[Qt-interest] Transferring a QPixmap through QTcpSocket

[Andre Somers]

Op Do, 7 april, 2011 1:34 pm, schreef sarvesh saran:
> On Thu, Apr 7, 2011 at 4:30 PM, Joshua W Joseph <
> joshua at blueprint-group.co.ke> wrote:
>
>> Hi All,
>>
>> I have two simple applications which are network based. The 'server'
>> takes
>> a screenshot of its computer. When a 'client' connects, it will receive
>> the
>> captured image. These are basically the fortune server/client examples
>> modified to transmit images instead of text.
>>
>>
>>
>> The client receives some data, but how to I:
>>     1. Ensure that all of the sent data is received, and
>>
>
>        your code is ensuring this already.
>
>
>
>>     2. Convert the received data into a QPixmap so that it can be
>> displayed.
>>
>
> the operator>> takes care of that (
> http://doc.qt.nokia.com/latest/qpixmap.html#operator-lt-lt-101).....its
> all
> there in your code!

Sorry, but that is wrong. It might very well be that you get the signal
that you have data to read, but not all data is available yet and trying
to use the >> operator on QDataStream to read the image will result in a
crash.

However, it seems that you are already waiting to see if you have received
all the data. What I would do, is stream first stream out the QPixmap to a
buffer. Then, see how big that buffer is, stream that out as a quint64,
and then stream out the raw data from the buffer to the network. This way,
you can first read the size of the image to expect, and then only if you
have received the complete data, read out the actual QPixmap. Note that
you also might store the image data in a buffer on the receiving end
untill the size of that buffer matches the size you received as the image
size.

André