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- #include "stdinc.h"
- #include "dat.h"
- #include "fns.h"
- enum
- {
- IDATSIZE = 20000,
- FilterNone = 0
- };
- typedef struct ZlibR ZlibR;
- typedef struct ZlibW ZlibW;
- struct ZlibR
- {
- uchar *data;
- int width;
- int dx;
- int dy;
- int x;
- int y;
- int pixwid;
- };
- struct ZlibW
- {
- Hio *io;
- uchar *buf;
- uchar *b;
- uchar *e;
- };
- static ulong *crctab;
- static uchar PNGmagic[] = { 137, 'P', 'N', 'G', '\r', '\n', 26, '\n'};
- static void
- put4(uchar *a, ulong v)
- {
- a[0] = v>>24;
- a[1] = v>>16;
- a[2] = v>>8;
- a[3] = v;
- }
- static void
- chunk(Hio *io, char *type, uchar *d, int n)
- {
- uchar buf[4];
- ulong crc = 0;
- if(strlen(type) != 4)
- return;
- put4(buf, n);
- hwrite(io, buf, 4);
- hwrite(io, type, 4);
- hwrite(io, d, n);
- crc = blockcrc(crctab, crc, type, 4);
- crc = blockcrc(crctab, crc, d, n);
- put4(buf, crc);
- hwrite(io, buf, 4);
- }
- static int
- zread(void *va, void *buf, int n)
- {
- int a, i, pixels, pixwid;
- uchar *b, *e, *img;
- ZlibR *z;
- z = va;
- pixwid = z->pixwid;
- b = buf;
- e = b+n;
- while(b+pixwid <= e){
- if(z->y >= z->dy)
- break;
- if(z->x == 0)
- *b++ = FilterNone;
- pixels = (e-b)/pixwid;
- if(pixels > z->dx - z->x)
- pixels = z->dx - z->x;
- img = z->data + z->width*z->y + pixwid*z->x;
- memmove(b, img, pixwid*pixels);
- if(pixwid == 4){
- /*
- * Convert to non-premultiplied alpha.
- */
- for(i=0; i<pixels; i++, b+=4){
- a = b[3];
- if(a != 0 && a != 255){
- if(b[0] >= a)
- b[0] = a;
- b[0] = (b[0]*255)/a;
- if(b[1] >= a)
- b[1] = a;
- b[1] = (b[1]*255)/a;
- if(b[2] >= a)
- b[2] = a;
- b[2] = (b[2]*255)/a;
- }
- }
- }else
- b += pixwid*pixels;
- z->x += pixels;
- if(z->x >= z->dx){
- z->x = 0;
- z->y++;
- }
- }
- return b - (uchar*)buf;
- }
- static void
- IDAT(ZlibW *z)
- {
- chunk(z->io, "IDAT", z->buf, z->b - z->buf);
- z->b = z->buf;
- }
- static int
- zwrite(void *va, void *buf, int n)
- {
- int m;
- uchar *b, *e;
- ZlibW *z;
- z = va;
- b = buf;
- e = b+n;
- while(b < e){
- m = z->e - z->b;
- if(m > e - b)
- m = e - b;
- memmove(z->b, b, m);
- z->b += m;
- b += m;
- if(z->b >= z->e)
- IDAT(z);
- }
- return n;
- }
- static Memimage*
- memRGBA(Memimage *i)
- {
- Memimage *ni;
- char buf[32];
- ulong dst;
-
- /*
- * [A]BGR because we want R,G,B,[A] in big-endian order. Sigh.
- */
- chantostr(buf, i->chan);
- if(strchr(buf, 'a'))
- dst = ABGR32;
- else
- dst = BGR24;
-
- if(i->chan == dst)
- return i;
- qlock(&memdrawlock);
- ni = allocmemimage(i->r, dst);
- if(ni)
- memimagedraw(ni, ni->r, i, i->r.min, nil, i->r.min, S);
- qunlock(&memdrawlock);
- return ni;
- }
- int
- writepng(Hio *io, Memimage *m)
- {
- static int first = 1;
- static QLock lk;
- uchar buf[200], *h;
- Memimage *rgb;
- ZlibR zr;
- ZlibW zw;
- if(first){
- qlock(&lk);
- if(first){
- deflateinit();
- crctab = mkcrctab(0xedb88320);
- first = 0;
- }
- qunlock(&lk);
- }
- rgb = memRGBA(m);
- if(rgb == nil)
- return -1;
- hwrite(io, PNGmagic, sizeof PNGmagic);
-
- /* IHDR chunk */
- h = buf;
- put4(h, Dx(m->r)); h += 4;
- put4(h, Dy(m->r)); h += 4;
- *h++ = 8; /* 8 bits per channel */
- if(rgb->chan == BGR24)
- *h++ = 2; /* RGB */
- else
- *h++ = 6; /* RGBA */
- *h++ = 0; /* compression - deflate */
- *h++ = 0; /* filter - none */
- *h++ = 0; /* interlace - none */
- chunk(io, "IHDR", buf, h-buf);
- /* image data */
- zr.dx = Dx(m->r);
- zr.dy = Dy(m->r);
- zr.width = rgb->width * sizeof(ulong);
- zr.data = rgb->data->bdata;
- zr.x = 0;
- zr.y = 0;
- zr.pixwid = chantodepth(rgb->chan)/8;
- zw.io = io;
- zw.buf = vtmalloc(IDATSIZE);
- zw.b = zw.buf;
- zw.e = zw.b + IDATSIZE;
- if(deflatezlib(&zw, zwrite, &zr, zread, 6, 0) < 0){
- free(zw.buf);
- return -1;
- }
- if(zw.b > zw.buf)
- IDAT(&zw);
- free(zw.buf);
- chunk(io, "IEND", nil, 0);
- if(m != rgb){
- qlock(&memdrawlock);
- freememimage(rgb);
- qunlock(&memdrawlock);
- }
- return 0;
- }
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