image.cpp

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/******************************************************************************
 *
 * Copyright (C) 1997-2022 by Dimitri van Heesch.
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation under the terms of the GNU General Public License is hereby
 * granted. No representations are made about the suitability of this software
 * for any purpose. It is provided "as is" without express or implied warranty.
 * See the GNU General Public License for more details.
 *
 * Documents produced by Doxygen are derivative works derived from the
 * input used in their production; they are not affected by this license.
 *
 */
 
// own header
#include "image.h"
 
// standard includes
#include <cmath>
#include <memory>
#include <vector>
 
// other includes
#include "lodepng.h"
#include "config.h"
 
typedef unsigned char  Byte;
 
/** Helper struct representing a RGBA color */
struct Color
{
  Byte red;
  Byte green;
  Byte blue;
  Byte alpha;
};
 
const int charSetWidth=80;
const int charHeight=12;
const int numChars=96;
 
const unsigned short charPos[numChars]    =
  {
      0,  5,  8, 13, 20, 27, 38, 47,
     50, 54, 58, 65, 72, 76, 83, 87,
     91, 98,105,112,119,126,133,140,
    147,154,161,164,167,174,181,188,
    195,207,216,224,233,242,250,258,
    267,276,279,286,294,301,312,321,
    331,339,349,357,365,372,380,389,
    400,409,418,427,430,434,437,443,
    450,453,460,467,474,481,488,492,
    499,506,509,512,518,521,530,537,
    544,551,557,562,568,571,578,585,
    594,600,607,613,617,620,624,631
  };
 
const unsigned char charWidth[numChars] =
  {
     5, 3, 5, 7, 7,11, 9, 3,
     4, 4, 7, 7, 4, 7, 4, 4,
 
     7, 7, 7, 7, 7, 7, 7, 7,
     7, 7, 3, 3, 7, 7, 7, 7,
    12, 9, 8, 9, 9, 8, 8, 9,
     9, 3, 7, 8, 7,11, 9,10,
     8,10, 8, 8, 7, 8, 9,11,
     9, 9, 9, 3, 4, 3, 6, 7,
     3, 7, 7, 7, 7, 7, 4, 7,
     7, 3, 3, 6, 3, 9, 7, 7,
     7, 6, 5, 6, 3, 7, 7, 9,
     6, 7, 6, 4, 3, 4, 7, 5
  };
 
