unsigned getFilterTypes(std::vector<unsigned char>& filterTypes, const std::vector<unsigned char>& png)
{
std::vector<std::vector<unsigned char> > passes;
unsigned error = getFilterTypesInterlaced(passes, png);
if(error) return error;
if(passes.size() == 1)
{
filterTypes.swap(passes[0]);
}
else
{
lodepng::State state;
unsigned w, h;
lodepng_inspect(&w, &h, &state, &png[0], png.size());
/*
Interlaced. Simplify it: put pass 6 and 7 alternating in the one vector so
that one filter per scanline of the uninterlaced image is given, with that
filter corresponding the closest to what it would be for non-interlaced
image.
*/
for(size_t i = 0; i < h; i++)
{
filterTypes.push_back(i % 2 == 0 ? passes[5][i / 2] : passes[6][i / 2]);
}
}
return 0; /* OK */
}
SDL_Surface *TCOD_sys_read_png(const char *filename) {
unsigned error;
unsigned char* image;
unsigned width, height, y, bpp;
unsigned char* png;
size_t pngsize;
LodePNGState state;
SDL_Surface *bitmap;
unsigned char *source;
unsigned int rowsize;
lodepng_state_init(&state);
/*optionally customize the state*/
if (!TCOD_sys_read_file(filename,&png,&pngsize)) return NULL;
lodepng_inspect(&width,&height,&state, png, pngsize);
bpp=lodepng_get_bpp(&state.info_png.color);
if ( bpp == 24 ) {
/* don't convert to 32 bits because libtcod's 24bits renderer is faster */
state.info_raw.colortype=LCT_RGB;
} else if ( bpp != 24 && bpp != 32 ) {
/* paletted png. convert to 24 bits */
state.info_raw.colortype=LCT_RGB;
state.info_raw.bitdepth=8;
bpp=24;
}
error = lodepng_decode(&image, &width, &height, &state, png, pngsize);
free(png);
if(error) {
printf("error %u: %s\n", error, lodepng_error_text(error));
lodepng_state_cleanup(&state);
return NULL;
}
/* create the SDL surface */
bitmap=TCOD_sys_get_surface(width,height,bpp==32);
source=image;
rowsize=width*bpp/8;
for (y=0; y< height; y++ ) {
Uint8 *row_pointer=(Uint8 *)(bitmap->pixels) + y * bitmap->pitch;
memcpy(row_pointer,source,rowsize);
source+=rowsize;
}
lodepng_state_cleanup(&state);
free(image);
return bitmap;
}
/*
Show the filtertypes of each scanline in this PNG image.
*/
void displayFilterTypes(const std::vector<unsigned char>& buffer, bool ignore_checksums)
{
//Get color type and interlace type
lodepng::State state;
if(ignore_checksums)
{
state.decoder.ignore_crc = 1;
state.decoder.zlibsettings.ignore_adler32 = 1;
}
unsigned w, h;
unsigned error;
error = lodepng_inspect(&w, &h, &state, &buffer[0], buffer.size());
if(error)
{
std::cout << "inspect error " << error << ": " << lodepng_error_text(error) << std::endl;
return;
}
if(state.info_png.interlace_method == 1)
{
std::cout << "showing filtertypes for interlaced PNG not supported by this example" << std::endl;
return;
}
//Read literal data from all IDAT chunks
const unsigned char *chunk, *begin, *end, *next;
end = &buffer.back() + 1;
begin = chunk = &buffer.front() + 8;
std::vector<unsigned char> zdata;
while(chunk + 8 < end && chunk >= begin)
{
char type[5];
lodepng_chunk_type(type, chunk);
if(std::string(type).size() != 4)
{
std::cout << "this is probably not a PNG" << std::endl;
return;
}
if(std::string(type) == "IDAT")
{
const unsigned char* cdata = lodepng_chunk_data_const(chunk);
unsigned clength = lodepng_chunk_length(chunk);
