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https://github.com/dz0ny/meshcore-sar.git
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Improve image zoom quality
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Janez T
274
lib/utils/image_message_parser.dart
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274
lib/utils/image_message_parser.dart
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@@ -0,0 +1,274 @@
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import 'dart:typed_data';
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/// Compressed image format used in the image packet protocol.
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enum ImageFormat {
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avif(0, 'AVIF'),
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jpeg(1, 'JPEG');
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const ImageFormat(this.id, this.label);
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final int id;
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final String label;
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static ImageFormat fromId(int id) => ImageFormat.values.firstWhere(
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(f) => f.id == id,
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orElse: () => ImageFormat.avif,
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);
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}
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/// A single binary fragment of a compressed image.
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///
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/// Binary format (direct contacts, via pushRawData / cmdSendRawData):
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/// [0x49 'I'][sessionId:4B][fmt:1B][idx:1B][total:1B][imageData...]
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///
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/// Max total packet size is 160 bytes → 152 bytes of image data per fragment.
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class ImagePacket {
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final String sessionId; // 8 hex chars (4 bytes)
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final ImageFormat format;
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final int index; // 0-based
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final int total; // total fragment count (1..255)
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final Uint8List data;
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const ImagePacket({
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required this.sessionId,
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required this.format,
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required this.index,
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required this.total,
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required this.data,
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});
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static const int _magic = 0x49; // 'I'
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static const int _headerLen = 8; // magic(1)+session(4)+fmt(1)+idx(1)+total(1)
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static const int maxDataBytes = 152; // 160 - 8 header bytes
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static bool isImageBinary(Uint8List payload) =>
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payload.isNotEmpty && payload[0] == _magic;
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static ImagePacket? tryParseBinary(Uint8List payload) {
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if (payload.length < _headerLen) return null;
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if (payload[0] != _magic) return null;
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try {
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final sessionId = payload
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.sublist(1, 5)
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.map((b) => b.toRadixString(16).padLeft(2, '0'))
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.join();
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final fmtId = payload[5];
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final index = payload[6];
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final total = payload[7];
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if (total < 1) return null;
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return ImagePacket(
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sessionId: sessionId,
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format: ImageFormat.fromId(fmtId),
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index: index,
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total: total,
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data: payload.sublist(_headerLen),
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);
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} catch (_) {
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return null;
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}
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}
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Uint8List encodeBinary() {
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final sessionBytes = Uint8List(4);
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for (var i = 0; i < 4; i++) {
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sessionBytes[i] = int.parse(
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sessionId.substring(i * 2, i * 2 + 2),
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radix: 16,
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);
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}
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final out = Uint8List(_headerLen + data.length);
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out[0] = _magic;
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out.setRange(1, 5, sessionBytes);
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out[5] = format.id;
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out[6] = index;
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out[7] = total;
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out.setRange(_headerLen, out.length, data);
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return out;
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}
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@override
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String toString() =>
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'ImagePacket($sessionId ${format.label} [$index/${total - 1}] ${data.length}B)';
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}
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/// Envelope announcing image availability (control plane).
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///
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/// Text format:
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/// IE1:{sid}:{fmt}:{total}:{w}:{h}:{bytes}:{senderKey6}:{ts}:{ver}
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/// Example:
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/// IE1:deadbeef:0:7:128:128:1050:aabbccddeeff:1700000000:1
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class ImageEnvelope {
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static const String prefix = 'IE1:';
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final String sessionId; // 8 hex chars
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final ImageFormat format;
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final int total; // total fragment count
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final int width;
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final int height;
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final int sizeBytes; // total compressed image size
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final String senderKey6; // 12 hex chars (6 bytes)
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final int timestampSec;
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final int version;
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const ImageEnvelope({
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required this.sessionId,
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required this.format,
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required this.total,
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required this.width,
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required this.height,
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required this.sizeBytes,
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required this.senderKey6,
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required this.timestampSec,
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this.version = 1,
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});
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static bool isEnvelope(String text) => text.startsWith(prefix);
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static ImageEnvelope? tryParse(String text) {
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if (!isEnvelope(text)) return null;
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final body = text.substring(prefix.length);
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final parts = body.split(':');
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if (parts.length != 9) return null;
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try {
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final sid = parts[0];
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final fmtId = int.tryParse(parts[1]);
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final total = int.tryParse(parts[2]);
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final w = int.tryParse(parts[3]);
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final h = int.tryParse(parts[4]);
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final bytes = int.tryParse(parts[5]);
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final senderKey6 = parts[6];
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final ts = int.tryParse(parts[7]);
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final ver = int.tryParse(parts[8]);
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if (!RegExp(r'^[0-9a-fA-F]{8}$').hasMatch(sid)) return null;
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if (fmtId == null) return null;
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if (total == null || total < 1 || total > 255) return null;
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if (w == null || h == null || w < 1 || h < 1) return null;
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if (bytes == null || bytes < 1) return null;
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if (!RegExp(r'^[0-9a-fA-F]{12}$').hasMatch(senderKey6)) return null;
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if (ts == null || ts <= 0) return null;
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if (ver == null || ver != 1) return null;
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return ImageEnvelope(
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sessionId: sid.toLowerCase(),
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format: ImageFormat.fromId(fmtId),
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total: total,
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width: w,
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height: h,
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sizeBytes: bytes,
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senderKey6: senderKey6.toLowerCase(),
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timestampSec: ts,
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version: ver,
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);
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} catch (_) {
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return null;
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}
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}
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String encode() =>
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'${prefix}${sessionId.toLowerCase()}:${format.id}:$total:$width:$height:$sizeBytes:${senderKey6.toLowerCase()}:$timestampSec:$version';
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}
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/// Direct request to fetch image fragments (control plane).
