book

Mastering Perl/Tk

by Stephen Lidie, Nancy Walsh

January 2002

Beginner

768 pages

25h 51m

English

O'Reilly Media, Inc.

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Mastering Perl/Tk
A Note Regarding Supplemental Files
Preface
History of This Book
What You Should Already Know
What’s in This Book
Reading Order
Typographical Conventions
We’d Like to Hear from You
Acknowledgments
SteveNancy

1. Hello, Perl/Tk
1.1. Perl/Tk Concepts
1.2. Some Perl/Tk History
1.2.1. The X Window System and Xlib1.2.2. The Coming of Tcl/Tk1.2.3. The Evolution of Perl/Tk1.2.4. Perl/Tk Meets Win32
1.3. Getting Started with Perl/Tk
1.3.1. Do You Need To Install Anything?1.3.2. Creating Widgets1.3.3. Specifying Options1.3.4. Toplevel, MainWindow, and Frame Widgets1.3.5. Displaying a Widget1.3.6. The Event Loop
1.4. Hello World Example
1.4.1. exit Versus destroy
1.5. Unsolicited Advice
1.5.1. Programming Style1.5.2. Naming Conventions for Widget Types1.5.3. Designing Your Windows
1.6. Debugging and PrototypingPerl/Tk Programs
2. Geometry Management
2.1. The pack Geometry Manager
2.1.1. Options for pack2.1.2. Positioning Widgets2.1.3. Allocation Rectangles2.1.4. Filling the Allocation Rectangle2.1.5. Expanding the Allocation Rectangle2.1.6. Anchoring a Widget in Its Allocation Rectangle2.1.7. Widget Order in the Window2.1.8. Padding the Size of the Widget2.1.8.1. Valid screen distances2.1.9. Displaying in a Parent Other Than Your Own2.1.10. Methods Associated with pack2.1.10.1. Unpacking a widget2.1.10.2. Retrieving pack information2.1.10.3. Disabling and enabling automatic resizing2.1.10.4. Listing widgets2.1.11. Demo Programs for pack
2.2. The grid Geometry Manager
2.2.1. Special Characters2.2.1.1. Spanning columns2.2.1.2. Empty cells2.2.2. grid Options2.2.3. Specifying Rows and Columns Explicitly2.2.4. Spanning Rows and Columns Explicitly2.2.5. Forcing a Widget to Fill a Cell2.2.6. Padding the Widget2.2.7. Specifying a Different Parent2.2.8. Configuring Columns and Rows2.2.8.1. Weight2.2.8.2. Minimum cell size2.2.8.3. Padding2.2.8.4. Bounding box2.2.9. Removing a Widget2.2.10. Getting Information2.2.11. Widget Location2.2.11.1. Propagation2.2.12. How Many Columns and Rows?2.2.13. gridSlaves
2.3. The place Geometry Manager
2.3.1. place Options2.3.2. Absolute Coordinates2.3.3. Relative Coordinates2.3.4. Anchoring the Widget2.3.5. Width and Height2.3.6. Border Options2.3.7. Methods Associated with place2.3.7.1. Removing the widget2.3.7.2. Place information2.3.7.3. Place slaves
2.4. The form Geometry Manager
2.4.1. Options for form2.4.2. Attachments2.4.2.1. Attaching to the grid2.4.2.2. Widget-to-widget attachments2.4.2.3. Attaching to nothing2.4.3. Springs2.4.4. form Methods2.4.4.1. Changing the grid size2.4.4.2. Removing a widget from a container2.4.4.3. Options info for form2.4.4.4. What’s managed by form?2.4.4.5. Circular dependency check
2.5. Geometry Management Summary
3. Fonts
3.1. Experimenting with Fonts
3.2. Dissecting a Font
3.3. Using Fonts
3.3.1. System Fonts
3.4. Using Fonts Dynamically
3.5. Font Manipulation Methods
3.5.1. One Last Example
