Many thanks for the interesting answer
As you can guess the thing is that I have a very rare crash that I am
not able to reproduce in debug conditions, so after many hours starring
at the code I saw that as a possible explanation.
I'll try to make a copy, I am reluctant because I must be very careful
with memory and time to copy.
Philippe.
Le 09-11-2019 18:12, Giuseppe D'Angelo via Interest a écrit :
Hi,
On 08/11/2019 18:33, maitai wrote:
All is in the tile, is QImage::copy threadsafe? The method is const
but
is it enough? Documentation does not state it is thread safe so I am
wondering.
My case is I have a QImage loaded in the main thread, and many many
threads that keep extracting small rectangles from it using
QImage::copy. No other operations occur on the QImage once loaded.
The short story is that const methods on Qt value classes are
generally thread safe. The exceptions are very very few (e.g.
QString::utf16).
I don't believe this is guaranteed anywhere in the documentation,
though. If you can live with the "implementation guarantee" then, by
all means, just use copy() from multiple threads.
On the other hand, you could just create copies of the image and give
them out to each worker thread. Copying a QImage is very cheap (it's
implicitly shared so it won't deep copy the data anyhow).
HTH,
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