Calling a C++ function from QML

**DisturbedRocks31** · 12-24-2012, 10:43 PM

I have never developed an app before and this is my first time, I've decided to go with BB10 Native cascades.

Anyways, I'm trying to call a C++ function from the main.QML file when a button is pressed. But it's not working!

I'm not sure what the problem is, I can get the button to do random stuff like show w.e. is in the input field but it doesn't call the C++ function.... It's also showing a warning: "Unknown Symbol 'HelloWorldBB10'" but I have no idea how to fix it. I thought adding the

Code:

qml->setContextProperty("HelloWorldBB10", this);

would fix that but it doesn't.

Anyone know what I'm not doing?

Relevant

Code:

DropDown {
            id: direction
            objectName: "direction"
            title : "Converting to ..."
            enabled : true
            topMargin: 50.0
            onSelectedIndexChanged : {
                console.log("SelectedIndex was changed to " + selectedIndex);
            }

            // text + description
            horizontalAlignment: HorizontalAlignment.Center
            Option {
                 text : "Numbers"
                 description : "English To NUmbers"
                 value : "r"
                 selected : true
             }
             Option {
                 text : "English"
                 description : "Numbers To English"
                 value : "e"
             }
		 }

 TextArea {
            id: inputText
            objectName: "inputText"
            hintText: "Enter or Paste Your Input Here!"
            inputMode: TextAreaInputMode.Default
            editable: true
            focusPolicy: FocusPolicy.Default
        }

        Button {
            id: convertButton
            objectName: "convertButton"
            text: "Convert"
            onClicked: {
                output.text = HelloWorldBB10.convert(inputText.text, direction.selectedValue);
            }
        }

        Label {
            id: output
            objectName: "output"
            text: ""
        }

Then, my HelloWorldBB10.hpp file is:

Code:

// Default empty project template
#ifndef HelloWorldBB10_HPP_
#define HelloWorldBB10_HPP_

#include <QtCore/QObject>
#include <QtCore/QMetaType>
#include <bb/cascades/Event>
#include <bb/cascades/UiObject>
#include <bb/cascades/Control>
#include <QObject>
#include <string.h>

namespace bb { namespace cascades { class Application; }}

/*!
 * @brief Application pane object
 *
 *Use this object to create and init app UI, to create context objects, to register the new meta types etc.
 */
class HelloWorldBB10 : public QObject
{
    Q_OBJECT
public:
    HelloWorldBB10(bb::cascades::Application *app);

    Q_INVOKABLE std::string convert(std::string input, char direction);

    virtual ~HelloWorldBB10() {}
};


#endif /* HelloWorldBB10_HPP_ */

and finally my HelloWorldBB10.cpp is:

Code:

HelloWorldBB10::HelloWorldBB10(bb::cascades::Application *app)
: QObject(app)
{
    // create scene document from main.qml asset
    // set parent to created document to ensure it exists for the whole application lifetime
    QmlDocument *qml = QmlDocument::create("asset:///main.qml").parent(this);
    qml->setContextProperty("HelloWorldBB10", this);
    // create root object for the UI
    AbstractPane *root = qml->createRootObject<AbstractPane>();
    // set created root object as a scene
    app->setScene(root);
}


std::string HelloWorldBB10::convert(std::string input, char direction)
{
//function left out...
return input;
}

**travisredpath** · 12-25-2012, 12:17 AM

I think the problem is that you're trying to use std::string in the Qt world, change them to QString and see if that fixes it. I think the char should work because it's just a short integer but if you still have problems there is also a QChar but you probably want an int.