4. Button, Checkbutton, and Radiobutton Widgets
4.1. Creating Button Widgets
4.2. Standard Options for Each Button Type
4.3. Table of Options for Button-Type Widgets
4.4. Displaying Text on Buttons
4.5. Displaying an Image or Bitmap
4.5.1. Images with Checkbuttons and Radiobuttons
4.6. Checkbutton and Radiobutton Indicator Status
4.7. On and Off Values for a Checkbutton
4.8. Radiobutton Values
4.9. The -command Option
4.10. Disabling a Button
4.11. Text Manipulation
4.12. Altering the Button’s Style
4.13. Changing the Size of a Button
4.14. Adding a Keyboard Mapping
4.15. Color Options
4.16. Indicator Colors
4.17. Hiding the Indicator
4.18. Focus Options
4.19. Altering the Highlight Rectangle
4.20. Configuring a Button
4.21. Flashing the Button
4.22. Invoking the Button
4.23. Turning a Checkbutton/Radiobutton On and Off
5. Label and Entry Widgets
5.1. The Label Widget
5.1.1. Creating a Label5.1.2. Label Options5.1.3. How a Label Differs from Other Widgets5.1.4. Relief5.1.5. Status Message Example5.1.6. Container Frames5.1.7. Label Configuration
5.2. The Entry Widget
5.2.1. Creating the Entry Widget5.2.2. Entry Options5.2.3. Assigning the Entry’s Contents to a Variable5.2.4. Relief5.2.5. Entry Indexes5.2.6. Text Selection Options5.2.7. The Insert Cursor5.2.8. Password Entries5.2.9. Entry Widget Validation5.2.10. Using a Scrollbar5.2.11. Configuring an Entry Widget5.2.12. Deleting Text5.2.13. Getting the Contents of an Entry Widget5.2.14. Moving the Insertion Cursor5.2.15. Getting a Numeric Index Value5.2.16. Inserting Text5.2.17. Scanning Text5.2.18. Working with the Selection5.2.19. Changing the View in the Entry Widget
5.3. The Perl/Tk LabEntry Mega-Widget
6. The Scrollbar Widget
6.1. Defining Scrollbar Parts
6.2. The Scrolled Method
6.2.1. Configuring the Scrollbar(s) Created with Scrolled
6.3. The Scrollbar Widget
6.3.1. Creating a Scrollbar Widget6.3.2. Scrollbar Options6.3.3. Scrollbar Colors6.3.4. Scrollbar Style6.3.5. Scrollbar Orientation6.3.6. Using the Arrows and the Slider6.3.7. Assigning a Callback6.3.8. How the Scrollbar Communicates with Other Widgets6.3.9. Scrollbar Configuration6.3.10. Defining What We Can See6.3.11. Getting the Current View6.3.12. Activating Elements in a Scrollbar6.3.13. Calculating Change from Pixels6.3.14. Locating a Point in the Trough6.3.15. Identifying Elements
6.4. Examples
6.4.1. Entry Widget6.4.2. Listbox, Text, and Canvas Widgets6.4.3. One Scrollbar, Multiple Widgets
7. The Listbox Widget
7.1. Creating and Filling a Listbox
7.2. Listbox Options
7.3. Selection Modes
7.3.1. Operating System Differences
7.4. Colors
7.5. Listbox Style
7.5.1. Style of Selected Items7.5.2. Special Listbox Resizing
7.6. Configuring a Listbox
7.7. Inserting Items
7.8. Deleting Items
7.9. Retrieving Elements
7.10. Selection Methods
7.10.1. Selecting Items7.10.2. Unselecting Items7.10.3. Testing for Selection7.10.4. Anchoring the Selection
7.11. Moving to a Specific Index
7.12. Translating Indexes
7.13. Counting Items
7.14. Active Versus Selected
7.15. Bounding Box
7.16. Finding an Index by y Coordinate
7.17. Scrolling Methods
7.18. Listbox Virtual Events
