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Tcl and Tk

Tcl and Tk. CSE 470 Fall 1999 Revised by Prasad. Objective . To use Tcl Tk to develop GUI and prototype of the project. What is Tcl/Tk ? . Tcl (Tools Command Lanuage): is a simple string based scripting language for controlling and extending applications.

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Tcl and Tk

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  1. Tcl and Tk CSE 470 Fall 1999 Revised by Prasad

  2. Objective • To use Tcl Tk to develop GUI and prototype of the project

  3. What is Tcl/Tk ? • Tcl (Tools Command Lanuage): is a simple string based scripting language for controlling and extending applications. • Tcl provides generic programming facilities such as variables, loops, and procedures. • Tk: a Tool kit based on X-window system. • Tk provides facilities (widgets) for building user interfaces. • Tcl/Tk are excellent tools for Rapid prototyping.

  4. Tcl/Tk .. continued • Tcl/Tk is interpreted rather than compiled ( The interpreter is in !/opt/bin/wish ) • It is a weakly typed language (strings and integer variables are interchangeable). • Tcl syntax is very much similar to UNIX shell programming.

  5. Tcl primitives • Assignment Value set name “ “ set ID 89 89 set number ID ID set number $ID 89 • if statement: if {$turn == “0”} { computer_move } else { player_move }

  6. Tcl Primitives • Procedures, expressions … proc diag {a b} { set c [expr sqrt($a * $a + $b * $b) ] return $c } • Loops (the while loop) while {$i <= 10} { set I [expr $i+1] }

  7. Tk Fundamentals • Tk provides commands for creating and manipulating widgets. • Widgets types include buttons, scroll bars, text boxes, scales, canvas etc. • The three step procedure for creating a widget. 1) Declare the widget 2) Define any event procedure 3) Pack the Widget.

  8. A simple example: Push Button • Declaring the widget button .pushbutton -text pushme -command procpush • Defining Event Procedure proc procpush {} { .pushbutton config -text “I am pushed” } • Packing pack .pushbutton -side top • Execute the script wish filename.tk

  9. Simple Example: contd ...

  10. Naming conventions • Widgets should be referred in a hierarchical fashion. • Names of all top level widgets start with a “. “ (period). • Example: Say we have top level entity as frame and inside it we have a button. frame .entryframe button .entryframe.pushbutton -text “push me” • Thus all widgets have a parent-child relationship.

  11. Timer • The after command: • after 1000 Makes the program wait for 1000ms before proceeding further. • after 1000 proc Fires the procedure proc after 1000ms but proceeds immediately to the next statement after after statement.

  12. Example 2

  13. Examples of widgets • Canvas canvas .colorwin -width 7c -height 2c • Scale scale .redscale -label Red -from 0 -to 255 -length 7c • Frame frame .entryframe • Text Box entry .entryframe.Namebox -width 7 -height 2

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