With the following code:
#include <QApplication>
#include <QWebEngineView>
#include <QWebEngineProfile>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QWebEngineView w;
QObject::connect(w.page(), &QWebEnginePage::featurePermissionRequested, [&](const QUrl &securityOrigin, QWebEnginePage::Feature feature)
{
w.page()->setFeaturePermission(securityOrigin, feature, QWebEnginePage::PermissionGrantedByUser);
});
w.setUrl(QUrl("https://mycurrentlocation.net/"));
w.show();
return a.exec();
}
and a USB dongle connected to my 64bit Archlinux system (with geoclue2 installed and working), I don't get the correct geolocation coordinates (which I get on the same website with Google Chrome).
There are both in France but 200km apart.
Update 1:
A similar issue with the same coordinates seems to appear when centering on my position with a QML Map componenent.
Do I need to setup something in order for it to work ?
The issue is not Qt related.
/usr/lib/geoclue-2.0/demos/where-am-i
returns wrong coordinates.
Related
Searching for an alternative to Qt's official VirtualKeyboard I came across this MockupVirtualKeyboard repository. It is based on QPlatformInputContext. I build and installed the plugin to Qt5.15.2/plugins/platforminputcontexts, but I dont know how to bring the Virtual Keyboard up.
What I would like to achieve, using QML, is:
TextInput{
text: ""
onFocusChanged: showVirtualInput()
}
If you want to use the keyboard then you must set the environment variable "QT_IM_MODULE" to be "mockup", and you can do that by placing the following line of code in the main.cpp:
int main(int argc, char *argv[])
{
qputenv("QT_IM_MODULE", QByteArray("mockup"));
#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
#endif
QGuiApplication app(argc, argv);
# ...
On the other hand, you must change:
Q_PLUGIN_METADATA(IID "org.qt-project.Qt.QPlatformInputContextFactoryInterface" FILE "mockup.json")
to
Q_PLUGIN_METADATA(IID "org.qt-project.Qt.QPlatformInputContextFactoryInterface.5.1" FILE "mockup.json")
in the mockupplatforminputcontextplugin.h file, recompile and install the file so that it is compatible with Qt 5.15.2
I need help in writing my static text to image file without using "QApplication app(argc, argv);" in main(). My version of QT is 5.12.2.
Currently I'm able to do this with the below code:
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QCoreApplication::addLibraryPath("./plugins");
QString imagePath(QStringLiteral("./images/output/testOutput1.png"));
QImage image(500, 400, QImage::Format_RGB888);
image.fill(Qt::red);
QPainter painter;
if (!painter.begin(&image))
return;
painter.setPen(QPen(Qt::black));
painter.setFont(QFont("Times", 12, QFont::Bold));
painter.drawText(image.rect(), Qt::AlignCenter, "writing text on image");
painter.end();
image.save(imagePath);
return 0;
}
I'm trying to get a similar type solution which does not uses "QApplication app(argc, argv);" in my code.
Currently if I remove the deceleration of "QApplication app(argc, argv);" my code crashes at "painter.drawText(...);".
The most you can do is to exchange the QApplication for a QGuiApplication (thus avoiding the useless dependency from the QtWidgets module).
Qt initializes most of its static/global stuff inside the bowels of QCoreApplication (for QtCore stuff)/QGuiApplication (for QtGui stuff)/QApplication (for QtWidgets stuff); each derives from the other, so if you have a QApplication you already have all the stuff from Gui and Core.
The font engine (and other paint-related stuff) is initialized inside the QGuiApplication constructor, as hinted in QFont documentation
Note that a QGuiApplication instance must exist before a QFont can be used.
so you are not going to paint without instantiating it (or a class derived from it).
I want to store QPoint in an object, which should be released automatically.
#include <QCoreApplication>
#include <memory>
#include <QPoint>
using namespace std;
class MyWidget{
public:
vector<std::unique_ptr<QPoint>> _points;
void f(QPoint point){
std::unique_ptr<QPoint> pos(new QPoint(point));
_points.push_back(pos);
}
};
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
MyWidget wid;
wid.f(QPoint(0,0));
return a.exec();
}
The error message is:
F:\Qt\Qt5.5.0\Tools\mingw492_32\i686-w64-mingw32\include\c++\ext\new_allocator.h:120:
error: use of deleted function 'std::unique_ptr<_Tp,
_Dp>::unique_ptr(const std::unique_ptr<_Tp, _Dp>&) [with _Tp = QPoint; _Dp = std::default_delete]' { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
^
Does it mean that I am not supposed to use unique_ptr to store QPoint?
No, the problem is that you can't push_back a copy of a unique_ptr.
Use push_back(std::move(ptr)) or emplacement construction.
Apart from this, I don't see the need to dynamically allocate a value class such as QPoint.
On 64 bit platforms, sizeof(QPoint*) == sizeof(QPoint): the pointer has the same size as the pointed-to-object in the case of QPoint. Moving around the pointers in a vector is no faster than moving around the point values. You're prematurely pessimizing by dynamically allocating these small things one-by-one.
Even on a 32 bit system, the overhead of dynamic allocation will have the performance suffer unnecessarily.
Use a QVector<QPoint> or std::vector<QPoint>, they'll all perform well with points.
TL;DR: Understand the data types that you use, especially if they are simple tuples of integers as QPoint is.
i want to read some exif informations with QExifImageHeader (from the QT Extended Library)
(see here)
Can someone say me how to get the informations from one tag?
I have this code:
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QExifImageHeader header;
header.loadFromJpeg("test.jpg");
QExifValue value=header.value(QExifImageHeader::ImageWidth );
qDebug()<<value.toByte();
return a.exec();
}
The result of the qDebug() is "0". But why?
I saw some other librarys (like exiv2). But they are to heavy for my project.
Greetings
The code
#include <QtCore>
#include <QtXml/QDomElement>
int main(int argc, char *argv[])
{
QCoreApplication app(argc, argv);
QDomElement* element = new QDomElement();
element->setTagName("feature");
qDebug() << element->tagName();
return app.exec();
}
prints simply "". However, as far as I can tell from the documentation it should print "feature". In fact
qDebug() << element->isNull();
prints true so something is not being set correctly. Does anyone know what I am doing wrong?
I'm using Qt 4.6.3 on openSUSE Linux 11.2.
You cannot use the default constructor. You need to use QDomDocument::createElement(const QString &tagName). The element needs to be part of a document. You cannot use it "standalone".
Here's what the documentation says for the QDomElement default constructor:
QDomElement::QDomElement ()
Constructs an empty element. Use the QDomDocument::createElement() function to construct elements with content.
By "empty" they mean null.