return of venti

1 files changed, 241 insertions, 0 deletions

diff --git a/src/cmd/venti/srv/png.c b/src/cmd/venti/srv/png.c
new file mode 100644
index 00000000..966b7e96
--- /dev/null
+++ b/src/cmd/venti/srv/png.c
@@ -0,0 +1,241 @@
+#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 == 255 || a == 0)
+					;
+				else{
+					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;
+}