i + 2];
          pix[j].g = m_rowBuffer[i = i + 2];
          pix[j].b = m_rowBuffer[i = i + 2];
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_RGBM)
          pix[j].r = m_rowBuffer[i = i + 2];
          pix[j].g = m_rowBuffer[i = i + 2];
          pix[j].b = m_rowBuffer[i = i + 2];
          pix[j].m = m_rowBuffer[i = i + 2];
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_BGRM)
          pix[j].b = m_rowBuffer[i = i + 2];
          pix[j].g = m_rowBuffer[i = i + 2];
          pix[j].r = m_rowBuffer[i = i + 2];
          pix[j].m = m_rowBuffer[i = i + 2];
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_MBGR)
          pix[j].m = m_rowBuffer[i = i + 2];
          pix[j].b = m_rowBuffer[i = i + 2];
          pix[j].g = m_rowBuffer[i = i + 2];
          pix[j].r = m_rowBuffer[i = i + 2];
#else
#error "unknown channel order"
#endif
        }
      } else {
        TPixel32 *pix = (TPixel32 *)buffer;
        int i         = 0;
        for (int j = 0; j < m_info.m_lx; j++) {
#if defined(TNZ_MACHINE_CHANNEL_ORDER_MRGB)
          pix[j].m = m_rowBuffer[i++];
          pix[j].r = m_rowBuffer[i++];
          pix[j].g = m_rowBuffer[i++];
          pix[j].b = m_rowBuffer[i++];
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_RGBM)
          pix[j].r                 = m_rowBuffer[i++];
          pix[j].g                 = m_rowBuffer[i++];
          pix[j].b                 = m_rowBuffer[i++];
          pix[j].m                 = m_rowBuffer[i++];
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_BGRM)
          pix[j].b                 = m_rowBuffer[i++];
          pix[j].g                 = m_rowBuffer[i++];
          pix[j].r                 = m_rowBuffer[i++];
          pix[j].m                 = m_rowBuffer[i++];
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_MBGR)
          pix[j].m                 = m_rowBuffer[i++];
          pix[j].b                 = m_rowBuffer[i++];
          pix[j].g                 = m_rowBuffer[i++];
          pix[j].r                 = m_rowBuffer[i++];
#else
#error "unknown channel order"
#endif
        }
      }
    } else  // qui gestisce RGB senza alpha.
    {       // grayscale e' gestito come RGB perche' si usa png_set_gray_to_rgb
      if (m_bit_depth == 16) {
        TPixel32 *pix = (TPixel32 *)buffer;
        int i         = -2;
        for (int j = 0; j < m_info.m_lx; j++) {
#if defined(TNZ_MACHINE_CHANNEL_ORDER_MRGB) ||                                 \
    defined(TNZ_MACHINE_CHANNEL_ORDER_RGBM)
          pix[j].r = m_rowBuffer[i = i + 2];
          pix[j].g = m_rowBuffer[i = i + 2];
          pix[j].b = m_rowBuffer[i = i + 2];
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_MBGR) ||                               \
    defined(TNZ_MACHINE_CHANNEL_ORDER_BGRM)
          pix[j].b = m_rowBuffer[i = i + 2];
          pix[j].g = m_rowBuffer[i = i + 2];
          pix[j].r = m_rowBuffer[i = i + 2];
#else
#error "unknown channel order"
#endif
          pix[j].m = 255;
        }
      } else {
        TPixel32 *pix = (TPixel32 *)buffer;
        int i         = 0;
        for (int j = 0; j < m_info.m_lx; j++) {
#if defined(TNZ_MACHINE_CHANNEL_ORDER_MRGB) ||                                 \
    defined(TNZ_MACHINE_CHANNEL_ORDER_RGBM)
          pix[j].r = m_rowBuffer[i++];
          pix[j].g = m_rowBuffer[i++];
          pix[j].b = m_rowBuffer[i++];
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_MBGR) ||                               \
    defined(TNZ_MACHINE_CHANNEL_ORDER_BGRM)
          pix[j].b                 = m_rowBuffer[i++];
          pix[j].g                 = m_rowBuffer[i++];
          pix[j].r                 = m_rowBuffer[i++];
#else
#error "unknown channel order"
#endif
          pix[j].m = 255;
        }
      }
    }
  }