const unsigned char fontRaw[charSetWidth*charHeight] = {
  0x02, 0x50, 0x01, 0x06, 0x20, 0x60, 0xc6, 0x04, 0x00, 0x00, 0x00, 0x27,
  0x04, 0x1c, 0x38, 0x11, 0xf1, 0xc7, 0xc7, 0x0e, 0x00, 0x00, 0x00, 0x03,
  0x81, 0xf0, 0x10, 0x7c, 0x1e, 0x3e, 0x1f, 0x9f, 0x87, 0x88, 0x24, 0x09,
  0x09, 0x02, 0x02, 0x41, 0x0f, 0x0f, 0x83, 0xc3, 0xe1, 0xe7, 0xf4, 0x24,
  0x12, 0x22, 0x41, 0x20, 0x9f, 0xce, 0x30, 0x00, 0x10, 0x04, 0x00, 0x01,
  0x00, 0x30, 0x08, 0x12, 0x41, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40,
  0x00, 0x00, 0x00, 0x00, 0x01, 0xac, 0x00, 0x00, 0x02, 0x51, 0x43, 0x89,
  0x40, 0x90, 0x49, 0x15, 0x00, 0x00, 0x00, 0x28, 0x9c, 0x22, 0x44, 0x31,
  0x02, 0x20, 0x48, 0x91, 0x00, 0x00, 0x00, 0x04, 0x46, 0x08, 0x28, 0x42,
  0x21, 0x21, 0x10, 0x10, 0x08, 0x48, 0x24, 0x09, 0x11, 0x03, 0x06, 0x61,
  0x10, 0x88, 0x44, 0x22, 0x12, 0x10, 0x84, 0x24, 0x12, 0x22, 0x22, 0x20,
  0x80, 0x4a, 0x11, 0x00, 0x20, 0x04, 0x00, 0x01, 0x00, 0x40, 0x08, 0x00,
  0x41, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00,
  0x02, 0x22, 0x00, 0x00, 0x02, 0x51, 0x45, 0x49, 0x40, 0x90, 0x89, 0x0a,
  0x00, 0x00, 0x00, 0x48, 0x84, 0x02, 0x04, 0x51, 0x02, 0x00, 0x88, 0x91,
  0x00, 0x00, 0x00, 0x04, 0x44, 0xd4, 0x28, 0x42, 0x40, 0x20, 0x90, 0x10,
  0x10, 0x08, 0x24, 0x09, 0x21, 0x03, 0x06, 0x51, 0x20, 0x48, 0x48, 0x12,
  0x12, 0x00, 0x84, 0x22, 0x22, 0x22, 0x22, 0x11, 0x00, 0x89, 0x12, 0x80,
  0x31, 0xc5, 0x87, 0x0d, 0x1c, 0xe3, 0x4b, 0x12, 0x49, 0x29, 0x16, 0x1c,
  0x58, 0x69, 0x4c, 0xe8, 0x91, 0x44, 0x61, 0x44, 0xf2, 0x22, 0x00, 0x00,
  0x02, 0x07, 0xe5, 0x06, 0x80, 0x60, 0x10, 0x95, 0x08, 0x00, 0x00, 0x48,
  0x84, 0x04, 0x18, 0x51, 0xe2, 0xc0, 0x87, 0x11, 0x24, 0x18, 0x03, 0x00,
  0x89, 0x24, 0x44, 0x42, 0x40, 0x20, 0x90, 0x10, 0x10, 0x08, 0x24, 0x09,
  0x41, 0x02, 0x8a, 0x51, 0x20, 0x48, 0x48, 0x12, 0x11, 0x80, 0x84, 0x22,
  0x21, 0x24, 0x14, 0x11, 0x01, 0x09, 0x14, 0x40, 0x02, 0x26, 0x48, 0x93,
  0x22, 0x44, 0xcc, 0x92, 0x51, 0x36, 0x99, 0x22, 0x64, 0x99, 0x92, 0x48,
  0x91, 0x44, 0x52, 0x44, 0x12, 0x22, 0x00, 0x00, 0x02, 0x01, 0x43, 0x80,
  0x80, 0xa0, 0x10, 0x84, 0x08, 0x00, 0x00, 0x88, 0x84, 0x08, 0x04, 0x90,
  0x13, 0x21, 0x08, 0x8f, 0x00, 0x61, 0xf0, 0xc0, 0x8a, 0x24, 0x44, 0x7c,
  0x40, 0x20, 0x9f, 0x9f, 0x11, 0xcf, 0xe4, 0x09, 0xc1, 0x02, 0x8a, 0x49,
  0x20, 0x4f, 0x88, 0x13, 0xe0, 0x60, 0x84, 0x22, 0x21, 0x54, 0x08, 0x0a,
  0x02, 0x08, 0x90, 0x00, 0x00, 0x24, 0x48, 0x11, 0x22, 0x44, 0x48, 0x92,
  0x61, 0x24, 0x91, 0x22, 0x44, 0x89, 0x10, 0x48, 0x91, 0x24, 0x8c, 0x44,
  0x22, 0x22, 0x64, 0x00, 0x02, 0x07, 0xe1, 0x41, 0x31, 0x14, 0x10, 0x80,
  0x3e, 0x07, 0xc0, 0x88, 0x84, 0x10, 0x05, 0x10, 0x12, 0x21, 0x08, 0x81,
  0x01, 0x80, 0x00, 0x31, 0x0a, 0x24, 0x7c, 0x42, 0x40, 0x20, 0x90, 0x10,
