TTrackBar

Fuente: source/classes/trackbar.prg

Inherits from: TControl

TTrackBar wraps the Win32 trackbar common control (slider). It allows the user to select a numeric value by dragging a thumb along a track, with optional tick marks. It is commonly used for volume controls, brightness sliders, and any ranged value input.

Key DATA Members

DATA	Type	Description
`nMin`	Numeric	Minimum value of the trackbar range
`nMax`	Numeric	Maximum value of the trackbar range
`nPos`	Numeric	Current thumb position
`nFreq`	Numeric	Tick mark frequency
`bChange`	Block	Code block executed when the position changes

Methods

Method	Description
`New( nRow, nCol, oWnd, nW, nH, nMin, nMax, nPos, nFreq )`	Create a new trackbar control
`SetPos( n )`	Set the thumb to position `n`
`GetPos()`	Return the current thumb position
`SetRange( nMin, nMax )`	Set the minimum and maximum range values
`SetTicFreq( n )`	Set the tick-mark frequency

Example: Volume Control 0-255

#include "FiveWin.ch"

function Main()

   local oWnd, oTrack, nVol := 128

   DEFINE WINDOW oWnd TITLE "Volume Control" SIZE 400, 150

   @ 40, 20 TRACKBAR oTrack VAR nVol ;
      SIZE 360, 30 OF oWnd ;
      RANGE 0, 255 ;
      ON CHANGE ( oWnd:SetText( "Volume: " + Str( nVol ) ) )

   ACTIVATE WINDOW oWnd CENTERED

return nil

Notes

TTrackBar wraps the native Win32 trackbar (TRACKBAR_CLASS). It supports both horizontal and vertical orientations depending on the dimensions passed to New().
The VAR clause binds a numeric variable that is updated automatically when the user moves the thumb.
Use SetTicFreq() to show tick marks at regular intervals. A frequency of 0 hides all tick marks.
The ON CHANGE clause sets bChange, which fires continuously as the user drags the thumb.

TTrackBar

Key DATA Members

Methods

Example: Volume Control 0-255

Notes

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