9b31387508
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75178 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
195 lines
8.2 KiB
C++
195 lines
8.2 KiB
C++
/////////////////////////////////////////////////////////////////////////////
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// Name: changes_since28.h
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// Purpose: topic overview
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// Author: Vadim Zeitlin
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// Created: 2008-05-08
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// Licence: wxWindows licence
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/////////////////////////////////////////////////////////////////////////////
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/**
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@page overview_changes_since28 Changes Since wxWidgets 2.8
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This topic describes backwards-incompatible changes in wxWidgets 3.0 compared
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to the last stable release and is very important to read if you are updating
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from the 2.8 or an older version. And even if you hadn't used any previous
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version of wxWidgets and are starting directly with 3.0, it can still be useful
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to have at least a quick look at it just to know that some of the older
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examples and tutorials may not be applicable any more to wxWidgets 3.0.
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The incompatible changes can be grouped into the following categories:
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@li @ref overview_changes_unicode
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@li @ref overview_changes_other
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<hr>
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@section overview_changes_unicode Unicode-related Changes
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If you used Unicode build of wxWidgets 2.8 or previous version, please read
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@ref overview_unicode for the details about how the API changed in 3.0 as a lot
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of the information which was correct before doesn't apply any longer.
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For example, the notorious (due to the confusion they created) macros @c wxT()
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and @c _T() are not needed at all any longer. Basically, you can remove them
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from any code which used them. On the other hand, there is no particular harm
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in leaving them neither as the code will still compile and work correctly --
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you only need to remove them if you think that your code looks tidier without
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them. You also don't need to use @c wxChar any longer but can directly use the
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standard @c wchar_t type even if, again, @c wxChar continues to work.
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The most serious backwards-incompatible change is related to the change of
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return type of wxString::c_str() method: it returns a special proxy object
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instead of a simple @c char* or @c wchar_t* now. Because of this, you cannot
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pass its result to any standard vararg functions such as @c printf() any more
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as described in @ref overview_unicode_compilation_errors. All wxWidgets
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functions, such as wxPrintf(), wxLogMessage() &c still work with it, but
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passing it to @c printf() will now result in a crash. It is strongly advised to
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recompile your code with a compiler warning about passing non-POD objects to
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vararg functions, such as g++.
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The change of the type of wxString::c_str() can also result in compilation
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errors when passing its result to a function overloaded to take both narrow and
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wide strings and in this case you must select the version which you really want
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to use, e.g.:
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@code
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void OpenLogFile(const char *filename);
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void OpenLogFile(const wchar_t *filename);
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wxString s;
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OpenLogFile(s); // ERROR: ambiguity
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OpenLogFile(s.c_str()); // ERROR: ambiguity
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OpenLogFile(s.wx_str()); // OK: function called depends on the build
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OpenLogFile(s.mb_str()); // OK: always calls narrow string overload
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OpenLogFile(s.wc_str()); // OK: always calls wide string overload
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@endcode
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A common example of such problem arises with @c std::fstream class constructor
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in Microsoft Visual C++ standard library implementation. In addition to a
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constructor from @c const @c char * which this class must have, it also
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provides a constructor taking a wide character file name. Because of this, code
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like the following
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@code
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#include <fstream>
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void MyFunc(const wxString& filename)
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{
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std::ifstream ifs(filename.c_str());
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...
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}
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@endcode
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does not compile when using Microsoft Visual C++ and needs to be changed to use
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mb_str() (which will not work for file names containing Unicode characters,
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consider using wxWidgets classes and functions to work with such file names as
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they are not supported by standard C++ library).
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The other class of incompatible changes is due to modifying some virtual
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methods to use @c wxString parameters instead of @c const @c wxChar* ones to
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make them accept both narrow and wide strings. This is not a problem if you
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simply call these functions but you need to change the signature of the derived
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class versions if you override them as otherwise they wouldn't be called any
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more. Again, the best way to ensure that this problem doesn't arise is to
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rebuild your code using a compiler which warns about function signature
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mismatch (you can use @c -Woverloaded-virtual g++ option).
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Finally, a few structure fields, notable @c wxCmdLineEntryDesc::shortName,
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@c longName and @c description fields have been changed to be of type @c const
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@c char* instead of @c const @c wxChar* so you will need to remove @c wxT() or
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@c _T() if you used it with their initializers.
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@section overview_changes_other Miscellaneous Other Changes
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- Default location of wxFileConfig files has changed under Windows, you will
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need to update your code if you access these files directly.
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- wxWindow::IsEnabled() now returns false if a window parent (and not
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necessarily the window itself) is disabled, new function IsThisEnabled()
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with the same behaviour as old IsEnabled() was added.
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- Generating wxNavigationKeyEvent events doesn't work any more under wxGTK (and
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other platforms in the future), use wxWindow::Navigate() or NavigateIn()
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instead.
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- Sizers distribute only the extra space between the stretchable items
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according to their proportions and not all available space. We believe the
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new behaviour corresponds better to user expectations but if you did rely
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on the old behaviour you will have to update your code to set the minimal
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sizes of the sizer items to be in the same proportion as the items
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proportions to return to the old behaviour.
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- wxWindow::Freeze/Thaw() are not virtual any more, if you overrode them in
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your code you need to override DoFreeze/Thaw() instead now.
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- wxCalendarCtrl has native implementation in wxGTK, but it has less features
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than the generic one. The native implementation is used by default, but you
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can still use wxGenericCalendarCtrl instead of wxCalendarCtrl in your code if
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you need the extra features.
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- wxDocument::FileHistoryLoad() and wxFileHistory::Load() now take const
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reference to wxConfigBase argument and not just a reference, please update
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your code if you overrode these functions and change the functions in the
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derived classes to use const reference as well.
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- Calling wxConfig::Write() with an enum value will fail to compile because
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wxConfig now tries to convert all unknown types to wxString automatically
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using wxToString() function.
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The simplest solution is to cast the enum value to int, e.g.
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@code
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enum Colour { Red, Green, Blue };
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wxConfig conf;
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conf.Write("MyFavouriteColour", Red); // ERROR: no match
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conf.Write("MyFavouriteColour", int(Red)); // OK
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@endcode
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Another possibility which exists now is to provide an overload of
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wxToString() (and wxFromString()) for your own type, e.g.
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@code
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wxString wxToString(Colour col)
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{
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return col == Red ? "R" : col == Green ? "G" : "B";
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}
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bool wxFromString(const wxString& s, Colour* col)
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{
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if ( s.length() != 1 )
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return false;
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switch ( s[0].GetValue() )
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{
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case 'R': *col = Red; return true;
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case 'G': *col = Green; return true;
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case 'B': *col = Blue; return true;
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}
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return false;
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}
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@endcode
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Of course, this will change the format of the wxConfig output which may be
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undesirable.
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- wxTE_AUTO_SCROLL style is deprecated as it's always on by default anyhow in
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the ports which support it so you should simply remove any mentions of it
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from your code.
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- If you use wxScrolled<T>::SetTargetWindow() you must override
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wxScrolled<T>::GetSizeAvailableForScrollTarget() method to compute the size
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available for the scroll target as function of the main window size, please
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see the documentation of this method for more details.
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- Signature of wxDataViewCustomRenderer::StartDrag() virtual method changed.
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You will need to change it in your derived renderer class too if you override
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it.
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- wxDataViewCustomRenderer::Activate() and
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wxDataViewCustomRenderer::LeftClick() were replaced with the new
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wxDataViewCustomRenderer::ActivateCell() method. You will need to change it
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in your derived renderer class accordingly.
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*/
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