  0x10, 0x48, 0x24, 0x09, 0x21, 0x02, 0x52, 0x45, 0x20, 0x48, 0x08, 0x92,
  0x20, 0x10, 0x84, 0x21, 0x41, 0x54, 0x14, 0x04, 0x04, 0x08, 0x90, 0x00,
  0x01, 0xe4, 0x48, 0x11, 0x3e, 0x44, 0x48, 0x92, 0x61, 0x24, 0x91, 0x22,
  0x44, 0x89, 0x0c, 0x48, 0x8a, 0x24, 0x8c, 0x48, 0x44, 0x21, 0x98, 0x00,
  0x02, 0x02, 0x85, 0x41, 0x49, 0x08, 0x10, 0x80, 0x08, 0x00, 0x00, 0x88,
  0x84, 0x20, 0x45, 0xf9, 0x12, 0x21, 0x08, 0x81, 0x00, 0x61, 0xf0, 0xc1,
  0x0a, 0x68, 0x82, 0x42, 0x40, 0x20, 0x90, 0x10, 0x10, 0x48, 0x24, 0x89,
  0x11, 0x02, 0x52, 0x45, 0x20, 0x48, 0x08, 0x52, 0x12, 0x10, 0x84, 0x21,
  0x40, 0x88, 0x22, 0x04, 0x08, 0x08, 0x90, 0x00, 0x02, 0x24, 0x48, 0x11,
  0x20, 0x44, 0x48, 0x92, 0x51, 0x24, 0x91, 0x22, 0x44, 0x89, 0x02, 0x48,
  0x8a, 0x2a, 0x92, 0x28, 0x42, 0x22, 0x00, 0x00, 0x00, 0x02, 0x85, 0x41,
  0x49, 0x18, 0x10, 0x80, 0x08, 0x00, 0x01, 0x08, 0x84, 0x20, 0x44, 0x11,
  0x12, 0x22, 0x08, 0x91, 0x00, 0x18, 0x03, 0x00, 0x09, 0xb0, 0x82, 0x42,
  0x21, 0x21, 0x10, 0x10, 0x08, 0xc8, 0x24, 0x89, 0x09, 0x02, 0x22, 0x43,
  0x10, 0x88, 0x04, 0x22, 0x12, 0x10, 0x84, 0x20, 0x80, 0x88, 0x22, 0x04,
  0x10, 0x08, 0x50, 0x00, 0x02, 0x26, 0x48, 0x93, 0x22, 0x44, 0xc8, 0x92,
  0x49, 0x24, 0x91, 0x22, 0x64, 0x99, 0x12, 0x49, 0x84, 0x11, 0x21, 0x28,
  0x82, 0x22, 0x00, 0x00, 0x02, 0x02, 0x83, 0x82, 0x30, 0xe4, 0x10, 0x80,
  0x00, 0x20, 0x05, 0x07, 0x04, 0x3e, 0x38, 0x10, 0xe1, 0xc2, 0x07, 0x0e,
  0x24, 0x00, 0x00, 0x01, 0x04, 0x00, 0x82, 0x7c, 0x1e, 0x3e, 0x1f, 0x90,
  0x07, 0x48, 0x24, 0x71, 0x05, 0xf2, 0x22, 0x41, 0x0f, 0x08, 0x03, 0xd2,
  0x11, 0xe0, 0x83, 0xc0, 0x80, 0x88, 0x41, 0x04, 0x1f, 0xc8, 0x50, 0x00,
  0x01, 0xd5, 0x87, 0x0d, 0x1c, 0x43, 0x48, 0x92, 0x45, 0x24, 0x91, 0x1c,
  0x58, 0x69, 0x0c, 0x66, 0x84, 0x11, 0x21, 0x10, 0xf2, 0x22, 0x00, 0x00,
  0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x09, 0x00, 0x00, 0x20, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
  0x03, 0xe0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x08, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x40, 0x02, 0x00, 0x00, 0x00, 0x00, 0x40, 0x08, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x10, 0x02, 0x22, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x09, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x08, 0x10, 0x1f, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x04, 0x40, 0x02,
  0x00, 0x00, 0x00, 0x00, 0x40, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x20,
  0x02, 0x22, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x06, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0c, 0x30, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0x80, 0x04, 0x00, 0x00, 0x00, 0x00,
  0x40, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x01, 0xac, 0x00, 0x00
};
 