7.19. Listbox Example
8. The Text, TextUndo,and ROText Widgets
8.1. Creating and Using a Text Widget
8.2. Text Widget Options
8.2.1. Fonts8.2.2. Widget Size8.2.3. Widget Style8.2.4. Line Spacing8.2.5. Tab Stops
8.3. A Short Break for a Simple Example
8.4. Text Indexes
8.4.1. Base Index Values8.4.2. Index Modifiers8.4.3. Text Index Examples
8.5. Text Tags
8.5.1. Tag Options8.5.2. A Simple Tag Example8.5.3. Selections in a Text Widget Using the “sel” Tag8.5.4. Configuring and Creating Tags8.5.5. Adding a Tag to Existing Text8.5.6. Using bind with Tags8.5.6.1. The Perl/Tk Text widget extended bindings8.5.7. Deleting All Instances of a Tag8.5.8. Removing a Tag from the Text8.5.9. Raising and Lowering Tags8.5.10. Getting Tag Names8.5.11. Determining Where a Tag Applies
8.6. Inserting Text
8.6.1. Inserting Lines Using print and printf
8.7. Deleting Text
8.8. Retrieving Text
8.9. Translating Index Values
8.10. Comparing Index Values
8.11. Showing an Index
8.12. Getting the Size of a Character
8.13. Getting Line Information
8.14. Searching the Contents of a Text Widget
8.15. Scrolling
8.16. Marks
8.16.1. Setting and Getting the Gravity8.16.2. Determining Mark Names8.16.3. Creating and Deleting Marks
8.17. Embedding Widgets
8.17.1. windowCreate, windowCget, and windowConfigure
8.18. Internal Debug Flag
8.18.1. Scanning
8.19. The Perl/Tk Text Widget Extended Methods
8.20. The TextUndo Widget
8.20.1. TextUndo Virtual Events
8.21. The ROText Widget
9. The Canvas Widget
9.1. Creating a Canvas
9.2. The Canvas Coordinate System
9.3. The Scrollable Region
9.4. Using bind with a Canvas
9.5. Canvas Options
9.5.1. Common Canvas Dash, Stipple, and Tile Options9.5.2. Additional Scrolling Options9.5.3. Canvas Widget Option List
9.6. Creating Items in a Canvas
9.6.1. The Arc Item9.6.2. The Bitmap Item9.6.3. The Image Item9.6.4. The Line Item9.6.5. The Oval Item9.6.6. The Polygon Item9.6.7. The Rectangle Item9.6.8. The Text Item9.6.8.1. Text item indexes9.6.8.2. Deleting characters9.6.8.3. Positioning the cursor9.6.8.4. Index information9.6.8.5. Adding text9.6.8.6. Selecting text9.6.9. The Widget Item9.6.10. The Grid Item9.6.11. The Group Item
9.7. Configuring the Canvas Widget
9.8. Configuring Items in the Canvas Widget
9.9. Tags
9.9.1. Binding Items Using Tags9.9.2. Finding Tags9.9.3. Getting Tags from a Specific Item
9.10. Retrieving Bounding Box Coordinates
9.11. Translating Coordinates
9.12. Moving Items Around
9.13. Changing the Display List
9.14. Deleting Items
9.15. Deleting Tags
9.16. Determining Item Type
9.17. Setting Keyboard Focus
9.18. Rendering the Canvas as PostScript
9.19. Scaling the Canvas
9.20. Scanning
9.20.1. Scrolling Methods
9.21. A Drawing Program Example
10. The Scale Widget
10.1. Creating a Scale
10.2. Assigning a Callback
10.3. Orientation
10.4. Minimum and Maximum Values
10.5. Displayed Versus Stored Value
10.6. Adding a Label
10.7. Displaying Value Increments
10.8. Changing the Size of the Scale
10.9. Options You’ll Probably Never Need
10.10. Configuring a Scale
10.11. Getting the Value of a Scale
10.12. Setting the Value of a Scale
