mapnik/include/mapnik/png_io.hpp
2012-02-22 22:46:35 +00:00

561 lines
19 KiB
C++

/*****************************************************************************
*
* This file is part of Mapnik (c++ mapping toolkit)
*
* Copyright (C) 2011 Artem Pavlenko
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*****************************************************************************/
#ifndef MAPNIK_PNG_IO_HPP
#define MAPNIK_PNG_IO_HPP
// mapnik
#include <mapnik/global.hpp>
#include <mapnik/palette.hpp>
#include <mapnik/octree.hpp>
#include <mapnik/hextree.hpp>
// zlib
#include <zlib.h>
extern "C"
{
#include <png.h>
}
#define MAX_OCTREE_LEVELS 4
namespace mapnik {
template <typename T>
void write_data (png_structp png_ptr, png_bytep data, png_size_t length)
{
T * out = static_cast<T*>(png_get_io_ptr(png_ptr));
out->write(reinterpret_cast<char*>(data), length);
}
template <typename T>
void flush_data (png_structp png_ptr)
{
T * out = static_cast<T*>(png_get_io_ptr(png_ptr));
out->flush();
}
template <typename T1, typename T2>
void save_as_png(T1 & file , T2 const& image, int compression = Z_DEFAULT_COMPRESSION, int strategy = Z_DEFAULT_STRATEGY)
{
png_voidp error_ptr=0;
png_structp png_ptr=png_create_write_struct(PNG_LIBPNG_VER_STRING,
error_ptr,0, 0);
if (!png_ptr) return;
// switch on optimization only if supported
#if defined(PNG_LIBPNG_VER) && (PNG_LIBPNG_VER >= 10200) && defined(PNG_MMX_CODE_SUPPORTED)
png_uint_32 mask, flags;
flags = png_get_asm_flags(png_ptr);
mask = png_get_asm_flagmask(PNG_SELECT_READ | PNG_SELECT_WRITE);
png_set_asm_flags(png_ptr, flags | mask);
#endif
png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE, PNG_FILTER_NONE);
png_infop info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
{
png_destroy_write_struct(&png_ptr,(png_infopp)0);
return;
}
jmp_buf* jmp_context = (jmp_buf*) png_get_error_ptr(png_ptr);
if (jmp_context)
{
png_destroy_write_struct(&png_ptr, &info_ptr);
return;
}
png_set_write_fn (png_ptr, &file, &write_data<T1>, &flush_data<T1>);
png_set_compression_level(png_ptr, compression);
png_set_compression_strategy(png_ptr, strategy);
png_set_compression_buffer_size(png_ptr, 32768);
png_set_IHDR(png_ptr, info_ptr,image.width(),image.height(),8,
PNG_COLOR_TYPE_RGB_ALPHA,PNG_INTERLACE_NONE,
PNG_COMPRESSION_TYPE_DEFAULT,PNG_FILTER_TYPE_DEFAULT);
png_write_info(png_ptr, info_ptr);
for (unsigned i=0;i<image.height();i++)
{
png_write_row(png_ptr,(png_bytep)image.getRow(i));
}
png_write_end(png_ptr, info_ptr);
png_destroy_write_struct(&png_ptr, &info_ptr);
}
template <typename T>
void reduce_8 (T const& in, image_data_8 & out, octree<rgb> trees[], unsigned limits[], unsigned levels, std::vector<unsigned> & alpha)
{
unsigned width = in.width();
unsigned height = in.height();
//unsigned alphaCount[alpha.size()];
std::vector<unsigned> alphaCount(alpha.size());
for(unsigned i=0; i<alpha.size(); i++)
{
alpha[i] = 0;
alphaCount[i] = 0;
}
for (unsigned y = 0; y < height; ++y)
{
mapnik::image_data_32::pixel_type const * row = in.getRow(y);
mapnik::image_data_8::pixel_type * row_out = out.getRow(y);
