Re: [Interest] Qt6 : QPA qxcb - Ubuntu 20.04 dev libraries dependencies
Turns out when I pasted a block of sudo apt-get install command to install the required dependencies, not all of them ran. Once I have ensure that all the dependencies are properly installed, libqxcb*.so was built on Ubuntu 20.04 for Qt6 Cheers On Sun, 24 Jan 2021 at 15:02, Andreas Buhr wrote: > Hi Nicholas, > > On 24.01.21 18:42, Nicholas Yue wrote: > >I am troubleshooting the failure to configure Qt6 qxcb for building > > on Ubuntu 20.04 > > > >A number of sites I saw references 18.04 which I tried to adapt but > > to no avail. > > > >Anyone know of the canonical list of dependencies required to build > > Qt6 with qxcb on Ubuntu 20.04 ? > > I guess you are familiar with these guidelines: > https://wiki.qt.io/Building_Qt_5_from_Git > > Could you maybe provide more details about the problem? What did you > try? Into what problem did you run? > > best, > Andreas > > -- > Andreas Buhr > Senior Software Engineer > > The Qt Company > Erich-Thilo-Str. 10 > 12489 Berlin > Germany > andreas.b...@qt.io > www.qt.io > > Geschäftsführer: Mika Pälsi, > Juha Varelius, Jouni Lintunen > Sitz der Gesellschaft: Berlin, > Registergericht: Amtsgericht > Charlottenburg, HRB 144331 B > ___ > Interest mailing list > Interest@qt-project.org > https://lists.qt-project.org/listinfo/interest > -- Nicholas Yue Graphics - Arnold, Alembic, RenderMan, OpenGL, HDF5 Custom Dev - C++ porting, OSX, Linux, Windows http://au.linkedin.com/in/nicholasyue https://vimeo.com/channels/naiadtools ___ Interest mailing list Interest@qt-project.org https://lists.qt-project.org/listinfo/interest
Re: [Interest] QVariant toBool() not working correctly?
Hi,
On Tue, Jan 26, 2021 at 5:38 PM Giuseppe D'Angelo via Interest
wrote:
> You've been bit by a combination of two things, one is Qt not supporting
> the BIT column type natively (that's QTBUG-21326), and mapping it to a
> string. The other that the string you're getting contains a NUL
> (U+), not a literal 0 (U+0030). When converting a QVariant
> containing a string to bool, Qt maps empty strings, the string "0" and
> the string "false" (in any case) to false and everything else to true:
>
> > https://code.qt.io/cgit/qt/qtbase.git/tree/src/corelib/kernel/qvariant.cpp?h=5.12#n344
Thanks Christian and Giuseppe for your help.
I am now using the following workaround:
bool Database::getBool(QVariant v, bool nullValue)
{
if (v.isNull())
return nullValue;
/* workaround for zero BIT value being loaded as "\0" instead of "0" */
if (v == QVariant(QChar(0)))
return false;
return v.toBool();
}
Kevin
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Re: [Interest] QVariant toBool() not working correctly?
On 26.01.21 17:37, Giuseppe D'Angelo via Interest wrote: You've been bit (...) LOL ... pun was intentional, I assume? ___ Interest mailing list Interest@qt-project.org https://lists.qt-project.org/listinfo/interest
Re: [Interest] QVariant toBool() not working correctly?
Hi, Il 26/01/21 16:52, Kevin André ha scritto: When reading a zero BIT value from the database, this outputs: getBool called for: QVariant(QString, "\u") getBool will convert QVariant(QString, "\u") to bool true The docs of toBool() claim that toBool should return false for a string value of "0". I am using Qt version 5.12.3. So is this a mismatch between the Qt version of the docs and the Qt version that I am using? Or am I missing something else here? You've been bit by a combination of two things, one is Qt not supporting the BIT column type natively (that's QTBUG-21326), and mapping it to a string. The other that the string you're getting contains a NUL (U+), not a literal 0 (U+0030). When converting a QVariant containing a string to bool, Qt maps empty strings, the string "0" and the string "false" (in any case) to false and everything else to true: https://code.qt.io/cgit/qt/qtbase.git/tree/src/corelib/kernel/qvariant.cpp?h=5.12#n344 Therefore, work around the issue and do the conversion yourself. (An alternative would be using TINYINT to represent bools.) HTH, -- Giuseppe D'Angelo | giuseppe.dang...@kdab.com | Senior Software Engineer KDAB (France) S.A.S., a KDAB Group company Tel. France +33 (0)4 90 84 08 53, http://www.kdab.com KDAB - The Qt, C++ and OpenGL Experts smime.p7s Description: Firma crittografica S/MIME ___ Interest mailing list Interest@qt-project.org https://lists.qt-project.org/listinfo/interest
Re: [Interest] QVariant toBool() not working correctly?
Am 26.01.2021 um 16:52 schrieb Kevin André:
Hi,
I am reading a boolean value from a database column with SQL type
"BIT" in MySQL. But I discovered that when a zero is stored in that
column, my program apparently interprets that zero value as a boolean
true value. I traced the problem to the QVariant->bool conversion:
bool Database::getBool(QVariant v, bool nullValue)
{
qDebug() << "getBool called for:" << v;
if (v.isNull())
return nullValue;
qDebug() << "getBool will convert" << v << "to bool" << v.toBool();
return v.toBool();
}
When reading a zero BIT value from the database, this outputs:
getBool called for: QVariant(QString, "\u")
getBool will convert QVariant(QString, "\u") to bool true
The docs of toBool() claim that toBool should return false for a
string value of "0".
But your string is not "0" - it's "\0".
Christian
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[Interest] QVariant toBool() not working correctly?
Hi,
I am reading a boolean value from a database column with SQL type
"BIT" in MySQL. But I discovered that when a zero is stored in that
column, my program apparently interprets that zero value as a boolean
true value. I traced the problem to the QVariant->bool conversion:
bool Database::getBool(QVariant v, bool nullValue)
{
qDebug() << "getBool called for:" << v;
if (v.isNull())
return nullValue;
qDebug() << "getBool will convert" << v << "to bool" << v.toBool();
return v.toBool();
}
When reading a zero BIT value from the database, this outputs:
getBool called for: QVariant(QString, "\u")
getBool will convert QVariant(QString, "\u") to bool true
The docs of toBool() claim that toBool should return false for a
string value of "0".
I am using Qt version 5.12.3.
So is this a mismatch between the Qt version of the docs and the Qt
version that I am using? Or am I missing something else here?
Thanks,
Kevin
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