How to use rosbag - 10 common examples

const currentConnection = this._currentConnection;
      if (!currentConnection || !isCurrent()) {
        return;
      }

      const currentBlockIndex = currentConnection.remainingBlockRange.start;
      // Only request topics that we don't already have.
      const topics = this._blocks[currentBlockIndex]
        ? currentConnection.topics.filter(
            (topic) => !this._blocks[currentBlockIndex] || !this._blocks[currentBlockIndex].messagesByTopic[topic]
          )
        : currentConnection.topics;

      // Get messages from the underlying provider.
      const startTime = TimeUtil.add(this._startTime, fromNanoSec(currentBlockIndex * MEM_CACHE_BLOCK_SIZE_NS));
      const endTime = TimeUtil.add(
        this._startTime,
        fromNanoSec(Math.min(this._totalNs, (currentBlockIndex + 1) * MEM_CACHE_BLOCK_SIZE_NS) - 1) // endTime is inclusive.
      );
      const messages = topics.length ? await this._provider.getMessages(startTime, endTime, topics) : [];

      // If we're not current any more, discard the messages, because otherwise we might write duplicate messages.
      if (!isCurrent()) {
        return;
      }

      // Create a new block if necessary.
      this._blocks[currentBlockIndex] = this._blocks[currentBlockIndex] || { messagesByTopic: {}, sizeInBytes: 0 };
      const currentBlock = this._blocks[currentBlockIndex];
      if (!currentBlock) {
        throw new Error("currentBlock should be set here");
      }

this._setCurrentTime(time);

    const seekTime = Date.now();
    this._lastSeekTime = seekTime;
    this._cancelSeekBackfill = false;
    // cancel any queued _emitState that might later emit messages from before we seeked
    this._messages = [];

    // do not _emitState if subscriptions have changed, but time has not
    if (isEqual(this._currentTime, time)) {
      this._emitState();
    }

    if (!this._isPlaying) {
      this._getMessages(
        TimeUtil.add(clampTime(time, TimeUtil.add(this._start, { sec: 0, nsec: SEEK_BACK_NANOSECONDS }), this._end), {
          sec: 0,
          nsec: -SEEK_BACK_NANOSECONDS,
        }),
        time
      ).then((messages) => {
        // Only emit the messages if we haven't seeked again / emitted messages since we
        // started loading them. Note that for the latter part just checking for `isPlaying`
        // is not enough because the user might have started playback and then paused again!
        // Therefore we really need something like `this._cancelSeekBackfill`.
        if (this._lastSeekTime === seekTime && !this._cancelSeekBackfill) {
          this._messages = messages;
          this._emitState();
        }
      });
    }
  }

while (true) {
      const currentConnection = this._currentConnection;
      if (!currentConnection || !isCurrent()) {
        return;
      }

      const currentBlockIndex = currentConnection.remainingBlockRange.start;
      // Only request topics that we don't already have.
      const topics = this._blocks[currentBlockIndex]
        ? currentConnection.topics.filter(
            (topic) => !this._blocks[currentBlockIndex] || !this._blocks[currentBlockIndex].messagesByTopic[topic]
          )
        : currentConnection.topics;

      // Get messages from the underlying provider.
      const startTime = TimeUtil.add(this._startTime, fromNanoSec(currentBlockIndex * MEM_CACHE_BLOCK_SIZE_NS));
      const endTime = TimeUtil.add(
        this._startTime,
        fromNanoSec(Math.min(this._totalNs, (currentBlockIndex + 1) * MEM_CACHE_BLOCK_SIZE_NS) - 1) // endTime is inclusive.
      );
      const messages = topics.length ? await this._provider.getMessages(startTime, endTime, topics) : [];

      // If we're not current any more, discard the messages, because otherwise we might write duplicate messages.
      if (!isCurrent()) {
        return;
      }

      // Create a new block if necessary.
      this._blocks[currentBlockIndex] = this._blocks[currentBlockIndex] || { messagesByTopic: {}, sizeInBytes: 0 };
      const currentBlock = this._blocks[currentBlockIndex];
      if (!currentBlock) {
        throw new Error("currentBlock should be set here");

async _getMessages(start: Time, end: Time, topics: string[]): Promise {
    // if our topics change we need to clear out the cached ranges, or if we're
    // reading from before the first range.
    if (
      intersection(this._topics, topics).length !== topics.length ||
      !this._current ||
      TimeUtil.isLessThan(start, this._current.start)
    ) {
      this._topics = topics;
      this._current = undefined;
      this._next = undefined;
    }
    let messages = [];
    const currentMatches = this._current && this._current.overlaps(start, end);
    const nextMatches = this._next && this._next.overlaps(start, end);
    if (/*:: this._current && */ currentMatches) {
      messages = messages.concat(await this._current.getMessages(start, end));
    }
    if (/*:: this._next && */ nextMatches) {
      messages = messages.concat(await this._next.getMessages(start, end));
    }
    if ((!currentMatches && !nextMatches) || (this._next && TimeUtil.isGreaterThan(end, this._next.end))) {
      let startTime = start;

