1 28994509 2004-04-21 devnull // based on PNG 1.2 specification, July 1999 (see also rfc2083)
2 28994509 2004-04-21 devnull // Alpha is not supported yet because of lack of industry acceptance and
3 28994509 2004-04-21 devnull // because Plan9 Image uses premultiplied alpha, so png can't be lossless.
4 28994509 2004-04-21 devnull // Only 24bit color supported, because 8bit may as well use GIF.
6 28994509 2004-04-21 devnull #include <u.h>
7 28994509 2004-04-21 devnull #include <libc.h>
8 28994509 2004-04-21 devnull #include <draw.h>
9 28994509 2004-04-21 devnull #include <memdraw.h>
10 28994509 2004-04-21 devnull #include <ctype.h>
11 28994509 2004-04-21 devnull #include <bio.h>
12 28994509 2004-04-21 devnull #include <flate.h>
13 28994509 2004-04-21 devnull #include "imagefile.h"
15 28994509 2004-04-21 devnull enum{ IDATSIZE = 20000,
16 28994509 2004-04-21 devnull FilterNone = 0,
19 28994509 2004-04-21 devnull typedef struct ZlibR{
20 28994509 2004-04-21 devnull uchar *data;
21 28994509 2004-04-21 devnull int width;
22 28994509 2004-04-21 devnull int nrow, ncol;
23 28994509 2004-04-21 devnull int row, col; // next pixel to send
26 28994509 2004-04-21 devnull typedef struct ZlibW{
27 28994509 2004-04-21 devnull Biobuf *bo;
28 28994509 2004-04-21 devnull uchar *buf;
29 28994509 2004-04-21 devnull uchar *b; // next place to write
30 28994509 2004-04-21 devnull uchar *e; // past end of buf
33 28994509 2004-04-21 devnull static ulong *crctab;
34 28994509 2004-04-21 devnull static uchar PNGmagic[] = {137,80,78,71,13,10,26,10};
36 28994509 2004-04-21 devnull static void
37 28994509 2004-04-21 devnull put4(uchar *a, ulong v)
39 28994509 2004-04-21 devnull a[0] = v>>24;
40 28994509 2004-04-21 devnull a[1] = v>>16;
41 28994509 2004-04-21 devnull a[2] = v>>8;
42 28994509 2004-04-21 devnull a[3] = v;
45 28994509 2004-04-21 devnull static void
46 28994509 2004-04-21 devnull chunk(Biobuf *bo, char *type, uchar *d, int n)
48 28994509 2004-04-21 devnull uchar buf[4];
49 28994509 2004-04-21 devnull ulong crc = 0;
51 28994509 2004-04-21 devnull if(strlen(type) != 4)
53 28994509 2004-04-21 devnull put4(buf, n);
54 28994509 2004-04-21 devnull Bwrite(bo, buf, 4);
55 28994509 2004-04-21 devnull Bwrite(bo, type, 4);
56 28994509 2004-04-21 devnull Bwrite(bo, d, n);
57 28994509 2004-04-21 devnull crc = blockcrc(crctab, crc, type, 4);
58 28994509 2004-04-21 devnull crc = blockcrc(crctab, crc, d, n);
59 28994509 2004-04-21 devnull put4(buf, crc);
60 28994509 2004-04-21 devnull Bwrite(bo, buf, 4);
63 28994509 2004-04-21 devnull static int
64 28994509 2004-04-21 devnull zread(void *va, void *buf, int n)
66 28994509 2004-04-21 devnull ZlibR *z = va;
67 28994509 2004-04-21 devnull int nrow = z->nrow;
68 28994509 2004-04-21 devnull int ncol = z->ncol;
69 28994509 2004-04-21 devnull uchar *b = buf, *e = b+n, *img;
70 9fe5a621 2005-01-30 devnull int pixels; // number of pixels in row that can be sent now
72 28994509 2004-04-21 devnull while(b+3 <= e){ // loop over image rows
