QtScript Bindings Generator ScriptShell Event Binding

Hi there!

How can I call the native event handler when using the scriptshell binding of the qt script binding generator?

I'm using the splendid qt script binding generator lab-project to make all qt classes fully scriptable. Through the scriptshells it allows binding a script function to otherwise inaccessible protected event handlers. In non script you would derive from the class to access these..

Code:

---

scriptcode:
 
var a = new QWidget();
a.setGeometry(50,50,200,100);
a.show();
a.event = function (event) {
  print(event.type().toString());
};

---

This works perfectly, but it hides the native implementation. If you look into the generated scriptshell files of the generator:

Code:

---

from: ..\com_trolltech_qt_gui\qtscriptshell_QWidget.cpp
 
bool  QtScriptShell_QWidget::event(QEvent*  arg__1)
{
    QScriptValue _q_function = __qtscript_self.property("event");
    if (!_q_function.isFunction() || QTSCRIPT_IS_GENERATED_FUNCTION(_q_function)
        || (__qtscript_self.propertyFlags("event") & QScriptValue::QObjectMember)) {
        return QWidget::event(arg__1);
    } else {
        QScriptEngine *_q_engine = __qtscript_self.engine();
        return qscriptvalue_cast<bool >(_q_function.call(__qtscript_self,
            QScriptValueList()
            << qScriptValueFromValue(_q_engine, arg__1)));
    }
}

---

So either the native or the script event handler is called. Now my question is, if I missed an obvious way to call the native event handler from script.

If thats not possible I'm thinking of changing the scriptshell-generator-code (..\generator\shellimplgenerator.cpp ) to call the native handler for all events that have not been accepted inside the script-method. That's easy enough, but I want to know, if there is an out-of-the-box way.

Thx!

Johannes

Hey there!

Here is what I came up with:

I changed the scriptshellgenerator code so that the generated code looks like this:

Code:

---

bool  QtScriptShell_QWidget::event(QEvent*  arg__1)
{
    QScriptValue _q_function = __qtscript_self.property("event");
    if (!_q_function.isFunction() || QTSCRIPT_IS_GENERATED_FUNCTION(_q_function)
        || (__qtscript_self.propertyFlags("event") & QScriptValue::QObjectMember)) {
        return QWidget::event(arg__1);
    } else {
        QScriptEngine *_q_engine = __qtscript_self.engine();
        // callmode. first bit: 1:callcpp|0:don't call cpp
        // 2nd-bit: 1:returncpp|0:returnscript
        int _callmode = 3;
        QScriptValue _q_callmode = __qtscript_self.property("event_callmode");
        if (_q_callmode.isValid()) _callmode = _q_callmode.toInt32();
        if ((_callmode & 1) > 0) {
            bool resultcpp = QWidget::event(arg__1);
            bool resultscript = qscriptvalue_cast<bool >(_q_function.call(__qtscript_self,
                QScriptValueList()
                << qScriptValueFromValue(_q_engine, arg__1)));
            if ((_callmode & 2) > 0) {
                return resultcpp;
            } else {
                return resultscript;
            }
        } else {
            return qscriptvalue_cast<bool >(_q_function.call(__qtscript_self,
                QScriptValueList()
                << qScriptValueFromValue(_q_engine, arg__1)));
        }
    }
}

---

instead of the above.. So the default behaviour is to call both. And to return the value of the c++ implementation. If you want another behaviour, you need to specifiy a value for <eventname>_callmode.

This is the ShellImplGenerator::write method in generator/shellimplgenerator.cpp which you need to change in the bindings generator.

