132 lines
2.9 KiB
C++
132 lines
2.9 KiB
C++
/* writer_png.c
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*
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* Definition of the PNG writer.
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*
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* Eryn Wells <eryn@erynwells.me>
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*/
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#include <csetjmp>
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#include <cstdlib>
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#include <string>
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#include "scene.h"
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#include "writer_png.h"
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extern "C" {
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#include <png.h>
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}
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static void png_user_error(png_structp png, png_const_charp msg);
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static void png_user_warning(png_structp png, png_const_charp msg);
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/*
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* PNGWriter::write_scene --
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*
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* Write the given scene to a file in PNG format.
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*/
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int
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PNGWriter::write_scene(const Scene &scene, const std::string &filename)
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{
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if (!scene.is_rendered()) {
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return -1;
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}
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FILE *file = fopen(filename.c_str(), "wb");
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if (!file) {
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return -1;
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}
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// Set up the PNG data structures. libpng requires two: a PNG object and an info object.
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png_structp png = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, png_user_error, png_user_warning);
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if (!png) {
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return -3;
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}
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png_infop png_info = png_create_info_struct(png);
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if (!png_info) {
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return -4;
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}
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// Set up libpng error handling. If an error occurs, libpng will longjmp back here... (Wat.)
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if (setjmp(png_jmpbuf(png))) {
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png_destroy_write_struct(&png, &png_info);
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return -5;
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}
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/*
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* Tell libpng about basic parameters for the image:
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* - 8 bit depth
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* - RGB (no alpha)
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* - No interlacing
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* - No compression
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*/
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png_set_IHDR(png, png_info,
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scene.get_width(), scene.get_height(),
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8, PNG_COLOR_TYPE_RGB,
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PNG_INTERLACE_NONE,
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PNG_COMPRESSION_TYPE_DEFAULT,
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PNG_FILTER_TYPE_DEFAULT);
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// Set up output.
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png_init_io(png, file);
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// Write header information.
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png_write_info(png, png_info);
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// Write it!
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const Color *pixels = scene.get_pixels();
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png_byte *row = NULL;
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int nbytes = 0;
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for (int y = 0; y < scene.get_height(); y++) {
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row = new png_byte[scene.get_width() * 3];
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if (row == NULL) {
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// TODO: DANGER! WILL ROBINSON!
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}
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for (int x = 0; x < scene.get_width(); x++) {
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Color c = pixels[y * scene.get_width() + x];
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row[x*3+0] = 0xff * c.red;
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row[x*3+1] = 0xff * c.green;
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row[x*3+2] = 0xff * c.blue;
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nbytes += 3;
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}
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png_write_row(png, row);
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delete[] row;
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}
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// Clean up!
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png_write_end(png, png_info);
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png_destroy_write_struct(&png, &png_info);
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// Return number of bytes written.
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return nbytes;
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}
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/*
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* png_user_error --
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*
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* Called by libpng when it encounters an error.
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*/
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/* static */ void
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png_user_error(png_structp png,
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png_const_charp msg)
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{
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}
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/*
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* png_user_warning --
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*
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* Called by libpng when it encounters an warning.
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*/
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/* static */ void
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png_user_warning(png_structp png,
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png_const_charp msg)
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{
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}
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