108 lines
2.2 KiB
C++
108 lines
2.2 KiB
C++
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#include <png.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdarg.h>
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void abort_(const char * s, ...)
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{
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va_list args;
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va_start(args, s);
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vfprintf(stderr, s, args);
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fprintf(stderr, "\n");
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va_end(args);
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abort();
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}
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int main() {
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int w = 100;
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int h = 100;
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unsigned int *data = new unsigned int[ w * h ];
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// red fades toward bottom
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// green fades toward right
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unsigned int **rows = new unsigned int *[ h ];
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for( int y=0; y<h; y++ ) {
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for( int x=0; x<w; x++ ) {
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unsigned char red = 255 - ( 255 * y / h );
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unsigned char green = 255 - ( 255 * x / h );
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data[ y * w + x ] = red | green << 8 | 255 << 24;
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}
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rows[y] = &( data[ y * w ] );
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}
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/* create file */
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FILE *fp = fopen( "test.png", "wb");
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if (!fp)
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abort_("[write_png_file] File %s could not be opened for writing",
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"test.png" );
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png_structp png_ptr;
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png_infop info_ptr;
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/* initialize stuff */
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png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
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if (!png_ptr)
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abort_("[write_png_file] png_create_write_struct failed");
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info_ptr = png_create_info_struct(png_ptr);
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if (!info_ptr)
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abort_("[write_png_file] png_create_info_struct failed");
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if (setjmp(png_jmpbuf(png_ptr)))
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abort_("[write_png_file] Error during init_io");
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png_init_io(png_ptr, fp);
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/* write header */
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if (setjmp(png_jmpbuf(png_ptr)))
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abort_("[write_png_file] Error during writing header");
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png_set_IHDR(png_ptr, info_ptr, w, h,
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8, PNG_COLOR_TYPE_RGB_ALPHA, PNG_INTERLACE_NONE,
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PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
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png_write_info(png_ptr, info_ptr);
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/* write bytes */
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if (setjmp(png_jmpbuf(png_ptr)))
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abort_("[write_png_file] Error during writing bytes");
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png_write_image(png_ptr, (png_byte**)rows);
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/* end write */
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if (setjmp(png_jmpbuf(png_ptr)))
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abort_("[write_png_file] Error during end of write");
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png_write_end(png_ptr, NULL);
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/* cleanup heap allocation */
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/*for (y=0; y<height; y++)
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free(row_pointers[y]);
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free(row_pointers);
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*/
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fclose(fp);
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}
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