[Solved] How to create an instance of a widget from a string?

Sam

I am storing objects of a class in a QList, The class contains information about the widget and its positioning inside a layout eg. GridLayout. In the class I have a getter and setter functions that returns the Widget name like "QLabel","QLineEdit" in string format. How can i instantiate these widgets based on the string name?

Thanks :)

sierdzio

Not much info, but this looks like a very crazy setup. Layouts usually manage themselves, you should use that.

As for instantiation:
@
if (myString == "QLabel")
label = new QLabel(this);
@

But I'm almost certain that is not what you have meant.

andre

Well... perhaps you should look at [[doc:QUiLoader]]? It also works based on a string, although that string is in XML format. But, indeed, it is not a normal setup to use this.

Sam

#sierdzio

Yes as of now i am using the same approch that you have provided, But the problem is that if i have 10 different widgets then foreach widget i have to write

@if(myString =="QLabel")
label = new QLabel(this);
label->setObjectName(/obj->getObjectName/);
label->setText(/obj->getText/);
layout->addWidget(label,/obj->getRow/,/obj->getColumn/,/obj->getRowSpan/,/obj->getColumnSpan/);

......
......
if(myString == "QLineEdit")
lineEdit = new QLineEdit(this)@

and so on.
Is there any other way to do the same. As i need to add the same properties for different widgets.

sierdzio

use only line 2 in your ifs. Move all the rest outside ifs and use QObject::setProperty() to change the properties.

You will have to do a qobject_cast<> to "downgrade" the pointer, though. Example:
@
QObject *currentObject;
if(myString =="QLabel")
{
label = new QLabel(this);
currentObject = qobject_cast<QObject>(label);
}
// all other ifs here

currentObject->setProperty("property name", obj->getText);
// etc...
@

// brain to terminal, not tested :) I might have used wrong method names, and so on.

andre

There is no need for the casting. Using properties works directly on any QObject derived class.
@
QObject *currentObject;
if(myString =="QLabel")
{
currentObject = new QLabel(this);
}
// all other ifs here

currentObject->setProperty("property name", obj->getText);
// etc...

@

I still wonder if this is really the way to go. Are you not looking for a property editor type thing? I successfully used "YAPE":http://qt-apps.org/content/show.php?content=100064 in the past for this, but there are plenty of alternatives around.

sierdzio

(casting) Ah yes, that's what I suspected, but was too lazy to check or think through :)

Sam

@sierdzio
Its works perfect :) Thanks for the help.

@Andre

Thanks for the help. The property editor thing is next on the list. Here i have a requirement where i need to load a form/frame from an xml file. The xml file contains the details of the type of layout and the positioning of each components.

Thanks for your time :)