  void writeRow(short *buffer) {
    if (m_color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
        m_color_type == PNG_COLOR_TYPE_GRAY_ALPHA ||
        m_color_type == PNG_COLOR_TYPE_PALETTE) {  // PNG_COLOR_TYPE_PALETTE is expanded to RGBA
      TPixel64 *pix = (TPixel64 *)buffer;
      int i         = -2;  // 0;
      for (int j = 0; j < m_info.m_lx; j++) {
#if defined(TNZ_MACHINE_CHANNEL_ORDER_MRGB) ||                                 \
    defined(TNZ_MACHINE_CHANNEL_ORDER_RGBM)
        pix[j].r = mySwap(m_rowBuffer[i = i + 2]);  // i++
        pix[j].g = mySwap(m_rowBuffer[i = i + 2]);
        pix[j].b = mySwap(m_rowBuffer[i = i + 2]);
        pix[j].m = mySwap(m_rowBuffer[i = i + 2]);
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_MBGR) ||                               \
    defined(TNZ_MACHINE_CHANNEL_ORDER_BGRM)
        pix[j].b = mySwap(m_rowBuffer[i = i + 2]);  // i++
        pix[j].g = mySwap(m_rowBuffer[i = i + 2]);
        pix[j].r = mySwap(m_rowBuffer[i = i + 2]);
        pix[j].m = mySwap(m_rowBuffer[i = i + 2]);
#else
#error "unknown channel order"
#endif
        // pix[j].m = 255;
      }
    } else  // qui gestisce RGB senza alpha.
    {       // grayscale e' gestito come RGB perche' si usa png_set_gray_to_rgb
      TPixel64 *pix = (TPixel64 *)buffer;
      int i         = -2;
      for (int j = 0; j < m_info.m_lx; j++) {
#if defined(TNZ_MACHINE_CHANNEL_ORDER_MRGB) ||                                 \
    defined(TNZ_MACHINE_CHANNEL_ORDER_RGBM)
        pix[j].r = mySwap(m_rowBuffer[i = i + 2]);
        pix[j].g = mySwap(m_rowBuffer[i = i + 2]);
        pix[j].b = mySwap(m_rowBuffer[i = i + 2]);
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_MBGR) ||                               \
    defined(TNZ_MACHINE_CHANNEL_ORDER_BGRM)
        pix[j].b = mySwap(m_rowBuffer[i = i + 2]);
        pix[j].g = mySwap(m_rowBuffer[i = i + 2]);
        pix[j].r = mySwap(m_rowBuffer[i = i + 2]);
#else
#error "unknown channel order"
#endif
        pix[j].m = mySwap(255);
      }
    }
  }

  void copyPixel(int count, int dstX, int dstDx, int dstY) {
    int channels = png_get_channels(m_png_ptr, m_info_ptr);
    int rowBytes = png_get_rowbytes(m_png_ptr, m_info_ptr);
    int lx       = m_info.m_lx;

    if ((channels == 4 || channels == 3) && m_bit_depth == 16) {
      for (int i = 0; i < count; i += 2) {
        for (int j = 0; j < channels * 2; j++) {
          (m_tempBuffer.get() +
           (dstY * rowBytes))[(i * dstDx + dstX) * channels + j] =
              m_rowBuffer[i * channels + j];
        }
      }
    } else if (channels == 2 && m_bit_depth == 16) {
      for (int i = 0; i < count; i += 2) {
        for (int j = 0; j < 4 * 2; j++) {
          (m_tempBuffer.get() +
           (dstY * rowBytes * 4))[(i * dstDx + dstX) * 4 + j] =
              m_rowBuffer[i * 4 + j];
        }
      }
    } else if (channels == 1 && m_bit_depth == 16) {
      for (int i = 0; i < count; i += 2) {
        for (int j = 0; j < 3 * 2; j++) {
          (m_tempBuffer.get() +
           (dstY * rowBytes * 4))[(i * dstDx + dstX) * 3 + j] =
              m_rowBuffer[i * 3 + j];
        }
      }
    } else if (channels == 1 && m_bit_depth == 8) {
      for (int i = 0; i < count; i++) {
        for (int j = 0; j < 3; j++) {
          (m_tempBuffer.get() +
           (dstY * rowBytes * 4))[(i * dstDx + dstX) * 3 + j] =
              m_rowBuffer[i * 3 + j];
        }
      }
    } else if (channels == 2 && m_bit_depth == 8) {
      for (int i = 0; i < count; i++) {
        for (int j = 0; j < 4; j++) {
          (m_tempBuffer.get() +
           (dstY * rowBytes * 4))[(i * dstDx + dstX) * 4 + j] =
              m_rowBuffer[i * 4 + j];
        }
      }
    } else if ((channels == 1 || channels == 2) && m_bit_depth < 8) {
      for (int i = 0; i < count; i++) {
        for (int j = 0; j < 3; j++) {
          (m_tempBuffer.get() + (dstY * lx * 3))[(i * dstDx + dstX) * 3 + j] =
              m_rowBuffer[i * 3 + j];
        }
      }
    } else {
      for (int i = 0; i < count; i++) {
        for (int j = 0; j < channels; j++) {
          (m_tempBuffer.get() +
           (dstY * rowBytes))[(i * dstDx + dstX) * channels + j] =
              m_rowBuffer[i * channels + j];
        }
      }
    }
  }