Code:

---

void ShellImplGenerator::write(QTextStream &s, const  AbstractMetaClass *meta_class)
{
    if (FileOut::license)
        writeQtScriptQtBindingsLicense(s);
 
    QString packName = meta_class->package().replace(".", "_");
 
    priGenerator->addSource(packName, fileNameForClass(meta_class));
 
    s << "#include \"qtscriptshell_" <<  meta_class->name() << ".h\"" << endl << endl;
 
    if (!meta_class->generateShellClass())
        return;
 
    s << "#include <QtScript/QScriptEngine>" << endl;
 
    IncludeList list = meta_class->typeEntry()->extraIncludes();
    qSort(list.begin(), list.end(), include_less_than);
    foreach (const Include &inc, list) {
        if (inc.type == Include::TargetLangImport)
            continue;
 
        s << "#include ";
        if (inc.type == Include::LocalPath)
            s << "\"";
        else
            s << "<";
 
        s << inc.name;
 
        if (inc.type == Include::LocalPath)
            s << "\"";
        else
            s << ">";
 
        s << endl;
    }
    s << endl;
 
    writeHelperCode(s, meta_class);
 
    // find constructors
    AbstractMetaFunctionList ctors;
    ctors =  meta_class->queryFunctions(AbstractMetaClass::Constructors
                                       | AbstractMetaClass::WasVisible
                                       |  AbstractMetaClass::NotRemovedFromTargetLang);
    // find member functions
    AbstractMetaFunctionList functions = meta_class->queryFunctions(
        AbstractMetaClass:: VirtualFunctions |  AbstractMetaClass::WasVisible
        | AbstractMetaClass::NotRemovedFromTargetLang
        );
 
    // write metatype declarations
    {
        QSet<QString> registeredTypeNames =  m_qmetatype_declared_typenames;
        declareFunctionMetaTypes(s, functions, registeredTypeNames);
        s << endl;
    }
 
    // write constructors
    foreach (const AbstractMetaFunction *ctor, ctors) {
        s << "QtScriptShell_" << meta_class->name()  << "::";
        writeFunctionSignature(s, ctor, 0, QString(),  Option(OriginalName | ShowStatic));
        s << endl;
        s << "    : " << meta_class->qualifiedCppName()  << "(";
        AbstractMetaArgumentList args = ctor->arguments();
        for (int i = 0; i < args.size(); ++i) {
            if (i > 0)
                s << ", ";
            s << args.at(i)->argumentName();
        }
        s << ")" << " {}" << endl << endl;
    }
 
    // write destructor
    s << "QtScriptShell_" << meta_class->name() <<  "::"
      << "~QtScriptShell_" << meta_class->name() <<  "()";
    if (!meta_class->destructorException().isEmpty())
        s << " " << meta_class->destructorException();
    s << " {}" << endl << endl;
 
    // write member functions
    for (int i = 0; i < functions.size(); ++i) {
        AbstractMetaFunction *fun = functions.at(i);
        writeFunctionSignature(s, fun, meta_class, QString(),
                               Option(OriginalName | ShowStatic |  UnderscoreSpaces),
                               "QtScriptShell_");
        s << endl << "{" << endl;
        QString scriptFunctionName = fun->name();
        {
            QPropertySpec *read = 0;
            for (const AbstractMetaClass *cls = meta_class; !read  && cls; cls = cls->baseClass())
                read = cls->propertySpecForRead(fun->name());
            if (read && (read->name() == fun->name())) {
                // use different name to avoid infinite recursion
                // ### not sure if this is the best solution though...
                scriptFunctionName.prepend("_qs_");
            }
        }
 
        s << "    QScriptValue _q_function =  __qtscript_self.property(\""
          << scriptFunctionName << "\");" << endl;
        s << "    if (!_q_function.isFunction() ||  QTSCRIPT_IS_GENERATED_FUNCTION(_q_function)" << endl
          << "        || (__qtscript_self.propertyFlags(\""  << scriptFunctionName << "\") &  QScriptValue::QObjectMember)) {" << endl;
 
        AbstractMetaArgumentList args = fun->arguments();
        s << "        ";
        if (fun->isAbstract()) {
            s << "qFatal(\"" << meta_class->name()  << "::" << fun->name()
              << "() is abstract!\");" << endl;
        } else {
            // call the C++ implementation
            if (fun->type()) {
                s << "return ";
            }
            s << meta_class->qualifiedCppName() << "::"  << fun->originalName() << "(";
            for (int i = 0; i < args.size(); ++i) {
                if (i > 0)
                    s << ", ";
                s << args.at(i)->argumentName();
            }
            s << ");" << endl;
        }
 
        s << "    } else {" << endl;
 
