New to Qt. Still learning it. I have clone.ui, clone.h and clone.cpp. clone ui has 2 buttons.
Browse button-> to Selection a destination path
Add button -> Clone(copy) a file
Clone.h
QString destination_path;
QFileDialog *fdialog;
Clone.cpp has
QFileInfo finfo; // Declare outside function to increase scope
QString destination_name;
void Clone:: on_pushButton__Browse_clicked()
{
/*get the destination path in QString using QFileDialog
Got destination_path */
QString destinatino_path = QFileDialog::getExistingDirectory(....);
QFile finfo(destination_path);
// QFileDialog finfo(destionation_path)
}`
In the same file Clone.cpp
void Clone:: on_btn_Add_clicked()
{
// how to get the same destination_path value here...
//using QFile or some other way?
}
I struck here, Am i missing anything? Any thoughts/suggestion highly useful.
You've create a class (Clone) which has a data member QString destination_path.
Since it is a member variable it has class scope (as in you can access the same variable in any Clone:: member function for the same Clone object).
The problem is that you've hidden it by declaring another QString destination_path in Clone::on_pushButton__Browse_clicked().
void Clone::on_pushButton__Browse_clicked()
{
...
// this *hides* the class member with the same name
QString destination_path = QFileDialog::getExistingDirectory(....);
...
}
The solution is to remove QString from the beginning of the line, which means you are now assigning to the class object's data member.
void Clone::on_pushButton__Browse_clicked()
{
...
// now you're assigning to your object's data member
destination_path = QFileDialog::getExistingDirectory(....);
...
}
Later, in Clone::on_btn_Add_clicked() you can access destination_path, and it will have the value assigned to it in Clone::on_pushButton__Browse_clicked
Related
I have in my header file the definition:
QAction actionPlay;
In my cpp file I have a function:
myFunc()
{
actionPlay = new QAction();
}
I want to make a change in my UI only the first time I enter the function myFunc().
I thought about checking if actionPlay has been initialized or not (if we have already called the line actionPlay = new QAction(); )
How can I do this ?
Thanks
The line:
actionPlay = new QAction()
is attempting to assign a pointer to a non pointer variable declared in
QAction actionPlay
so wont works as is.
If you changed the code to:
QAction * actionPlay = 0;
It would work, and you could then check if it was initialized:
if(!actionPlay) actionPlay = new QAction();
If you want to init action for every object:
QACtion *actionPay = nullptr; // *.h file
if(!actionPay) { actionPay = new QAction(); ..... } // *.cpp file
or don't use pointer
if(!actionPay.isEnabled()) { ... enable actionPay ...} // *.cpp file
if you want do one action:
//in your function *.cpp file
static bool once = true;
if(once) {
once = false;
... some code executed in the first call ...
}
I've made an app with two forms.
When I press the save button in the second form, it updates the DB Record, and returns back to the first form. I've connected the two forms via Signal-Slot with this code:
DruckerData.h
signals:
void btnSavePressed(QString printerName);
DruckerData.cpp
UiMainWindow frmMain;
connect(this,SIGNAL(btnSavePressed(QString)),&frmMain,SLOT(refreshSaved( QString )));
emit btnSavePressed(ui->ledit_druckerName->text());
this->hide();
UiMainWindow.h
public slots:
void refreshSaved(QString printerName);
UiMainWindow.cpp
void UiMainWindow::refreshSaved(QString printerName){
qDebug()<<"Updated: "<<printerName;
show_list(); //<<<<<<<<<<<<<<<<<<<<<< this function
}
show_list
void UiMainWindow::show_list (){
QList<DB_Printers_lvs> list;
DB_Printers_lvsTransporter t("LVS");
QString wc;
this->setCursor(Qt::WaitCursor);
wc = QString("where 1=1 order by nam_printer");
if (!t.load_dbPrinters_lvs_wc(&list,wc))
{
log()<< "get printers failed"<< wc << t.getLastError();
this->setCursor(Qt::ArrowCursor);
return;
}
ui.treeWidget->clear();
foreach (DB_Printers_lvs db, list)
{
QTreeWidgetItem *item = new QTreeWidgetItem(0);
printer_to_qtreewidgetitem(item, db);
ui.treeWidget->insertTopLevelItem(ui.treeWidget->topLevelItemCount(), item);
}
ui.treeWidget->header()->resizeSections(QHeaderView::ResizeToContents);
ui.bow_search->apply();
this->setCursor(Qt::ArrowCursor);
}
When I press the button on the second form and the first form shows I see debug writing Updated with printer name but the problem is how can I call or start this funktion show_list()?