if(chunk + clength + 12 > end || clength > buffer.size() || chunk + clength + 12 < begin) {
std::cout << "invalid chunk length" << std::endl;
return;
}
for(unsigned i = 0; i < clength; i++)
{
zdata.push_back(cdata[i]);
}
}
next = lodepng_chunk_next_const(chunk);
if (next <= chunk) break; // integer overflow
chunk = next;
}
//Decompress all IDAT data
std::vector<unsigned char> data;
error = lodepng::decompress(data, &zdata[0], zdata.size());
if(error)
{
std::cout << "decompress error " << error << ": " << lodepng_error_text(error) << std::endl;
return;
}
//A line is 1 filter byte + all pixels
size_t linebytes = 1 + lodepng_get_raw_size(w, 1, &state.info_png.color);
if(linebytes == 0)
{
std::cout << "error: linebytes is 0" << std::endl;
return;
}
std::cout << "Filter types: ";
for(size_t i = 0; i < data.size(); i += linebytes)
{
std::cout << (int)(data[i]) << " ";
}
std::cout << std::endl;
}
unsigned getFilterTypesInterlaced(std::vector<std::vector<unsigned char> >& filterTypes,
const std::vector<unsigned char>& png)
{
//Get color type and interlace type
lodepng::State state;
unsigned w, h;
unsigned error;
error = lodepng_inspect(&w, &h, &state, &png[0], png.size());
if(error) return 1;
//Read literal data from all IDAT chunks
const unsigned char *chunk, *begin, *end, *next;
end = &png.back() + 1;
begin = chunk = &png.front() + 8;
std::vector<unsigned char> zdata;
while(chunk + 8 < end && chunk >= begin)
{
char type[5];
lodepng_chunk_type(type, chunk);
if(std::string(type).size() != 4) return 1; //Probably not a PNG file
if(std::string(type) == "IDAT")
{
const unsigned char* cdata = lodepng_chunk_data_const(chunk);
unsigned clength = lodepng_chunk_length(chunk);
if(chunk + clength + 12 > end || clength > png.size() || chunk + clength + 12 < begin) {
// corrupt chunk length
return 1;
}
for(unsigned i = 0; i < clength; i++)
{
zdata.push_back(cdata[i]);
}
}
next = lodepng_chunk_next_const(chunk);
if (next <= chunk) return 1; // integer overflow
chunk = next;
}
//Decompress all IDAT data
std::vector<unsigned char> data;
error = lodepng::decompress(data, &zdata[0], zdata.size());
if(error) return 1;
if(state.info_png.interlace_method == 0)
{
filterTypes.resize(1);
//A line is 1 filter byte + all pixels
size_t linebytes = 1 + lodepng_get_raw_size(w, 1, &state.info_png.color);
for(size_t i = 0; i < data.size(); i += linebytes)
{
filterTypes[0].push_back(data[i]);
}
}
else
{
//Interlaced
filterTypes.resize(7);
static const unsigned ADAM7_IX[7] = { 0, 4, 0, 2, 0, 1, 0 }; /*x start values*/
static const unsigned ADAM7_IY[7] = { 0, 0, 4, 0, 2, 0, 1 }; /*y start values*/
static const unsigned ADAM7_DX[7] = { 8, 8, 4, 4, 2, 2, 1 }; /*x delta values*/
static const unsigned ADAM7_DY[7] = { 8, 8, 8, 4, 4, 2, 2 }; /*y delta values*/
size_t pos = 0;
for(size_t j = 0; j < 7; j++)
{
unsigned w2 = (w - ADAM7_IX[j] + ADAM7_DX[j] - 1) / ADAM7_DX[j];
unsigned h2 = (h - ADAM7_IY[j] + ADAM7_DY[j] - 1) / ADAM7_DY[j];
if(ADAM7_IX[j] >= w || ADAM7_IY[j] >= h) w2 = h2 = 0;
size_t linebytes = 1 + lodepng_get_raw_size(w2, 1, &state.info_png.color);
for(size_t i = 0; i < h2; i++)
{
filterTypes[j].push_back(data[pos]);
pos += linebytes;
}
}
}
return 0; /* OK */
}
