X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/880efa2a137ce3e3f39236d0dc85f5d2dacdda12..328a3a009fd86bb7df6efc4e0086074af34846ab:/docs/doxygen/overviews/refcount.h diff --git a/docs/doxygen/overviews/refcount.h b/docs/doxygen/overviews/refcount.h index 8aab3dd2ff..90f392ff3b 100644 --- a/docs/doxygen/overviews/refcount.h +++ b/docs/doxygen/overviews/refcount.h @@ -3,7 +3,7 @@ // Purpose: topic overview // Author: wxWidgets team // RCS-ID: $Id$ -// Licence: wxWindows license +// Licence: wxWindows licence ///////////////////////////////////////////////////////////////////////////// /** @@ -41,19 +41,20 @@ operation on it is the same. @section overview_refcount_equality Object Comparison -The == and != operators of the reference counted classes always do a @c deep -comparison. This means that the equality operator will return @true if two -objects are identical and not only if they share the same data. +The == and != operators of @ref overview_refcount_list "the reference counted classes" +always do a deep comparison. This means that the equality operator +will return @true if two objects are identical and not only if they share the +same data. Note that wxWidgets follows the STL philosophy: when a comparison -operator can not be implemented efficiently (like for e.g. wxImage's == +operator cannot be implemented efficiently (like for e.g. wxImage's == operator which would need to compare the entire image's data, pixel-by-pixel), it's not implemented at all. That's why not all reference counted classes provide comparison operators. Also note that if you only need to do a @c shallow comparison between two wxObject derived classes, you should not use the == and != operators but -rather the wxObject::IsSameAs function. +rather the wxObject::IsSameAs() function. @section overview_refcount_destruct Object Destruction @@ -77,6 +78,12 @@ operators and copy constructors since they are reference-counted: @li wxBrush @li wxCursor @li wxFont +@li wxGraphicsBrush +@li wxGraphicsContext +@li wxGraphicsFont +@li wxGraphicsMatrix +@li wxGraphicsPath +@li wxGraphicsPen @li wxIcon @li wxImage @li wxMetafile @@ -90,14 +97,20 @@ operators and copy constructors since they are reference-counted: Note that the list above reports the objects which are reference counted in all ports of wxWidgets; some ports may use this technique also for other classes. +All the objects implement a function @b IsOk() to test if they are referencing valid +data; when the objects are in uninitialized state, you can only use the @b IsOk() getter; +trying to call any other getter, e.g. wxBrush::GetStyle() on the ::wxNullBrush object, +will result in an assert failure in debug builds. + @section overview_refcount_object Making Your Own Reference Counted Class -Reference counting can be implemented easily using wxObject and wxObjectRefData -classes. Alternatively, you can also use the wxObjectDataPtr template. +Reference counting can be implemented easily using wxObject or using +the intermediate wxRefCounter class directly. +Alternatively, you can also use the wxObjectDataPtr template. -First, derive a new class from wxObjectRefData and put there the -memory-consuming data. +First, derive a new class from wxRefCounter (or wxObjectRefData when +using a wxObject derived class) and put the memory-consuming data in it. Then derive a new class from wxObject and implement there the public interface which will be seen by the user of your class. You'll probably want to add a @@ -115,7 +128,7 @@ In fact, any time you need to read the data from your wxObject-derived class, you will need to call this function. @note Any time you need to actually modify the data placed inside your wxObject -derived class, you must first call the wxObject::UnShare function to ensure +derived class, you must first call the wxObject::UnShare() function to ensure that the modifications won't affect other instances which are eventually sharing your object's data.