[Qt-interest] change centralwidget in qtcreator
zhao_yunsong
zhao_yunsong at 163.com
Wed Apr 27 18:58:09 CEST 2011
I want to change the centralwidget (which is a instance of QWidget by default) of a mainwindow program in qtcreator, how can i do this.
2011-04-28
zhao_yunsong
发件人： qt-interest-request
发送时间： 2011-04-28 00:54:56
收件人： qt-interest
抄送：
主题： Qt-interest Digest, Vol 5, Issue 127
Send Qt-interest mailing list submissions to
qt-interest at qt.nokia.com
To subscribe or unsubscribe via the World Wide Web, visit
http://lists.qt.nokia.com/mailman/listinfo/qt-interest
or, via email, send a message with subject or body 'help' to
qt-interest-request at qt.nokia.com
You can reach the person managing the list at
qt-interest-owner at qt.nokia.com
When replying, please edit your Subject line so it is more specific
than "Re: Contents of Qt-interest digest..."
Today's Topics:
1. Re: large xml over the network - problem (Jeroen De Wachter)
2. Re: large xml over the network - problem (Bill Crocker)
3. Re: large xml over the network - problem (Jeroen De Wachter)
4. Re: Adding arbitrary depth to Graphics Scene & Friends (Jason H)
----------------------------------------------------------------------
Message: 1
Date: Wed, 27 Apr 2011 17:20:39 +0200
From: Jeroen De Wachter <jeroen.dewachter at elis.ugent.be>
Subject: Re: [Qt-interest] large xml over the network - problem
To: franki <franki at franki.eu.org>
Cc: qt-interest at trolltech.com
Message-ID: <1303917639.23813.22.camel at LoneWolf>
Content-Type: text/plain; charset="UTF-8"
Hey Marek,
Whenever the size of a data type is important, I try to use types that
specify the size in no uncertain terms (this avoids surprises on other
platforms/with other compilers), so I'd use quint32 or uint32_t
Your solution with sending the size first should work.
However, Qt also provides some serialization/deserialization
functionality all on its own (which takes care of communicating the
length before sending the type)
You should take a look at QDataStream:
http://doc.trolltech.com/4.7/qdatastream.html
Kind regards,
Jeroen
On Wed, 2011-04-27 at 16:50 +0200, franki wrote:
> Wednesday 27 of April 2011 16:23:22 Jeroen.DeWachter at elis.ugent.be napisa?(a):
> > Hi,
> >
> > You do know quint16 is limited to 65536, right?
> > So if you're using strings that are longer than that (and you seem to do
> > just that, judging from your example), the length can't be specified
> > correctly in the two bytes you are trying to use for it...
>
> Yes... in my example block.size() on server side is 69496 and quint16 is
> limited to 65536 so... 65536 - 69496 =- 3960 and in my example quint size was
> 3958 (very close), so If I change from quint16 to int (which is four bytes,
> or at least I think so?) should it be OK ?
>
> And answering to Jason, I putted the size of packet at the beginning because
> sometimes there are lots of packets emitted from server to client, each with
> some unique data, how do I know if last message xml has ended before I start
> parsing it? I'm only beginner but wouldn't be a problem when a few xml's are
> sended one after another and client hasn't finished processing of first xml
> command when two or more has arrived. You know, what can separate xml's on
> client side? to process then one by one? I thought that I can ensure myself
> that I'm reading these xml's one by one by putting size at the beginning?
> (besides it was in fortune client example)
>
> best regards
> Marek
>
> >
> > That would certainly be an explanation for the huge discrepancy in your
> > block size and the quint size...
> >
> > Kind regards,
> >
> > Jeroen
> >
> > Quoting franki <franki at franki.eu.org>:
> > > Hi all,
> > >
> > > I have client-server application which exchange data using xml's
> > > over the net.
> > > With relatively small xml's everything goes fine, but when I try to send
> > > big ones there is problem with receiving it (not always just from time to
> > > time), and if I double the size of xml, they are always lost.
