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// Copyright 2009-2020 Intel Corporation
// SPDX-License-Identifier: Apache-2.0
#ifdef EMBREE_TUTORIALS_LIBPNG
#include "image.h"
#include <iostream>
#include <cstring>
#include <cstdio>
#include <png.h>
namespace embree
{
struct AutoCloseFile
{
FILE* file;
AutoCloseFile (FILE* file) : file(file) {}
~AutoCloseFile () { if (file) fclose(file); }
};
/*! read PNG file from disk */
Ref<Image> loadPNG(const FileName& fileName)
{
size_t width, height;
//header for testing if it is a png
png_byte header[8];
//open file as binary
FILE* fp = fopen(fileName.c_str(), "rb");
if (!fp) THROW_RUNTIME_ERROR("cannot open file "+fileName.str());
//ON_SCOPE_EXIT(fclose(fp));
AutoCloseFile close_file(fp);
//read the header
if (fread(header, 1, 8, fp) != 8)
THROW_RUNTIME_ERROR("invalid PNG file "+fileName.str());
//test if png
int is_png = !png_sig_cmp(header, 0, 8);
if (!is_png)
THROW_RUNTIME_ERROR("invalid PNG file "+fileName.str());
//create png struct
png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
if (!png_ptr) THROW_RUNTIME_ERROR("invalid PNG file "+fileName.str());
ON_SCOPE_EXIT(png_destroy_read_struct(&png_ptr, (png_infopp) nullptr, (png_infopp) nullptr));
//create png info struct
png_infop info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
THROW_RUNTIME_ERROR("invalid PNG file "+fileName.str());
//create png info struct
png_infop end_info = png_create_info_struct(png_ptr);
if (!end_info)
THROW_RUNTIME_ERROR("invalid PNG file "+fileName.str());
//png error stuff, not sure libpng man suggests this.
//if (setjmp(png_jmpbuf(png_ptr))) {
/// return (TEXTURE_LOAD_ERROR);
//}
//init png reading
png_init_io(png_ptr, fp);
//let libpng know you already read the first 8 bytes
png_set_sig_bytes(png_ptr, 8);
// read all the info up to the image data
png_read_info(png_ptr, info_ptr);
//variables to pass to get info
int bit_depth, color_type;
png_uint_32 twidth, theight;
// get info about png
png_get_IHDR(png_ptr, info_ptr, &twidth, &theight, &bit_depth, &color_type,
nullptr, nullptr, nullptr);
//update width and height based on png info
width = twidth;
height = theight;
Ref<Image> img = new Image4uc(width,height,fileName);
// Update the png info struct.
png_read_update_info(png_ptr, info_ptr);
// Row size in bytes.
int rowbytes = png_get_rowbytes(png_ptr, info_ptr);
// Allocate the image_data as a big block, to be given to opengl
std::vector<png_byte> data(rowbytes * height);
// row_pointers is for pointing to image_data for reading the png with libpng
std::vector<png_bytep> row_pointers(height);
// set the individual row_pointers to point at the correct offsets of image_data
for (size_t i = 0; i < height; ++i)
row_pointers[i] = (unsigned char*) &data[i * rowbytes];
// read the png into image_data through row_pointers
png_read_image(png_ptr, row_pointers.data());
if (color_type == PNG_COLOR_TYPE_RGB && bit_depth == 8)
{
for (size_t y=0;y<height;y++)
for (size_t x=0;x<width;x++)
{
unsigned char* texel = data.data() + (y * width + x) * 3;
Color4 c( (float)texel[0] * 1.0f/255.0f, (float)texel[1] * 1.0f/255.0f, (float)texel[2] * 1.0f/255.0f, 0.0f );
img.ptr->set(x,y,c);
}
}
else if (color_type == PNG_COLOR_TYPE_RGBA && bit_depth == 8)
{
for (size_t y=0;y<height;y++)
for (size_t x=0;x<width;x++)
{
unsigned char *texel = data.data() + (y * width + x) * 4;
Color4 c( (float)texel[0] * 1.0f/255.0f, (float)texel[1] * 1.0f/255.0f, (float)texel[2] * 1.0f/255.0f, (float)texel[3] * 1.0f/255.0f );
img.ptr->set(x,y,c);
}
}
else
THROW_RUNTIME_ERROR("invalid color type in PNG file "+fileName.str());
return img;
}
}
#endif
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