10.13. Determining Coordinates
10.14. Identifying Parts of a Scale
11. Frame, MainWindow,and Toplevel Widgets
11.1. Creating a Frame
11.2. Creating a Toplevel Widget
11.3. Options
11.3.1. Frame-Specific Options11.3.2. Toplevel-Specific Options11.3.3. Viewing a Frame11.3.4. Adding a Label to a Frame11.3.5. Frames Aren’t Interactive11.3.6. Colormap Complications11.3.7. The Magical Class Option
11.4. Frame Methods
11.5. Toplevel Methods
11.5.1. Sizing a Toplevel11.5.2. Maximum Size11.5.3. Minimum Size11.5.4. Limiting Resizing11.5.5. Using a Size Aspect11.5.6. Setting the Title11.5.7. Showing the Toplevel11.5.8. Withdrawing the Toplevel11.5.9. Iconifying the Toplevel11.5.10. Specifying the Icon Bitmap11.5.11. Specifying the Icon Mask11.5.12. Setting the Name of the Icon11.5.13. Setting the Icon Position11.5.14. Using a Window Instead of an Icon11.5.15. Determining the State11.5.16. Assigning a Client Name11.5.17. Window Properties11.5.18. The Colormap Property11.5.19. The Command Property11.5.20. The Focus Model11.5.21. Getting a Widget’s Window ID11.5.22. The Application Grid11.5.23. Being the Leader11.5.24. Removing Decorations11.5.25. Who Placed the Window?11.5.26. Who Sized It?11.5.27. Transient Windows
11.6. Creating Multiple MainWindows
11.7. Putting Two MainWindows to Work
12. The Menu System
12.1. Menu System Components
12.1.1. Menus and Menu Items12.1.2. Menu Indexes12.1.3. Manipulating Menus12.1.4. Manipulating Menu Items12.1.5. Menubars12.1.6. Menu Options
12.2. Menubars and Pulldown Menus
12.2.1. Menubars the Clunky, Casual, Old-Fashioned Way12.2.2. Menubars the Slick, Sophisticated, New-Fashioned Way
12.3. The Win32 System Menu Item
12.4. Classical Menubars
12.4.1. Menubutton Options12.4.2. Button-Only Options
12.5. Popup Menus
12.5.1. The post and Post Methods12.5.2. The Popup Method12.5.2.1. Popup examples
12.6. Option Menus
12.6.1. Tk::Optionmenu12.6.2. A Native Option Menu
12.7. Menu Virtual Events
12.8. Pie Menus
12.8.1. Fitts’ Law
13. Miscellaneous Perl/Tk Methods
13.1. Managing Widgets with configure and cget
13.1.1. The configure Method13.1.2. The cget Method
13.2. Building a Family Tree
13.2.1. Widget’s Children13.2.2. Name of a Widget13.2.3. Parent of a Widget13.2.4. The Widget’s Toplevel13.2.5. Widget’s Manager13.2.6. The Widget’s class
13.3. Widget’s ID
13.3.1. Widget’s PathName From Its X11 ID
13.4. Color-Related Methods
13.4.1. Is the Colormap Full?13.4.2. Cell Count13.4.3. Color Depth13.4.4. Translate to RGB Value13.4.5. Setting Colors13.4.6. Predefined Color Scheme
13.5. The Application’s Name
13.6. Widget Existence
13.7. Is the Widget Mapped?
13.8. Converting Screen Distances
13.9. Size of Widget
13.9.1. Widget’s Geometry13.9.2. Requested Height13.9.3. Requested Width13.9.4. Actual Width13.9.5. Actual Height
13.10. Widget Position
13.10.1. Position Relative to the Root Window13.10.2. Coordinates Relative to the Parent13.10.3. Coordinates Relative to the Root Window13.10.4. Virtual Desktop Coordinates13.10.5. Cursor Coordinates Relative to the Desktop
13.11. Screen Information
