The
qt3to4
tool provides help when moving a project from Qt 3 to Qt 4. It is designed to automate the most tedious part of the porting effort.
见 Porting to Qt 4 and Porting UI Files to Qt 4 for more information about porting Qt 3 applications to Qt 4.
qt3to4
can be run either on individual C++ source or header files, or on an entire project specified by a
qmake
.pro
文件：
qt3to4 myfile.cpp qt3to4 myapp.pro
In project mode,
qt3to4
reads the
.pro
file and converts all files specified in it. The tool modifies the files in place. You might want to make a copy of your project before you run the tool.
The Qt porting tool loads its porting rules from an XML file called
q3porting.xml
located in Qt's
tools/porting/src
directory. By editing this file, you can add your own rules or remove some rules.
标准
q3porting.xml
file specifies the following conversions:
QFileDialog
with
Q3FileDialog
).
QButton::On
with
QCheckBox::On
) or members of the Qt namespace (e.g., replace
QWidget::red
with
Qt::red
).
#include
directives that might be needed in Qt 4.
You can now specify the location of the
qt3porting.xml
file with the
-f
command line option. This is useful if you want to use a modified file with your own rules.
If you you don't want to maintain a modified
qt3porting.xml
it is possible to create a "patch" file that includes the original file and adds or disables rules. The syntax for this file looks like this:
<Rules> <Include>/path/to/q3porting.xml</Include> <item Type="RenamedHeader" Disable="True" > <Qt4>q3sqlselectcursor.h</Qt4> <Qt3>qsqlselectcursor.h</Qt3> </item> <item Type="RenamedHeader" > <Qt4>newclass.h</Qt4> <Qt3>oldclass.h</Qt3> </item> </Rules>
The porting tool logs all changes to a file called
portinglog.txt
in the current directory. This file lists all changes made to the source files.
When porting,
qt3to4
parses the source files and ports the contents according to the C++ language rules. This C++ parsing step can be disabled with the
-disableCppParsing
选项。
If C++ parsing is enabled,
qt3to4
must be able to locate the headers included from the source files. Necessary headers include the public Qt headers and any headers that declares names that may conflict with names in the public Qt headers. The standard C++ headers and system headers are usually not needed.
You can tell
qt3to4
where to look for headers by using the
-I
command-line option. Qt 3.3 header information is built in, so it is normaly not necessary to specify the location of the Qt headers. If you are porting from a different version of Qt 3, you may want to disable the built-in headers with
-disableBuiltInQt3Headers
, and then add the path to the actual headers with the
-I
选项。
When porting a project,
qt3to4
will read the
INCLUDEPATH
and
DEPENDPATH
variables from the
.pro
file and add the paths specified here to the list of include search directories.
To see which headers that are not found, use the
-missingFileWarnings
选项。
In some cases, you might get compiler errors because of identifiers in the global namespace (e.g.,
CTRL
). Adding
using namespace Qt;
at the beginning of the source file that contains the indentifier solves the problem.
Some source code in
qt3to4
is licensed under specific highly permissive licenses from the original authors. Nokia gratefully acknowledges these contributions to
qt3to4
and all uses of
qt3to4
should also acknowledge these contributions and quote the following license statements in an appendix to the documentation.