Hi; I'm working on getting Python (PySide) able to export Python types to QML the same way you can do with C++ types, i.e.:
class Foo(QObject):
...
qmlRegisterType(Foo, "foo.bar.com", 1, 0, "FooOnQml_huhu")
I took a look on QtDeclarative sources and faced some issues to integrate
Python or any other language to QML.
First, QML uses qmlRegisterType<T> function to register a type, this function
just fills a struct with some info and pass it to the depths of QML, one of
these fields is a function pointer, this function pointer is used as a factory
function by QML to create instances of the exported type T. So what's the
problem?
Using a template function everything can be decided at compile time, so we
have a different factory function for each type exported to QML, perfect for
C++ but Qt bindings doesn't have the information about user created types at
compile time, so we can't have a factory function for each type created by the
user as we have on C++.
One way to ease the work of people doing Qt bindings to support QML is adding
a bit more info on this factory function, so we can use a Proxy object to
decide what type need to be instantiated.
I attached a pseudo-patch that implements this idea, pseudo because I wrote it
just to show what changes are needed, if I get a thumbs up about it I can
work, test and create a merge request for it.
Any comments? Any chances to get it or something like it into the mainline for
Qt4.7.1?
--
Hugo Parente Lima
INdT - Instituto Nokia de Tecnologia
From 90d3b18456eea4eb3c88366945cff62191c04331 Mon Sep 17 00:00:00 2001
From: Hugo Parente Lima <hugo...@gmail.com>
Date: Mon, 25 Oct 2010 18:59:58 -0200
Subject: [PATCH] Makes possible to Qt bindings to export user types to QML.
---
src/declarative/qml/qdeclarativemetatype.cpp | 2 +-
src/declarative/qml/qdeclarativeprivate.h | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/src/declarative/qml/qdeclarativemetatype.cpp b/src/declarative/qml/qdeclarativemetatype.cpp
index 7a78a1f..c16dd15 100644
--- a/src/declarative/qml/qdeclarativemetatype.cpp
+++ b/src/declarative/qml/qdeclarativemetatype.cpp
@@ -379,7 +379,7 @@ QObject *QDeclarativeType::create() const
d->init();
QObject *rv = (QObject *)operator new(d->m_allocationSize);
- d->m_newFunc(rv);
+ d->m_newFunc(rv, d->m_name, d->m_version_maj, d->m_version_min);
if (rv && !d->m_metaObjects.isEmpty())
(void *)new QDeclarativeProxyMetaObject(rv, &d->m_metaObjects);
diff --git a/src/declarative/qml/qdeclarativeprivate.h b/src/declarative/qml/qdeclarativeprivate.h
index d45ddbc..2325638 100644
--- a/src/declarative/qml/qdeclarativeprivate.h
+++ b/src/declarative/qml/qdeclarativeprivate.h
@@ -91,7 +91,7 @@ namespace QDeclarativePrivate
};
template<typename T>
- void createInto(void *memory) { new (memory) QDeclarativeElement<T>; }
+ void createInto(void *memory, const QString&, int, int) { new (memory) QDeclarativeElement<T>; }
template<typename T>
QObject *createParent(QObject *p) { return new T(p); }
@@ -197,7 +197,7 @@ namespace QDeclarativePrivate
int typeId;
int listId;
int objectSize;
- void (*create)(void *);
+ void (*create)(void *, const QString&, int, int);
QString noCreationReason;
const char *uri;
--
1.7.3.2
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