13.11.1. Screen Name13.11.2. Screen Height and Width13.11.3. Cell Count13.11.4. Screen Depth13.11.5. Color Type13.11.6. Server Type13.11.7. Is the Widget Viewable?
13.12. Atom Methods
13.13. Ringing a Bell
13.14. Clipboard and Selection Methods
13.14.1. Clipboard Methods13.14.2. Selection Methods13.14.2.1. Clearing the selection13.14.2.2. Getting the selection13.14.2.3. Assigning a callback13.14.2.4. Determining the owner13.14.2.5. Setting the owner13.14.3. Exporting the Selection to the Outside World
13.15. Destroying a Widget
13.16. Focus Methods
13.16.1. Keyboard Traversal13.16.1.1. Tabbing between widgets13.16.1.2. Default widget bindings13.16.1.3. Menu Traversal
13.17. Grab Methods
13.18. Marking a Widget Busy and Unbusy
13.19. Widget Mapping and Layering
13.20. Interapplication Communication
13.21. Waiting for Events to Happen
13.21.1. File Events
13.22. Time Delays
13.23. Parsing Command-Line Options
13.24. Really Miscellaneous Methods
14. Creating Custom Widgets in Pure Perl/Tk
14.1. A Mega-Widget Quick-Start
14.2. The Perl/Tk Class Hierarchy
14.3. Mega-Widget Implementation Details
14.3.1. Tk::Widget::new, the Real Perl/Tk Widget Constructor14.3.2. Subroutine ClassInit14.3.3. Subroutine CreateArgs14.3.4. Subroutine SetBindtags14.3.5. Subroutine Populate14.3.6. Subroutine ConfigSpecs14.3.6.1. ConfigSpecs Examples14.3.7. Subroutine Delegates14.3.8. Other Useful Methods14.3.8.1. Subroutine Advertise14.3.8.2. Subroutine Callback14.3.8.3. Subroutine Component14.3.8.4. Subroutine Descendants14.3.8.5. Subroutine Subwidget14.3.8.6. Subroutine Walk14.3.9. Mega-Widget Instance Variables
14.4. Composite Mega-Widgets
14.4.1. Tk::Thermometer
14.5. Derived Mega-Widgets
14.5.1. Tk::NavListbox14.5.2. Tk::CanvasPlot14.5.3. Tk::LCD
14.6. Packaging a Mega-Widget for Public Distribution
14.6.1. Packaging for CPAN14.6.2. Packaging for PPM
15. Anatomy of the MainLoop
15.1. Creating a Callback
15.1.1. Callbacks and Closures
15.2. Binding to Events
15.2.1. Event Descriptor Syntax15.2.1.1. Event descriptor modifiers15.2.1.2. Event descriptor types15.2.2. The Event Structure15.2.2.1. The exporter tag :variables15.2.2.2. Event information methods15.2.3. Widget Class Bindings15.2.4. Widget Instance Bindings15.2.5. Binding to a MouseWheel Event15.2.6. Canvas Bindings
15.3. The bindtags Command
15.3.1. How Might We Use bindtags?15.3.2. bindDump—Dump Lots of Binding Information
15.4. Executing Nonblocking System Commands
15.4.1. fileevent Syntax15.4.2. Tk::ExecuteCommand15.4.3. An MPG Player—tkmpg123
15.5. Tracing Perl/Tk Variables
15.5.1. Tie::Watch
15.6. Nonblocking Wait Activities
15.6.1. Tk::waitVariableX
15.7. Splash Screens
15.7.1. Tk::Splashscreen
15.8. Synthesizing Virtual Events
15.9. Coexisting with Other GUI Main Loops
15.9.1. Embedding OpenGL in a Perl/Tk Window15.9.2. Flying the Enterprise
16. User Customization
16.1. Using the Command Line
16.1.1. Colors, Fonts, and Titles16.1.2. Initial MainWindow Placement16.1.3. Choosing a Display16.1.4. Option Database Lookups16.1.5. Synchronizing Window Messages
16.2. Using the Option Database
16.2.1. Manipulating Resources with option* Methods16.2.2. Manipulating Resources with Tk::CmdLine Subroutines
