@dualbox/dualbox-lib-upng
Version:
PNG encoder/decoder
531 lines (483 loc) • 25 kB
JavaScript
/* eslint-env es6 */
// I don't know why, but this is required for Uint* stuff
var UPNG = {};
var pako = require('pako');
UPNG.toRGBA8 = function(out)
{
//console.log(out.ctype, out.depth);
var w = out.width, h = out.height, area = w*h, bpp = UPNG.decode._getBPP(out);
var bpl = Math.ceil(w*bpp/8); // bytes per line
var bf = new Uint8Array(area*4), bf32 = new Uint32Array(bf.buffer);
var data = out.data, ctype = out.ctype, depth = out.depth;
var rs = UPNG._bin.readUshort;
if (ctype==6) { // RGB + alpha
var qarea = area<<2;
if(depth== 8) for(var i=0; i<qarea;i++) { bf[i] = data[i]; /*if((i&3)==3) bf[i]=255;*/ }
if(depth==16) for(var i=0; i<qarea;i++) { bf[i] = data[i<<1]; }
}
else if(ctype==2) { // RGB
var ts=out.tabs["tRNS"], tr=-1, tg=-1, tb=-1;
if(ts) { tr=ts[0]; tg=ts[1]; tb=ts[2]; }
if(depth== 8) for(var i=0; i<area; i++) { var qi=i<<2, ti=i*3; bf[qi] = data[ti]; bf[qi+1] = data[ti+1]; bf[qi+2] = data[ti+2]; bf[qi+3] = 255;
if(tr!=-1 && data[ti] ==tr && data[ti+1] ==tg && data[ti+2] ==tb) bf[qi+3] = 0; }
if(depth==16) for(var i=0; i<area; i++) { var qi=i<<2, ti=i*6; bf[qi] = data[ti]; bf[qi+1] = data[ti+2]; bf[qi+2] = data[ti+4]; bf[qi+3] = 255;
if(tr!=-1 && rs(data,ti)==tr && rs(data,ti+2)==tg && rs(data,ti+4)==tb) bf[qi+3] = 0; }
}
else if(ctype==3) { // palette
var p=out.tabs["PLTE"], ap=out.tabs["tRNS"], tl=ap?ap.length:0;
if(depth==1) for(var y=0; y<h; y++) { var s0 = y*bpl, t0 = y*w;
for(var i=0; i<w; i++) { var qi=(t0+i)<<2, j=((data[s0+(i>>3)]>>(7-((i&7)<<0)))& 1), cj=3*j; bf[qi]=p[cj]; bf[qi+1]=p[cj+1]; bf[qi+2]=p[cj+2]; bf[qi+3]=(j<tl)?ap[j]:255; }
}
if(depth==2) for(var y=0; y<h; y++) { var s0 = y*bpl, t0 = y*w;
for(var i=0; i<w; i++) { var qi=(t0+i)<<2, j=((data[s0+(i>>2)]>>(6-((i&3)<<1)))& 3), cj=3*j; bf[qi]=p[cj]; bf[qi+1]=p[cj+1]; bf[qi+2]=p[cj+2]; bf[qi+3]=(j<tl)?ap[j]:255; }
}
if(depth==4) for(var y=0; y<h; y++) { var s0 = y*bpl, t0 = y*w;
for(var i=0; i<w; i++) { var qi=(t0+i)<<2, j=((data[s0+(i>>1)]>>(4-((i&1)<<2)))&15), cj=3*j; bf[qi]=p[cj]; bf[qi+1]=p[cj+1]; bf[qi+2]=p[cj+2]; bf[qi+3]=(j<tl)?ap[j]:255; }
}
if(depth==8) for(var i=0; i<area; i++ ) { var qi=i<<2, j=data[i] , cj=3*j; bf[qi]=p[cj]; bf[qi+1]=p[cj+1]; bf[qi+2]=p[cj+2]; bf[qi+3]=(j<tl)?ap[j]:255; }
}
else if(ctype==4) { // gray + alpha
if(depth== 8) for(var i=0; i<area; i++) { var qi=i<<2, di=i<<1, gr=data[di]; bf[qi]=gr; bf[qi+1]=gr; bf[qi+2]=gr; bf[qi+3]=data[di+1]; }
if(depth==16) for(var i=0; i<area; i++) { var qi=i<<2, di=i<<2, gr=data[di]; bf[qi]=gr; bf[qi+1]=gr; bf[qi+2]=gr; bf[qi+3]=data[di+2]; }
