A property alias is the equivalent of the "alias" keyword in QML. It
provides the same API as QProperty, but redirects any access to the
QProperty it was initialized with. When the original property is
destroyed the binding becomes invalid and ignores any further acccess.
Task-number: QTBUG-84370
Change-Id: I0aef8d50e73a2aa9e7703d51194d4c5480573578
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Previously, only the first observer would get notified. Also, make sure
that the notifiers are always retained when switching between bindings
and values.
Change-Id: I9c25c0f2e288dac3a335b68e618f7ddeb44be25a
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Passing the QExplicitlySharedDataPointer by reference may lead compilers
to wanting to have visibility to the destructor of the contained type
(QPropertyBindingPrivate), which is not public. Fortunately
QExplicitlySharedDataPointer is safe to use with raw pointers and those
can be safely forward declared.
Change-Id: I131ab6363eaee10b6dce196fb2c769e09a5c9557
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
When a class has multiple QProperty members to implement functionality,
it is common to have functions in the class that react to changes. For
example to emit a compatibility signal, in case of Qt Quick to mark the
scene graph as dirty, etc. etc.
To faciliate this use-case, this patch adds an internal
QPropertyMemberChangeHandler template that allows connecting a QProperty
field to a member function callback.
At the moment that callback is still 3 * sizeof(pointer). This could in
theory be reduced to 2 by eliminating the back-pointer (prev) as the
observer lives as long as the property. That however belongs into maybe
a future patch.
In order to get a pointer back to the surrounding object that holds the
QProperty as well as provides the callback function, the property system
was changed to pass through the address of the QProperty member at
run-time, and at compile time the delta from the QProperty member to the
beginning of the surrounding class is calculated. Through subtraction we
obtain the pointer to the owning object.
Change-Id: Ia2976357053f474ff44d0d6f60527c3b8e1f613a
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
QtQml needs the private just for one detail which nobody else should
need it for: Tracking additional dependencies and marking the binding as
dirty. Exporting the private requires hiding some variables and
providing accessors, to compile with MSVC - including the removal of
QVarLengthArray usage. Upside: The binding structure shrinks by 8 bytes
and the encapsulation makes it a little easier to change things without
breaking declarative, ... in the unlikely event ;-)
Also remove setDirty() from the public API as it's not needed by QtQml
and using it is dangerous, because it means that there's a risk of
somebody keeping a reference (count) to the untyped binding from within
the binding closure, which introduces a memory leak.
Change-Id: I43bd56f4bdf218efb54fa23e2d627ad3acfafeb5
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
This replaces the private tagged pointer and the use of enums for the
tag makes the observer handling code more readable. The
pointer-to-tagged-pointer class remains in qpropertyprivate.h due to its
exoticness.
Change-Id: Icc88799136c6839426d994b42368526463265e66
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
A generic binding allows implementing the binding function in a way that
enables the QML engine to run binding scripts and convert the V4::Value
into a QVariant and then assign the value to the property with the help
of QMetaType::construct.
Change-Id: Id4807be92eee7e3501908e6c5e4c861cfcb7772a
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
This implements the core value based property binding system with
automatic dependency tracking. More features are to be added later, and
the documentation will need further improvements as well.
Change-Id: I77ec9163ba4dace6c4451f5933962ebe1b3b4b14
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Ulf Hermann
Simon Hausmann