  void readLineInterlace(char *buffer, int x0, int x1, int shrink) {
    // m_png_ptr->row_number è l'indice di riga che scorre quando chiamo la
    // png_read_row
    int rowNumber = png_get_current_row_number(m_png_ptr);
    // numRows è il numero di righe processate in ogni passo
    int numRows = (int)png_get_image_height(m_png_ptr, m_info_ptr) / 8;

    int passPng = png_get_current_pass_number(m_png_ptr);

    int passRow = 5 + (m_y & 1);  // passo desiderato per la riga corrente

    int channels = png_get_channels(m_png_ptr, m_info_ptr);

    int rowBytes          = png_get_rowbytes(m_png_ptr, m_info_ptr);
    png_bytep row_pointer = m_rowBuffer.get();

    int lx = m_info.m_lx;

    while (passPng <= passRow &&
           rowNumber <=
               numRows)  // finchè il passo d'interlacciamento è minore o uguale
    // <             //del passo desiderato effettua tante volte le lettura
    // della riga
    // quant'è il passo desiderato per quella riga
    {
      rowNumber = png_get_current_row_number(m_png_ptr);
      png_read_row(m_png_ptr, row_pointer, NULL);
      numRows = png_get_image_height(m_png_ptr, m_info_ptr);
      // devo memorizzare la riga letta nel buffer di appoggio in base al passo
      // di riga
      // e al blocchetto di appartenenza della riga

      // copio i pixel che desidero nel buffer temporaneo

      // il membro di PngReader copyPixel deve tener conto della riga processata
      // e del passo che si è effettuato ( e in base a quello so quanti pixel
      // copiare!)

      if (m_bit_depth == 16) {
        if (passPng == 0)
          copyPixel(lx / 4, 0, 8, rowNumber * 8);
        else if (passPng == 1)
          copyPixel(lx / 4, 8, 8, rowNumber * 8);
        else if (passPng == 2)
          copyPixel(lx / 2, 0, 4, rowNumber * 8 + 4);
        else if (passPng == 3)
          copyPixel(lx / 2, 4, 4, rowNumber * 4);
        else if (passPng == 4)
          copyPixel(lx, 0, 2, rowNumber * 4 + 2);
        else if (passPng == 5)
          copyPixel(lx, 2, 2, rowNumber * 2);
        else if (passPng == 6)
          copyPixel(2 * lx, 0, 1, rowNumber * 2 + 1);
      } else {
        if (passPng == 0)
          copyPixel((lx + 7) / 8, 0, 8, rowNumber * 8);
        else if (passPng == 1)
          copyPixel((lx + 3) / 8, 4, 8, rowNumber * 8);
        else if (passPng == 2)
          copyPixel((lx + 3) / 4, 0, 4, rowNumber * 8 + 4);
        else if (passPng == 3)
          copyPixel((lx + 1) / 4, 2, 4, rowNumber * 4);
        else if (passPng == 4)
          copyPixel((lx + 1) / 2, 0, 2, rowNumber * 4 + 2);
        else if (passPng == 5)
          copyPixel(lx / 2, 1, 2, rowNumber * 2);
        else if (passPng == 6)
          copyPixel(lx, 0, 1, rowNumber * 2 + 1);
      }

      passPng = png_get_current_pass_number(m_png_ptr);
    }

    // fase di copia
    if (channels == 1 || channels == 2) {
      if (m_bit_depth < 8)
        memcpy(m_rowBuffer.get(), m_tempBuffer.get() + ((m_y)*lx * 3), lx * 3);
      else
        memcpy(m_rowBuffer.get(), m_tempBuffer.get() + ((m_y)*rowBytes * 4),
               rowBytes * 4);
    } else {
      memcpy(m_rowBuffer.get(), m_tempBuffer.get() + ((m_y)*rowBytes),
             rowBytes);
    }