}
else if(ctype==0) { // gray
var tr = out.tabs["tRNS"] ? out.tabs["tRNS"] : -1;
if(depth== 1) for(var i=0; i<area; i++) { var gr=255*((data[i>>3]>>(7 -((i&7) )))& 1), al=(gr==tr*255)?0:255; bf32[i]=(al<<24)|(gr<<16)|(gr<<8)|gr; }
if(depth== 2) for(var i=0; i<area; i++) { var gr= 85*((data[i>>2]>>(6 -((i&3)<<1)))& 3), al=(gr==tr* 85)?0:255; bf32[i]=(al<<24)|(gr<<16)|(gr<<8)|gr; }
if(depth== 4) for(var i=0; i<area; i++) { var gr= 17*((data[i>>1]>>(4 -((i&1)<<2)))&15), al=(gr==tr* 17)?0:255; bf32[i]=(al<<24)|(gr<<16)|(gr<<8)|gr; }
if(depth== 8) for(var i=0; i<area; i++) { var gr=data[i ] , al=(gr ==tr)?0:255; bf32[i]=(al<<24)|(gr<<16)|(gr<<8)|gr; }
if(depth==16) for(var i=0; i<area; i++) { var gr=data[i<<1], al=(rs(data,i<<1)==tr)?0:255; bf32[i]=(al<<24)|(gr<<16)|(gr<<8)|gr; }
}
else console.log("unsupported color type", ctype);
return bf;
}
UPNG.encode = function(buff, w, h, ps)
{
if(ps==null) ps=0;
var img = new Uint8Array(buff);
var data = new Uint8Array(img.length+100);
var wr=[0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a];
for(var i=0; i<8; i++) data[i]=wr[i];
var offset = 8, bin = UPNG._bin, crc = UPNG.crc.crc;
var nimg = UPNG.encode.compress(img, w, h, ps);
bin.writeUint (data,offset, 13); offset+=4;
bin.writeASCII(data,offset,"IHDR"); offset+=4;
bin.writeUint (data,offset,w); offset+=4;
bin.writeUint (data,offset,h); offset+=4;
data[offset] = nimg.depth; offset++; // depth
data[offset] = nimg.ctype; offset++; // ctype
data[offset] = 0; offset++; // compress
data[offset] = 0; offset++; // filter
data[offset] = 0; offset++; // interlace
bin.writeUint (data,offset,crc(data,offset-17,17)); offset+=4; // crc
// 9 bytes to say, that it is sRGB
bin.writeUint (data,offset, 1); offset+=4;
bin.writeASCII(data,offset,"sRGB"); offset+=4;
data[offset] = 1; offset++;
bin.writeUint (data,offset,crc(data,offset-5,5)); offset+=4; // crc
if(nimg.ctype==3) {
var dl = nimg.plte.length;
bin.writeUint (data,offset, dl*3); offset+=4;
bin.writeASCII(data,offset,"PLTE"); offset+=4;
for(var i=0; i<dl; i++){
var ti=i*3, c=nimg.plte[i], r=(c)&255, g=(c>>8)&255, b=(c>>16)&255;
data[offset+ti+0]=r; data[offset+ti+1]=g; data[offset+ti+2]=b;
}
offset+=dl*3;
bin.writeUint (data,offset,crc(data,offset-dl*3-4,dl*3+4)); offset+=4; // crc
if(nimg.gotAlpha) {
bin.writeUint (data,offset, dl); offset+=4;
bin.writeASCII(data,offset,"tRNS"); offset+=4;
for(var i=0; i<dl; i++) data[offset+i]=(nimg.plte[i]>>24)&255;
offset+=dl;
bin.writeUint (data,offset,crc(data,offset-dl-4,dl+4)); offset+=4; // crc