17. Images and Animations
17.1. An Overview of Perl/Tk Image Types
17.2. Methods Common to All Image Types
17.3. Bitmap Primitives
17.4. DefineBitmap
17.5. The Bitmap Image Type
17.5.1. Cool Tricks with an Empty Bitmap17.5.1.1. An invisible cursor17.5.1.2. Filling a transparent Canvas item
17.6. The Pixmap Image Type
17.7. The Photo Image Type
17.7.1. Creating a Color Palette with the put Method17.7.2. Using put to Create a Progress Bar with a 3D Look17.7.3. Capturing a Window with Tk::WinPhoto17.7.3.1. What you see is not always what you get17.7.4. Tk::Thumbnail
17.8. The Compound Image Type
17.9. Tk::Animation
17.10. tkneko—Animating the Neko on a Canvas
17.11. Tile and Transparent Images
17.12. Miscellaneous Image Methods
17.13. Simple Photo Rotations
18. A Tk Interface Extension Tour
18.1. Display Items
18.2. Item Styles
18.2.1. Item Style Methods
18.3. The TList Widget
18.3.1. TList Indexes and Methods
18.4. The HList Family of Widgets
18.4.1. Using Indicators with HList18.4.2. HList Methods18.4.3. The Tree Widget18.4.4. Tree Methods18.4.5. The DirTree Widget18.4.6. Adding a Directory
18.5. Tix Images
19. Interprocess Communicationwith Pipes and Sockets
19.1. Handling Unsolicited Media Changes
19.1.1. The Media Change Client, mediachangec19.1.2. The Media Change Server, mediachanged
19.2. IPADM Design Considerations
19.3. The Perl/Tk IPADM Client, ipadm
19.3.1. Creating the Hypertext User Interface19.3.2. The Subnet Widget Edits a Subnet Description19.3.3. Starting the IPADM Helper Task19.3.4. fileevent Keeps ipadm Happy
19.4. The IPADM Helper, ipadmh
19.5. The IPADM Daemon, ipadmd
19.5.1. The Forking Server19.5.2. IPADM Message Handling19.5.3. Locking an SDB File19.5.4. Updating the DHCP and DNS Configuration Files19.5.5. What About Security?
19.6. Polling Win32 Sockets
20. IPC with send
20.1. Security and Inter-Language Considerations
20.1.1. Application Names20.1.2. Tk::Receive
20.2. Computing π with Parallel Message Passing
20.2.1. The Message Passing Protocol20.2.2. Tcl/Tk Slave Processor Code20.2.3. Tcl/Tk Master Processor Code
20.3. TclRobots
20.3.1. TclRobots.pm, the Perl Interface to TclRobots20.3.1.1. Tk::Receive handles tclrobots to Perl communications20.3.1.2. The RCP API handles Perl to tclrobots communications20.3.2. Robot Control Programs
21. C Widget Internals
21.1. The Tk::Square Widget
21.1.1. Tcl/Tk Example21.1.2. Overview of the Perl/Tk Distribution21.1.3. Layout of a Typical C Widget21.1.3.1. Tk::Square instance structure21.1.3.2. Tk::Square configuration specifications21.1.3.3. Tk::Square instance constructor21.1.3.4. Tk::Square method processors21.1.3.5. Tk::Square option configurator21.1.3.6. Tk::Square event handler21.1.3.7. Tk::Square drawing handler21.1.3.8. Tk::Square destructor
21.2. Interfacing tkSquare.c with Perl/Tk
21.2.1. Makefile.PL21.2.2. Square.xs21.2.3. Square.pm21.2.4. pTk/Makefile.PL
21.3. Building and Testing Tk::Square
21.3.1. t/square_demo.t
21.4. How Not to Port Tk::Square
22. Perl/Tk and the Web
22.1. Library for WWW Access in Perl