    // fase di copia vecchia
    // memcpy(m_rowBuffer, m_tempBuffer+((m_y)*rowBytes), rowBytes);

    // tutto quello che segue lo metto in una funzione in cui scrivo il buffer
    // di restituzione della readLine
    //è una funzione comune alle ReadLine
    writeRow(buffer);
  }

  void readLineInterlace(short *buffer, int x0, int x1, int shrink) {
    // m_png_ptr->row_number è l'indice di riga che scorre quando chiamo la
    // png_read_row
    int rowNumber = png_get_current_row_number(m_png_ptr);
    // numRows è il numero di righe processate in ogni passo
    int numRows = png_get_image_height(m_png_ptr, m_info_ptr) / 8;

    int passPng = png_get_current_pass_number(
        m_png_ptr);  // conosco il passo d'interlacciamento

    int passRow = 5 + (m_y & 1);  // passo desiderato per la riga corrente

    int channels = png_get_channels(m_png_ptr, m_info_ptr);
    int lx       = m_info.m_lx;

    int rowBytes          = png_get_rowbytes(m_png_ptr, m_info_ptr);
    png_bytep row_pointer = m_rowBuffer.get();

    while (passPng <= passRow &&
           rowNumber <
               numRows)  // finchè il passo d'interlacciamento è minore o uguale
    // del passo desiderato effettua tante volte le lettura della riga
    // quant'è il passo desiderato per quella riga
    {
      rowNumber = png_get_current_row_number(m_png_ptr);
      png_read_row(m_png_ptr, row_pointer, NULL);
      numRows = png_get_image_height(m_png_ptr, m_info_ptr);
      int lx  = m_info.m_lx;

      // devo memorizzare la riga letta nel buffer di appoggio in base al passo
      // di riga
      // e al blocchetto di appartenenza della riga

      // copio i pixel che desidero nel buffer temporaneo

      // il membro di PngReader copyPixel deve tener conto della riga processata
      // e del passo che si è effettuato ( e in base a quello so quanti pixel
      // copiare!)

      int channels = png_get_channels(m_png_ptr, m_info_ptr);

      if (passPng == 0)
        copyPixel(lx / 4, 0, 8, rowNumber * 8);
      else if (passPng == 1)
        copyPixel(lx / 4, 8, 8, rowNumber * 8);
      else if (passPng == 2)
        copyPixel(lx / 2, 0, 4, rowNumber * 8 + 4);
      else if (passPng == 3)
        copyPixel(lx / 2, 4, 4, rowNumber * 4);
      else if (passPng == 4)
        copyPixel(lx, 0, 2, rowNumber * 4 + 2);
      else if (passPng == 5)
        copyPixel(lx, 2, 2, rowNumber * 2);
      else if (passPng == 6)
        copyPixel(2 * lx, 0, 1, rowNumber * 2 + 1);

      passPng = png_get_current_pass_number(m_png_ptr);
    }

    // fase di copia
    if (channels == 1 || channels == 2) {
      memcpy(m_rowBuffer.get(), m_tempBuffer.get() + ((m_y)*rowBytes * 4),
             rowBytes * 4);
    } else {
      memcpy(m_rowBuffer.get(), m_tempBuffer.get() + ((m_y)*rowBytes),
             rowBytes);
    }

    // fase di copia
    // memcpy(m_rowBuffer, m_tempBuffer+((m_y)*rowBytes), rowBytes);

    // tutto quello che segue lo metto in una funzione in cui scrivo il buffer
    // di restituzione della readLine
    //è una funzione comune alle ReadLine
    writeRow(buffer);
  }
};

//=========================================================

Tiio::PngWriterProperties::PngWriterProperties()
    : m_matte("Alpha Channel", true)

{
  bind(m_matte);
}

void Tiio::PngWriterProperties::updateTranslation() {
  m_matte.setQStringName(tr("Alpha Channel"));
}

//=========================================================

class PngWriter final : public Tiio::Writer {
  png_structp m_png_ptr;
  png_infop m_info_ptr;
  FILE *m_chan;
  bool m_matte;
  std::vector<TPixel> *m_colormap;

public:
  PngWriter();
  ~PngWriter();

  void open(FILE *file, const TImageInfo &info) override;
  void writeLine(char *buffer) override;
  void writeLine(short *buffer) override;

  Tiio::RowOrder getRowOrder() const override { return Tiio::TOP2BOTTOM; }

  void flush() override;

  bool write64bitSupported() const override { return true; }
  // m_matte is set to "Alpha Channel" property value in the function open()
  bool writeAlphaSupported() const override { return m_matte; };
};