for (unsigned x = 0; x < width; ++x)
{
unsigned val = row[x];
mapnik::rgb c(U2RED(val), U2GREEN(val), U2BLUE(val));
byte index = 0;
int idx = -1;
for(int j=levels-1; j>0; j--){
if (U2ALPHA(val)>=limits[j] && trees[j].colors()>0) {
index = idx = trees[j].quantize(c);
break;
}
}
if (idx>=0 && idx<(int)alpha.size())
{
alpha[idx]+=U2ALPHA(val);
alphaCount[idx]++;
}
row_out[x] = index;
}
}
for(unsigned i=0; i<alpha.size(); i++)
{
if (alphaCount[i]!=0)
alpha[i] /= alphaCount[i];
}
}
template <typename T>
void reduce_4 (T const& in, image_data_8 & out, octree<rgb> trees[], unsigned limits[], unsigned levels, std::vector<unsigned> & alpha)
{
unsigned width = in.width();
unsigned height = in.height();
//unsigned alphaCount[alpha.size()];
std::vector<unsigned> alphaCount(alpha.size());
for(unsigned i=0; i<alpha.size(); i++)
{
alpha[i] = 0;
alphaCount[i] = 0;
}
for (unsigned y = 0; y < height; ++y)
{
mapnik::image_data_32::pixel_type const * row = in.getRow(y);
mapnik::image_data_8::pixel_type * row_out = out.getRow(y);
for (unsigned x = 0; x < width; ++x)
{
unsigned val = row[x];
mapnik::rgb c(U2RED(val), U2GREEN(val), U2BLUE(val));
byte index = 0;
int idx=-1;
for(int j=levels-1; j>0; j--){
if (U2ALPHA(val)>=limits[j] && trees[j].colors()>0) {
index = idx = trees[j].quantize(c);
break;
}
}
if (idx>=0 && idx<(int)alpha.size())
{
alpha[idx]+=U2ALPHA(val);
alphaCount[idx]++;
}
if (x%2 == 0) index = index<<4;
row_out[x>>1] |= index;
}
}
for(unsigned i=0; i<alpha.size(); i++)
{
if (alphaCount[i]!=0)
alpha[i] /= alphaCount[i];
}
}
// 1-bit but only one color.
template <typename T>
void reduce_1(T const&, image_data_8 & out, octree<rgb> /*trees*/[], unsigned /*limits*/[], std::vector<unsigned> & /*alpha*/)
{
out.set(0); // only one color!!!
}
template <typename T>
void save_as_png(T & file, std::vector<mapnik::rgb> const& palette,
mapnik::image_data_8 const& image,
unsigned width,
unsigned height,
unsigned color_depth,
int compression,
int strategy,
std::vector<unsigned> const&alpha)
{
png_voidp error_ptr=0;
png_structp png_ptr=png_create_write_struct(PNG_LIBPNG_VER_STRING,
error_ptr,0, 0);
if (!png_ptr) return;
// switch on optimization only if supported
#if defined(PNG_LIBPNG_VER) && (PNG_LIBPNG_VER >= 10200) && defined(PNG_MMX_CODE_SUPPORTED)
png_uint_32 mask, flags;
flags = png_get_asm_flags(png_ptr);
mask = png_get_asm_flagmask(PNG_SELECT_READ | PNG_SELECT_WRITE);
png_set_asm_flags(png_ptr, flags | mask);
#endif
png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE, PNG_FILTER_NONE);
png_infop info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
{
png_destroy_write_struct(&png_ptr,(png_infopp)0);
return;
}
jmp_buf* jmp_context = (jmp_buf*) png_get_error_ptr(png_ptr);
if (jmp_context)
{
png_destroy_write_struct(&png_ptr, &info_ptr);
return;
}
png_set_write_fn (png_ptr, &file, &write_data<T>, &flush_data<T>);
png_set_compression_level(png_ptr, compression);
png_set_compression_strategy(png_ptr, strategy);
png_set_compression_buffer_size(png_ptr, 32768);
png_set_IHDR(png_ptr, info_ptr,width,height,color_depth,
PNG_COLOR_TYPE_PALETTE,PNG_INTERLACE_NONE,
