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Convert writer_png to C++; add Writer class; add PNGWriter class

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Eryn Wells 2013-09-10 21:01:29 -07:00
parent 568e3f4c55
commit 5d8a940f30
4 changed files with 58 additions and 26 deletions
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124
src/writer_png.c
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@ -1,124 +0,0 @@
/* writer_png.c
*
* Definition of the PNG writer.
*
* Eryn Wells <eryn@erynwells.me>
*/
#include <setjmp.h>
#include <stdlib.h>
#include <png.h>
#include "writer_png.h"
static void png_user_error(png_structp png, png_const_charp msg);
static void png_user_warning(png_structp png, png_const_charp msg);
/*
* write_scene_png --
*
* Write the given scene to file in PNG format.
*/
int
write_scene_png(Scene *scene, FILE *file)
{
if (!scene->is_rendered) {
return -1;
}
if (!file) {
return -2;
}
// Set up the PNG data structures. libpng requires two: a PNG object and an info object.
png_structp png = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, png_user_error, png_user_warning);
if (!png) {
return -3;
}
png_infop png_info = png_create_info_struct(png);
if (!png_info) {
return -4;
}
// Set up libpng error handling. If an error occurs, libpng will longjmp back here... (Wat.)
if (setjmp(png_jmpbuf(png))) {
png_destroy_write_struct(&png, &png_info);
return -5;
}
/*
* Tell libpng about basic parameters for the image:
* - 8 bit depth
* - RGB (no alpha)
* - No interlacing
* - No compression
*/
png_set_IHDR(png, png_info,
scene->width, scene->height,
8, PNG_COLOR_TYPE_RGB,
PNG_INTERLACE_NONE,
PNG_COMPRESSION_TYPE_DEFAULT,
PNG_FILTER_TYPE_DEFAULT);
// Set up output.
png_init_io(png, file);
// Write header information.
png_write_info(png, png_info);
// Write it!
int nbytes = 0;
for (int y = 0; y < scene->height; y++) {
png_byte *row = malloc(png_sizeof(png_byte) * scene->width * 3);
if (row == NULL) {
// TODO: DANGER! WILL ROBINSON!
}
for (int x = 0; x < scene->width; x++) {
row[x*3+0] = scene->pixels[y * scene->width + x].red;
row[x*3+1] = scene->pixels[y * scene->width + x].green;
row[x*3+2] = scene->pixels[y * scene->width + x].blue;
nbytes += 3;
}
png_write_row(png, row);
free(row);
}
// Clean up!
png_write_end(png, png_info);
png_destroy_write_struct(&png, &png_info);
// Return number of bytes written.
return nbytes;
}
/*
* png_user_error --
*
* Called by libpng when it encounters an error.
*/
/* static */ void
png_user_error(png_structp png,
png_const_charp msg)
{
}
/*
* png_user_warning --
*
* Called by libpng when it encounters an warning.
*/
/* static */ void
png_user_warning(png_structp png,
png_const_charp msg)
{
}