 
struct Image::Private
{
  uint32_t width;
  uint32_t height;
  std::vector<uint8_t> data;
  std::vector<Color> palette =
  {
    { 0xff, 0xff, 0xff, 0x00 },
    { 0x00, 0x00, 0x00, 0xff },
    { 0xff, 0xff, 0xc0, 0xff },
    { 0x9f, 0x9f, 0x60, 0xff },
    { 0xa7, 0x38, 0x30, 0xff },
    { 0x29, 0x70, 0x18, 0xff },
    { 0x97, 0xCC, 0xE8, 0xff },
    { 0xe0, 0xe0, 0xe0, 0xff },
    { 0xff, 0xff, 0xff, 0xff }
  };
};
 
Image::Image(uint32_t w,uint32_t h) : p(std::make_unique<Private>())
{
  int hue   = Config_getInt(HTML_COLORSTYLE_HUE);
  int sat   = Config_getInt(HTML_COLORSTYLE_SAT);
  int gamma = Config_getInt(HTML_COLORSTYLE_GAMMA);
 
  double red1=0.0 ,green1=0.0 ,blue1=0.0;
  double red2=0.0, green2=0.0, blue2=0.0;
 
  ColoredImage::hsl2rgb(hue/360.0,                  // hue
                        sat/255.0,                  // saturation
                        pow(235/255.0,gamma/100.0), // luma (gamma corrected)
                        &red1,&green1,&blue1
                       );
 
  ColoredImage::hsl2rgb(hue/360.0,                  // hue
                        sat/255.0,                  // saturation
                        pow(138/255.0,gamma/100.0), // luma (gamma corrected)
                        &red2,&green2,&blue2
                       );
 
  p->palette[2].red   = static_cast<Byte>(red1   * 255.0);
  p->palette[2].green = static_cast<Byte>(green1 * 255.0);
  p->palette[2].blue  = static_cast<Byte>(blue1  * 255.0);
 
  p->palette[3].red   = static_cast<Byte>(red2   * 255.0);
  p->palette[3].green = static_cast<Byte>(green2 * 255.0);
  p->palette[3].blue  = static_cast<Byte>(blue2  * 255.0);
 
  p->data.resize(w*h);
  p->width = w;
  p->height = h;
}
 
uint32_t Image::width() const  { return p->width; }
uint32_t Image::height() const { return p->height; }
 
Image::~Image() = default;
 
void Image::setPixel(uint32_t x,uint32_t y,uint8_t val)
{
  if (x<p->width && y<p->height) p->data[y*p->width+x] = val;
}
 
uint8_t Image::getPixel(uint32_t x,uint32_t y) const
{
  return (x<p->width && y<p->height) ? p->data[y*p->width+x] : 0;
}
 
