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@ -1,4 +1,4 @@
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#include <sys/mman.h>
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#include <zlib.h>
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#include <arpa/inet.h>
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#include "visual-details.h"
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#include "internal.h"
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@ -16,19 +16,26 @@
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static const unsigned char PNGHEADER[] = "\x89PNG\x0d\x0a\x1a\x0a";
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// number of bytes necessary to encode (uncompressed) the visual specified by
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// |ncv|. if alphap is non-zero, an alpha channel will be used, increasing the
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// size of the data by 1/3.
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size_t compute_png_size(const ncvisual* ncv, unsigned alphap,
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char** deflated, size_t* dlen){
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// FIXME need to do the deflation here
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*deflated = NULL;
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*dlen = 0;
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uint64_t databytes = ncv->pixx * ncv->pixy * (3 + !!alphap);
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uint64_t fullchunks = databytes / CHUNK_MAX_DATA; // full 2GB IDATs
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// |ncv|. on error, *|deflated| will be NULL.
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size_t compute_png_size(const ncvisual* ncv, void** deflated, size_t* dlen){
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uint64_t databytes = ncv->pixx * ncv->pixy * 4;
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unsigned long bound = compressBound(databytes);
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*deflated = malloc(bound);
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if(*deflated == NULL){
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return 0;
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}
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int cret = compress(*deflated, &bound, (const unsigned char*)ncv->data, databytes);
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if(cret != Z_OK){
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free(*deflated);
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logerror("Error compressing %zuB (%d)\n", databytes, cret);
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return 0;
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}
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*dlen = bound;
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uint64_t fullchunks = *dlen / CHUNK_MAX_DATA; // full 2GB IDATs
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return (sizeof(PNGHEADER) - 1) + // PNG header
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CHUNK_DESC_BYTES + IHDR_DATA_BYTES + // mandatory IHDR chunk
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(CHUNK_DESC_BYTES + CHUNK_MAX_DATA) * fullchunks +
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(CHUNK_DESC_BYTES + databytes % CHUNK_MAX_DATA) +
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(CHUNK_DESC_BYTES + *dlen % CHUNK_MAX_DATA) +
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CHUNK_DESC_BYTES; // mandatory IEND chunk
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}
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@ -54,7 +61,7 @@ chunk_crc(const char* buf){
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// write the ihdr at |buf|, which is guaranteed to be large enough (25B).
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static size_t
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write_ihdr(const ncvisual* ncv, char* buf, unsigned alphap){
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write_ihdr(const ncvisual* ncv, char* buf){
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uint32_t length = htonl(IHDR_DATA_BYTES);
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memcpy(buf, &length, 4);
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static const char ctype[] = "IHDR";
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@ -65,7 +72,7 @@ write_ihdr(const ncvisual* ncv, char* buf, unsigned alphap){
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memcpy(buf + 12, &height, 4);
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uint8_t depth = 8; // 8 bits per channel
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memcpy(buf + 16, &depth, 1);
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uint8_t color = 2 + alphap ? 4 : 0; // RGB with possible alpha
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uint8_t color = 6; // RGBA
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memcpy(buf + 17, &color, 1);
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uint8_t compression = 0; // deflate, max window 32768
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memcpy(buf + 18, &compression, 1);
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@ -106,11 +113,10 @@ write_iend(char* buf){
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// deflated data |deflated| of |dlen| bytes. |buf| must be large enough to
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// write all necessary data; it ought have been sized with compute_png_size().
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static size_t
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create_png(const ncvisual* ncv, void* buf, unsigned alphap,
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const char* deflated, size_t dlen){
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create_png(const ncvisual* ncv, void* buf, const char* deflated, size_t dlen){
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size_t written = sizeof(PNGHEADER) - 1;
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memcpy(buf, PNGHEADER, written);
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size_t r = write_ihdr(ncv, (char*)buf + written, alphap);
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size_t r = write_ihdr(ncv, (char*)buf + written);
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written += r;
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r = write_idats((char*)buf + written, deflated, dlen);
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written += r;
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@ -130,11 +136,14 @@ mmap_round_size(size_t s){
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// larger than this, but the end is immaterial padding). returns MMAP_FAILED
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// on a failure. if |fd| is negative, an anonymous map will be made.
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void* create_png_mmap(const ncvisual* ncv, size_t* bsize, int fd){
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const unsigned alphap = 1; // FIXME 0 if no alpha used, for smaller output
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char* deflated;
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void* deflated;
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size_t dlen;
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size_t mlen;
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*bsize = compute_png_size(ncv, alphap, &deflated, &dlen);
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*bsize = compute_png_size(ncv, &deflated, &dlen);
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if(deflated == NULL){
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logerror("Couldn't compress to %d\n", fd);
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return MAP_FAILED;
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}
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mlen = mmap_round_size(*bsize);
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if(mlen == 0){
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return MAP_FAILED;
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@ -155,7 +164,7 @@ void* create_png_mmap(const ncvisual* ncv, size_t* bsize, int fd){
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logerror("Couldn't get %zuB map for %d\n", mlen, fd);
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return MAP_FAILED;
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}
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size_t w = create_png(ncv, map, alphap, deflated, dlen);
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size_t w = create_png(ncv, map, deflated, dlen);
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loginfo("Wrote %zuB PNG to %d\n", w, fd);
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return map;
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}
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