}
}
var dl = nimg.data.length;
bin.writeUint (data,offset, dl); offset+=4;
bin.writeASCII(data,offset,"IDAT"); offset+=4;
for(var i=0; i<dl; i++) data[offset+i] = nimg.data[i];
offset += dl;
bin.writeUint (data,offset,crc(data,offset-dl-4,dl+4)); offset+=4; // crc
bin.writeUint (data,offset, 0); offset+=4;
bin.writeASCII(data,offset,"IEND"); offset+=4;
bin.writeUint (data,offset,crc(data,offset-4,4)); offset+=4; // crc
return data.buffer.slice(0,offset);
}
UPNG.encode.compress = function(img, w, h, ps)
{
if(ps!=0) img = UPNG.quantize(img, w, h, ps);
var ctype = 6, depth = 8, plte=[], bpp = 4, bpl = 4*w;
var img32 = new Uint32Array(img.buffer);
var gotAlpha=false, cmap=[];
for(var i=0; i<img.length; i+=4) {
var c = img32[i>>2]; if(plte.length<600 && cmap[c]==null) { cmap[c]=plte.length; plte.push(c); }
if(img[i+3]!=255) gotAlpha = true;
}
var cc=plte.length;
if(cc<=256) {
if(cc<= 2) depth=1; else if(cc<= 4) depth=2; else if(cc<=16) depth=4; else depth=8;
bpl = Math.ceil(depth*w/8), nimg = new Uint8Array(bpl*h);
for(var y=0; y<h; y++) { var i=y*bpl, ii=y*w;
if(depth==1) for(var x=0; x<w; x++) nimg[i+(x>>3)] |= (cmap[img32[ii+x]]<<(7-(x&7) ));
if(depth==2) for(var x=0; x<w; x++) nimg[i+(x>>2)] |= (cmap[img32[ii+x]]<<(6-(x&3)*2));
if(depth==4) for(var x=0; x<w; x++) nimg[i+(x>>1)] |= (cmap[img32[ii+x]]<<(4-(x&1)*4));
if(depth==8) for(var x=0; x<w; x++) nimg[i+ x ] = cmap[img32[ii+x]];
}
img=nimg; ctype=3; bpp=1;
}
else if(gotAlpha==false) {
var nimg = new Uint8Array(w*h*3), area=w*h;
for(var i=0; i<area; i++) { var ti=i*3, qi=i*4; nimg[ti]=img[qi]; nimg[ti+1]=img[qi+1]; nimg[ti+2]=img[qi+2]; }
img=nimg; ctype=2; bpp=3; bpl=3*w;
}
var data = new Uint8Array(w*h*bpp+h);
return {ctype:ctype, depth:depth, plte:plte, gotAlpha:gotAlpha, data: UPNG.encode._filterZero(img,h,bpp,bpl,data) };
}
UPNG.encode._filterZero = function(img,h,bpp,bpl,data)
{
var fls = [];
for(var t=0; t<5; t++) { if(h*bpl>500000 && (t==2 || t==3 || t==4)) continue;
for(var y=0; y<h; y++) UPNG.encode._filterLine(data, img, y, bpl, bpp, t);
fls.push(pako["deflate"](data)); if(bpp==1) break;
}
var ti, tsize=1e9;
for(var i=0; i<fls.length; i++) if(fls[i].length<tsize) { ti=i; tsize=fls[i].length; }
//console.log("top filter", ti);
return fls[ti];
}
UPNG.encode._filterLine = function(data, img, y, bpl, bpp, type)
{
var i = y*bpl, di = i+y, paeth = UPNG.decode._paeth
data[di]=type; di++;
if(type==0) for(var x=0; x<bpl; x++) data[di+x] = img[i+x];
else if(type==1) {
for(var x= 0; x<bpp; x++) data[di+x] = img[i+x];
for(var x=bpp; x<bpl; x++) data[di+x] = (img[i+x]-img[i+x-bpp]+256)&255;
