I want to create a GUI application using Qt. For that I need to get the filename using:
QString fileName=getOpenFileName(.....)
I am using Windows and want to have the filename path in C:\a\b\c format and pass it to a function accepting char variables. How can I implement this?
According to the Qt FAQ
QString path = QFileDialog::getOpenFileName(...);
QByteArray byteArray = path.toLocal8Bit();
const char *charPath = byteArray.data();
Related
I try to show a persian string in Qt:
QMessageBox msg;
QString str = "یا حسین";
msg.setText(QString::fromUtf8(str));
msg.exec();
but it shows the following error :
/home/msi/Desktop/VoMail
Project/Project/VoMail-build-desktop-Qt_4_8_1_in_PATH__System__Release/../VoMail/mainwindow.cpp:40:
error: no matching function for call to 'QString::fromUtf8(QString&)'
I want to use a string variable, and not a string directly.
How can I convert a QString variable to Utf8?
As seen here, QString::fromUtf8() does not accept an argument of type QString. You must give it a const char *, so you could rewrite it like this:
QMessageBox msg;
QString str = QString::fromUtf8("یا حسین");
msg.setText(str);
msg.exec();
its not good idea write like that
using this must be better
QString str(tr("ya hossein");
and use linguist and add persian translation file to your project http://qt-project.org/doc/qt-4.8/linguist-translators.html
and if you dont want use this, you must be sure your IDE or code editor (like qtcreator) use utf8 for saving files and just use
QString str("یا حسین");
it must be ok, i tested that so many times
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I am creating a GUI for windows PC. I want to store a series of images on the PC. The name of the images is identical. But I want to append them with timestamps. So, how to save image using timestamp in Qt?
in addition to that, the images shud be saved something like this example:
referenceImage<.date.><.time.>jpg
where date and time correspond to the date on and time at which the image was saved on the windows PC. I have tried the following too
Here i have implemented this at the click of a push button:-
void MainWindow::on_generateImagePushButton_clicked()
{
QDate date = QDate::currentDate();
QString dateString = date.toString();
QString path = QString("E:\\QT1\\timeStampTrial\\goldenRefImg[%1].jpg").arg(dateString);
qDebug()<<"path: "<<path;
/*display current time*/
QTime time = QTime::currentTime();
QString timeString = time.toString();
QString path2 = QString("E:\\QT1\\timeStampTrial\\goldenRefImg[%1 %2].jpg").arg(dateString).arg(timeString);
qDebug()<<"path2: "<<path2;
/*converting from QString to char* */
QByteArray bA = path2.toLocal8Bit();
const char *c_charArray = bA.data();
/*saving image*/
IplImage *imgWithTimeStamp = cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,3);
cvSaveImage(c_charArray, imgWithTimeStamp);
}
The image gets saved with dateStamp, ie eg. goldenRefImg[Wed Feb 5 2014].jpg when I use string-path. But when I use string-path2, it does NOT save with dateStamp & timeStamp as i expect it to, i.e. goldenRefImg[Wed Feb 5 2014 10:47:32].jpg
But the qDebug statements showing path and path2 are displayed correctly.
Application Output:
Starting E:\QT1\timepass-build-desktop-Qt_4_8_1_for_Desktop_-_MSVC2010__Qt_SDK__Debug\debug\timepass.exe...
path: "E:\QT1\timeStampTrial\goldenRefImg[Wed Feb 5 2014].jpg"
path2: "E:\QT1\timeStampTrial\goldenRefImg[Wed Feb 5 2014 10:47:23].jpg"
Now i have just recollected that an image cannot be saved with special characters such as the colon : which's there in timeStamp. Can the time format be changed?
I tried this way:
path2.replace(":","-");
But the E:\ also gets converted into E-.Please guide. Thank u.
const QDateTime now = QDateTime::currentDateTime();
const QString timestamp = now.toString(QLatin1String("yyyyMMdd-hhmmsszzz"));
const QString filename = QString::fromLatin1("/some/path/someimage-%1.jpg").arg(timestamp);
This takes the current date/time, converts it to a string using QDateTime::toString() (the documentation lists the formatting options) and constructs the file name out of it.