        // call the script function
        if (args.size() > 0)
            s << "        QScriptEngine *_q_engine =  __qtscript_self.engine();" << endl;
 
        // NTS Addon
        if (!fun->isAbstract()) {
            s << "        // callmode. first bit:  1:callcpp|0:don't call cpp" << endl;
            s << "        // 2nd-bit: 1:returncpp|0:returnscript"  << endl;
            s << "        int _callmode = 3;" << endl;
            s << "        QScriptValue _q_callmode =  __qtscript_self.property(\""
              << scriptFunctionName << "_callmode\");"  << endl;
            s << "        if (_q_callmode.isValid()) _callmode =  _q_callmode.toInt32();" << endl;
            s << "        if ((_callmode & 1) > 0) {"  << endl;
 
            // First call the c++ implementation
            s << "            ";
                if (fun->type()) {
                    writeTypeInfo(s, fun->type());
                    s << "resultcpp = ";
                }
                s << meta_class->qualifiedCppName() <<  "::" << fun->originalName() << "(";
                for (int i = 0; i < args.size(); ++i) {
                    if (i > 0)
                        s << ", ";
                    s << args.at(i)->argumentName();
                }
                s << ");" << endl;
 
            // Then call the script implementation
            s << "            ";
            if (fun->type()) {
                writeTypeInfo(s, fun->type());
                s << "resultscript = qscriptvalue_cast<";
                writeTypeInfo(s, fun->type());
                s << ">(";
            }
            s << "_q_function.call(__qtscript_self";
            if (args.size() > 0) {
                s << "," << endl;
                s << "                QScriptValueList()";
                int i = 0;
                for (int j = 0; j < args.size(); ++j) {
                    if (fun->argumentRemoved(j+1))
                        continue;
                    s << endl << "                <<  ";
                    s << "qScriptValueFromValue(_q_engine, ";
                    AbstractMetaType *atype = args.at(j)->type();
                    QString asig = atype->cppSignature();
                    bool constCastArg = asig.endsWith('*') &&  asig.startsWith("const ");
                    if (constCastArg)
                        s << "const_cast<" << asig.mid(6)  << ">(";
                    s << args.at(i)->argumentName() <<  ")";
                    if (constCastArg)
                        s << ")";
                    ++i;
                }
            }
            s << ")";
            if (fun->type())
                s << ")";
            s << ";" << endl;
 
            if (fun->type()) {
            // Decide which value to return
            s << "            if ((_callmode & 2) > 0) {"  << endl;
            s << "                return resultcpp;" <<  endl;
            s << "            } else {" << endl;
            s << "                return resultscript;" <<  endl;
            s << "            }"<< endl;
            }
 
            s << "        } else {" << endl;
        }
 
        // only call the script implementation
        s << "            ";
        if (fun->type()) {
            s << "return qscriptvalue_cast<";
            writeTypeInfo(s, fun->type());
            s << ">(";
        }
        s << "_q_function.call(__qtscript_self";
        if (args.size() > 0) {
            s << "," << endl;
            s << "                QScriptValueList()";
            int i = 0;
            for (int j = 0; j < args.size(); ++j) {
                if (fun->argumentRemoved(j+1))
                    continue;
                s << endl << "                << ";
                s << "qScriptValueFromValue(_q_engine, ";
                AbstractMetaType *atype = args.at(j)->type();
                QString asig = atype->cppSignature();
                bool constCastArg = asig.endsWith('*') &&  asig.startsWith("const ");
                if (constCastArg)
                    s << "const_cast<" << asig.mid(6)  << ">(";
                s << args.at(i)->argumentName() << ")";
                if (constCastArg)
                    s << ")";
                ++i;
            }
        }
        s << ")";
        if (fun->type())
            s << ")";
        s << ";" << endl;
 
        if (!fun->isAbstract()) {
            s << "        }" << endl;
        }
 
        s << "    }" << endl;
 
        s << "}" << endl << endl;
    }
}

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Cheers,

Johannes