TButton / TBtnBmp

Standard push buttons and bitmap buttons for dialogs and toolbars

TButton

Fuente: source/classes/button.prg  |  Parent: TControl

TButton wraps the standard Windows push button control. It is the most basic interactive element -- a labeled rectangle that executes an action when clicked. Buttons can be designated as the default button (activated by Enter) or the cancel button (activated by Escape).

Class Hierarchy

TButton Properties

TButton Methods

TButton Command Syntax

@ nRow, nCol BUTTON oBtn PROMPT "text" ;
   [ OF oWnd ] ;
   [ SIZE nWidth, nHeight ] ;
   [ ACTION codeblock ] ;
   [ DEFAULT ] ;
   [ CANCEL ] ;
   [ FONT oFont ] ;
   [ WHEN bWhen ]

Button State Machine

TBtnBmp

Fuente: source/classes/btnbmp.prg  |  Parent: TControl

TBtnBmp is an owner-drawn bitmap button that supports multiple visual states (normal, pressed, mouse-over, disabled). It is the button type used in toolbars (TButtonBar) and anywhere you need graphical buttons with icons.

TBtnBmp Properties

TBtnBmp Command Syntax

@ nRow, nCol BTNBMP oBtn ;
   [ OF oWnd ] ;
   [ SIZE nWidth, nHeight ] ;
   [ ACTION codeblock ] ;
   [ FILENAME cBmpFile | RESOURCE cResName ] ;
   [ TOOLTIP cText ] ;
   [ FLAT ] ;
   [ PROMPT cText ] ;
   [ WHEN bWhen ]

4-State Bitmap System

TBtnBmp supports four distinct visual states, each with its own bitmap. The button automatically switches between them based on user interaction:

For resource-based buttons, bitmap IDs follow Borland conventions: the normal bitmap uses the base ID, the pressed bitmap uses base_id + 10000, the disabled bitmap uses base_id + 20000, and the hover bitmap uses base_id + 30000. File-based buttons use four separate files or a multi-image strip, specified via the FILENAME clause.

Advanced Rendering Options

Additional visual enhancements are available through TBtnBmp DATA members:

• lGDIP -- Enables GDI+ alpha-blended rendering, providing anti-aliased edges and smooth transparency for PNG and 32-bit BMP bitmaps.
• bColorMap -- A codeblock for dynamic color remapping on the button bitmap, allowing per-state or per-button color substitution (e.g., changing icon color for active vs. inactive states).
• bAlphaLevel -- A codeblock that returns a custom alpha value (0-255) per state, enabling granular transparency control for each button state independently.

BUTTONBAR (Toolbar)

The DEFINE BUTTONBAR command creates a TButtonBar container that hosts TBtnBmp buttons as a toolbar at the top of a window.

DEFINE BUTTONBAR oBar OF oWnd SIZE nBtnW, nBtnH [ 2007 | 2010 | 2013 | 2015 ]

DEFINE BUTTON oBtn1 OF oBar ;
   RESOURCE "NEW" ;
   TOOLTIP "New record" ;
   ACTION NewRecord()

DEFINE BUTTON oBtn2 OF oBar ;
   RESOURCE "EDIT" ;
   TOOLTIP "Edit record" ;
   ACTION EditRecord()

DEFINE BUTTON oBtn3 OF oBar ;
   RESOURCE "PRINT" ;
   TOOLTIP "Print report" ;
   ACTION PrintReport() ;
   GROUP                      // visual separator before this button

Code Examples

Example 1: Standard Dialog Buttons

#include "FiveWin.ch"

FUNCTION TestButtons()
   LOCAL oDlg, oBtn1, oBtn2

   DEFINE DIALOG oDlg TITLE "Button Demo" SIZE 400, 250

   @ 2, 2 BUTTON oBtn1 PROMPT "&Save" ;
      OF oDlg SIZE 80, 25 ;
      ACTION ( MsgInfo( "Saved!" ), oDlg:End() ) ;
      DEFAULT

   @ 2, 12 BUTTON oBtn2 PROMPT "&Cancel" ;
      OF oDlg SIZE 80, 25 ;
      ACTION oDlg:End() ;
      CANCEL

   // A button with a WHEN clause -- disabled until data is valid
   @ 4, 2 BUTTON PROMPT "&Delete" ;
      OF oDlg SIZE 80, 25 ;
      ACTION DeleteRecord() ;
      WHEN ( !Empty( cRecId ) )

   ACTIVATE DIALOG oDlg CENTERED
RETURN NIL

Example 2: Bitmap Buttons

#include "FiveWin.ch"

FUNCTION TestBmpButtons()
   LOCAL oWnd, oBtn

   DEFINE WINDOW oWnd TITLE "Bitmap Button Demo"

   // Bitmap button from a file
   @ 2, 2 BTNBMP oBtn OF oWnd ;
      SIZE 120, 40 ;
      FILENAME "..\bitmaps\save.bmp" ;
      PROMPT "Save" ;
      ACTION MsgInfo( "Saving..." ) ;
      FLAT

   // Bitmap button from a resource
   @ 5, 2 BTNBMP OF oWnd ;
      SIZE 120, 40 ;
      RESOURCE "PRINT" ;
      PROMPT "Print" ;
      ACTION PrintReport() ;
      TOOLTIP "Print current report"

   ACTIVATE WINDOW oWnd
RETURN NIL

Example 3: Complete Toolbar

#include "FiveWin.ch"

FUNCTION Main()
   LOCAL oWnd, oBar

   DEFINE WINDOW oWnd TITLE "Application with Toolbar"

   DEFINE BUTTONBAR oBar OF oWnd SIZE 56, 56 2015

   DEFINE BUTTON OF oBar ;
      RESOURCE "NEW"   TOOLTIP "New"   ACTION NewDoc()
   DEFINE BUTTON OF oBar ;
      RESOURCE "OPEN"  TOOLTIP "Open"  ACTION OpenDoc()
   DEFINE BUTTON OF oBar ;
      RESOURCE "SAVE"  TOOLTIP "Save"  ACTION SaveDoc()

   DEFINE BUTTON OF oBar ;
      RESOURCE "PRINT" TOOLTIP "Print" ACTION PrintDoc() GROUP

   DEFINE BUTTON OF oBar ;
      RESOURCE "HELP"  TOOLTIP "Help"  ACTION HelpDoc() GROUP

   SET MESSAGE OF oWnd TO "Ready" CENTERED

   ACTIVATE WINDOW oWnd
RETURN NIL

Tips

• Use & in the PROMPT to define an accelerator key: "&Save" makes Alt+S activate the button.
• Only one button per dialog should be DEFAULT and one should be CANCEL.
• For modern toolbar looks, use the 2015 style on DEFINE BUTTONBAR.
• TBtnBmp supports PNG files with alpha transparency for high-quality icons.
• Use the GROUP clause to insert a visual separator between logical groups of toolbar buttons.

Ver También

• TControl -- parent class
• TMenu -- menus often paired with toolbars
• TDialog -- typical container for TButton