Then just use filename with QImage::save() or QImageWriter.
/*display current date*/
QDate date = QDate::currentDate();
QString dateString = date.toString();
QString path = QString("E:\\QT1\\timeStampTrial\\goldenRefImg[%1].jpg").arg(dateString);
qDebug()<<"path: "<<path;
/*display current time*/
QTime time = QTime::currentTime();
QString timeString = time.toString();
QString path2 = QString("E:\\QT1\\timeStampTrial\\goldenRefImg[%1 %2].jpg").arg(dateString).arg(timeString);
qDebug()<<"path2: "<<path2;
path2.replace(":","-");
path2.replace(1,1,":");
QByteArray bA = path2.toLocal8Bit();
const char *c_charArray = bA.data();
IplImage *imgWithTimeStamp = cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,3);
cvSaveImage(c_charArray, imgWithTimeStamp);
Thank you for all your suggestions #Dmitri Sazonov and #Frank Osterfeld
QDir *temp = new QDir("%USERPROFILE%");
bool ok = temp->mkdir("abc");
and it does not work.
For portable Qt code, use static method QProcessEnvironment::systemEnvironment():
QProcessEnvironment env(QProcessEnvironment::systemEnvironment());
QDir *temp = new QDir(env.value("USERPROFILE")); // returns empty string for unset variable
bool ok = temp->mkdir("abc");
Alternative, as suggested in a comment of the actual question, you can also use
#include <cstdio>
QString envValue(QString::fromLocal8bit(::getenv("USERPROFILE"))); // standard, yet deprecated in Windows...
I'd prefer using the first alternative, letting Qt take care of character encoding stuff. If you want to use non-Qt functions, I think in Windows you should use getenv_s or _wgetenv_s to do this "properly".
I have some number of qm files for my app. (pr_en.qm, pr_ru.qm). I can load they by
translator.load(fileName, '.');
qApp->installTranslator(translator);
I want build dynamic menu (English, Russian) to select language. But, how can I extract such constants (English, Russian) from qm file instead of it's names (pr_en.qm, pr_ru.qm). Thanks.
I would suggest two ways of doing it:
First would be declaring special translator field like:
tr("__LANGNAME__") that would be in every translation file filled with proper language name (even native). Then you could list all available translations, load them one by one and use QTranslator::translate(const char * context, const char * sourceText, const char * disambiguation = 0) method.
Example:
QStringList availableLanguages;
QDirIterator qmIt(pathToQm, QStringList() << "*.qm", QDir::Files);
while(qmIt.hasNext())
{
qmIt.next();
QFileInfo finfo = qmIt.fileInfo();
QTranslator translator;
translator.load(finfo.baseName(), pathToQm);
availableLanguages << translator.translate("__LANGNAME__");
}
qDebug() << availableLanguages;
My second aproach would be with QLocale and QLocale::Language. I would create QLocale object for each base name of file in qm dir, and then use QLocale::Language enum to get language name with QLocale::languageToString method.
I try to parse json string using this method:
QString ourJSONData = QString('{"couchdb":"Welcome","version":"1.0.1"}');
QString response = QString("[") + QString(ourJSONData) + QString("]");
QScriptEngine engine;
QScriptValue sc = engine.evaluate(response);
ui->label->setText(sc.toString());
But label return
SyntaxError: Parse error
I using Qt 4.7.4
What i do wrong? Thanks.
UPD:
Sorry, problem was in that string:
QString ourJSONData = QString('{"couchdb":"Welcome","version":"1.0.1"}');
need change to:
QString ourJSONData = QString("{\"couchdb\":\"Welcome\",\"version\":\"1.0.1\"}");
P.S. this method i found at http://blog.siegerstein.com/archives/134
I built your code in QtCreator in got a very helpful error message:
character constant too long for its type
It's because your ourJSONData variable is initialised with a text in single quotes, which is for single characters.
This will correct that initialisation. (I put a \ before each double-quote, and then changed the single-quotes to double):
QString ourJSONData = QString("{\"couchdb\":\"Welcome\",\"version\":\"1.0.1\"}");