topic Re: Is there a known time for which it is safe to reuse the buffer passed to PictureMarkerSymbol.SetSource? in .NET Maps SDK Questions

Is there a known time for which it is safe to reuse the buffer passed to PictureMarkerSymbol.SetSource?

carloscasanova — Fri, 29 Apr 2016 12:38:56 GMT

If it is possible, I would like to reuse the buffer. However, without knowing when the runtime is "done" reading from it, I don't know when it is safe.

I already verified that the buffer is not read from right away by writing to it immediately after setting it. Also, I saw that SetSource executes superfast (microseconds on my machine) lending further evidence that it is probably not doing any decoding right away.

Why do I want to reuse the buffer? I want to create less garbage (and hence GC pressure). I am attempting to use the PictureMarkerSymbol as a way to include general raster content generated on the fly. I am writing my own renderer that draws to a bitmap, encodes it, and then sends it to the runtime. Yes, this is very awkward, but the other runtime APIs do not satisfy my use case. See draw a million or more small lines. data set updated at 1-10Hz

Re: Is there a known time for which it is safe to reuse the buffer passed to PictureMarkerSymbol.SetSource?

MichaelBranscomb — Mon, 02 May 2016 17:11:40 GMT

Hi,

Are you able to write to the buffer once the call to SetSourceAsync completes?

Cheers

Mike

Re: Is there a known time for which it is safe to reuse the buffer passed to PictureMarkerSymbol.SetSource?

carloscasanova — Mon, 02 May 2016 18:05:36 GMT

Hi Mike, that did the trick.

After "awaiting", I can party on the buffer with no ill consequence.

Here is some more context in case others run into my problem:

I was using a MemoryStream. I could only get it to work with SetSource and not with SetSourceAsync because I forgot to set the seek point on the stream to the beginning before passing it to SetSourceAsync. From my testing, the operation is async with both SetSource and SetSourceAsync. SetSourceAsync just allows to monitor when that async operation completes. Because the operation is async, I noticed an occasional error when I would write to the stream right away after passing it to SetSource because I was writing data that the runtime was reading at the same time.