Thanks for help.
The problem that you create second instance of UiMainWindow here:
UiMainWindow frmMain;
Then you connect signal with this second instance, call it's slots, but you don't even show this second instance of MainForm. Instead of this, you should connect signal and slot inside the UiMainWindow just after you create DruckerData form. Unfortunatly there is no this code at your question so i can't show exactly place. This should be something like this:
//Inside UiMainWindow
DruckerData *data = new DruckerData(this);
connect(data, SIGNAL(btnSavePressed(QString)),this,SLOT(refreshSaved( QString )));
data->show();
I need to draw dash instead of null in QSpinBox. Also I need to make dash key pressing equalling null key pressing.
How can I do this?
You can use setSpecialValueText();
QSpinBox spinBox;
spinBox->setSpecialValueText(tr("-"));
You can then check if the special value is selected by connecting valueChanged(QString) function. Note that this is different from valueChanged(int) You can then check the value of the passed string in a slot, and if it is equal to special text, you can do something.
main()
{
connect(spinBox, SIGNAL(valueChanged(QString)), this, SLOT(doSomething(QString)));
}
void doSomething(QString valueStr)
{
if(valueStr == spinBox->specialValueText())
// Do something
else
//Convert valueStr to int and do other stuff
}
Or you could do something like this:
main()
{
connect(spinBox, SIGNAL(valueChanged()), this, SLOT(doSomething()));
}
void doSomething()
{
if(spinBox->value() == 0)
// Do something with dash
else
//Do something with the value
}
For your other question, you need to create a keyPressEvent and check if pressed key is dash or not. If it's dash you can call another function to do something. Edit: BTW, the index of specialValueText() is 0.
Edit: Or you can create a QShortcut in your main function.
new QShortcut(QKeySequence(Qt::Key_Minus), this, SLOT(doSomething()));
Edit continued: doSomething() is a slot function. Put, for example void doSomething(); in the private slots: section of your header file. And in the cpp file define a function similar to this:
void MainWindow::doSomething()
{
ui->spinBox->setValue(0);
//This is the slot called when you press dash.
}
Edit still continued:
You need to declare a protected: function in the header like this:
virtual void keyPressEvent(QKeyEvent *event);
Then you need to define this function in your cpp file. Like this:
void MainWindow::keyPressEvent(QKeyEvent *event)
{
if(event->key() == Qt::Key_Minus)
ui->spinBox->setValue(0);
}
You don't have to connect any signals or slots for this function. It's an event.
That means when dash is pressed ui->spinBox->setValue(0);
Because of that, you need to create a spinBox with a range starting from 0.
spinBox->setRange(0, 100);
That means,
if(spinBox->value() == 0)
//Then specialValueText is selected.
