Making PyQt4 widgets with SIP
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3 November 2008
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SIP is a tool for making a Python API for C and C++ libraries, and it is used to make PyQt. Both packages we will find in many Linux distributions. SIP has a documentation - for Qt3, or "look at python qscintilla bindings" :) But with the help of Phil and Google I've came up with a working solution for making PyQt4 widgets from Qt4 widgets.
To make a PyQt4 API we need the widget header file - like QLabel.h, and the libraries it "depends" on. When we have that file we will have to create few extra:
- afile.sip - file named (recommended) like the header file. Contains SIP-readable description of the wrapped class.
- config.py - config file, that will make Makefile and other goodies for compiling
- config.py.in - extra config file (usualy blank?)
Making QTermWidget PyQt4 API
As a example I've selected from qt-apps.org a nice widget - QTermWidget. Unpack the source, and:qmake make make install
class QTermWidget : public QWidget
{
Q_OBJECT
public:
enum ScrollBarPosition
{
/** Do not show the scroll bar. */
NoScrollBar=0,
/** Show the scroll bar on the left side of the display. */
ScrollBarLeft=1,
/** Show the scroll bar on the right side of the display. */
ScrollBarRight=2
};
//Creation of widget
QTermWidget(int startnow = 1, //start shell programm immediatelly
QWidget *parent = 0);
~QTermWidget();
//start shell program if it was not started in constructor
void startShellProgram();
//look-n-feel, if you don`t like defaults
// Terminal font
// Default is application font with family Monospace, size 10
void setTerminalFont(QFont &font);
// Shell program, default is /bin/bash
void setShellProgram(QString &progname);
// Shell program args, default is none
void setArgs(QStringList &args);
//Text codec, default is UTF-8
void setTextCodec(QTextCodec *codec);
//Color scheme, default is white on black
void setColorScheme(int scheme);
//set size
void setSize(int h, int v);
// History size for scrolling
void setHistorySize(int lines); //infinite if lines < 0
// Presence of scrollbar
void setScrollBarPosition(ScrollBarPosition);
// Send some text to terminal
void sendText(QString &text);
signals:
void finished();
protected:
virtual void resizeEvent(QResizeEvent *);
protected slots:
void sessionFinished();
private:
void init();
TermWidgetImpl *m_impl;
};
%Module QtermWidget 0
%Import QtCore/QtCoremod.sip
%Import QtGui/QtGuimod.sip
class QTermWidget : QWidget {
%TypeHeaderCode
#include <qtermwidget.h>
%End
public:
QTermWidget(int startnow = 1, QWidget *parent = 0);
~QTermWidget();
enum ScrollBarPosition
{
NoScrollBar=0,
ScrollBarLeft=1,
ScrollBarRight=2
};
void setTerminalFont(QFont &font);
void setShellProgram(QString &progname);
void setArgs(QStringList &args);
void setTextCodec(QTextCodec *codec);
void setColorScheme(int scheme);
void setSize(int h, int v);
void setHistorySize(int lines);
void setScrollBarPosition(ScrollBarPosition);
void sendText(QString &text);
private:
void *createTermWidget(int startnow, void *parent);
};
- %Module QtermWidget 0 - name of the module
%Import QtCore/QtCoremod.sip %Import QtGui/QtGuimod.sip
this adds PyQt4 SIP files needed to describe a Qt4 widget for SIP%TypeHeaderCode #include
adding the header file, where wrapped class can be found%End
Next stage is the config file. config.py looks like this:
import os
import sipconfig
from PyQt4 import pyqtconfig
# The name of the SIP build file generated by SIP and used by the build
# system.
build_file = "qtermwidget.sbf"
# Get the PyQt configuration information.
config = pyqtconfig.Configuration()
# Get the extra SIP flags needed by the imported qt module. Note that
# this normally only includes those flags (-x and -t) that relate to SIP's
# versioning system.
qt_sip_flags = config.pyqt_sip_flags
# Run SIP to generate the code. Note that we tell SIP where to find the qt
# module's specification files using the -I flag.
os.system(" ".join([config.sip_bin, "-c", ".", "-b", build_file, "-I", config.pyqt_sip_dir, qt_sip_flags, "qtermwidget.sip"]))
# We are going to install the SIP specification file for this module and
# its configuration module.
installs = []
installs.append(["qtermwidget.sip", os.path.join(config.default_sip_dir, "qtermwidget")])
installs.append(["qtermwidgetconfig.py", config.default_mod_dir])
# Create the Makefile. The QtModuleMakefile class provided by the
# pyqtconfig module takes care of all the extra preprocessor, compiler and
# linker flags needed by the Qt library.
makefile = pyqtconfig.QtGuiModuleMakefile(
configuration=config,
build_file=build_file,
installs=installs
)
# Add the library we are wrapping. The name doesn't include any platform
# specific prefixes or extensions (e.g. the "lib" prefix on UNIX, or the
# ".dll" extension on Windows).
makefile.extra_libs = ["qtermwidget"]
# Generate the Makefile itself.
makefile.generate()
# Now we create the configuration module. This is done by merging a Python
# dictionary (whose values are normally determined dynamically) with a
# (static) template.
content = {
# Publish where the SIP specifications for this module will be
# installed.
"qtermwidget_sip_dir": config.default_sip_dir,
# Publish the set of SIP flags needed by this module. As these are the
# same flags needed by the qt module we could leave it out, but this
# allows us to change the flags at a later date without breaking
# scripts that import the configuration module.
"qtermwidget_sip_flags": qt_sip_flags
}
# This creates the qtermwidgetconfig.py module from the qtermwidgetconfig.py.in
# template and the dictionary.
sipconfig.create_config_module("qtermwidgetconfig.py", "config.py.in", content)
If we have all the configuration done we can finish our work by compiling the API. First parse sip file with:
sip -t Qt_4_4_1 -I /usr/share/sip/ -t WS_X11 -c . *sip
Where:
- Qt_4_4_1: is the ID of PyQt4 install (can be found in /usr/lib/python*/site-packages/PyQt4/pyqtconfig.py)
- /usr/share/sip/: path to SIP folder, with installed sip files (for example PyQt4 sip files that we need)
python config.py make make install
import sys
from PyQt4 import Qt
import QtermWidget
a = Qt.QApplication(sys.argv)
w = QtermWidget.QTermWidget()
#public methods can be used, for example setting font
#w.setTerminalFont(Qt.QFont('Terminus'))
w.show()
a.exec_()

Widgets Code
My PyQt4 widget bindings can be found on PyQt4 Extrawidgets.
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