TCheckBox / TRadio

Boolean checkboxes and mutually-exclusive radio button groups

TCheckBox

Source: source/classes/checkbox.prg  |  Parent: TControl

TCheckBox wraps the standard Windows checkbox control. It binds to a logical variable -- .T. when checked, .F. when unchecked. Checkboxes are independent; any number can be checked simultaneously.

TCheckBox Properties

TCheckBox Methods

TCheckBox Command

@ nRow, nCol CHECKBOX oChk VAR lVar ;
   PROMPT "Label text" ;
   [ OF oWnd ] ;
   [ SIZE nWidth, nHeight ] ;
   [ ON CHANGE bChange ] ;
   [ WHEN bWhen ] ;
   [ FONT oFont ]

TRadio and TRadMenu

Source: source/classes/radio.prg  |  Parent: TControl

TRadio represents a single radio button. Radio buttons are mutually exclusive within a group -- selecting one deselects all others. The group is managed by a TRadMenu object, which binds to a numeric variable indicating which option is selected (1-based).

Radio Group Architecture

TRadio Properties

Radio Command

@ nRow, nCol RADIO oRad VAR nChoice ;
   PROMPT "Option text" ;
   [ OF oWnd ] ;
   [ WHEN bWhen ] ;
   [ ON CHANGE bChange ]

When multiple RADIO commands share the same VAR, FiveWin automatically groups them into a TRadMenu.

Checkbox vs. Radio: When to Use Which

Code Examples

Example 1: Checkboxes for Options

#include "FiveWin.ch"

FUNCTION PrintOptions()
   LOCAL oDlg
   LOCAL lLandscape  := .F.
   LOCAL lColor      := .T.
   LOCAL lDuplex     := .F.
   LOCAL lCollate    := .T.
   LOCAL lPreview    := .F.

   DEFINE DIALOG oDlg TITLE "Print Options" SIZE 350, 320

   @ 1.0, 2 SAY "Select print options:" OF oDlg

   @ 2.5, 2 CHECKBOX lLandscape PROMPT "&Landscape orientation" OF oDlg SIZE 200, 18
   @ 4.0, 2 CHECKBOX lColor     PROMPT "&Color printing"        OF oDlg SIZE 200, 18
   @ 5.5, 2 CHECKBOX lDuplex    PROMPT "&Duplex (two-sided)"    OF oDlg SIZE 200, 18
   @ 7.0, 2 CHECKBOX lCollate   PROMPT "Co&llate copies"        OF oDlg SIZE 200, 18
   @ 8.5, 2 CHECKBOX lPreview   PROMPT "Print Pre&view"         OF oDlg SIZE 200, 18

   @ 11, 5  BUTTON "&Print"  OF oDlg SIZE 80, 25 ;
      ACTION ( PrintDoc( lLandscape, lColor, lDuplex, lCollate, lPreview ), ;
               oDlg:End() ) DEFAULT
   @ 11, 15 BUTTON "&Cancel" OF oDlg SIZE 80, 25 ACTION oDlg:End() CANCEL

   ACTIVATE DIALOG oDlg CENTERED
RETURN NIL

Example 2: Radio Button Group

#include "FiveWin.ch"

FUNCTION ShippingMethod()
   LOCAL oDlg
   LOCAL nShipping := 1   // 1=Standard, 2=Express, 3=Overnight

   DEFINE DIALOG oDlg TITLE "Shipping Method" SIZE 350, 280

   @ 1.0, 2 SAY "Select shipping method:" OF oDlg

   @ 2.5, 3 RADIO nShipping PROMPT "&Standard (5-7 days)"  OF oDlg
   @ 4.0, 3 RADIO nShipping PROMPT "&Express (2-3 days)"   OF oDlg
   @ 5.5, 3 RADIO nShipping PROMPT "&Overnight (1 day)"    OF oDlg

   @ 8, 5  BUTTON "&OK" OF oDlg SIZE 80, 25 ;
      ACTION ( ShowShippingCost( nShipping ), oDlg:End() ) DEFAULT
   @ 8, 15 BUTTON "&Cancel" OF oDlg SIZE 80, 25 ACTION oDlg:End() CANCEL

   ACTIVATE DIALOG oDlg CENTERED
RETURN NIL

STATIC FUNCTION ShowShippingCost( nMethod )
   LOCAL aCosts := { 4.99, 12.99, 29.99 }
   LOCAL aNames := { "Standard", "Express", "Overnight" }