PNG_COMPRESSION_TYPE_DEFAULT,PNG_FILTER_TYPE_DEFAULT);
png_color* pal = const_cast<png_color*>(reinterpret_cast<const png_color*>(&palette[0]));
png_set_PLTE(png_ptr, info_ptr, pal, palette.size());
// make transparent lowest indexes, so tRNS is small
if (alpha.size()>0)
{
std::vector<png_byte> trans(alpha.size());
unsigned alphaSize=0;//truncate to nonopaque values
for(unsigned i=0; i < alpha.size(); i++)
{
trans[i]=alpha[i];
if (alpha[i]<255)
alphaSize = i+1;
}
if (alphaSize>0)
png_set_tRNS(png_ptr, info_ptr, (png_bytep)&trans[0], alphaSize, 0);
}
png_write_info(png_ptr, info_ptr);
for (unsigned i=0;i<height;i++)
{
png_write_row(png_ptr,(png_bytep)image.getRow(i));
}
png_write_end(png_ptr, info_ptr);
png_destroy_write_struct(&png_ptr, &info_ptr);
}
template <typename T1,typename T2>
void save_as_png8_oct(T1 & file, T2 const& image, const unsigned max_colors = 256,
int compression = Z_DEFAULT_COMPRESSION, int strategy = Z_DEFAULT_STRATEGY, int trans_mode = -1)
{
// number of alpha ranges in png8 format; 2 results in smallest image with binary transparency
// 3 is minimum for semitransparency, 4 is recommended, anything else is worse
const unsigned TRANSPARENCY_LEVELS = (trans_mode==2||trans_mode<0)?MAX_OCTREE_LEVELS:2;
unsigned width = image.width();
unsigned height = image.height();
unsigned alphaHist[256];//transparency histogram
unsigned semiCount = 0;//sum of semitransparent pixels
unsigned meanAlpha = 0;
for(int i=0; i<256; i++){
alphaHist[i] = 0;
}
for (unsigned y = 0; y < height; ++y){
for (unsigned x = 0; x < width; ++x){
unsigned val = U2ALPHA((unsigned)image.getRow(y)[x]);
if (trans_mode==0)
val=255;
alphaHist[val]++;
meanAlpha += val;
if (val>0 && val<255)
semiCount++;
}
}
meanAlpha /= width*height;
// transparency ranges division points
unsigned limits[MAX_OCTREE_LEVELS+1];
limits[0] = 0;
limits[1] = (alphaHist[0]>0)?1:0;
limits[TRANSPARENCY_LEVELS] = 256;
unsigned alphaHistSum = 0;
for(unsigned j=1; j<TRANSPARENCY_LEVELS; j++)
limits[j] = limits[1];
for(unsigned i=1; i<256; i++){
alphaHistSum += alphaHist[i];
for(unsigned j=1; j<TRANSPARENCY_LEVELS; j++){
if (alphaHistSum<semiCount*(j)/4)
limits[j] = i;
}
}
// avoid too wide full transparent range
if (limits[1]>256/(TRANSPARENCY_LEVELS-1))
limits[1]=256/(TRANSPARENCY_LEVELS-1);
// avoid too wide full opaque range
if (limits[TRANSPARENCY_LEVELS-1]<212)
limits[TRANSPARENCY_LEVELS-1]=212;
if (TRANSPARENCY_LEVELS==2) {
limits[1]=127;
}
// estimated number of colors from palette assigned to chosen ranges
unsigned cols[MAX_OCTREE_LEVELS];
// count colors
for(unsigned j=1; j<=TRANSPARENCY_LEVELS; j++) {
cols[j-1] = 0;
for(unsigned i=limits[j-1]; i<limits[j]; i++){
cols[j-1] += alphaHist[i];
}
}
unsigned divCoef = width*height-cols[0];
if (divCoef==0) divCoef = 1;
cols[0] = cols[0]>0?1:0; // fully transparent color (one or not at all)
if (max_colors>=64) {
// give chance less populated but not empty cols to have at least few colors(12)
unsigned minCols = (12+1)*divCoef/(max_colors-cols[0]);
for(unsigned j=1; j<TRANSPARENCY_LEVELS; j++) if (cols[j]>12 && cols[j]<minCols) {