void Image::writeChar(uint32_t x,uint32_t y,char c,uint8_t fg)
{
  if (c>=' ')
  {
    uint32_t ci=c-' ';
    uint32_t rowOffset=0;
    uint32_t cw = charWidth[ci];
    uint32_t cp = charPos[ci];
    for (uint32_t yf=0;yf<charHeight;yf++)
    {
      unsigned short bitPattern=0;
      uint32_t bitsLeft=cw;
      uint32_t byteOffset = rowOffset+(cp>>3);
      uint32_t bitOffset  = cp&7;
      // get the bit pattern for row yf of the character from the font data
      while (bitsLeft>0)
      {
        uint32_t bits=8-bitOffset;
        if (bits>bitsLeft) bits=bitsLeft;
        bitPattern<<=bits;
        bitPattern|=((fontRaw[byteOffset]<<bitOffset)&0xff)>>(8-bits);
        bitsLeft-=bits;
        bitOffset=0;
        byteOffset++;
      }
      if (cw>0 && cw<32)
      {
        uint32_t mask=(uint32_t)1<<(cw-1);
        // draw character row yf
        for (uint32_t xf=0;xf<cw;xf++)
        {
          setPixel(x+xf,y+yf,(bitPattern&mask) ? fg : getPixel(x+xf,y+yf));
          mask>>=1;
        }
        rowOffset+=charSetWidth;
      }
    }
  }
}
 
void Image::writeString(uint32_t x,uint32_t y,const DString &s,uint8_t fg)
{
  if (!s.empty())
  {
    const char *ps = s.data();
    char c = 0;
    while ((c=*ps++))
    {
      writeChar(x,y,c,fg);
      x+=charWidth[c-' '];
    }
  }
}
 
uint32_t Image::stringLength(const DString &s)
{
  uint32_t w=0;
  if (!s.empty())
  {
    const char *ps = s.data();
    char c = 0;
    while ((c=*ps++)) w+=charWidth[c-' '];
  }
  return w;
}
 
void Image::drawHorzLine(uint32_t y,uint32_t xs,uint32_t xe,uint8_t colIndex,uint32_t mask)
{
  uint32_t i=0,j=0;
  for (uint32_t x=xs;x<=xe;x++,j++)
  {
    if (j&1) i++;
    if (mask&(1<<(i&0x1f))) setPixel(x,y,colIndex);
  }
}
 
void Image::drawHorzArrow(uint32_t y,uint32_t xs,uint32_t xe,uint8_t colIndex,uint32_t mask)
{
  drawHorzLine(y,xs,xe,colIndex,mask);
  for (uint32_t i=0;i<6;i++)
  {
    uint32_t h=i>>1;
    drawVertLine(xe-i,y-h,y+h,colIndex,0xffffffff);
  }
}
 
void Image::drawVertLine(uint32_t x,uint32_t ys,uint32_t ye,uint8_t colIndex,uint32_t mask)
{
  uint32_t i=0;
  for (uint32_t y=ys;y<=ye;y++,i++)
  {
    if (mask&(1<<(i&0x1f))) setPixel(x,y,colIndex);
  }
}
 
void Image::drawVertArrow(uint32_t x,uint32_t ys,uint32_t ye,uint8_t colIndex,uint32_t mask)
{
  drawVertLine(x,ys,ye,colIndex,mask);
  for (uint32_t i=0;i<6;i++)
  {
    uint32_t h=i>>1;
    drawHorzLine(ys+i,x-h,x+h,colIndex,0xffffffff);
  }
}
 
void Image::drawRect(uint32_t x,uint32_t y,uint32_t w,uint32_t h,uint8_t colIndex,uint32_t mask)
{
  drawHorzLine(y,x,x+w-1,colIndex,mask);
  drawHorzLine(y+h-1,x,x+w-1,colIndex,mask);
  drawVertLine(x,y,y+h-1,colIndex,mask);
  drawVertLine(x+w-1,y,y+h-1,colIndex,mask);
}
 
void Image::fillRect(uint32_t x,uint32_t y,uint32_t width,uint32_t height,uint8_t colIndex,uint32_t mask)
{
  for (uint32_t yp=y,yi=0;yp<y+height;yp++,yi++)
    for (uint32_t xp=x,xi=0;xp<x+width;xp++,xi++)
      if (mask&(1<<((xi+yi)&0x1f)))
        setPixel(xp,yp,colIndex);
      else
        setPixel(xp,yp,8);
}
 
