Archives/notcurses
2
0
Fork 0
mirror of https://github.com/dankamongmen/notcurses.git synced 2024-11-20 03:25:47 +00:00
Code Issues Packages Projects Releases Wiki Activity

start writing up PNGs

Browse Source
This commit is contained in:
nick black 2021-07-14 20:01:07 -04:00 committed by nick black
parent 0dfe103f4f
commit 277fd3931e
1 changed files with 23 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
src/lib/png.c
View File

@ -3,14 +3,34 @@
#include "internal.h"
#include "png.h"
// 4-byte length, 4-byte type, 4-byte CRC, plus data
#define CHUNK_DESC_BYTES 12
#define IHDR_DATA_BYTES 13
static const unsigned char PNGHEADER[] = "\x89\x50\x4e\x47\x0d\x0a\x1a\x0a";
size_t compute_png_size(const ncvisual* ncv){
return 0;
uint64_t databytes = ncv->pixx * ncv->pixy * 4; // FIXME 3 for pure RGB
uint64_t fullchunks = databytes / 0x100000000llu; // full 4GB IDATs
return (sizeof(PNGHEADER) - 1) + // PNG header
CHUNK_DESC_BYTES + IHDR_DATA_BYTES + // mandatory IHDR chunk
(CHUNK_DESC_BYTES + 0xffffffffllu) * fullchunks +
(CHUNK_DESC_BYTES + databytes % 0xffffffffllu) +
CHUNK_DESC_BYTES; // mandatory IEND chunk
}
// write a PNG at the provided buffer using the ncvisual
int create_png(const ncvisual* ncv, void* buf, size_t* bsize){
// FIXME fill it in
return -1;
size_t totalsize = compute_png_size(ncv);
if(*bsize < totalsize){
logerror("%zuB buffer too small for %zuB PNG\n", *bsize, totalsize);
return -1;
}
*bsize = totalsize;
memcpy(buf, PNGHEADER, sizeof(PNGHEADER) - 1);
// FIXME fill in IHDR
// FIXME fill in data chunks
// FIXME fill in IEND
return 0;
}
static inline size_t