divCoef += minCols-cols[j];
cols[j] = minCols;
}
}
unsigned usedColors = cols[0];
for(unsigned j=1; j<TRANSPARENCY_LEVELS-1; j++){
cols[j] = cols[j]*(max_colors-cols[0])/divCoef;
usedColors += cols[j];
}
// use rest for most opaque group of pixels
cols[TRANSPARENCY_LEVELS-1] = max_colors-usedColors;
//no transparency
if (trans_mode == 0)
{
limits[1] = 0;
cols[0] = 0;
cols[1] = max_colors;
}
// octree table for separate alpha range with 1-based index (0 is fully transparent: no color)
octree<rgb> trees[MAX_OCTREE_LEVELS];
for(unsigned j=1; j<TRANSPARENCY_LEVELS; j++)
trees[j].setMaxColors(cols[j]);
for (unsigned y = 0; y < height; ++y)
{
typename T2::pixel_type const * row = image.getRow(y);
for (unsigned x = 0; x < width; ++x)
{
unsigned val = row[x];
// insert to proper tree based on alpha range
for(unsigned j=TRANSPARENCY_LEVELS-1; j>0; j--){
if (cols[j]>0 && U2ALPHA(val)>=limits[j]) {
trees[j].insert(mapnik::rgb(U2RED(val), U2GREEN(val), U2BLUE(val)));
break;
}
}
}
}
unsigned leftovers = 0;
std::vector<rgb> palette;
palette.reserve(max_colors);
if (cols[0])
palette.push_back(rgb(0,0,0));
for(unsigned j=1; j<TRANSPARENCY_LEVELS; j++) {
if (cols[j]>0) {
if (leftovers>0) {
cols[j] += leftovers;
trees[j].setMaxColors(cols[j]);
leftovers = 0;
}
std::vector<rgb> pal;
trees[j].setOffset(palette.size());
trees[j].create_palette(pal);
assert(pal.size() <= max_colors);
leftovers = cols[j]-pal.size();
cols[j] = pal.size();
for(unsigned i=0; i<pal.size(); i++){
palette.push_back(pal[i]);
}
assert(palette.size() <= 256);
}
}
//transparency values per palette index
std::vector<unsigned> alphaTable;
//alphaTable.resize(palette.size());//allow semitransparency also in almost opaque range
if (trans_mode != 0)
alphaTable.resize(palette.size() - cols[TRANSPARENCY_LEVELS-1]);
if (palette.size() > 16 )
{
// >16 && <=256 colors -> write 8-bit color depth
image_data_8 reduced_image(width,height);
reduce_8(image, reduced_image, trees, limits, TRANSPARENCY_LEVELS, alphaTable);
save_as_png(file,palette,reduced_image,width,height,8,compression,strategy,alphaTable);
}
else if (palette.size() == 1)
{
// 1 color image -> write 1-bit color depth PNG
unsigned image_width = width > 7 ? (int(0.125*width) + 1)&~1 : 1;
unsigned image_height = height;
image_data_8 reduced_image(image_width,image_height);
reduce_1(image,reduced_image,trees, limits, alphaTable);
if (meanAlpha<255 && cols[0]==0) {
alphaTable.resize(1);
alphaTable[0] = meanAlpha;
}
save_as_png(file,palette,reduced_image,width,height,1,compression,strategy,alphaTable);
}
else
{
// <=16 colors -> write 4-bit color depth PNG
unsigned image_width = width > 3 ? (int(0.5*width) + 3)&~3 : 4;
unsigned image_height = height;
image_data_8 reduced_image(image_width,image_height);
reduce_4(image, reduced_image, trees, limits, TRANSPARENCY_LEVELS, alphaTable);
save_as_png(file,palette,reduced_image,width,height,4,compression,strategy,alphaTable);
}
}
template <typename T1, typename T2, typename T3>
void save_as_png8(T1 & file, T2 const& image, T3 const & tree,
std::vector<mapnik::rgb> const& palette, std::vector<unsigned> const& alphaTable,