I have this class:
class JavaScript : public QObject {
Q_OBJECT
public:
JavaScript();
bool executeFromFile(QString file);
bool enabled;
public slots:
void setEnabled( bool enabled );
bool isEnabled() const;
private:
QScriptEngine engine;
};
The methods are defined like this:
#include "javascript.h"
JavaScript::JavaScript() {
executeFromFile("test.js");
}
bool JavaScript::executeFromFile(QString file) {
QFile scriptFile(file);
if (!scriptFile.open(QIODevice::ReadOnly)) return false;
QTextStream stream(&scriptFile);
QString contents = stream.readAll();
scriptFile.close();
engine.evaluate(contents, file);
return true;
}
void JavaScript::setEnabled( bool enabled ) {
JavaScript::enabled = enabled;
}
bool JavaScript::isEnabled() const {
return enabled;
}
I’m trying to access the public slots previously defined in the header file like the documentation says:
http://doc.qt.digia.com/qt/scripting.html#making-a-c-object-available-to-scripts-written-in-qtscript
The test.js file looks like this, just like the examples of the docs:
var obj = new JavaScript();
obj.setEnabled( true );
print( "obj is enabled: " + obj.isEnabled() );
But i’m not getting anything. It seems it doesn’t find the JavaScript object. What am I missing?
Doing a simple
print(1+1)
works just fine.
EDIT: An example in the qt4 webpage implements Q_PROPERTY. I tried this, but got the same result:
Q_PROPERTY(bool enabled READ isEnabled WRITE setEnabled)
EDIT 1: Tried implementing the initializer like this:
// javascript.h:
JavaScript(QObject *parent = 0);
// javascript.cpp:
JavaScript::JavaScript(QObject *parent) : QObject(parent) {}
Still nothing...
EDIT 2: Some examples inherits from QScriptable too:
class JavaScript : public QObject, public QScriptable {}
But that makes no difference either.
You need to create QScriptClass instead of QObject. Qt contains example of how to extend script capabilites in Qt. Take a look on Custom Script Class Example
What I think you are actually missing is adding it to the script engine.
At some point you will have to declare a script engine
QScriptEngine * engine = new QScriptEngine(this);
Then you are going to want to add your object to the engine
JavaScript* js= new JavaScript();
QScriptValue jsobj = engine->newQObject(js);
engine->globalObject().setProperty("JavaScript", jsobj );
I'm by no means an expert but I think there is something else you need to do to say
var obj = new JavaScript();
at that point you probably need to take Kamil's advice and make JavaScript a subclass of QScriptClass
I want to save an alredy-existing QSettings object into some INI file for backup.
The QSettings comes from the application's global settings, ie. it can be registry, ini file, etc.
In case it helps, my context is:
class Params
{
// All params as data members
// ...
void loadGlobal ()
{
Qettings s; // Global parameters, paths set by application
// Fill data members: s.value (...);
}
};
class Algo
{
Result run (Params p)
{
Result r = F(p);
return r;
}
};
int main (...)
{
Params p;
p.loadGlobal ();
Algo a;
Result r = a.run (p);
// At this point, save Result and Params into a specific directory
// Is there a way to do:
p.saveToIni ("myparams.ini"); // <-- WRONG
}
A solution would be to add a saveTo (QSetting & s) method into the Params class:
class Params
{
void saveTo (QSettings & s)
{
s.setValue (...);
}
};
int main (...)
{
Params p;
p.loadGlobal ();
QSettings bak ("myparams.ini", ...);
p.saveTo (bak);
}
But I am looking for a solution without modifying the Params class.
Well, no, QT Doesn't really support this directly. I think your best bet is writing a helper class...something like:
void copySettings( QSettings &dst, QSettings &src )
{
QStringList keys = src.allKeys();
for( QStringList::iterator i = keys.begin(); i != keys.end(); i++ )
{
dst.setValue( *i, src.value( *i ) );
}
}
I think there are 2 issues:
QSettings does not have a copy constructor or assignment operator (that I know of), so you'll probably have to write your own copy using allKeys().
You can't save QSettings to an arbitrary file, but what you can do is set the path used for a specific format and scope using the static method QSettings::setPath(). Note that you need to do that before your backup QSettings object is created (and you would use format IniFormat).
If you're OK not having complete control over the resulting path, this should be sufficient. If not, you could still do the above, then get the file name using fileName() and use a system call to copy/move the file to the desired final location.