> > > Snippet of code on server side:
> > >
> > > void NetThread::sendToClient(QDomDocument xml) {
> > > QByteArray block;
> > > QDataStream out(&block, QIODevice::ReadWrite);
> > > out.setVersion(QDataStream::Qt_4_0);
> > > out << (quint16)0;
> > > out << xml.toString();
> > > out.device()->seek(0);
> > > out << (quint16)(block.size() - sizeof(quint16));
> > > qDebug() <<" quint size:"<<(quint16)(block.size() - sizeof(quint16))
> > > qDebug() <<" block size:"<<block.size();
> > > qDebug() <<" string size:"<<xml.toString().size();
> > > tcpSocket->write(block);
> > > }
> > >
> > > code on client side look's like this (dataSize is quint16):
> > > void NetManager::readData() {
> > > QDataStream in(socket);
> > > in.setVersion(QDataStream::Qt_4_0);
> > > if (dataSize == 0) {
> > > if (socket->bytesAvailable() < (int)sizeof(quint16))
> > > return;
> > > in >> dataSize;
> > > }
> > > if(socket->bytesAvailable() < dataSize)
> > > return;
> > >
> > > QString text;
> > > in >> text;
> > > qDebug() << " dataSize:"<<dataSize<<" received:"<<text;
> > > dataSize=0;
> > > this->parseData(text);
> > > if(socket->bytesAvailable())
> > > this->readData();
> > > }
> > >
> > > On the server side, during transmission debug says:
> > > quint size: 3958
> > > block size: 69496
> > > string size: 34745
> > >
> > > On client side when there is successful transmision I got:
> > > NetManager::readData dataSize: 3958 received: "very long_xml_string"
> > >
> > > When there is problem with transmission I got:
> > > Debug: NetManager::readData bytes: 3958 received: ""
> > > Debug: NetManager::parseData parse error
> > > Debug: NetManager::readData bytes: 61 received: ""
> > > Debug: NetManager::parseData parse error
> > > Debug: NetManager::readData bytes: 51 received: ""
> > > Debug: NetManager::parseData parse error
> > > Debug: NetManager::readData bytes: 56 received: ""
> > > Debug: NetManager::parseData parse error
> > >
> > > So in second example the packet length is the same 3958 but the function
> > > is called 4 times and I'm quite sure that application on server side
> > > doesn't send anything except for this xml.
> > > So please can someone point me on my errors?
> > >
> > > best regards
> > > Marek
> > > _______________________________________________
> > > Qt-interest mailing list
> > > Qt-interest at qt.nokia.com
> > > http://lists.qt.nokia.com/mailman/listinfo/qt-interest
> >
> > ----------------------------------------------------------------
> > This message was sent using IMP, the Internet Messaging Program.
>
>
------------------------------
Message: 2
Date: Wed, 27 Apr 2011 11:24:23 -0400
From: Bill Crocker <william.crocker at analog.com>
Subject: Re: [Qt-interest] large xml over the network - problem
To: "qt-interest at trolltech.com" <qt-interest at trolltech.com>
Message-ID: <4DB83527.1030204 at analog.com>
Content-Type: text/plain; charset="ISO-8859-1"; format=flowed
Jason H wrote:
> Why in the world are you doing that?
>
> in >> buffer;
Because this will block until all of the data arrives
and his app may have better things to do?
Bill
> QDomDocument xml;
> xml.setContent(buffer.toString());
>
>
>
>
>
> ----- Original Message ----
> From: franki <franki at franki.eu.org>
> To: qt-interest at trolltech.com
> Sent: Wed, April 27, 2011 10:08:35 AM
> Subject: [Qt-interest] large xml over the network - problem
>
> Hi all,
>
> I have client-server application which exchange data using xml's over the net.
> With relatively small xml's everything goes fine, but when I try to send big
> ones there is problem with receiving it (not always just from time to time),
> and if I double the size of xml, they are always lost.
> Snippet of code on server side:
>
> void NetThread::sendToClient(QDomDocument xml) {
> QByteArray block;
> QDataStream out(&block, QIODevice::ReadWrite);
> out.setVersion(QDataStream::Qt_4_0);
> out << (quint16)0;
> out << xml.toString();
> out.device()->seek(0);
> out << (quint16)(block.size() - sizeof(quint16));
> qDebug() <<" quint size:"<<(quint16)(block.size() - sizeof(quint16))
> qDebug() <<" block size:"<<block.size();
> qDebug() <<" string size:"<<xml.toString().size();
> tcpSocket->write(block);
> }
>
> code on client side look's like this (dataSize is quint16):
> void NetManager::readData() {
> QDataStream in(socket);
> in.setVersion(QDataStream::Qt_4_0);
> if (dataSize == 0) {
> if (socket->bytesAvailable() < (int)sizeof(quint16))
> return;/net/neuro/disk1/apache/website/htdocs/adice/adiceinfo/log_r10.txt
> in >> dataSize;
> }
> if(socket->bytesAvailable() < dataSize)
> return;
>
> QString text;
> in >> text;
> qDebug() << " dataSize:"<<dataSize<<" received:"<<text;
> dataSize=0;
> this->parseData(text);
> if(socket->bytesAvailable())
> this->readData();
> }
>
> On the server side, during transmission debug says:
> quint size: 3958
> block size: 69496
> string size: 34745
>
> On client side when there is successful transmision I got:
> NetManager::readData dataSize: 3958 received: "very long_xml_string"
>
> When there is problem with transmission I got:
> Debug: NetManager::readData bytes: 3958 received: ""
> Debug: NetManager::parseData parse error
> Debug: NetManager::readData bytes: 61 received: ""
> Debug: NetManager::parseData parse error
> Debug: NetManager::readData bytes: 51 received: ""
> Debug: NetManager::parseData parse error
> Debug: NetManager::readData bytes: 56 received: ""
> Debug: NetManager::parseData parse error
>
> So in second example the packet length is the same 3958 but the function is
> called 4 times and I'm quite sure that application on server side doesn't
> send anything except for this xml.