   MsgInfo( aNames[ nMethod ] + " shipping: $" + ;
            LTrim( Str( aCosts[ nMethod ], 8, 2 ) ) )
RETURN NIL

Example 3: Mixed Checkboxes and Radios in a Settings Dialog

#include "FiveWin.ch"

FUNCTION AppSettings()
   LOCAL oDlg, oFld, oDlg1, oDlg2
   // Display settings
   LOCAL lShowToolbar := .T.
   LOCAL lShowStatus  := .T.
   LOCAL lFullScreen  := .F.
   LOCAL nTheme       := 1    // 1=Light, 2=Dark, 3=System
   // Behavior settings
   LOCAL lAutoSave    := .T.
   LOCAL lConfirmDel  := .T.
   LOCAL lSounds      := .F.
   LOCAL nStartup     := 1    // 1=Last file, 2=New file, 3=Nothing

   DEFINE DIALOG oDlg TITLE "Application Settings" SIZE 450, 400

   @ 0.3, 0.3 FOLDER oFld OF oDlg ;
      PROMPTS "Display", "Behavior" ;
      DIALOGS oDlg1, oDlg2 ;
      SIZE 420, 280

   // --- Display page ---
   @ 1.0, 2 CHECKBOX lShowToolbar PROMPT "Show &Toolbar"      OF oDlg1 SIZE 200, 18
   @ 2.5, 2 CHECKBOX lShowStatus  PROMPT "Show &Status Bar"   OF oDlg1 SIZE 200, 18
   @ 4.0, 2 CHECKBOX lFullScreen  PROMPT "&Full Screen Mode"  OF oDlg1 SIZE 200, 18

   @ 6.0, 2 SAY "Color Theme:" OF oDlg1
   @ 7.5, 3 RADIO nTheme PROMPT "&Light"  OF oDlg1
   @ 9.0, 3 RADIO nTheme PROMPT "&Dark"   OF oDlg1
   @ 10.5, 3 RADIO nTheme PROMPT "&System" OF oDlg1

   // --- Behavior page ---
   @ 1.0, 2 CHECKBOX lAutoSave   PROMPT "&Auto-save every 5 minutes" OF oDlg2 SIZE 250, 18
   @ 2.5, 2 CHECKBOX lConfirmDel PROMPT "&Confirm before deleting"   OF oDlg2 SIZE 250, 18
   @ 4.0, 2 CHECKBOX lSounds    PROMPT "Enable &Sounds"             OF oDlg2 SIZE 250, 18

   @ 6.0, 2 SAY "On startup:" OF oDlg2
   @ 7.5, 3 RADIO nStartup PROMPT "Open &last file"    OF oDlg2
   @ 9.0, 3 RADIO nStartup PROMPT "Create &new file"   OF oDlg2
   @ 10.5, 3 RADIO nStartup PROMPT "Do ¬hing"        OF oDlg2

   // Buttons on the parent dialog
   @ 23, 8  BUTTON "&Save"   OF oDlg SIZE 80, 25 ;
      ACTION ( SaveSettings( lShowToolbar, lShowStatus, lFullScreen, nTheme, ;
                             lAutoSave, lConfirmDel, lSounds, nStartup ), ;
               oDlg:End() ) DEFAULT
   @ 23, 18 BUTTON "&Cancel" OF oDlg SIZE 80, 25 ACTION oDlg:End() CANCEL

   ACTIVATE DIALOG oDlg CENTERED
RETURN NIL

Tips

• Checkbox binds to a logical variable. Radio group binds to a numeric variable (the option index).
• FiveWin auto-groups consecutive RADIO commands sharing the same VAR into a TRadMenu.
• Use & in the PROMPT to set an Alt-key accelerator: "&Landscape" means Alt+L toggles it.
• For a checkbox bound to a DBF logical field, use FieldWBlock( "ACTIVE", Select() ) as the bSetGet.
• The ON CHANGE clause fires after each state change, useful for enabling/disabling dependent controls.
• Radio buttons support arrow-key navigation within the group automatically.
• For more than 5-6 options, consider using a TComboBox instead of a long radio group.

See Also

• TControl -- parent class
• TComboBox -- alternative for selecting one of many items
• TGet -- text input controls
• TFolder -- tab control often used to organize checkboxes and radios