//---------------------------------------------------------

PngWriter::PngWriter()
    : m_png_ptr(0), m_info_ptr(0), m_matte(true), m_colormap(0) {}

//---------------------------------------------------------

PngWriter::~PngWriter() {
  if (m_png_ptr) {
    png_destroy_write_struct(&m_png_ptr, &m_info_ptr);
  }
  if (m_chan) {
    fflush(m_chan);
    m_chan = 0;
  }
}

//---------------------------------------------------------

png_color palette[256];
png_byte alpha[1];

void PngWriter::open(FILE *file, const TImageInfo &info) {
  m_info    = info;
  m_png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
                                      (png_voidp)0,  // user_error_ptr,
                                      0,             // user_error_fn,
                                      0);            // user_warning_fn);
  if (!m_png_ptr) return;
  m_info_ptr = png_create_info_struct(m_png_ptr);
  if (!m_info_ptr) {
    png_destroy_write_struct(&m_png_ptr, (png_infopp)0);
    return;
  }

  m_chan = file;
  png_init_io(m_png_ptr, m_chan);

  if (!m_properties) m_properties = new Tiio::PngWriterProperties();

  TBoolProperty *alphaProp =
      (TBoolProperty *)(m_properties->getProperty("Alpha Channel"));
  TPointerProperty *colormap =
      (TPointerProperty *)(m_properties->getProperty("Colormap"));
  m_matte = (alphaProp && alphaProp->getValue()) ? true : false;
  if (colormap) m_colormap = (vector<TPixel> *)colormap->getValue();

  TUINT32 x_pixels_per_meter = tround(m_info.m_dpix / 0.0254);
  TUINT32 y_pixels_per_meter = tround(m_info.m_dpiy / 0.0254);

  if (!m_colormap)
    png_set_IHDR(m_png_ptr, m_info_ptr, m_info.m_lx, m_info.m_ly,
                 info.m_bitsPerSample,
                 m_matte ? PNG_COLOR_TYPE_RGB_ALPHA : PNG_COLOR_TYPE_RGB,
                 PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT,
                 PNG_FILTER_TYPE_DEFAULT);
  else {
    png_set_IHDR(m_png_ptr, m_info_ptr, m_info.m_lx, m_info.m_ly, 8,
                 PNG_COLOR_TYPE_PALETTE, PNG_INTERLACE_NONE,
                 PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
    for (unsigned int i = 0; i < m_colormap->size(); i++) {
      /*unsigned char red = (i>>5)&0x7;
      unsigned char green = (i>>2)&0x7;
      unsigned char blue = i&0x3;
      palette[i].red = (red>>1) | (red<<2) | (red<<5);
      palette[i].green = (green>>1) | (green<<2) | (green<<5);
      palette[i].blue = blue | (blue<<2) | (blue<<4) | (blue<<6);
      if (red==0 && green==0) alpha[i] = 0; else if (blue==0 && green==0)
      alpha[i] = 128; else alpha[i] = 255;*/
      palette[i].red   = (*m_colormap)[i].r;
      palette[i].green = (*m_colormap)[i].g;
      palette[i].blue  = (*m_colormap)[i].b;
    }

    png_set_PLTE(m_png_ptr, m_info_ptr, palette, m_colormap->size());
  }

// png_set_dither(m_png_ptr, palette, 256, 256, 0, 1);

#if defined(TNZ_MACHINE_CHANNEL_ORDER_MBGR)
  png_set_bgr(m_png_ptr);
  png_set_swap_alpha(m_png_ptr);
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_BGRM)
  png_set_bgr(m_png_ptr);
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_MRGB)
  png_set_swap_alpha(m_png_ptr);
#elif !defined(TNZ_MACHINE_CHANNEL_ORDER_RGBM)
#error "unknownchannel order"
#endif

  png_write_info(m_png_ptr, m_info_ptr);
  png_set_pHYs(m_png_ptr, m_info_ptr, x_pixels_per_meter, y_pixels_per_meter,
               1);

  if (m_colormap && m_matte) {
    alpha[0] = 0;
    // png_set_tRNS(m_png_ptr, m_info_ptr, alpha, 1, PNG_COLOR_TYPE_PALETTE);
    png_color_16 bgcolor;
    bgcolor.index = 0;
    png_set_tRNS(m_png_ptr, m_info_ptr, alpha, 1, &bgcolor);
  }
}

