I'm working at a browser-like project based on QtWebKit.
It can display any webpage as good as any other browser can, but I can't make display local html documents!
I am using a QtWebView in a QMainWindow and I'm loading pages with
view->show();
Can anyone tell me what is wrong?
Thank you wery much!!!
I don't see anything different than loading a normal web page, but anyway this is taken from my answer here:
#include <QtGui/QApplication>
#include <QWebView>
int main(int argc, char* argv[])
{
QApplication a(argc, argv);
QWebView view;
view.setUrl(QUrl("file:///home/luca/mypage.html"));
view.show();
return a.exec();
}
Related
I need some help in Qt since I don't really undestand the way Qt libraries can be used in visual studio projects. I try to use the QXmlSchemaValidator class from QtXmlPatterns to validate an xml file against schema, but I can't instantiate a QApplication object since I don't have access to the main.cpp file. I don't want to create a Qt project, just try to use this schemaValidator class in one of a class' method.
This is how I try to load the schema:
QUrl url("http://.../schema.xsd");
QXmlSchema schema;
if (schema.load(url))
qDebug() << "schema is valid";
else
qDebug() << "schema is invalid";
I get this warning: "Please instantiate the QApplication object first".
I found a solution here: QEventLoop: Cannot be used without QApplication that says I need the main function to look like this:
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}
Is there a way to load the schema and validate my xml files without a QApplication object?
Thanks in advance!
Yes, use QCoreApplication instead.
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
//your code here
return a.exec();
}
Seriously, if some Qt features you like require an event loop, you just can't get away with it without one. About not having a "Qt project" (and maybe you mean you're not using qmake) but yet using Qt classes: good luck.
Looking at a simplest Qt Widget sample application that you can find from almost every Qt tutorial:
#include "notepad.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
Notepad w;
w.show();
return a.exec();
}
There is one thing puzzles me. There are two major variables a and w here. a.exec() starts Qt's main loop, which suppose to interact with the main GUI component w. However, both of them live on stack and I don't see any code pass w somehow to a. So how does a be aware of the existence of w?
Does the constructor of w initializes a static data structure that a can access to check the top-level widgets?
Qt preprocess your code and build the real c++ code before compiling, its at this moment QApplication wrap all Q object in the main.cpp file and build the rest of the code from it.
I receive this error (title, below) whenever I try to run the following code:
#include <QCoreApplication>
#include <QQuickView>
int main(int argc, char *argv[]){
QCoreApplication app(argc, argv);
QQuickView view;
view.setSource(QUrl::fromLocalFile("app.qml"));
QObject *object = (QObject*)view.rootObject();
view.show();
delete object;
return app.exec();
}
Cannot create window: no screens available
The program has unexpectedly finished.
All I can find online for that error are bug reports arising from specific conditions significantly more involved than the above.
app.qml is a file that runs fine alone, i.e. without the above C++ and in a separate project configured as a 'Qt Quick UI'. Giving it's qrc:// path, or deliberately specifying a file which does not exist has no effect.
Note the QObject* cast - this was not present in the docs, but without it:
/main.cpp:11: error: cannot initialize a variable of type 'QObject *' with an rvalue of type 'QQuickItem *'
How should this be done?
The QCoreApplication can be used with console application, not with GUI ones, i.e. you have to use a QGuiApplication object. It seems to me that you created a console application instead of a graphical one.
You can create a proper application via the Qt Quick Application, add your "app.qml" as a resource to that project and call such a file instead of the default "main.qml", provided by the project template.
If you want to quick fix your current project, just check that the .pro file is set to import GUI libraries:
QT += gui qml quick
Set your qml file as a resource:
Create a new resource file via file -> new File or Project... -> Qt -> Qt Resource File
Right click the newly created .qrc file and click add existing file to add your "app.qml" file
Finally, rewrite your main like this:
#include <QQuickView>
#include <QGuiApplication>
int main(int argc, char *argv[])
{
QGuiApplication a(argc, argv); // GUI APPLICATION!!!
QQuickView view;
view.setSource(QUrl(QStringLiteral("qrc:///app.qml")));
view.show();
return a.exec();
}
However, going for the Qt Quick Application project would be the wiser choice.
I'm working on an QT HTML5 application and I was wondering how i could add an top menu just like normal program ( with the default file, tools, help... options ).
I think that I've to change something in the html5applicationviewer.cpp, but I've got 0 knowledge of that ( I'm learning this... )
Even if you could point me a little bit in the right direction, I'm grateful. I've searched around, but found absolutely nothing about this topic ( but maybe i didn't search right... )
If you need more info, please ask.
Simplest way to add normal "desktop"-style menus to a Qt app is to use QMainWindow which has good support for menus.
Here's something to get you started. First I created the default HTML5 Qt application with Qt Creator (SDK version 5.2.1). Then I edited the main.cpp and added some lines. Result is below, original lines without comment and all added lines with comment.
#include <QApplication>
#include <QMainWindow> // added
#include <QMenuBar> // added
#include <QMenu> // added
#include <QAction> // added
#include "html5applicationviewer.h"
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QMainWindow w; // important, viewer is in stack so w must be before it!
Html5ApplicationViewer viewer;
w.setCentralWidget(&viewer); // set viewer as the central widget
QMenu *fileMenu = w.menuBar()->addMenu("&File"); // create file menu
QAction *exitAction = fileMenu->addAction("&Exit"); // create exit action
QObject::connect(exitAction, SIGNAL(triggered()), qApp, SLOT(quit())); // make the action do something
viewer.setOrientation(Html5ApplicationViewer::ScreenOrientationAuto);
//viewer.showExpanded(); // will be shown by main window
viewer.loadFile(QLatin1String("html/index.html"));
w.show(); // show main window
return app.exec();
}
I have a C++ function that checks if Bluetooth is activated. I want to display a simple dialog telling the user to activate his Bluetooth and try again. As I have a QML interface this can be done through C++ or QML.
You can use the built-in information message box:
#include <QApplication>
#include <QDebug>
#include <QMessageBox>
int main(int argc, char *argv[]) {
QApplication app(argc, argv);
QMessageBox::information(0, "Try Again", "Please try to activate your Bluetooth again.");
}
Qt Components have some dialogs out of box:
http://doc.qt.nokia.com/qt-components-symbian-1.0/qml-querydialog.html