73 28994509 2004-04-21 devnull if(z->row >= nrow)
75 28994509 2004-04-21 devnull if(z->col==0)
76 28994509 2004-04-21 devnull *b++ = FilterNone;
77 28994509 2004-04-21 devnull pixels = (e-b)/3;
78 28994509 2004-04-21 devnull if(pixels > ncol - z->col)
79 28994509 2004-04-21 devnull pixels = ncol - z->col;
80 28994509 2004-04-21 devnull img = z->data + z->width * z->row + 3 * z->col;
82 9fe5a621 2005-01-30 devnull memmove(b, img, 3*pixels);
83 9fe5a621 2005-01-30 devnull b += 3*pixels;
85 28994509 2004-04-21 devnull z->col += pixels;
86 28994509 2004-04-21 devnull if(z->col >= ncol){
87 28994509 2004-04-21 devnull z->col = 0;
88 28994509 2004-04-21 devnull z->row++;
91 28994509 2004-04-21 devnull return b - (uchar*)buf;
94 28994509 2004-04-21 devnull static void
95 28994509 2004-04-21 devnull IDAT(ZlibW *z)
97 28994509 2004-04-21 devnull chunk(z->bo, "IDAT", z->buf, z->b - z->buf);
98 28994509 2004-04-21 devnull z->b = z->buf;
101 28994509 2004-04-21 devnull static int
102 28994509 2004-04-21 devnull zwrite(void *va, void *buf, int n)
104 28994509 2004-04-21 devnull ZlibW *z = va;
105 28994509 2004-04-21 devnull uchar *b = buf, *e = b+n;
108 28994509 2004-04-21 devnull while(b < e){ // loop over IDAT chunks
109 28994509 2004-04-21 devnull m = z->e - z->b;
110 28994509 2004-04-21 devnull if(m > e - b)
111 28994509 2004-04-21 devnull m = e - b;
112 28994509 2004-04-21 devnull memmove(z->b, b, m);
113 28994509 2004-04-21 devnull z->b += m;
115 28994509 2004-04-21 devnull if(z->b >= z->e)
116 28994509 2004-04-21 devnull IDAT(z);
118 28994509 2004-04-21 devnull return n;
121 28994509 2004-04-21 devnull static Memimage*
122 28994509 2004-04-21 devnull memRGB(Memimage *i)
124 28994509 2004-04-21 devnull Memimage *ni;
127 9fe5a621 2005-01-30 devnull * BGR24 because we want R,G,B in big-endian order. Sigh.
129 9fe5a621 2005-01-30 devnull if(i->chan == BGR24)
130 28994509 2004-04-21 devnull return i;
132 9fe5a621 2005-01-30 devnull ni = allocmemimage(i->r, BGR24);
133 28994509 2004-04-21 devnull if(ni == nil)
134 28994509 2004-04-21 devnull return ni;
135 28994509 2004-04-21 devnull memimagedraw(ni, ni->r, i, i->r.min, nil, i->r.min, S);
136 28994509 2004-04-21 devnull return ni;
140 28994509 2004-04-21 devnull memwritepng(Biobuf *bo, Memimage *r, ImageInfo *II)
142 28994509 2004-04-21 devnull uchar buf[200], *h;
143 28994509 2004-04-21 devnull ulong vgamma;
144 28994509 2004-04-21 devnull int err, n;
145 28994509 2004-04-21 devnull ZlibR zr;
146 28994509 2004-04-21 devnull ZlibW zw;
147 28994509 2004-04-21 devnull int nrow = r->r.max.y - r->r.min.y;
148 28994509 2004-04-21 devnull int ncol = r->r.max.x - r->r.min.x;
150 28994509 2004-04-21 devnull Memimage *rgb;
152 28994509 2004-04-21 devnull rgb = memRGB(r);
153 28994509 2004-04-21 devnull if(rgb == nil)
154 28994509 2004-04-21 devnull return "allocmemimage nil";
155 28994509 2004-04-21 devnull crctab = mkcrctab(0xedb88320);
156 28994509 2004-04-21 devnull if(crctab == nil)
