I have some troubles translating my application from Russian to English using QTranslator. That is a way i tried to do it:
1) my .pro file contains the following strings:
CODECFORTR = UTF-8
CODECFORSRC = UTF-8
TRANSLATIONS += app_en.ts
2) that is my main.cpp file:
#include <QLabel>
#include <QTranslator>
#include <QApplication>
int main(int argc, char *argv[]) {
QApplication app(argc, argv);
QTranslator translator;
bool ok = translator.load(":/app_en.qm");
ok = app.installTranslator(&translator);
QLabel label(QObject::tr("Some text in Russian"));
label.show();
return app.exec();
}
3) I have used lupdate to generate .ts file, than linguist to generate.qm file. But when I run my application russian text stays on Russian.
4) I also tried to swap languages - use English as source and than translate it to Russian using the same steps - everything works ok and I got correct translation. It seems that I didn't specify something to make Qt know i need to translate Russian (which is a native language for my system) to Englih. Can anyone help?
Related
Here is the qt code that crash:
Writing the content of a 130MB binary file will crash, but writing a 2MB binary file will not.
Is there any solution for writeTextElement to write big file content? Thanks
env: qt opensource 4.8.7
Visual Studio 2010
Windows 10
big file: https://1drv.ms/u/s!Ap_EAuwC9QkXijOmXqxp9DEav3gm?e=iha0uI
test project: https://1drv.ms/u/s!Ap_EAuwC9QkXijWzOlpaWmtzOdtz?e=fDpo93
#include <QtCore/QCoreApplication>
#include <QFile>
#include <QXmlStreamWriter>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QByteArray mContentBuffer;
QFile file("C:\\Work\\bigfile.xar");
if(!file.open(QFile::ReadOnly))
{
return -1;
}
mContentBuffer = file.readAll();
file.close();
QFile profile("C:\\Work\\profile.xml");
if(!profile.open(QFile::WriteOnly|QFile::Truncate))
{
return -1;
}
QXmlStreamWriter stream(&profile);
stream.setAutoFormatting(true);
stream.writeStartDocument();
stream.writeStartElement("Profile");
stream.writeTextElement("Content", mContentBuffer.toBase64());
stream.writeEndElement(); // Profile
stream.writeEndDocument();
return a.exec();
}
The minimal reproducible example was a life saver.
Several things seem to be required to solve your issue in a clean way.
Mainly, the file must be read in chunks.To be precise and as mentioned in that other question, in chunks whose size is a multiple of 3 bytes (I have hardcoded 9000 below).You will need to look for the value that gives you the best performance while guaranteeing it never fails yourself.
Instead of writing in the XML in 1 go, I made it so the XML file is being written each chunk at a time.To achieve that, the code creates the node first, then uses the writeCharacters method to write text in it.
Note the if (mContentBuffer.isEmpty()) right before writing. It is indeed specified in Qt Assistant that the read function has no way of reporting errors; returning an empty QByteArray can mean either that no data was currently available for reading, or that an error occurred. Considering the while loop, it can only be an error, so we abort everything.BTW, I think but have not tested that you can just end the document, and the XML stream writer will close everything it needs to have a valid XML.
Just to make it clean, I reordered the lines of codes so that the XML file is opened before the xar file. I also added QtCore/ on every include. Not sure that last point is going to be useful on your real code.
This code implements all the above changes.It should not crash and while you will not be able to test the output on the 130MB file, you should be able to test your code vs mine on the 2MB file you has successfully read from before.
#include <QtCore/QCoreApplication>
#include <QtCore/QFile>
#include <QtCore/QXmlStreamWriter>
int main(int argc, char* argv[])
{
QCoreApplication a(argc, argv);
QFile profile("C:\\Work\\profile.xml");
if (!profile.open(QFile::WriteOnly | QFile::Truncate))
return -1;
QXmlStreamWriter stream(&profile);
stream.setAutoFormatting(true);
stream.writeStartDocument();
stream.writeStartElement("Profile");
stream.writeStartElement("Content");
QFile file("C:\\Work\\bigfile.xar");
if (!file.open(QFile::ReadOnly))
return -1;
while (!file.atEnd()) {
QByteArray mContentBuffer = file.read(9000);
if (mContentBuffer.isEmpty()) {
stream.writeEndDocument();
file.close();
profile.close();
return -1;
}
stream.writeCharacters(mContentBuffer.toBase64());
}
file.close();
stream.writeEndElement(); // </Content>
stream.writeEndElement(); // </Profile>
stream.writeEndDocument();
return a.exec();
}
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 have no idea why, but i can´t get the simplest example of QTemporaryFile to run... My real intent is to write data from QAudioInput into a temporary file before it is processed later.
After trying several times I realized that neither .read(), .readLine(), .readAll() or .write() would have any effect... The error string is always "Unknown Error" and it neither works for QFile or QTemporaryFile.