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///
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/// Text format:
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/// IR1:{sid}:{want}:{requesterKey6}:{ts}:{ver}
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/// Example:
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/// IR1:deadbeef:a:aabbccddeeff:1700000010:1
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class ImageFetchRequest {
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static const String prefix = 'IR1:';
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final String sessionId;
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final String want; // always 'all'
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final String requesterKey6; // 12 hex chars
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final int timestampSec;
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final int version;
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const ImageFetchRequest({
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required this.sessionId,
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this.want = 'all',
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required this.requesterKey6,
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required this.timestampSec,
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this.version = 1,
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});
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static bool isRequest(String text) => text.startsWith(prefix);
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static ImageFetchRequest? tryParse(String text) {
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if (!isRequest(text)) return null;
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final body = text.substring(prefix.length);
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final parts = body.split(':');
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if (parts.length != 5) return null;
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try {
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final sid = parts[0];
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final wantToken = parts[1];
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final requesterKey6 = parts[2];
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final ts = int.tryParse(parts[3]);
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final ver = int.tryParse(parts[4]);
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final normalizedWant = wantToken == 'a' ? 'all' : wantToken;
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if (!RegExp(r'^[0-9a-fA-F]{8}$').hasMatch(sid)) return null;
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if (normalizedWant != 'all') return null;
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if (!RegExp(r'^[0-9a-fA-F]{12}$').hasMatch(requesterKey6)) return null;
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if (ts == null || ts <= 0) return null;
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if (ver == null || ver != 1) return null;
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return ImageFetchRequest(
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sessionId: sid.toLowerCase(),
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want: normalizedWant,
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requesterKey6: requesterKey6.toLowerCase(),
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timestampSec: ts,
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version: ver,
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);
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} catch (_) {
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return null;
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}
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}
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String encode() {
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final wantToken = want == 'all' ? 'a' : want;
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return '${prefix}${sessionId.toLowerCase()}:$wantToken:${requesterKey6.toLowerCase()}:$timestampSec:$version';
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}
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}
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/// Fragment the compressed image bytes into [ImagePacket] list.
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///
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/// [sessionId] must be 8 lowercase hex chars.
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/// [format] is the image format used.
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/// Returns at most 255 packets; excess bytes are silently dropped.
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List<ImagePacket> fragmentImage({
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required String sessionId,
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required ImageFormat format,
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required Uint8List bytes,
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}) {
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const chunkSize = ImagePacket.maxDataBytes;
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final chunks = <Uint8List>[];
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for (var offset = 0; offset < bytes.length; offset += chunkSize) {
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final end = (offset + chunkSize).clamp(0, bytes.length);
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chunks.add(bytes.sublist(offset, end));
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if (chunks.length == 255) break; // protocol limit
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}
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final total = chunks.length;
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return [
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for (var i = 0; i < total; i++)
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ImagePacket(
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sessionId: sessionId,
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format: format,
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index: i,
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total: total,
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data: chunks[i],
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),
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];
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}
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/// Reassemble image bytes from received [packets].
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///
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/// Returns null if any fragment is missing.
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Uint8List? reassembleImage(List<ImagePacket?> packets) {
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if (packets.isEmpty) return null;
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if (packets.any((p) => p == null)) return null;
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final merged = <int>[];
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for (final p in packets) {
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merged.addAll(p!.data);
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}
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return Uint8List.fromList(merged);
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}
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