}
else if(y==0) {
for(var x= 0; x<bpp; x++) data[di+x] = img[i+x];
if(type==2) for(var x=bpp; x<bpl; x++) data[di+x] = img[i+x];
if(type==3) for(var x=bpp; x<bpl; x++) data[di+x] = (img[i+x] - (img[i+x-bpp]>>1) +256)&255;
if(type==4) for(var x=bpp; x<bpl; x++) data[di+x] = (img[i+x] - paeth(img[i+x-bpp], 0, 0) +256)&255;
}
else {
if(type==2) { for(var x= 0; x<bpl; x++) data[di+x] = (img[i+x]+256 - img[i+x-bpl])&255; }
if(type==3) { for(var x= 0; x<bpp; x++) data[di+x] = (img[i+x]+256 - (img[i+x-bpl]>>1))&255;
for(var x=bpp; x<bpl; x++) data[di+x] = (img[i+x]+256 - ((img[i+x-bpl]+img[i+x-bpp])>>1))&255; }
if(type==4) { for(var x= 0; x<bpp; x++) data[di+x] = (img[i+x]+256 - paeth(0, img[i+x-bpl], 0))&255;
for(var x=bpp; x<bpl; x++) data[di+x] = (img[i+x]+256 - paeth(img[i+x-bpp], img[i+x-bpl], img[i+x-bpp-bpl]))&255; }
}
}
UPNG.crc = {
table : ( function() {
var tab = new Uint32Array(256);
for (var n=0; n<256; n++) {
var c = n;
for (var k=0; k<8; k++) {
if (c & 1) c = 0xedb88320 ^ (c >>> 1);
else c = c >>> 1;
}
tab[n] = c; }
return tab; })(),
update : function(c, buf, off, len) {
for (var i=0; i<len; i++) c = UPNG.crc.table[(c ^ buf[off+i]) & 0xff] ^ (c >>> 8);
return c;
},
crc : function(b,o,l) { return UPNG.crc.update(0xffffffff,b,o,l) ^ 0xffffffff; }
}
UPNG.quantize = function(img, w, h, ps)
{
var nimg = new Uint8Array(img.length), pind = new Uint16Array(w*h), area=w*h, edist=UPNG.quantize.dist;
for(var i=0; i<area; i++) {
var qi=i<<2, a=img[qi+3]/255;
nimg[qi+0] = img[qi+0]*a; nimg[qi+1] = img[qi+1]*a; nimg[qi+2] = img[qi+2]*a; nimg[qi+3] = img[qi+3];
}
var plte=[], used=[], pr=0, plim = Math.max(100, 10*ps);
while(true) {
used=[]; plte=[];
var msk = 0xff - ((1<<pr)-1), add = ((1<<pr))>>1;
for(var i=0; i<area; i++) { var qi=i<<2; var r=nimg[qi],g=nimg[qi+1],b=nimg[qi+2],a=nimg[qi+3];
var nr=(r&msk)+add, ng=(g&msk)+add, nb=(b&msk)+add, na=(a&msk)+add, key=(na<<24)|(nb<<16)|(ng<<8)|nr;
if(used[key]) { var pv=plte[used[key]]; pv.occ++; }
else { used[key]=plte.length; plte.push( {occ:1, r:nr,g:ng,b:nb,a:na} ); }
if(plte.length>plim) break;
}
if(plte.length>plim) { pr++; continue; }
break;
}
if(pr==0 && plte.length<=ps) return img;
plte.sort(function(a,b) {return b.occ-a.occ;});
ps = Math.min(ps, plte.length);
var nplte = new Uint8Array(ps*4);
for(var i=0; i<ps; i++) { var qi=i<<2,c=plte[i]; nplte[qi]=c.r; nplte[qi+1]=c.g; nplte[qi+2]=c.b; nplte[qi+3]=c.a; }
plte = nplte; //*/
var icnt = Math.max(1, Math.min(10, Math.floor(1024/ps)));
for(var it=0; it<icnt; it++)
{
var hist=new Uint32Array(ps), nplt=new Uint32Array(ps*4);