//---------------------------------------------------------

void PngWriter::flush() {
  png_write_end(m_png_ptr, m_info_ptr);
  fflush(m_chan);
}

//---------------------------------------------------------

void PngWriter::writeLine(short *buffer) {
  {
    TPixel64 *pix = (TPixel64 *)buffer;
    unsigned short *tmp;
    tmp = (unsigned short *)malloc((m_info.m_lx + 1) * 3);
    // unsigned short tmp[10000];
    int k = 0;
    for (int j = 0; j < m_info.m_lx; j++, pix++) {
      // depremultiply here
      TPixel64 depremult_pix(*pix);
      if (m_matte && depremult_pix.m != 0) depremult(depremult_pix);

#if defined(TNZ_MACHINE_CHANNEL_ORDER_MRGB) ||                                 \
    defined(TNZ_MACHINE_CHANNEL_ORDER_RGBM)
      tmp[k++] = mySwap(pix->r);
      tmp[k++] = mySwap(pix->g);
      tmp[k++] = mySwap(pix->b);
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_MBGR) ||                               \
    defined(TNZ_MACHINE_CHANNEL_ORDER_BGRM)
      tmp[k++] = mySwap(pix->b);
      tmp[k++] = mySwap(pix->g);
      tmp[k++] = mySwap(pix->r);
#else
#error "unknown channel order"
#endif
      if (m_matte)
        tmp[k++] = mySwap(pix->m);  // ?? does it take care MRGB or MBGR case?
    }
    png_write_row(m_png_ptr, (unsigned char *)tmp);
  }
}

//=========================================================

void PngWriter::writeLine(char *buffer) {
  // TBoolProperty* alphaProp =
  // (TBoolProperty*)(m_properties->getProperty("Alpha Channel"));
  if (m_matte || m_colormap) {
    unsigned char *tmp = new unsigned char[(m_info.m_lx + 1) * 4];
    TPixel32 *pix      = (TPixel32 *)buffer;
    int k              = 0;
    for (int j = 0; j < m_info.m_lx; j++, pix++) {
      // depremultiply here
      TPixel32 depremult_pix(*pix);
      if (depremult_pix.m != 0) depremult(depremult_pix);
#if defined(TNZ_MACHINE_CHANNEL_ORDER_MRGB)
      tmp[k++] = depremult_pix.m;
      tmp[k++] = depremult_pix.r;
      tmp[k++] = depremult_pix.g;
      tmp[k++] = depremult_pix.b;
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_RGBM)
      tmp[k++] = depremult_pix.r;
      tmp[k++] = depremult_pix.g;
      tmp[k++] = depremult_pix.b;
      tmp[k++] = depremult_pix.m;
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_MBGR)
      tmp[k++] = depremult_pix.m;
      tmp[k++] = depremult_pix.b;
      tmp[k++] = depremult_pix.g;
      tmp[k++] = depremult_pix.r;
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_BGRM)
      tmp[k++]                     = depremult_pix.b;
      tmp[k++]                     = depremult_pix.g;
      tmp[k++]                     = depremult_pix.r;
      tmp[k++]                     = depremult_pix.m;
#else
#error "unknown channel order"
#endif
    }
    png_write_row(m_png_ptr, tmp);
    delete[] tmp;
  } else {
    TPixel32 *pix      = (TPixel32 *)buffer;
    unsigned char *tmp = new unsigned char[(m_info.m_lx + 1) * 3];

    int k = 0;
    for (int j = 0; j < m_info.m_lx; j++) {
// tmp = (pix->r&0xe0)|((pix->g&0xe0)>>3) | ((pix->b&0xc0)>>6);

#if defined(TNZ_MACHINE_CHANNEL_ORDER_MRGB) ||                                 \
    defined(TNZ_MACHINE_CHANNEL_ORDER_RGBM)
      tmp[k++] = pix->r;
      tmp[k++] = pix->g;
      tmp[k++] = pix->b;
#elif defined(TNZ_MACHINE_CHANNEL_ORDER_MBGR) ||                               \
    defined(TNZ_MACHINE_CHANNEL_ORDER_BGRM)
      tmp[k++] = pix->b;
      tmp[k++] = pix->g;
      tmp[k++] = pix->r;
#else
#error "unknown channel order"
#endif

      ++pix;
    }
    png_write_row(m_png_ptr, tmp);
    delete[] tmp;
  }
}

//=========================================================

Tiio::Reader *Tiio::makePngReader() { return new PngReader(); }

Tiio::Writer *Tiio::makePngWriter() { return new PngWriter(); }