book

Programming with Qt, 2nd Edition

by Matthias Kalle Dalheimer

January 2002

Beginner to intermediate

522 pages

14h 36m

English

O'Reilly Media, Inc.

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A Productive WeekendWhat You Should KnowOrganization of This BookConventions Used in This BookComments and QuestionsAcknowledgments
Why GUI Toolkits?Why Portability?Why Qt?Implementing Cross-Platform GUI LibrariesAPI LayeringAPI EmulationGUI EmulationAcquiring QtQt EditionsHow Free Is Qt?Compiling and Installing QtInstalling Qt or Qt/Embedded on Unix or MacOS X systemsCompiling and Installing Qt on WindowsC++ as Used by QtGetting Help
Hello, world!ExercisesUsing the Qt Reference DocumentationExercisesAdding an Exit ButtonExercisesIntroduction to Signals and SlotsThe Problem of Callback FunctionsA New ApproachSignals and Slots in QtAnother Example of Signals and SlotsRunning mocExercisesEvent Handling and Simple Drawings with QPainterExercises
Adding MenusExercisesAdding a Scrolled ViewExercisesAdding a Context MenuExerciseFile I/OExercises
General Widget ParametersWidget StylesButtonsPush ButtonsRadio Buttons and CheckboxesSelection WidgetsList BoxesCombo BoxesWidgets for Bounded-Range InputSlidersDialsSpin BoxesWidgets for Entering Date and TimeScrollbarsMenu-Related WidgetsArrangersFramesGroup BoxesSplittersWidget StacksSize GripsTab-Related WidgetsText-Entry FieldsLabelsSimple LabelsQLCDNumberWidgets for the OfficeThe Main WindowToolbarsStatus BarsMultiple Document Interface (MDI)Docking WindowsTooltips and “What’s This” WindowsProgress BarsScrolled ViewsList ViewsIcon ViewsWidgets for Tabular MaterialWidgets for Displaying Rich Text
Predefined Dialog BoxesFile Selection Dialog BoxesColor Dialog BoxesFont Dialog BoxesMessage BoxesInput Dialog BoxesProgress Dialog BoxesError Message Dialog BoxesBuilding Blocks for Your Own Dialog BoxesTab Dialog BoxesWizards
Layout Manager BasicsLaying Out Widgets in Rows and ColumnsNested Layout ManagersGrid LayoutImplicit Geometry Management

Available Container ClassesChoosing a Container ClassWorking with Reference-Based Container ClassesBasic UsageCaching DataIteratorsStacks and QueuesWorking with Value-Based Container Classes
AnimationsPrintingManaging ColorsColor AllocationColor ModelsColor Groups and PalettesBasic QPainter: Drawing FiguresSelecting Brushes, Colors, and PensDrawing Operations in QPainterAdvanced QPainterTwo-Dimensional TransformationsView TransformationsClippingDouble-Buffering and Other Nifty TechniquesIndependently Movable Objects with QCanvasAdding Different Items to the CanvasWorking with StylesLoading and Saving Custom Image FormatsSetting a Cursor
Internationalization and Localization of On-Screen TextInternationalizing a Qt ApplicationLocalizing Your ApplicationValidating User InputWorking with Regular ExpressionsReading and Writing XML FilesProcessing XML with SAXProcessing XML with DOMRich Text
Reading a Text FileTraversing a DirectoryFile InformationReading and Writing Configuration Data
Using the ClipboardDrag-and-Drop
Working with Date and Time ValuesLoading Code Libraries DynamicallySpawning Child ProcessesPlaying Sounds
Implementing a Coordinate SelectorImplementing a Browse Box
Event FiltersSending Synthetic Events
Signals and Slots RevisitedConnecting Several Buttons to One SlotActions
Installation of the SQL ModuleConnecting to a DatabaseSimple Data RetrievalData Retrieval with CursorsData DisplayData ManipulationAnything Else?MetadataTransactionsMore Features
Configuring Qt for MultithreadingUsing Qt’s Multithreading ClassesMultithreading PitfallsAlternatives to Multithreading
Why Portability Is DesirableHow to Write Portable ProgramsDanger Ahead: When Even Qt Is Not PortableBuilding Projects Portably with qmake
Low-Level Socket AccessHigher-Level Network Access
OpenGL Programming with QtWriting Netscape Plug-insIntegrating Xt WidgetsInterfacing Qt with Perl
Importing an Existing MakefileCreating Your Own Project from ScratchUsing qmake to Create a Project FileUsing the MS Visual Studio Integration
Why Do You Need A GUI Designer?Creating a Simple Application with the Help of Qt DesignerBecoming Familiar with Qt DesignerA first look at the property editorA first look at the form editorMore Widgets for Our FormGenerating C++ source code from the Qt Designer filePutting It All TogetherAdding Functionality to a Dialog Box by SubclassingContinuing Work on an Already Existing Dialog BoxAdding Functionality to the Push ButtonsInitializing the State of Widgets in the FormConnecting Widgets to One AnotherUsing Layout ManagementPutting a Form Together with LayoutsPopular Mechanics: Working with SpacersUseful TechniquesWorking with Signals and SlotsThe connection toolThe slots toolChanging the Tab OrderAll About Layout ManagementIntegrating Qt Designer Files into Your ProjectUsing qmake for Generating and Building Qt Designer FilesUsing Project ManagementCreating Main WindowsAccessing Databases from Qt DesignerAccessing the Help SystemDynamically Creating Forms at RuntimeCustom Widgets
Answers to Exercises in Chapter 2Answers to Exercises in the Section “Hello, world!”Answers to Exercises in the Section “Using the Qt Reference Documentation”Answers to Exercises in the Section “Adding an Exit Button”Answers to Exercises in the Section “Introduction to Signals and Slots”Answers to Exercises in the Section “Event Handling and Simple Drawings with QPainter”Answers to Exercises in Chapter 3Answers to Exercises in the Section “Adding Menus”Answers to Exercises in the Section “Adding a Scrolled View”Answers to Exercises in the Section “Adding a Context Menu”Answers to Exercises in the Section “File I/O”

Content preview from Programming with Qt, 2nd Edition

Chapter 11. Working with Files and Directories

Few programs don’t deal with files and directories in some way. Filesystem manipulation is another inherently platform-dependent area. If you don’t plan to make your application available on multiple platforms and you are absolutely sure that nobody will ever ask you to, you can use the native functions to access files and directories provided by your operating system or development environment. However, if you need or want to be portable, using the classes that Qt provides might be a better choice. Even if portability is not important for you, the Qt classes might be useful because they provide easy, type-safe access to this functionality.

The Qt API for accessing files and directories mainly consists of the classes QIODevice, QFile, QFileInfo, and QDir. Two classes, QDataStream and QTextStream, are used to write binary and text data to files. Finally, the class QSettings makes it easy to store and retrieve simple configuration-like data.

We explain how to use these classes by means of three examples: reading a text file, recursing over a directory tree, and outputting information about one file. Then we finish the chapter by showing how to use QSettings.

Reading a Text File

To read a text file, you create a QFile object, assign the filename to this object, and open it. You then create a QTextStream object that works with the QFile object and read the data by means of the normal C++ input operators or with QTextStream::readLine() ...