#include <QCoreApplication>
#include <QTemporaryFile>
#include <QDebug>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QTemporaryFile tf;
tf.open();
tf.write("Test");
QTextStream in(&tf);
qDebug() << "Testprogramm";
qDebug() << tf.isOpen();
qDebug() << tf.errorString();
qDebug() << in.readLine();
qDebug() << tf.readAll();
tf.close();
return a.exec();
}
The debug posts:
Testprogramm
true
"Unknown error"
""
""
Thank you in advance!
You need to move the file pointer back to the beginning of the file. This has to be done on the file itself when there's no stream on the file, or using the stream when one exists. Also - QFile is a proper C++ class that manages the file resource. There's no need to manually close the file. QFile::~QFile does that job.
The following works just fine:
#include <QtCore>
int main() {
auto line = QLatin1String("Test");
QTemporaryFile tf;
tf.open();
Q_ASSERT(tf.isOpen());
tf.write(line.data());
tf.reset(); // or tf.seek(0)
QTextStream in(&tf);
Q_ASSERT(in.readLine() == line);
in.seek(0); // not in.reset() nor tf.reset()!
Q_ASSERT(in.readLine() == line);
}
The above also demonstrates the following techniques applicable to sscce-style code:
Inclusion of entire Qt module(s). Remember that modules include their dependencies, i.e. #include <QtWidgets> is sufficient by itself.
Absence of main() arguments where unnecessary.
Absence of QCoreApplication instance where unnecessary. You will get clear runtime errors if you need the application instance but don't have one.
Use of asserts to indicate conditions that are expected to be true - that way you don't need to look at the output to verify that it is correct.
Use of QLatin1String over QStringLiteral where ASCII strings need to be compared to both C strings and QStrings. Implicit ASCII casts can be a source of bugs and are discouraged.
QLatin1String is a constant (read-only) wrapper, designed to wrap C string literals - thus there's no need to make line additionally const, although in real projects you'd want to follow the project's style guide here.
I'm making a simple Qt app that reads stuff from a CSV file and generates a PCAP data file out of it for reading by some other software.
And so soon as I invoque pcap_open_dead, pcap_dump_open or pcap_dump, I get no more console output upon running my small converter. Even the Hello World that comes at the beginning of the main doesn't show up any more. From the code below, if I simply comment out those three methods, the console output and "Hello World" come back.
Being new and therefore clueless about pcap, I ask for help.
#include <QCoreApplication>
#include <iostream>
#include "pcap.h"
using namespace std;
struct pcapWriter_S
{
bool isAvailable;
int m_OutPcapIpId;
pcap_t* m_OutPcapHandle;
pcap_dumper_t* m_OutPcapFile;
}m_pcapWriter;
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
cout << "Hello World!" << endl;
//m_pcapWriter.m_OutPcapHandle = pcap_open_dead(DLT_EN10MB,65535);
//m_pcapWriter.m_OutPcapFile = pcap_dump_open(m_pcapWriter.m_OutPcapHandle, QString("tmp_csv_out.pcap").toAscii().data());
m_pcapWriter.m_OutPcapIpId = 1;
if (m_pcapWriter.m_OutPcapFile != 0)
{
m_pcapWriter.isAvailable = true;
}
QByteArray pkt_data;
// Omitted code to generate pkt data from input file
m_pcapWriter.m_OutPcapIpId++;
//pcap_dump((unsigned char*)m_pcapWriter.m_OutPcapFile, &header, (unsigned char*)pkt_data.data());
return a.exec();
}
Somehow this was due to me calling pcap_open but not pcap_close quite yet. In between console stuff gets lost - can't swear it gets written on the pcap thing but it blocks the console anyway.
I am using the qUncompress of Qt and head to a problem I cant find more information to solve it.
Here is my code:
#include <QCoreApplication>
#include <QByteArray>
#include <QFile>
#include <QDebug>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QFile f("/user/XXXXX/home/AgeRegression"); // hided
if (f.exists())
qDebug() << "File exists";
else
qDebug() << "Missing file";
f.open(QIODevice::ReadOnly);
QByteArray qb = f.readAll();
qb = qUncompress(qb);
qDebug()<<"Successfully";
const char *qt_version = qVersion();
qDebug()<< QString(qt_version);
return a.exec();
}
Here is the output:
File exists
qUncompress: Z_DATA_ERROR: Input data is corrupted
Successfully
"5.3.2"
From the documentation of Qt(you can find here):
Note: If you want to use this function to uncompress external data that was compressed using zlib, you first need to prepend a four byte header to the byte array containing the data. The header must contain the expected length (in bytes) of the uncompressed data, expressed as an unsigned, big-endian, 32-bit integer.
So what exactly should I do here? Do I have to find the length of uncompressed data (is there a way? I just have compressed data.)? An example would be appreciated.
qUncompress is not a general-purpose decompression function. It should only be used with data compressed with qCompress.
If your data was compressed using something other than qCompress, you must decompress it in the same way - using zlib directly, using an external utility, etc.
By using qUncompress like you do, you're relying on an implementation detail that may change at any moment. Don't do that. Simply assume that qCompress is a black box and uses an alien compressor implementation that nobody else does.