bool Image::save(const DString &fileName)
{
  uint8_t* buffer = nullptr;
  size_t bufferSize = 0;
  LodePNG_Encoder encoder;
  LodePNG_Encoder_init(&encoder);
  for (const auto &col : p->palette)
  {
    LodePNG_InfoColor_addPalette(&encoder.infoPng.color,
                                 col.red,col.green,col.blue,col.alpha);
  }
  encoder.infoPng.color.colorType = 3;
  encoder.infoRaw.color.colorType = 3;
  LodePNG_encode(&encoder, &buffer, &bufferSize, &p->data[0], p->width, p->height);
  LodePNG_saveFile(buffer, bufferSize, fileName.data());
  free(buffer);
  LodePNG_Encoder_cleanup(&encoder);
  return true;
}
 
//----------------------------------------------------------------
 
void ColoredImage::hsl2rgb(double h,double s,double l,
                         double *pRed,double *pGreen,double *pBlue)
{
  double r = l;   // default to gray
  double g = l;
  double b = l;
  double v = (l <= 0.5) ? (l * (1.0 + s)) : (l + s - l * s);
  if (v > 0)
  {
    double m       = l + l - v;
    double sv      = ( v - m ) / v;
    h      *= 6.0;
    int sextant = static_cast<int>(h);
    double fract   = h - sextant;
    double vsf     = v * sv * fract;
    double mid1    = m + vsf;
    double mid2    = v - vsf;
    switch (sextant)
    {
      case 0:
        r = v;
        g = mid1;
        b = m;
        break;
      case 1:
        r = mid2;
        g = v;
        b = m;
        break;
      case 2:
        r = m;
        g = v;
        b = mid1;
        break;
      case 3:
        r = m;
        g = mid2;
        b = v;
        break;
      case 4:
        r = mid1;
        g = m;
        b = v;
        break;
      case 5:
        r = v;
        g = m;
        b = mid2;
        break;
    }
  }
  *pRed   = r;
  *pGreen = g;
  *pBlue  = b;
}
 
struct ColoredImage::Private
{
  uint32_t width;
  uint32_t height;
  std::vector<uint8_t> data;
  bool hasAlpha;
};
 
ColoredImage::ColoredImage(uint32_t width,uint32_t height,
           const uint8_t *greyLevels,const uint8_t *alphaLevels,
           int saturation,int hue,int gamma) : p(std::make_unique<Private>())
{
  p->hasAlpha = alphaLevels!=nullptr;
  p->width    = width;
  p->height   = height;
  p->data.resize(width*height*4);
  for (uint32_t i=0;i<width*height;i++)
  {
    double red=0.0, green=0.0, blue=0.0;
    hsl2rgb(hue/360.0,                            // hue
            saturation/255.0,                     // saturation
            pow(greyLevels[i]/255.0,gamma/100.0), // luma (gamma corrected)
            &red,&green,&blue);
    Byte r = static_cast<Byte>(red  *255.0);
    Byte g = static_cast<Byte>(green*255.0);
    Byte b = static_cast<Byte>(blue *255.0);
    Byte a = alphaLevels ? alphaLevels[i] : 255;
    p->data[i*4+0]=r;
    p->data[i*4+1]=g;
    p->data[i*4+2]=b;
    p->data[i*4+3]=a;
  }
}
 
ColoredImage::~ColoredImage() = default;
 
bool ColoredImage::save(const DString &fileName)
{
  uint8_t *buffer = nullptr;
  size_t bufferSize = 0;
  LodePNG_Encoder encoder;
  LodePNG_Encoder_init(&encoder);
  encoder.infoPng.color.colorType = p->hasAlpha ? 6 : 2; // 2=RGB 24 bit, 6=RGBA 32 bit
  encoder.infoRaw.color.colorType = 6; // 6=RGBA 32 bit
  LodePNG_encode(&encoder, &buffer, &bufferSize, &p->data[0], p->width, p->height);
  LodePNG_saveFile(buffer, bufferSize, fileName.data());
  LodePNG_Encoder_cleanup(&encoder);
  free(buffer);
  return true;
}