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webvirtcloud/static/js/spice-html5/png.js
2020-01-23 15:49:43 +03:00

262 lines
6.9 KiB
JavaScript
Executable file

"use strict";
/*
Copyright (C) 2012 by Jeremy P. White <jwhite@codeweavers.com>
This file is part of spice-html5.
spice-html5 is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
spice-html5 is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with spice-html5. If not, see <http://www.gnu.org/licenses/>.
*/
/*----------------------------------------------------------------------------
** crc logic from rfc2083 ported to Javascript
**--------------------------------------------------------------------------*/
import { SpiceDataView } from './spicedataview.js';
var rfc2083_crc_table = Array(256);
var rfc2083_crc_table_computed = 0;
/* Make the table for a fast CRC. */
function rfc2083_make_crc_table()
{
var c;
var n, k;
for (n = 0; n < 256; n++)
{
c = n;
for (k = 0; k < 8; k++)
{
if (c & 1)
c = ((0xedb88320 ^ (c >>> 1)) >>> 0) & 0xffffffff;
else
c = c >>> 1;
}
rfc2083_crc_table[n] = c;
}
rfc2083_crc_table_computed = 1;
}
/* Update a running CRC with the bytes buf[0..len-1]--the CRC
should be initialized to all 1's, and the transmitted value
is the 1's complement of the final running CRC (see the
crc() routine below)). */
function rfc2083_update_crc(crc, u8buf, at, len)
{
var c = crc;
var n;
if (!rfc2083_crc_table_computed)
rfc2083_make_crc_table();
for (n = 0; n < len; n++)
{
c = rfc2083_crc_table[(c ^ u8buf[at + n]) & 0xff] ^ (c >>> 8);
}
return c;
}
function rfc2083_crc(u8buf, at, len)
{
return rfc2083_update_crc(0xffffffff, u8buf, at, len) ^ 0xffffffff;
}
function crc32(mb, at, len)
{
var u8 = new Uint8Array(mb);
return rfc2083_crc(u8, at, len);
}
function PngIHDR(width, height)
{
this.width = width;
this.height = height;
this.depth = 8;
this.type = 6;
this.compression = 0;
this.filter = 0;
this.interlace = 0;
}
PngIHDR.prototype =
{
to_buffer: function(a, at)
{
at = at || 0;
var orig = at;
var dv = new SpiceDataView(a);
dv.setUint32(at, this.buffer_size() - 12); at += 4;
dv.setUint8(at, 'I'.charCodeAt(0)); at++;
dv.setUint8(at, 'H'.charCodeAt(0)); at++;
dv.setUint8(at, 'D'.charCodeAt(0)); at++;
dv.setUint8(at, 'R'.charCodeAt(0)); at++;
dv.setUint32(at, this.width); at += 4;
dv.setUint32(at, this.height); at += 4;
dv.setUint8(at, this.depth); at++;
dv.setUint8(at, this.type); at++;
dv.setUint8(at, this.compression); at++;
dv.setUint8(at, this.filter); at++;
dv.setUint8(at, this.interlace); at++;
dv.setUint32(at, crc32(a, orig + 4, this.buffer_size() - 8)); at += 4;
return at;
},
buffer_size: function()
{
return 12 + 13;
}
}
function adler()
{
this.s1 = 1;
this.s2 = 0;
}
adler.prototype.update = function(b)
{
this.s1 += b;
this.s1 %= 65521;
this.s2 += this.s1;
this.s2 %= 65521;
}
function PngIDAT(width, height, bytes)
{
if (bytes.byteLength > 65535)
{
throw new Error("Cannot handle more than 64K");
}
this.data = bytes;
this.width = width;
this.height = height;
}
PngIDAT.prototype =
{
to_buffer: function(a, at)
{
at = at || 0;
var orig = at;
var x, y, i, j;
var dv = new SpiceDataView(a);
var zsum = new adler();
dv.setUint32(at, this.buffer_size() - 12); at += 4;
dv.setUint8(at, 'I'.charCodeAt(0)); at++;
dv.setUint8(at, 'D'.charCodeAt(0)); at++;
dv.setUint8(at, 'A'.charCodeAt(0)); at++;
dv.setUint8(at, 'T'.charCodeAt(0)); at++;
/* zlib header. */
dv.setUint8(at, 0x78); at++;
dv.setUint8(at, 0x01); at++;
/* Deflate header. Specifies uncompressed, final bit */
dv.setUint8(at, 0x80); at++;
dv.setUint16(at, this.data.byteLength + this.height); at += 2;
dv.setUint16(at, ~(this.data.byteLength + this.height)); at += 2;
var u8 = new Uint8Array(this.data);
for (i = 0, y = 0; y < this.height; y++)
{
/* Filter type 0 - uncompressed */
dv.setUint8(at, 0); at++;
zsum.update(0);
for (x = 0; x < this.width && i < this.data.byteLength; x++)
{
zsum.update(u8[i]);
dv.setUint8(at, u8[i++]); at++;
zsum.update(u8[i]);
dv.setUint8(at, u8[i++]); at++;
zsum.update(u8[i]);
dv.setUint8(at, u8[i++]); at++;
zsum.update(u8[i]);
dv.setUint8(at, u8[i++]); at++;
}
}
/* zlib checksum. */
dv.setUint16(at, zsum.s2); at+=2;
dv.setUint16(at, zsum.s1); at+=2;
/* FIXME - something is not quite right with the zlib code;
you get an error from libpng if you open the image in
gimp. But it works, so it's good enough for now... */
dv.setUint32(at, crc32(a, orig + 4, this.buffer_size() - 8)); at += 4;
return at;
},
buffer_size: function()
{
return 12 + this.data.byteLength + this.height + 4 + 2 + 1 + 2 + 2;
}
}
function PngIEND()
{
}
PngIEND.prototype =
{
to_buffer: function(a, at)
{
at = at || 0;
var orig = at;
var i;
var dv = new SpiceDataView(a);
dv.setUint32(at, this.buffer_size() - 12); at += 4;
dv.setUint8(at, 'I'.charCodeAt(0)); at++;
dv.setUint8(at, 'E'.charCodeAt(0)); at++;
dv.setUint8(at, 'N'.charCodeAt(0)); at++;
dv.setUint8(at, 'D'.charCodeAt(0)); at++;
dv.setUint32(at, crc32(a, orig + 4, this.buffer_size() - 8)); at += 4;
return at;
},
buffer_size: function()
{
return 12;
}
}
function create_rgba_png(width, height, bytes)
{
var i;
var ihdr = new PngIHDR(width, height);
var idat = new PngIDAT(width, height, bytes);
var iend = new PngIEND;
var mb = new ArrayBuffer(ihdr.buffer_size() + idat.buffer_size() + iend.buffer_size());
var at = ihdr.to_buffer(mb);
at = idat.to_buffer(mb, at);
at = iend.to_buffer(mb, at);
var u8 = new Uint8Array(mb);
var str = "";
for (i = 0; i < at; i++)
{
str += "%";
if (u8[i] < 16)
str += "0";
str += u8[i].toString(16);
}
return "%89PNG%0D%0A%1A%0A" + str;
}
export {
create_rgba_png,
};