if (this._isPlaying) {
      return; // Only run once
    }
    this._isPlaying = true;
    logger.info("AutomatedRunPlayer._run()");
    await this._emitState([], this._providerResult.start);

    let currentTime = this._providerResult.start;
    this._client.start({
      bagLengthMs: toMillis(subtractTimes(this._providerResult.end, this._providerResult.start), "round-up"),
    });

    const nsBagTimePerFrame = Math.round(this._msPerFrame * this._speed * 1000000);

    let frameCount = 0;
    while (TimeUtil.isLessThan(currentTime, this._providerResult.end)) {
      if (this._error) {
        return;
      }
      const end = TimeUtil.add(currentTime, { sec: 0, nsec: nsBagTimePerFrame });
      this._client.markTotalFrameStart();
      const messages = await this._getMessages(currentTime, end);

      this._client.markFrameRenderStart();
      await this._emitState(messages, end);
      this._client.markTotalFrameEnd();
      this._client.markFrameRenderEnd();

      await this._client.onFrameFinished(frameCount);

      currentTime = TimeUtil.add(end, { sec: 0, nsec: 1 });
      frameCount++;

async readFrames(onFrame) {
    const bag = await open(this.bagPath);

    let frame = {};
    function flushFrame() {
      if (frame.keyTopic) {
        onFrame(frame);
        frame = {};
      }
    }

    await bag.readMessages({topics: this.topics}, result => {
      // rosbag.js reuses the data buffer for subsequent messages, so we need to make a copy
      if (result.message.data) {
        result.message.data = Buffer.from(result.message.data);
      }
      if (result.topic === this.keyTopic) {
        flushFrame();

async readFrameByKeyTopic(start, end) {
    const bag = await open(this.bagPath);
    let frame = {};

    async function flushFrame() {
      if (frame.keyTopic) {
        // This needs to be address, was used to flush on keyTopic message to sync
        // await onFrame(frame);
        frame = {};
      }
    }

    const options = {
      startTime: TimeUtil.fromDate(new Date(start * 1e3)),
      endTime: TimeUtil.fromDate(new Date(end * 1e3))
    };

    if (this.topics) {

extensionPoint.progressCallback({
              fullyLoadedFractionRanges: ranges.map(({ start, end }) => ({
                start: Math.max(0, start / approximateSize),
                end: Math.min(1, end / approximateSize),
              })),
            });
          }
        },
      });
      await remoteReader.open(); // Important that we call this first, because it might throw an error if the file can't be read.
      approximateSize = remoteReader.size() * 0.99; // Chop off the last percentage or so for the indexes.

      this._bag = new Bag(new BagReader(remoteReader));
      await this._bag.open();
    } else {
      this._bag = await open(bagPath.file);
      extensionPoint.progressCallback({ fullyLoadedFractionRanges: [{ start: 0, end: 1 }] });
    }

    const { startTime, endTime } = this._bag;
    const connections = ((Object.values(this._bag.connections): any): Connection[]);
    if (!startTime || !endTime || !connections.length) {
      // This will abort video generation:
      reportError("Invalid bag", "Bag is empty or corrupt.", "user");
      return new Promise(() => {}); // Just never finish initializing.
    }

    this._connectionsByTopic = keyBy(connections, "topic");
    return {
      start: startTime,
      end: endTime,
      topics: bagConnectionsToTopics(connections),

}

    const {timestamp, message} = msg[msg.length - 1];

    // Every frame *MUST* have a pose. The pose can be considered
    // the core reference point for other data and usually drives the timing
    // of the system.
    // Position, decimal degrees
    const rotation = quaternionToEuler(message.pose.orientation);
    const {position} = message.pose;
    xvizBuilder
      .pose(this.xvizStream)
      .mapOrigin(this.origin.longitude, this.origin.latitude, this.origin.altitude)
      .position(position.x, position.y, 0)
      .orientation(rotation.roll, rotation.pitch, rotation.yaw)
      .timestamp(TimeUtil.toDate(timestamp).getTime() / 1e3);
  }

isExpired(currentTime: Time) {
    // cannot tell if a marker is expired if we don't have a clock yet
    if (!currentTime) {
      return false;
    }
    const lifetime = this.getLifetime();

    // we use the receive time (clock) instead of the header stamp
    // to match the behavior of rviz
    const expiresAt = TimeUtil.add(this.receiveTime, lifetime);

    return TimeUtil.isGreaterThan(currentTime, expiresAt);
  }