var ndst=new Uint32Array(ps), nind=new Uint32Array(ps );
for(var i=0; i<ps; i++) { var qi=i<<2;
var r=plte[qi], g=plte[qi+1], b=plte[qi+2], a=plte[qi+3];
var ci=0; cd=1e9;
for(var j=0; j<ps; j++) { if(j==i) continue;
var dst = edist(r,g,b,a,plte,j<<2);
if(dst<cd) { ci=j; cd=dst; }
}
ndst[i]=cd; nind[i]=ci;
}
for(var i=0; i<area; i++) { var qi=i<<2;
var r=nimg[qi], g=nimg[qi+1], b=nimg[qi+2], a=nimg[qi+3];
var ci=0, cd=1e9;
ci=pind[i]; cd=edist(r,g,b,a,plte,ci<<2); if(cd<=(ndst[ci]>>1)) {} else
for(var j=0; j<ps; j++) {
var dst = edist(r,g,b,a,plte,j<<2);
if(dst<cd) { ci=j; cd=dst;
if(dst<=(ndst[ci]>>1)) break;
var dst = edist(r,g,b,a,plte,nind[j]<<2);
if(dst<=(ndst[ci]>>1)) { ci=nind[j]; break; }
}
}
pind[i]=ci; hist[ci]++; var qci=ci<<2;
nplt[qci]+=r; nplt[qci+1]+=g; nplt[qci+2]+=b; nplt[qci+3]+=a;
}
for(var i=0; i<ps; i++) { var qi=i<<2, den=1/hist[i];
plte[qi]=nplt[qi]*den; plte[qi+1]=nplt[qi+1]*den; plte[qi+2]=nplt[qi+2]*den; plte[qi+3]=nplt[qi+3]*den;
}
}
//UPNG.quantize.dither(nimg, w,h, pind,plte, ps); // I think that (current) dithering is not worth it
for(var i=0; i<area; i++) {
var qi=i<<2, ci=pind[i], qci=ci<<2, ia = plte[qci+3]==0 ? 0 : 255/plte[qci+3];
nimg[qi+0] = plte[qci+0]*ia; nimg[qi+1] = plte[qci+1]*ia; nimg[qi+2] = plte[qci+2]*ia; nimg[qi+3] = plte[qci+3];
}
return nimg;
}
UPNG.quantize.dist = function(r,g,b,a,ba,bi)
{
var pr=ba[bi], pg=ba[bi+1], pb=ba[bi+2], pa=ba[bi+3];
return (pr-r)*(pr-r)+(pg-g)*(pg-g)+(pb-b)*(pb-b)+(pa-a)*(pa-a);
}
UPNG.quantize.dither = function(nimg, w, h, pind, plte, ps)
{
var err = new Float32Array(w*h*4), i16 = 1/16;
var edist = UPNG.quantize.dist, round=Math.round, qw=w<<2;
for(var y=0; y<h; y++)
for(var x=0; x<w; x++) {
var i = y*w+x, qi=i<<2;
for(var j=0; j<4; j++) err[qi+j] = Math.max(-8, Math.min(8, err[qi+j]));
var r=round(nimg[qi]+err[qi]), g=round(nimg[qi+1]+err[qi+1]), b=round(nimg[qi+2]+err[qi+2]), a=round(nimg[qi+3]+err[qi+3]);
var ci=0, cd=1e9;
for(var j=0; j<ps; j++) {
var dst = edist(r,g,b,a,plte,j<<2);
if(dst<cd) { ci=j; cd=dst; }
}
pind[i]=ci;
var ciq = ci<<2;
var dr=r-plte[ciq], dg=g-plte[ciq+1], db=b-plte[ciq+2], da=a-plte[ciq+3];
err[qi +4+0] += (7*dr*i16); err[qi +4+1] += (7*dg*i16); err[qi +4+2] += (7*db*i16); err[qi +4+3] += (7*da*i16);
err[qi+qw-4+0] += (3*dr*i16); err[qi+qw-4+1] += (3*dg*i16); err[qi+qw-4+2] += (3*db*i16); err[qi+qw-4+3] += (3*da*i16);
err[qi+qw +0] += (5*dr*i16); err[qi+qw +1] += (5*dg*i16); err[qi+qw +2] += (5*db*i16); err[qi+qw +3] += (5*da*i16);
err[qi+qw+4+0] += (1*dr*i16); err[qi+qw+4+1] += (1*dg*i16); err[qi+qw+4+2] += (1*db*i16); err[qi+qw+4+3] += (1*da*i16);