> So please can someone point me on my errors?
>
> best regards
> Marek
> _______________________________________________
> Qt-interest mailing list
> Qt-interest at qt.nokia.com
> http://lists.qt.nokia.com/mailman/listinfo/qt-interest
>
> _______________________________________________
> Qt-interest mailing list
> Qt-interest at qt.nokia.com
> http://lists.qt.nokia.com/mailman/listinfo/qt-interest
>
------------------------------
Message: 3
Date: Wed, 27 Apr 2011 17:43:35 +0200
From: Jeroen De Wachter <jeroen.dewachter at elis.ugent.be>
Subject: Re: [Qt-interest] large xml over the network - problem
To: franki <franki at franki.eu.org>
Cc: qt-interest at trolltech.com
Message-ID: <1303919015.23813.30.camel at LoneWolf>
Content-Type: text/plain; charset="UTF-8"
Hey Marek,
I just remembered I once talked about the QDataStream on the qt IRC
channel and it might be important for you.
If you send a large chunk of data through the QDataStream, if might
cause trouble with buffering (in combination with the tcp connection) or
if the connection shuts down (and you may have no way of knowing sending
the data failed). I don't remember the specifics, I just recall there
was some discussion.
Maybe you could test the QDataStream stuff and just see if it works (I
think it's more elegant than breaking up a string into size and data
fields yourself), but keep your current solution in mind as a fallback.
Just wanted to give you a heads-up...
Kind regards,
Jeroen
On Wed, 2011-04-27 at 17:20 +0200, Jeroen De Wachter wrote:
> Hey Marek,
>
> Whenever the size of a data type is important, I try to use types that
> specify the size in no uncertain terms (this avoids surprises on other
> platforms/with other compilers), so I'd use quint32 or uint32_t
>
> Your solution with sending the size first should work.
>
> However, Qt also provides some serialization/deserialization
> functionality all on its own (which takes care of communicating the
> length before sending the type)
> You should take a look at QDataStream:
>
> http://doc.trolltech.com/4.7/qdatastream.html
>
> Kind regards,
>
> Jeroen
>
> On Wed, 2011-04-27 at 16:50 +0200, franki wrote:
> > Wednesday 27 of April 2011 16:23:22 Jeroen.DeWachter at elis.ugent.be napisa?(a):
> > > Hi,
> > >
> > > You do know quint16 is limited to 65536, right?
> > > So if you're using strings that are longer than that (and you seem to do
> > > just that, judging from your example), the length can't be specified
> > > correctly in the two bytes you are trying to use for it...
> >
> > Yes... in my example block.size() on server side is 69496 and quint16 is
> > limited to 65536 so... 65536 - 69496 =- 3960 and in my example quint size was
> > 3958 (very close), so If I change from quint16 to int (which is four bytes,
> > or at least I think so?) should it be OK ?
> >
> > And answering to Jason, I putted the size of packet at the beginning because
> > sometimes there are lots of packets emitted from server to client, each with
> > some unique data, how do I know if last message xml has ended before I start
> > parsing it? I'm only beginner but wouldn't be a problem when a few xml's are
> > sended one after another and client hasn't finished processing of first xml
> > command when two or more has arrived. You know, what can separate xml's on
> > client side? to process then one by one? I thought that I can ensure myself
> > that I'm reading these xml's one by one by putting size at the beginning?
> > (besides it was in fortune client example)
> >
> > best regards
> > Marek
> >
> > >
> > > That would certainly be an explanation for the huge discrepancy in your
> > > block size and the quint size...
> > >
> > > Kind regards,
> > >
> > > Jeroen
> > >
> > > Quoting franki <franki at franki.eu.org>:
> > > > Hi all,
> > > >
> > > > I have client-server application which exchange data using xml's
> > > > over the net.
> > > > With relatively small xml's everything goes fine, but when I try to send
> > > > big ones there is problem with receiving it (not always just from time to
> > > > time), and if I double the size of xml, they are always lost.
