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/*
* noVNC: HTML5 VNC client
* Copyright (C) 2021 The noVNC Authors
* Licensed under MPL 2.0 (see LICENSE.txt)
*
* See README.md for usage and integration instructions.
*
*/
import Inflate from "../inflator.js";
const ZRLE_TILE_WIDTH = 64;
const ZRLE_TILE_HEIGHT = 64;
export default class ZRLEDecoder {
constructor() {
this._length = 0;
this._inflator = new Inflate();
this._pixelBuffer = new Uint8Array(ZRLE_TILE_WIDTH * ZRLE_TILE_HEIGHT * 4);
this._tileBuffer = new Uint8Array(ZRLE_TILE_WIDTH * ZRLE_TILE_HEIGHT * 4);
}
decodeRect(x, y, width, height, sock, display, depth) {
if (this._length === 0) {
if (sock.rQwait("ZLib data length", 4)) {
return false;
}
this._length = sock.rQshift32();
}
if (sock.rQwait("Zlib data", this._length)) {
return false;
}
const data = sock.rQshiftBytes(this._length);
this._inflator.setInput(data);
for (let ty = y; ty < y + height; ty += ZRLE_TILE_HEIGHT) {
let th = Math.min(ZRLE_TILE_HEIGHT, y + height - ty);
for (let tx = x; tx < x + width; tx += ZRLE_TILE_WIDTH) {
let tw = Math.min(ZRLE_TILE_WIDTH, x + width - tx);
const tileSize = tw * th;
const subencoding = this._inflator.inflate(1)[0];
if (subencoding === 0) {
// raw data
const data = this._readPixels(tileSize);
display.blitImage(tx, ty, tw, th, data, 0, false);
} else if (subencoding === 1) {
// solid
const background = this._readPixels(1);
display.fillRect(tx, ty, tw, th, [background[0], background[1], background[2]]);
} else if (subencoding >= 2 && subencoding <= 16) {
const data = this._decodePaletteTile(subencoding, tileSize, tw, th);
display.blitImage(tx, ty, tw, th, data, 0, false);
} else if (subencoding === 128) {
const data = this._decodeRLETile(tileSize);
display.blitImage(tx, ty, tw, th, data, 0, false);
} else if (subencoding >= 130 && subencoding <= 255) {
const data = this._decodeRLEPaletteTile(subencoding - 128, tileSize);
display.blitImage(tx, ty, tw, th, data, 0, false);
} else {
throw new Error('Unknown subencoding: ' + subencoding);
}
}
}
this._length = 0;
return true;
}
_getBitsPerPixelInPalette(paletteSize) {
if (paletteSize <= 2) {
return 1;
} else if (paletteSize <= 4) {
return 2;
} else if (paletteSize <= 16) {
return 4;
}
}
_readPixels(pixels) {
let data = this._pixelBuffer;
const buffer = this._inflator.inflate(3*pixels);
for (let i = 0, j = 0; i < pixels*4; i += 4, j += 3) {
data[i] = buffer[j];
data[i + 1] = buffer[j + 1];
data[i + 2] = buffer[j + 2];
data[i + 3] = 255; // Add the Alpha
}
return data;
}
_decodePaletteTile(paletteSize, tileSize, tilew, tileh) {
const data = this._tileBuffer;
const palette = this._readPixels(paletteSize);
const bitsPerPixel = this._getBitsPerPixelInPalette(paletteSize);
const mask = (1 << bitsPerPixel) - 1;
let offset = 0;
let encoded = this._inflator.inflate(1)[0];
for (let y=0; y<tileh; y++) {
let shift = 8-bitsPerPixel;
for (let x=0; x<tilew; x++) {
if (shift<0) {
shift=8-bitsPerPixel;
encoded = this._inflator.inflate(1)[0];
}
let indexInPalette = (encoded>>shift) & mask;
data[offset] = palette[indexInPalette * 4];
data[offset + 1] = palette[indexInPalette * 4 + 1];
data[offset + 2] = palette[indexInPalette * 4 + 2];
data[offset + 3] = palette[indexInPalette * 4 + 3];
offset += 4;
shift-=bitsPerPixel;
}
if (shift<8-bitsPerPixel && y<tileh-1) {
encoded = this._inflator.inflate(1)[0];
}
}
return data;
}
_decodeRLETile(tileSize) {
const data = this._tileBuffer;
let i = 0;
while (i < tileSize) {
const pixel = this._readPixels(1);
const length = this._readRLELength();
for (let j = 0; j < length; j++) {
data[i * 4] = pixel[0];
data[i * 4 + 1] = pixel[1];
data[i * 4 + 2] = pixel[2];
data[i * 4 + 3] = pixel[3];
i++;
}
}
return data;
}
_decodeRLEPaletteTile(paletteSize, tileSize) {
const data = this._tileBuffer;
// palette
const palette = this._readPixels(paletteSize);
let offset = 0;
while (offset < tileSize) {
let indexInPalette = this._inflator.inflate(1)[0];
let length = 1;
if (indexInPalette >= 128) {
indexInPalette -= 128;
length = this._readRLELength();
}
if (indexInPalette > paletteSize) {
throw new Error('Too big index in palette: ' + indexInPalette + ', palette size: ' + paletteSize);
}
if (offset + length > tileSize) {
throw new Error('Too big rle length in palette mode: ' + length + ', allowed length is: ' + (tileSize - offset));
}
for (let j = 0; j < length; j++) {
data[offset * 4] = palette[indexInPalette * 4];
data[offset * 4 + 1] = palette[indexInPalette * 4 + 1];
data[offset * 4 + 2] = palette[indexInPalette * 4 + 2];
data[offset * 4 + 3] = palette[indexInPalette * 4 + 3];
offset++;
}
}
return data;
}
_readRLELength() {
let length = 0;
let current = 0;
do {
current = this._inflator.inflate(1)[0];
length += current;
} while (current === 255);
return length + 1;
}
}
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