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Diffstat (limited to 'core/decoders/zrle.js')
| -rw-r--r-- | core/decoders/zrle.js | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/core/decoders/zrle.js b/core/decoders/zrle.js new file mode 100644 index 0000000..97fbd58 --- /dev/null +++ b/core/decoders/zrle.js @@ -0,0 +1,185 @@ +/* + * 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; + } +} |