}
}
UPNG.decode = function(buff)
{
var data = new Uint8Array(buff), offset = 8, bin = UPNG._bin, rUs = bin.readUshort;
var out = {tabs:{}};
var dd = new Uint8Array(data.length), doff = 0; // put all IDAT data into it
while(true)
{
var len = bin.readUint(data, offset); offset += 4;
var type = bin.readASCII(data, offset, 4); offset += 4;
//console.log(offset, len, type);
if (type=="IHDR") { UPNG.decode._IHDR(data, offset, out); }
else if(type=="IDAT") {
for(var i=0; i<len; i++) dd[doff+i] = data[offset+i];
doff += len;
}
else if(type=="pHYs") {
out.tabs[type] = [bin.readUint(data, offset), bin.readUint(data, offset+4), data[offset+8]];
}
else if(type=="cHRM") {
out.tabs[type] = [];
for(var i=0; i<8; i++) out.tabs[type].push(bin.readUint(data, offset+i*4));
}
else if(type=="tEXt") {
if(out.tabs[type]==null) out.tabs[type] = {};
var nz = bin.nextZero(data, offset);
var keyw = bin.readASCII(data, offset, nz-offset);
var text = bin.readASCII(data, nz+1, offset+len-nz-1);
out.tabs[type][keyw] = text;
}
else if(type=="iTXt") {
if(out.tabs[type]==null) out.tabs[type] = {};
var nz = 0, off = offset;
nz = bin.nextZero(data, off);
var keyw = bin.readASCII(data, off, nz-off); off = nz + 1;
var cflag = data[off], cmeth = data[off+1]; off+=2;
nz = bin.nextZero(data, off);
var ltag = bin.readASCII(data, off, nz-off); off = nz + 1;
nz = bin.nextZero(data, off);
var tkeyw = bin.readUTF8(data, off, nz-off); off = nz + 1;
var text = bin.readUTF8(data, off, len-(off-offset));
out.tabs[type][keyw] = text;
}
else if(type=="PLTE") {
out.tabs[type] = bin.readBytes(data, offset, len);
}
else if(type=="hIST") {
var pl = out.tabs["PLTE"].length/3;
out.tabs[type] = []; for(var i=0; i<pl; i++) out.tabs[type].push(rUs(data, offset+i*2));
}
else if(type=="tRNS") {
if (out.ctype==3) out.tabs[type] = bin.readBytes(data, offset, len);
else if(out.ctype==0) out.tabs[type] = rUs(data, offset);
else if(out.ctype==2) out.tabs[type] = [ rUs(data,offset),rUs(data,offset+2),rUs(data,offset+4) ];
else console.log("tRNS for unsupported color type",out.ctype, len);
}
else if(type=="gAMA") out.tabs[type] = bin.readUint(data, offset)/100000;
else if(type=="sRGB") out.tabs[type] = data[offset];
else if(type=="bKGD")
{
if (out.ctype==0 || out.ctype==4) out.tabs[type] = [rUs(data, offset)];
else if(out.ctype==2 || out.ctype==6) out.tabs[type] = [rUs(data, offset), rUs(data, offset+2), rUs(data, offset+4)];
else if(out.ctype==3) out.tabs[type] = data[offset];
}
else if(type=="IEND") {
if(out.compress ==0) dd = UPNG.decode._inflate(dd);