22.1.1. LWP::Simple, the Easiest Way to the Web22.1.2. Fetching Web Content with LWP::UserAgent22.1.3. lwp-request and fileevent Rule22.1.4. The Recipe for Displaying Web Images22.1.5. Win32 Considerations22.1.5.1. fork and local Win32 sockets22.1.5.2. fork and LWP::UserAgent22.1.5.3. Win32::Process and shared memory22.1.6. Tidying an Ugly Mess
22.2. The PerlPlus Browser Plug-in
22.2.1. Embedding Perl/Tk in Other Windows22.2.2. Embedded Versus Full-Screen Mode22.2.3. How You Can Contribute to the PerlPlus Plug-in Project
23. Plethora of pTk Potpourri
23.1. pTk Special Variables and Exporter Symbols
23.1.1. Global Variables23.1.2. Symbols Exported by Default23.1.3. Optionally Exported Symbols23.1.4. Exporter Tags
23.2. Manipulating the Cursor
23.2.1. Creating Your Own Custom Cursor Shape
23.3. Dialog Boxes
23.3.1. The Dialog Widget23.3.2. The messageBox Method23.3.3. The DialogBox Widget23.3.4. Using ErrorDialog23.3.5. chooseColor Dialog23.3.6. getOpenFile and getSaveFile Dialogs
23.4. The Adjuster Widget
23.5. The Balloon Widget
23.6. The BrowseEntry Widget
23.7. The LabFrame Widget
23.7.1. LabFrame Options
23.8. The NoteBook Widget
23.8.1. Creating Pages23.8.2. WordCount Example Using a NoteBook23.8.3. NoteBook Limitations
23.9. The Pane Widget
23.9.1. Pane Options
23.10. The ProgressBar Widget
23.10.1. ProgressBar Options
23.11. Widgets Not in the Perl/Tk Distribution
A. Installing Perl/Tk
A.1. Installing Perl/Tk for Unix
A.2. Installing Perl/Tk for Win32
B. Options and Default Valuesfor Each Widget
B.1. Adjuster
B.2. Balloon
B.3. Bitmap
B.4. BrowseEntry
B.5. Button
B.6. Canvas
B.7. Checkbutton
B.8. ColorEditor
B.9. Dialog
B.10. DirTree
B.11. Entry
B.12. ErrorDialog
B.13. FileSelect
B.14. Frame
B.15. HList
B.16. Label
B.17. LabEntry
B.18. LabFrame
B.19. Listbox
B.20. MainWindow
B.21. Menu
B.22. Menubutton
B.23. Message
B.24. NoteBook
B.25. Optionmenu
B.26. Pane
B.27. Photo
B.28. ProgressBar
B.29. Radiobutton
B.30. ROText
B.31. Scale
B.32. Scrollbar
B.33. Table
B.34. Text
B.35. TextUndo
B.36. Tiler
B.37. TList
B.38. Toplevel
B.39. Tree
C. Complete Program Listings
C.1. Tk::CollapsableFrame
C.2. Tk::MacCopy
C.3. Tk::ExecuteCommand
C.4. Proc::Killfam
C.5. tkmpg123
C.6. Tk::Trace
C.7. tkhp16c
C.8. Tk::MacProgressBar
C.9. TclRobots.pm
C.10. Robot Control Program complex.ptr
C.11. clock-bezier.ppl
C.12. tkhanoi.ppl
Index
About the Authors
Colophon
Copyright

Content preview from Mastering Perl/Tk

Widget Existence

To determine if a widget has been created and not destroyed, use Exists($widget):

if (Exists($widget)) {
   ...
}

Note the uppercase E on this method. The Exists method is different from the built-in Perl exists function. Make sure you don’t confuse the two.

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ISBN: 1565927168Errata Page

Cloud Computing

Data Engineering

Data Science

AI & ML

Programming Languages

Software Architecture

IT/Ops

Security

Design

Business

Soft Skills

Mastering Perl/Tk

by Stephen Lidie, Nancy Walsh

Widget Existence

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Addison B.

Amir M.

Mark W.

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