Graphical Applications with TCL and TK Book

Section I: Writing Applications in Tcl/Tk ..... 1

Chapter 1: Your First Tcl Programs ..... 3

What is a Tcl program ..... 3

Make a Wish ..... 4

The First Tcl Program ..... 7
The First Commands in Depth ..... 8

Widget Names ..... 8
Button Options ..... 9

Looking Up Information on Tcl and Tk Commands ..... 10
The pack Command ..... 12
Making Your Tcl Script from Our Commands ..... 13
Making Your Tcl Scripts Look Like Real Programs ..... 16

Making Your Tcl Scripts Look Like Real Programs on Windows ..... 17
Making Your Tcl Scripts Look Like Real Programs on UNIX ..... 18
What Happens If You Try This From tclsh? ..... 24

Testing Your Tcl Programs ..... 24
Summary ..... 25

Tcl/Tk Commands Introduced in This Chapter ..... 26

Chapter 2: Tcl Basics ..... 27

Tcl Syntax ..... 27
Tcl Variables ..... 33

Variables and Substitutions ..... 34

Command Substitution ..... 35
Changing Data in Variables ..... 38
Array Variables ..... 38

The array Command ..... 40
Searching Through Arrays ..... 42
Emulating Multidimensional Arrays ..... 43

Special Arrays for Environment Variables ..... 44
Special Arrays to Describe Your Computing Platform ..... 45
Controlling the Flow of the Script ..... 46
Expressions ..... 48
Better to Switch Than Fight ..... 50

Trade-Offs with the switch Command ..... 52
More Expressive Comparisons ..... 52
More Example Globs ..... 54
Regular Expression or Regex Matches ..... 55
The regexp Command ..... 59
Using -regexp in the switch Command .....60
The regsub Command ..... 65

Looping Commands ..... 66

The foreach Command ..... 68
The while Command ..... 69

Jumping Out of Things ..... 70
Built-In Procedures in Tcl ..... 74
Writing Your Own Procedures ..... 79

Returning Values from Procedures ..... 83
Global and Local Variables ..... 84

Call by Reference ..... 85

Renaming Procedures ..... 88
Procedures with a Variable Number of Arguments ..... 89
Procedure Families ..... 91
Defining Procedures Within Procedures ..... 94

Math in Tcl ..... 95

Numeric Notation ..... 98
Math Procedures ..... 99

Summary ..... 101

Tcl/Tk Commands Introduced in This Chapter ..... 102

Chapter 3: Interacting with the User ..... 103

The Tk Toolkit ..... 103

Widgets ..... 104

The Tour de Widgets ..... 104

Where Widgets Appear ..... 106

Pushing Buttons ..... 107

When to Use a button ..... 107
Creating Widgets ..... 107
Common Widget Options ..... 108
Widget Examples ..... 111
Colored Buttons ..... 112

Color Names ..... 114

RGB Colors ..... 116

Fonts ..... 116

The font Command ..... 117
Other Ways to Name Fonts ..... 133
System-Specific Fonts ..... 140

Calling Code from Widgets ..... 143
Text Options ..... 145
Changing Widgets Once Created ..... 148
Displaying Text Messages with Labels ..... 150
Multiline Labels ..... 151
Radio- and Checkbuttons ..... 153

When To Use Radio- and Checkbuttons ..... 153
Working with Radio- and Checkbuttons ..... 153
Radiobuttons ..... 155
Flashing Radiobuttons ..... 159

The Scale Widget ..... 160

When To Use a scale Widget ..... 160
Controlling the Scale ..... 161
Controlling Floating-Point Conversions ..... 162
Executing Tcl Code When the Scale Changes ..... 163
Making Scales Bigger ..... 165
Special Scale Widget Commands ..... 165
RGB Scales ..... 166

How the Widget Packer Works ..... 168

Inserting Widgets into the Layout ..... 172
Filler Up ..... 174
Padding ..... 176
Finding Out About the Packer ..... 176
Placing Widgets ..... 177

The grid Layout Manager ..... 178

When to Use the grid Command for L