else console.log("unsupported compression method:", out.interlace);
if(out.filter!=0) console.log("unsupported filter method:", out.filter);
if(out.interlace==0) out.data = UPNG.decode._filterZero(dd, out, 0, out.width, out.height);
else if(out.interlace==1) out.data = UPNG.decode._readInterlace(dd, out);
else console.log("unsupported interlace method:", out.interlace);
break;
}
else { console.log("unknown chunk type", type, len); }
offset += len;
var crc = bin.readUint(data, offset); offset += 4;
}
delete out.compress; delete out.interlace; delete out.filter;
return out;
}
UPNG.decode._inflate = function(data) { return pako["inflate"](data); }
UPNG.decode._readInterlace = function(data, out)
{
var w = out.width, h = out.height;
var bpp = UPNG.decode._getBPP(out), cbpp = bpp>>3, bpl = Math.ceil(w*bpp/8);
var img = new Uint8Array( h * bpl );
var di = 0;
var starting_row = [ 0, 0, 4, 0, 2, 0, 1 ];
var starting_col = [ 0, 4, 0, 2, 0, 1, 0 ];
var row_increment = [ 8, 8, 8, 4, 4, 2, 2 ];
var col_increment = [ 8, 8, 4, 4, 2, 2, 1 ];
var pass=0;
while(pass<7)
{
var ri = row_increment[pass], ci = col_increment[pass];
var sw = 0, sh = 0;
var cr = starting_row[pass]; while(cr<h) { cr+=ri; sh++; }
var cc = starting_col[pass]; while(cc<w) { cc+=ci; sw++; }
var bpll = Math.ceil(sw*bpp/8);
UPNG.decode._filterZero(data, out, di, sw, sh);
var y=0, row = starting_row[pass];
while(row<h)
{
var col = starting_col[pass];
var cdi = (di+y*bpll)<<3;
while(col<w)
{
if(bpp==1) {
var val = data[cdi>>3]; val = (val>>(7-(cdi&7)))&1;
img[row*bpl + (col>>3)] |= (val << (7-((col&3)<<0)));
}
if(bpp==2) {
var val = data[cdi>>3]; val = (val>>(6-(cdi&7)))&3;
img[row*bpl + (col>>2)] |= (val << (6-((col&3)<<1)));
}
if(bpp==4) {
var val = data[cdi>>3]; val = (val>>(4-(cdi&7)))&15;
img[row*bpl + (col>>1)] |= (val << (4-((col&1)<<2)));
}
if(bpp>=8) {
var ii = row*bpl+col*cbpp;
for(var j=0; j<cbpp; j++) img[ii+j] = data[(cdi>>3)+j];
}
cdi+=bpp; col+=ci;
}
y++; row += ri;
}
if(sw*sh!=0) di += sh * (1 + bpll);
pass = pass + 1;
}
return img;
}
UPNG.decode._getBPP = function(out) {
var noc = [1,null,3,1,2,null,4][out.ctype];
if(noc==null) console.log("unsupported color type", out.ctype);
return noc * out.depth;
}
UPNG.decode._filterZero = function(data, out, off, w, h)
{
var bpp = UPNG.decode._getBPP(out), bpl = Math.ceil(w*bpp/8), paeth = UPNG.decode._paeth;
bpp = Math.ceil(bpp/8);
for(var y=0; y<h; y++) {
var i = off+y*bpl, di = i+y+1;
var type = data[di-1];
if (type==0) for(var x= 0; x<bpl; x++) data[i+x] = data[di+x];
else if(type==1) {
for(var x= 0; x<bpp; x++) data[i+x] = data[di+x];
