PyQt for Desktop and Embedded Devices

Transcription

1 PyQt for Desktop and Embedded Devices David Boddie PyCon Tre, Firenze, 8 th 10 th May 2009

2 About Qt Developed by Qt Software (Nokia) Cross-platform C++ framework Linux, Windows, Mac OS X, other Unixes Embedded Linux, Windows CE, Series 60 Not just a widget toolkit other features Available under the GPL (version 3) Available under the LGPL (version 2 1) Also available under a Commercial License

3 About PyQt Developed by Riverbank Computing Ltd. Set of Python bindings to Qt Upcoming PyQt 4.5 will support Python 3 Bindings are generated using SIP Includes most features of Qt Available under the GPL (version 2 and 3) Also available under a Commercial License

4 PyQt Modules PyQt exposes many of Qt's 21 modules. We'll take a quick look at these: QtCore QtDesigner QtGui QtHelp QtNetwork QtOpenGL QtScript QtSql QtSvg QtWebKit QtXmlPatterns Phonon

5 PyQt Modules PyQt exposes many of Qt's 21 modules. We'll take a quick look at these: QtCore QtDesigner QtGui QtHelp QtNetwork QtOpenGL QtScript QtSql QtSvg QtWebKit QtXmlPatterns Phonon

6 Graphical User Interfaces PyQt includes a comprehensive set of widgets: QCheckBox import sys from PyQt4.QtGui import * QComboBox app = QApplication(sys.argv) QSpinBox checkbox = QCheckBox("C&ase sensitive") checkbox.show() QPushButton QSlider QRadioButton pushbutton = QPushButton("Cancel") pushbutton.show() calendar = QCalendarWidget() calendar.show() sys.exit(app.exec_()) QCalendarWidget QTableWidget QTextEdit

7 Graphical User Interfaces PyQt includes a comprehensive set of widgets: QCheckBox import sys from PyQt4.QtGui import * QComboBox app = QApplication(sys.argv) QSpinBox checkbox = QCheckBox("C&ase sensitive") checkbox.show() QPushButton QSlider QRadioButton pushbutton = QPushButton("Cancel") pushbutton.show() calendar = QCalendarWidget() calendar.show() sys.exit(app.exec_()) QCalendarWidget QTableWidget QTextEdit

8 Widgets and Layouts class PyPIWidget(QWidget): def init (self, parent = None): QWidget. init (self, parent) self.fieldcombo = QComboBox() self.fieldcombo.additems(["name", "version", "author", "author_ ", "maintainer", "maintainer_ ", "home_page", "license", "summary", "description", "keywords", "platform", "download_url"]) self.termsedit = QLineEdit() layout = QFormLayout() layout.addrow(self.tr("search &field:"), self.fieldcombo) layout.addrow(self.tr("search &terms:"), self.termsedit) self.treewidget = QTreeWidget() self.treewidget.setalternatingrowcolors(true) self.treewidget.setrootisdecorated(false) self.treewidget.setheaderlabels( [self.tr("name"), self.tr("description")]) mainlayout = QVBoxLayout() mainlayout.addlayout(layout) mainlayout.addwidget(self.treewidget) self.connect(self.termsedit, SIGNAL("returnPressed()"), self.search)

12 Graphics View The Graphics View framework provides a canvas: Interactive items (drag and drop) Nested items and groups Animation OpenGL rendering Embedded widgets Printing

13 Multimedia Support Phonon handles audio and video: class Player(QWidget): def init (self, parent = None): QWidget. init (self, parent) self.player = VideoPlayer(VideoCategory) #... def play(self): if self.player.isplaying(): self.player.stop() else: url = QUrl(self.urlEdit.text()) self.player.play(mediasource(url))

14 XML Processing Use XPath, XQuery and XSLT to process XML: <sun rise=" t05:32:17" set=" t20:23:58" /> <forecast> def fetchforecast(self, place): <tabular> <time from=" t06:00:00" to=" t12:00:00" url = " period="1"> + \ <symbol number="2" name="fair" /> place + "/forecast.xml" <precipitation value="0.0" /> b = QBuffer() <winddirection deg="114.6" code="ese" b.setdata(query_string) name="east-southeast" /> <windspeed mps="0.8" name="light air" /> b.open(qbuffer.readonly) <temperature unit="celcius" value="8" /> <pressure unit="hpa" value="1022.2" /> query = QXmlQuery() </time> query.bindvariable("url",... QXmlItem(QVariant(url))) declare variable $url external; query.setquery(b) ( b.close() string(doc($url)//sun/@rise), string(doc($url)//sun/@set), if query.isvalid(): self.results.clear() for $time in doc($url)//tabular/time query.evaluateto(self.results) order by $time/@from return (string($time/@from), self.updatetable() string($time/symbol/@name), string($time/symbol/@number), string($time/temperature/@value), string($time/temperature/@unit)) ) Could be useful if combined with GPS...