> > > > Snippet of code on server side:
> > > >
> > > > void NetThread::sendToClient(QDomDocument xml) {
> > > > QByteArray block;
> > > > QDataStream out(&block, QIODevice::ReadWrite);
> > > > out.setVersion(QDataStream::Qt_4_0);
> > > > out << (quint16)0;
> > > > out << xml.toString();
> > > > out.device()->seek(0);
> > > > out << (quint16)(block.size() - sizeof(quint16));
> > > > qDebug() <<" quint size:"<<(quint16)(block.size() - sizeof(quint16))
> > > > qDebug() <<" block size:"<<block.size();
> > > > qDebug() <<" string size:"<<xml.toString().size();
> > > > tcpSocket->write(block);
> > > > }
> > > >
> > > > code on client side look's like this (dataSize is quint16):
> > > > void NetManager::readData() {
> > > > QDataStream in(socket);
> > > > in.setVersion(QDataStream::Qt_4_0);
> > > > if (dataSize == 0) {
> > > > if (socket->bytesAvailable() < (int)sizeof(quint16))
> > > > return;
> > > > in >> dataSize;
> > > > }
> > > > if(socket->bytesAvailable() < dataSize)
> > > > return;
> > > >
> > > > QString text;
> > > > in >> text;
> > > > qDebug() << " dataSize:"<<dataSize<<" received:"<<text;
> > > > dataSize=0;
> > > > this->parseData(text);
> > > > if(socket->bytesAvailable())
> > > > this->readData();
> > > > }
> > > >
> > > > On the server side, during transmission debug says:
> > > > quint size: 3958
> > > > block size: 69496
> > > > string size: 34745
> > > >
> > > > On client side when there is successful transmision I got:
> > > > NetManager::readData dataSize: 3958 received: "very long_xml_string"
> > > >
> > > > When there is problem with transmission I got:
> > > > Debug: NetManager::readData bytes: 3958 received: ""
> > > > Debug: NetManager::parseData parse error
> > > > Debug: NetManager::readData bytes: 61 received: ""
> > > > Debug: NetManager::parseData parse error
> > > > Debug: NetManager::readData bytes: 51 received: ""
> > > > Debug: NetManager::parseData parse error
> > > > Debug: NetManager::readData bytes: 56 received: ""
> > > > Debug: NetManager::parseData parse error
> > > >
> > > > So in second example the packet length is the same 3958 but the function
> > > > is called 4 times and I'm quite sure that application on server side
> > > > doesn't send anything except for this xml.
> > > > So please can someone point me on my errors?
> > > >
> > > > best regards
> > > > Marek
> > > > _______________________________________________
> > > > Qt-interest mailing list
> > > > Qt-interest at qt.nokia.com
> > > > http://lists.qt.nokia.com/mailman/listinfo/qt-interest
> > >
> > > ----------------------------------------------------------------
> > > This message was sent using IMP, the Internet Messaging Program.
> >
> >
>
>
> _______________________________________________
> Qt-interest mailing list
> Qt-interest at qt.nokia.com
> http://lists.qt.nokia.com/mailman/listinfo/qt-interest
------------------------------
Message: 4
Date: Wed, 27 Apr 2011 09:47:20 -0700 (PDT)
From: Jason H <scorp1us at yahoo.com>
Subject: Re: [Qt-interest] Adding arbitrary depth to Graphics Scene &
Friends
To: Javier Urien <javierurien at gmail.com>
Cc: qt-interest at trolltech.com
Message-ID: <698755.91203.qm at web120716.mail.ne1.yahoo.com>
Content-Type: text/plain; charset="us-ascii"
In theory no, but in practice yes.
You'll have to make a QAppliction instance, but you [probably] won't have to
call app.exec().
main ()
{
QApplication app;
QGraphicsView gv...
/* do your manipulation here */
/* do your output here */
/* no need for exec (most likely) */
return 0;
}
________________________________
From: Javier Urien <javierurien at gmail.com>
To: Jason H <scorp1us at yahoo.com>
Cc: qt-interest at trolltech.com
Sent: Wed, April 27, 2011 10:43:29 AM
Subject: Re: [Qt-interest] Adding arbitrary depth to Graphics Scene & Friends
On Tue, Apr 26, 2011 at 18:28, Javier Urien <javierurien at gmail.com> wrote:
>
>
>On Tue, Apr 26, 2011 at 16:20, Jason H <scorp1us at yahoo.com> wrote:
>
>Yes. a Qt Image IO plugin.
>>
>>http://doc.qt.nokia.com/qq/qq17-imageio.html
>>
>>
>Excellent!!!
>
>
>Thanks for all your answers!
One more question. Does all this depend on the application loop or can it be
used without a QApplication instance?
Regards.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.qt.nokia.com/pipermail/qt-interest/attachments/20110427/3da636ad/attachment.html
------------------------------
_______________________________________________
Qt-interest mailing list
Qt-interest at qt.nokia.com
http://lists.qt.nokia.com/mailman/listinfo/qt-interest
End of Qt-interest Digest, Vol 5, Issue 127
*******************************************
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.qt-project.org/pipermail/qt-interest-old/attachments/20110428/7a7bf1b1/attachment.html
More information about the Qt-interest-old
mailing list