for(var x=bpp; x<bpl; x++) data[i+x] = (data[di+x] + data[i+x-bpp])&255;
}
else if(y==0) {
for(var x= 0; x<bpp; x++) data[i+x] = data[di+x];
if(type==2) for(var x=bpp; x<bpl; x++) data[i+x] = (data[di+x])&255;
if(type==3) for(var x=bpp; x<bpl; x++) data[i+x] = (data[di+x] + (data[i+x-bpp]>>1) )&255;
if(type==4) for(var x=bpp; x<bpl; x++) data[i+x] = (data[di+x] + paeth(data[i+x-bpp], 0, 0) )&255;
}
else {
if(type==2) { for(var x= 0; x<bpl; x++) data[i+x] = (data[di+x] + data[i+x-bpl])&255; }
if(type==3) { for(var x= 0; x<bpp; x++) data[i+x] = (data[di+x] + (data[i+x-bpl]>>1))&255;
for(var x=bpp; x<bpl; x++) data[i+x] = (data[di+x] + ((data[i+x-bpl]+data[i+x-bpp])>>1) )&255; }
if(type==4) { for(var x= 0; x<bpp; x++) data[i+x] = (data[di+x] + paeth(0, data[i+x-bpl], 0))&255;
for(var x=bpp; x<bpl; x++) data[i+x] = (data[di+x] + paeth(data[i+x-bpp], data[i+x-bpl], data[i+x-bpp-bpl]) )&255; }
}
}
return data;
}
UPNG.decode._paeth = function(a,b,c)
{
var p = a+b-c, pa = Math.abs(p-a), pb = Math.abs(p-b), pc = Math.abs(p-c);
if (pa <= pb && pa <= pc) return a;
else if (pb <= pc) return b;
return c;
}
UPNG.decode._IHDR = function(data, offset, out)
{
var bin = UPNG._bin;
out.width = bin.readUint(data, offset); offset += 4;
out.height = bin.readUint(data, offset); offset += 4;
out.depth = data[offset]; offset++;
out.ctype = data[offset]; offset++;
out.compress = data[offset]; offset++;
out.filter = data[offset]; offset++;
out.interlace = data[offset]; offset++;
}
UPNG._bin = {
nextZero : function(data,p) { while(data[p]!=0) p++; return p; },
readUshort : function(buff,p) { return (buff[p]<< 8) | buff[p+1]; },
writeUshort: function(buff,p,n){ buff[p] = (n>>8)&255; buff[p+1] = n&255; },
readUint : function(buff,p) { return (buff[p]*(256*256*256)) + ((buff[p+1]<<16) | (buff[p+2]<< 8) | buff[p+3]); },
writeUint : function(buff,p,n){ buff[p]=(n>>24)&255; buff[p+1]=(n>>16)&255; buff[p+2]=(n>>8)&255; buff[p+3]=n&255; },
readASCII : function(buff,p,l){ var s = ""; for(var i=0; i<l; i++) s += String.fromCharCode(buff[p+i]); return s; },
writeASCII : function(data,p,s){ for(var i=0; i<s.length; i++) data[p+i] = s.charCodeAt(i); },
readBytes : function(buff,p,l){ var arr = []; for(var i=0; i<l; i++) arr.push(buff[p+i]); return arr; },
pad : function(n) { return n.length < 2 ? "0" + n : n; },
readUTF8 : function(buff, p, l) {
var s = "", ns;
for(var i=0; i<l; i++) s += "%" + UPNG._bin.pad(buff[p+i].toString(16));
try { ns = decodeURIComponent(s); }
catch(e) { return UPNG._bin.readASCII(buff, p, l); }
return ns;
}
}
module.exports = UPNG;