int compression = Z_DEFAULT_COMPRESSION, int strategy = Z_DEFAULT_STRATEGY)
{
unsigned width = image.width();
unsigned height = image.height();
if (palette.size() > 16 )
{
// >16 && <=256 colors -> write 8-bit color depth
image_data_8 reduced_image(width, height);
for (unsigned y = 0; y < height; ++y)
{
mapnik::image_data_32::pixel_type const * row = image.getRow(y);
mapnik::image_data_8::pixel_type * row_out = reduced_image.getRow(y);
for (unsigned x = 0; x < width; ++x)
{
row_out[x] = tree.quantize(row[x]);
}
}
save_as_png(file, palette, reduced_image, width, height, 8, compression, strategy, alphaTable);
}
else if (palette.size() == 1)
{
// 1 color image -> write 1-bit color depth PNG
unsigned image_width = width > 7 ? (int(0.125*width) + 1)&~1 : 1;
unsigned image_height = height;
image_data_8 reduced_image(image_width, image_height);
reduced_image.set(0);
save_as_png(file, palette, reduced_image, width, height, 1, compression, strategy, alphaTable);
}
else
{
// <=16 colors -> write 4-bit color depth PNG
unsigned image_width = width > 3 ? (int(0.5*width) + 3)&~3 : 4;
unsigned image_height = height;
image_data_8 reduced_image(image_width, image_height);
for (unsigned y = 0; y < height; ++y)
{
mapnik::image_data_32::pixel_type const * row = image.getRow(y);
mapnik::image_data_8::pixel_type * row_out = reduced_image.getRow(y);
byte index = 0;
for (unsigned x = 0; x < width; ++x)
{
index = tree.quantize(row[x]);
if (x%2 == 0) index = index<<4;
row_out[x>>1] |= index;
}
}
save_as_png(file, palette, reduced_image, width, height, 4, compression, strategy, alphaTable);
}
}
template <typename T1,typename T2>
void save_as_png8_hex(T1 & file, T2 const& image, int colors = 256,
int compression = Z_DEFAULT_COMPRESSION, int strategy = Z_DEFAULT_STRATEGY,
int trans_mode = -1, double gamma = 2.0)
{
unsigned width = image.width();
unsigned height = image.height();
// structure for color quantization
hextree<mapnik::rgba> tree(colors);
if (trans_mode >= 0)
tree.setTransMode(trans_mode);
if (gamma > 0)
tree.setGamma(gamma);
for (unsigned y = 0; y < height; ++y)
{
typename T2::pixel_type const * row = image.getRow(y);
for (unsigned x = 0; x < width; ++x)
{
unsigned val = row[x];
tree.insert(mapnik::rgba(U2RED(val), U2GREEN(val), U2BLUE(val), U2ALPHA(val)));
}
}
//transparency values per palette index
std::vector<mapnik::rgba> pal;
tree.create_palette(pal);
assert(int(pal.size()) <= colors);
std::vector<mapnik::rgb> palette;
std::vector<unsigned> alphaTable;
for(unsigned i=0; i<pal.size(); i++)
{
palette.push_back(rgb(pal[i].r, pal[i].g, pal[i].b));
alphaTable.push_back(pal[i].a);
}
save_as_png8<T1, T2, hextree<mapnik::rgba> >(file, image, tree, palette, alphaTable, compression, strategy);
}
template <typename T1, typename T2>
void save_as_png8_pal(T1 & file, T2 const& image, rgba_palette const& pal,
int compression = Z_DEFAULT_COMPRESSION, int strategy = Z_DEFAULT_STRATEGY)
{
save_as_png8<T1, T2, rgba_palette>(file, image, pal, pal.palette(), pal.alphaTable(), compression, strategy);
}
}
#endif // MAPNIK_PNG_IO_HPP