lz.js
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"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/>.
*/
/*----------------------------------------------------------------------------
** lz.js
** Functions for handling SPICE_IMAGE_TYPE_LZ_RGB
** Adapted from lz.c .
**--------------------------------------------------------------------------*/
function lz_rgb32_decompress(in_buf, at, out_buf, type, default_alpha)
{
var encoder = at;
var op = 0;
var ctrl;
var ctr = 0;
for (ctrl = in_buf[encoder++]; (op * 4) < out_buf.length; ctrl = in_buf[encoder++])
{
var ref = op;
var len = ctrl >> 5;
var ofs = (ctrl & 31) << 8;
//if (type == LZ_IMAGE_TYPE_RGBA)
//console.log(ctr++ + ": from " + (encoder + 28) + ", ctrl " + ctrl + ", len " + len + ", ofs " + ofs + ", op " + op);
if (ctrl >= 32) {
var code;
len--;
if (len == 7 - 1) {
do {
code = in_buf[encoder++];
len += code;
} while (code == 255);
}
code = in_buf[encoder++];
ofs += code;
if (code == 255) {
if ((ofs - code) == (31 << 8)) {
ofs = in_buf[encoder++] << 8;
ofs += in_buf[encoder++];
ofs += 8191;
}
}
len += 1;
if (type == LZ_IMAGE_TYPE_RGBA)
len += 2;
ofs += 1;
ref -= ofs;
if (ref == (op - 1)) {
var b = ref;
//if (type == LZ_IMAGE_TYPE_RGBA) console.log("alpha " + out_buf[(b*4)+3] + " dupped into pixel " + op + " through pixel " + (op + len));
for (; len; --len) {
if (type == LZ_IMAGE_TYPE_RGBA)
{
out_buf[(op*4) + 3] = out_buf[(b*4)+3];
}
else
{
for (i = 0; i < 4; i++)
out_buf[(op*4) + i] = out_buf[(b*4)+i];
}
op++;
}
} else {
//if (type == LZ_IMAGE_TYPE_RGBA) console.log("alpha copied to pixel " + op + " through " + (op + len) + " from " + ref);
for (; len; --len) {
if (type == LZ_IMAGE_TYPE_RGBA)
{
out_buf[(op*4) + 3] = out_buf[(ref*4)+3];
}
else
{
for (i = 0; i < 4; i++)
out_buf[(op*4) + i] = out_buf[(ref*4)+i];
}
op++; ref++;
}
}
} else {
ctrl++;
if (type == LZ_IMAGE_TYPE_RGBA)
{
//console.log("alpha " + in_buf[encoder] + " set into pixel " + op);
out_buf[(op*4) + 3] = in_buf[encoder++];
}
else
{
out_buf[(op*4) + 0] = in_buf[encoder + 2];
out_buf[(op*4) + 1] = in_buf[encoder + 1];
out_buf[(op*4) + 2] = in_buf[encoder + 0];
if (default_alpha)
out_buf[(op*4) + 3] = 255;
encoder += 3;
}
op++;
for (--ctrl; ctrl; ctrl--) {
if (type == LZ_IMAGE_TYPE_RGBA)
{
//console.log("alpha " + in_buf[encoder] + " set into pixel " + op);
out_buf[(op*4) + 3] = in_buf[encoder++];
}
else
{
out_buf[(op*4) + 0] = in_buf[encoder + 2];
out_buf[(op*4) + 1] = in_buf[encoder + 1];
out_buf[(op*4) + 2] = in_buf[encoder + 0];
if (default_alpha)
out_buf[(op*4) + 3] = 255;
encoder += 3;
}
op++;
}
}
}
return encoder - 1;
}
function convert_spice_lz_to_web(context, lz_image)
{
var at;
if (lz_image.type === LZ_IMAGE_TYPE_RGB32 || lz_image.type === LZ_IMAGE_TYPE_RGBA)
{
var u8 = new Uint8Array(lz_image.data);
var ret = context.createImageData(lz_image.width, lz_image.height);
at = lz_rgb32_decompress(u8, 0, ret.data, LZ_IMAGE_TYPE_RGB32, lz_image.type != LZ_IMAGE_TYPE_RGBA);
if (lz_image.type == LZ_IMAGE_TYPE_RGBA)
lz_rgb32_decompress(u8, at, ret.data, LZ_IMAGE_TYPE_RGBA, false);
}
else if (lz_image.type === LZ_IMAGE_TYPE_XXXA)
{
var u8 = new Uint8Array(lz_image.data);
var ret = context.createImageData(lz_image.width, lz_image.height);
lz_rgb32_decompress(u8, 0, ret.data, LZ_IMAGE_TYPE_RGBA, false);
}
else
return undefined;
return ret;
}