157 28994509 2004-04-21 devnull sysfatal("mkcrctab error");
158 28994509 2004-04-21 devnull deflateinit();
160 28994509 2004-04-21 devnull Bwrite(bo, PNGmagic, sizeof PNGmagic);
161 28994509 2004-04-21 devnull // IHDR chunk
162 28994509 2004-04-21 devnull h = buf;
163 28994509 2004-04-21 devnull put4(h, ncol); h += 4;
164 28994509 2004-04-21 devnull put4(h, nrow); h += 4;
165 28994509 2004-04-21 devnull *h++ = 8; // bit depth = 24 bit per pixel
166 28994509 2004-04-21 devnull *h++ = 2; // color type = rgb
167 28994509 2004-04-21 devnull *h++ = 0; // compression method = deflate
168 28994509 2004-04-21 devnull *h++ = 0; // filter method
169 28994509 2004-04-21 devnull *h++ = 0; // interlace method = no interlace
170 28994509 2004-04-21 devnull chunk(bo, "IHDR", buf, h-buf);
172 28994509 2004-04-21 devnull tm = gmtime(time(0));
173 28994509 2004-04-21 devnull h = buf;
174 28994509 2004-04-21 devnull *h++ = (tm->year + 1900)>>8;
175 28994509 2004-04-21 devnull *h++ = (tm->year + 1900)&0xff;
176 28994509 2004-04-21 devnull *h++ = tm->mon + 1;
177 28994509 2004-04-21 devnull *h++ = tm->mday;
178 28994509 2004-04-21 devnull *h++ = tm->hour;
179 28994509 2004-04-21 devnull *h++ = tm->min;
180 28994509 2004-04-21 devnull *h++ = tm->sec;
181 28994509 2004-04-21 devnull chunk(bo, "tIME", buf, h-buf);
183 28994509 2004-04-21 devnull if(II->fields_set & II_GAMMA){
184 28994509 2004-04-21 devnull vgamma = II->gamma*100000;
185 28994509 2004-04-21 devnull put4(buf, vgamma);
186 28994509 2004-04-21 devnull chunk(bo, "gAMA", buf, 4);
189 28994509 2004-04-21 devnull if(II->fields_set & II_COMMENT){
190 28994509 2004-04-21 devnull strncpy((char*)buf, "Comment", sizeof buf);
191 28994509 2004-04-21 devnull n = strlen((char*)buf)+1; // leave null between Comment and text
192 28994509 2004-04-21 devnull strncpy((char*)(buf+n), II->comment, sizeof buf - n);
193 28994509 2004-04-21 devnull chunk(bo, "tEXt", buf, n+strlen((char*)buf+n));
196 28994509 2004-04-21 devnull // image chunks
197 28994509 2004-04-21 devnull zr.nrow = nrow;
198 28994509 2004-04-21 devnull zr.ncol = ncol;
199 28994509 2004-04-21 devnull zr.width = rgb->width * sizeof(ulong);
200 28994509 2004-04-21 devnull zr.data = rgb->data->bdata;
201 28994509 2004-04-21 devnull zr.row = zr.col = 0;
202 28994509 2004-04-21 devnull zw.bo = bo;
203 28994509 2004-04-21 devnull zw.buf = malloc(IDATSIZE);
204 28994509 2004-04-21 devnull zw.b = zw.buf;
205 28994509 2004-04-21 devnull zw.e = zw.b + IDATSIZE;
206 28994509 2004-04-21 devnull err = deflatezlib(&zw, zwrite, &zr, zread, 6, 0);
207 28994509 2004-04-21 devnull if(zw.b > zw.buf)
208 28994509 2004-04-21 devnull IDAT(&zw);
209 28994509 2004-04-21 devnull free(zw.buf);
211 28994509 2004-04-21 devnull sysfatal("deflatezlib %s\n", flateerr(err));
212 28994509 2004-04-21 devnull chunk(bo, "IEND", nil, 0);
214 28994509 2004-04-21 devnull if(r != rgb)
215 28994509 2004-04-21 devnull freememimage(rgb);
216 28994509 2004-04-21 devnull return nil;
