Implement gradient filter of tight decoder, fixing issue #1767

This commit is a basic implementation of the gradient filter required by
qemu `lossy` option.
This commit is contained in:
Jiang XueQian 2024-05-02 20:41:38 +08:00
parent 10ee10ce56
commit c187b2e5e0
1 changed files with 67 additions and 1 deletions

View File

@ -285,7 +285,73 @@ export default class TightDecoder {
}
_gradientFilter(streamId, x, y, width, height, sock, display, depth) {
throw new Error("Gradient filter not implemented");
// assume the TPIXEL is 3 bytes long
const uncompressedSize = width * height * 3;
let data;
if (uncompressedSize === 0) {
return true;
}
if (uncompressedSize < 12) {
if (sock.rQwait("TIGHT", uncompressedSize)) {
return false;
}
data = sock.rQshiftBytes(uncompressedSize);
} else {
data = this._readData(sock);
if (data === null) {
return false;
}
this._zlibs[streamId].setInput(data);
data = this._zlibs[streamId].inflate(uncompressedSize);
this._zlibs[streamId].setInput(null);
}
let rgbx = new Uint8Array(4 * width * height);
let rgbxIndex = 0, dataIndex = 0;
let left = new Uint8Array(3);
for (let x = 0; x < width; x++) {
for (let c = 0; c < 3; c++) {
const prediction = left[c];
const value = data[dataIndex++] + prediction;
rgbx[rgbxIndex++] = value;
left[c] = value;
}
rgbx[rgbxIndex++] = 255;
}
let upperIndex = 0;
let upper = new Uint8Array(3),
upperleft = new Uint8Array(3);
for (let y = 1; y < height; y++) {
left.fill(0);
upperleft.fill(0);
for (let x = 0; x < width; x++) {
for (let c = 0; c < 3; c++) {
upper[c] = rgbx[upperIndex++];
let prediction = left[c] + upper[c] - upperleft[c];
if (prediction < 0) {
prediction = 0;
} else if (prediction > 255) {
prediction = 255;
}
const value = data[dataIndex++] + prediction;
rgbx[rgbxIndex++] = value;
upperleft[c] = upper[c];
left[c] = value;
}
rgbx[rgbxIndex++] = 255;
upperIndex++;
}
}
display.blitImage(x, y, width, height, rgbx, 0, false);
return true;
}
_readData(sock) {