Python and Qt Guide to PyQt

643 Pages·2008·6.95 MB·English

Rapid GUI Programming
with Python and Qt
Prentice Hall
Open Source Software Development Series
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Rapid GUI Programming
with Python and Qt
The DefinitiveGuide to PyQt Programming
Mark Summerfield
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Libraryof CongressCataloging-in-PublicationData
Summerfield,Mark
RapidGUIprogrammingwithPythonandQt:thedefinitiveguidetoPyQtprogramming/Mark
Summerfield.
p. cm.
Includesbibliographicalreferencesandindex.
ISBN978-0-13-235418-9 (hardcover:alk. paper)
1. Qt(Electronicresource) 2. Graphicaluserinterfaces(Computersystems) 3. Python(Computer
programlanguage) I. Title.
QA76.9.U83S892007
005.1’2—dc22
2007034852
Copyright©2008PearsonEducation,Inc.
Allrightsreserved. PrintedintheUnitedStatesofAmerica.
Trolltech®,Qt®andtheTrolltechlogoareregisteredtrademarksofTrolltechASA.
ISBN-13: 978-0-13-235418-9
ISBN-10: 0-13-235418-7
TextprintedintheUnitedStatesonrecycledpaperatEdwardsBrothersinAnnArbor,Michigan.
Firstprinting,October2007
Thisbook isdedicatedto
Andrea Summerfield
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Contents
Foreword ......................................................... xiii
Introduction ...................................................... 1
PartI: Python Programming
Chapter1. DataTypesandDataStructures ..................... 9
ExecutingPythonCode ......................................... 10
VariablesandObjects ........................................... 12
NumbersandStrings ........................................... 15
IntegersandLongIntegers ................................. 16
FloatsandDecimals ........................................ 17
Bytestrings,UnicodeStrings,andQStrings .................. 20
Collections ..................................................... 29
Tuples ..................................................... 29
Lists....................................................... 31
Dictionaries................................................ 35
Sets ....................................................... 37
Built-inFunctions .............................................. 37
Summary ...................................................... 41
Exercises ...................................................... 42
Chapter2. ControlStructures ................................... 45
ConditionalBranching.......................................... 46
Looping ........................................................ 49
ListComprehensionsandGenerators ....................... 53
Functions ...................................................... 55
GeneratorFunctions ....................................... 58
UsingKeywordArguments ................................. 59
LambdaFunctions ......................................... 61
DynamicFunctionCreation ................................ 62
PartialFunctionApplication ................................ 63
ExceptionHandling ............................................ 66
vii
Summary ...................................................... 72
Exercises ...................................................... 72
Chapter3. ClassesandModules ................................. 75
CreatingInstances ............................................. 77
MethodsandSpecialMethods ................................... 79
StaticData,andStaticMethodsandDecorators ............. 85
Example:TheLengthClass ................................. 86
CollectionClasses .......................................... 92
Example:TheOrderedDictClass ............................ 92
InheritanceandPolymorphism.................................. 99
ModulesandMultifileApplications .............................. 104
UsingthedoctestModule ................................... 105
Summary ...................................................... 107
Exercises ...................................................... 108
PartII: Basic GUI Programming
Chapter4. IntroductiontoGUIProgramming .................. 111
APop-UpAlertin25Lines ...................................... 112
AnExpressionEvaluatorin30Lines ............................ 116
ACurrencyConverterin70Lines ............................... 121
SignalsandSlots ............................................... 127
Summary ...................................................... 136
Exercise ....................................................... 137
Chapter5. Dialogs ............................................... 139
DumbDialogs .................................................. 141
StandardDialogs ............................................... 147
ModalOK/Cancel-StyleDialogs ............................. 148
SmartDialogs .................................................. 154
ModelessApply/Close-StyleDialogs ......................... 155
Modeless“Live”Dialogs .................................... 159
Summary ...................................................... 162
Exercise ....................................................... 163
Chapter6. MainWindows........................................ 165
CreatingaMainWindow ....................................... 166
ActionsandKeySequences ................................. 171
ResourceFiles ............................................. 172
viii
CreatingandUsingActions................................. 174
RestoringandSavingtheMainWindow’sState .............. 181
HandlingUserActions ......................................... 190
HandlingFileActions ...................................... 191
HandlingEditActions ...................................... 197
HandlingHelpActions ..................................... 200
Summary ...................................................... 201
Exercise ....................................................... 202
Chapter7. UsingQtDesigner .................................... 205
DesigningUserInterfaces ...................................... 208
ImplementingDialogs .......................................... 216
TestingDialogs................................................. 221
Summary ...................................................... 223
Exercise ....................................................... 224
Chapter8. DataHandlingandCustomFileFormats............ 227
MainWindowResponsibilities .................................. 229
DataContainerResponsibilities................................. 235
SavingandLoadingBinaryFiles ................................ 240
WritingandReadingUsingQDataStream................... 240
WritingandReadingUsingthepickleModule ............... 246
SavingandLoadingTextFiles .................................. 249
WritingandReadingUsingQTextStream ................... 250
WritingandReadingUsingthecodecsModule ............... 255
SavingandLoadingXMLFiles.................................. 256
WritingXML .............................................. 256
ReadingandParsingXMLwithPyQt’sDOMClasses ........ 259
ReadingandParsingXMLwithPyQt’sSAXClasses ......... 262
Summary ...................................................... 265
Exercise ....................................................... 266
PartIII: Intermediate GUI Programming
Chapter9. LayoutsandMultipleDocuments.................... 269
LayoutPolicies ................................................. 270
TabWidgetsandStackedWidgets ............................... 272
ExtensionDialogs .......................................... 276
Splitters ....................................................... 280
SingleDocumentInterface(SDI) ................................ 283
ix