15 XML Processing Use XPath, XQuery and XSLT to process XML: <sun rise=" t05:32:17" set=" t20:23:58" /> <forecast> def fetchforecast(self, place): <tabular> <time from=" t06:00:00" to=" t12:00:00" url = " period="1"> + \ <symbol number="2" name="fair" /> place + "/forecast.xml" <precipitation value="0.0" /> b = QBuffer() <winddirection deg="114.6" code="ese" b.setdata(query_string) name="east-southeast" /> <windspeed mps="0.8" name="light air" /> b.open(qbuffer.readonly) <temperature unit="celcius" value="8" /> <pressure unit="hpa" value="1022.2" /> query = QXmlQuery() </time> query.bindvariable("url",... QXmlItem(QVariant(url))) declare variable $url external; query.setquery(b) ( b.close() string(doc($url)//sun/@rise), string(doc($url)//sun/@set), if query.isvalid(): self.results.clear() for $time in doc($url)//tabular/time query.evaluateto(self.results) order by $time/@from return (string($time/@from), self.updatetable() string($time/symbol/@name), string($time/symbol/@number), string($time/temperature/@value), string($time/temperature/@unit)) ) Could be useful if combined with GPS...

16 Web Browser Engine WebKit is integrated into Qt: Web browser widget JavaScript, SVG, CSS, SSL, etc. Control over browser settings and history Support for Netscape and native Qt plugins Client-side storage Support for in-page editing Python/C++ objects can be added to pages

17 Web Browser Engine WebKit is integrated into Qt: Web browser widget JavaScript, SVG, CSS, SSL, etc. Control over browser settings and history Support for Netscape and native Qt plugins Client-side storage Support for in-page editing Python/C++ objects can be added to pages

18 Intermission These features are nice on the desktop! We can also use them on embedded hardware.

19 Embedded Platforms Where is Embedded Linux used: Disadvantages: Advantages: Phones, Qt Small runs screens on media Embedded ( players ) Linux, Windows CE, Can Series be portable 60 GPS Python Low memory devices, runs on Web ( Embedded 64 tablets MB) Linux, Windows Accelerometers CE, Series 60 Set Slow PyQt top processors runs boxes on Embedded ( 300 MHz) Linux Touch screens Different Routers, Windows plug architectures CE?, computing Series 60? GPS Limited Handhelds, storage toys, ( kit 128MB) computing GSM, Wi-Fi, Bluetooth Cut down environments Cameras

22 Embedded Python Ways Not Nice so to I built build nice things things Python about about for Python Linux Python (2.x): Devices: (2.x): Portable Annoying OpenEmbedded Scratchbox C to implementation cross-compile (despite a good foundation) Fairly Relies Scratchbox Used small on to a try native (compared PyQt interpreter on Maemo to all the at various Qt libraries) points Few Buildroot Runs There dependencies setup.py are packages using available the built now interpreter Crosstool Batteries Needs a included native interpreter to build a parser generator Package-specific Distribution Used to try packages PyQt checks on a (e.g., Greenphone Debian)... OpenSSL, Curses, pyexpat, Tkinter Batteries included (even old ones) Used to create toolchains and/or whole systems.

26 Qt and PyQt on Linux Devices Which Developing graphics and system Simulating to use? X11-based QWS-based Common (Qt for approach: X11): devices: Fairly Use Xephyr a virtual standard (nested framebuffer procedure X server) for VNC to building simulate to simulate Qt a and small the PyQt screen Not Applications all that common can be developed to cross-compile on desktops Qt for using X11 PyQt Run or simulate the device's window system Qt Obviously, works better look with and feel X extensions may be a (Render) bit different The No need Maemo for SDK a dedicated emulates window the device manager environment Develop The APIs Possible to using should use PyQt be the Need to build your system own for same PyQt X11 libraries to prototype for desktop applications and device Care must be taken with the widgets used: Beware of version differences QWS Input (Qt widgets for Embedded without Linux): a keyboard... Fairly Scrollbars easy to on build a small Qt for screen... Embedded Linux PyQt needs patching for cross-compilation Xephyr python Qt uses -ac application.py the -extension framebuffer Composite -qws -display -screen VNC:0:size=240x x480 :1 DISPLAY=:1 vncviewer :0 python application.py Develop using PyQt derived from PyQt for X11

30 Demonstrations Two devices: Nokia N800: Greenphone: CPU: 400 MHz OMAP2420 Screen: CPU: 312 MHz Intel PXA270 Screen:

31 At this point we show some demonstrations...

32 Cutting Out Features Inappropriate features: Configuring Qt for Embedded Linux: Classic dialogs too large for small screen devices Menu bars, dock windows follow the wrong paradigm On desktops, we want as many features as possible... Unnecessary features:...but......on Devices embedded with touch devices, screens we might don't not need want cursors everything. Specialized displays don't need all the widget styles Redundant features: We don't really need: four sets of XML classes, two JavaScript engines, two ways to access networked resources QConfig lets you remove features from an embedded build

35 Finishing Up PyQt makes it possible to Write code that works on different (embedded) platforms Despite allowances for differences between devices You get to work around those at a high level Prototype applications on the desktop Python makes it possible to Ignore problems like cross-compiling Build on top of existing pure-python code Write portable, deployable applications Take advantage of interactivity to prototype on devices

36 Finishing Up PyQt makes it possible to Write code that works on different (embedded) platforms Despite allowances for differences between devices You get to work around those at a high level Prototype applications on the desktop Python makes it possible to Ignore problems like cross-compiling Build on top of existing pure-python code Write portable, deployable applications Take advantage of interactivity to prototype on devices

37 Resources Qt PyQt PyQt and PyKDE Wiki Develer Rapid GUI Programming with Python and Qt by Mark Summerfield