TSlider

Fuente: source/classes/slider.prg

Inherits from: TControl

TSlider provides a trackbar / slider control for selecting a numeric value by dragging a thumb along a track. It supports horizontal and vertical orientation, tick marks, snap-to-grid (exact) positioning, and a slim style with a colored thumb.

Command Syntax

@ nRow, nCol SLIDER oSld VAR nValue RANGE nMin, nMax SIZE nW, nH PIXEL OF oWnd ;
   HORIZONTAL MARKS nMarks EXACT ON CHANGE bBlock

Key DATA Members

DATA	Type	Description
`lHorizontal`	Logical	Horizontal orientation (.T.) or vertical (.F.)
`nMin`	Numeric	Minimum value of the slider range
`nMax`	Numeric	Maximum value of the slider range
`nMarks`	Numeric	Number of tick marks along the track (0 = no marks)
`lExact`	Logical	Snap the thumb to the nearest tick mark
`nClrBtn`	Numeric	Color of the slider thumb button
`lSlimStyle`	Logical	Render with a slim track and colored thumb
`nDirection`	Numeric	Tick mark direction (1=top, 2=left, 3=bottom, 4=right)

Methods

Method	Description
`New( nRow, nCol, bSetGet, lHorizontal, lDirect1, lDirect2, nMin, nMax, nMarks, lExact, oWnd, bChange, bPos, nWidth, nHeight, lPixel, cMsg, nClrFore, nClrBack, nClrBtn, lDesign, lUpdate, lSlim )`	Create a new TSlider control
`ReDefine( nId, bSetGet, lHorizontal, lDirect1, lDirect2, nMin, nMax, nMarks, lExact, oWnd, bChange, bPos, cMsg, nClrFore, nClrBack, nClrBtn, lUpdate, lSlim )`	Redefine from dialog resource
`Set( nVal )`	Programmatically set the slider to a value
`Change()`	Execute bChange code block with the current value
`Default()`	Recalculate positions and redraw

Examples

Volume Slider (0-100)

#include "FiveWin.ch"

function Main()

   local oWnd, oSld, nVolume := 50

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

   @ 40, 30 SLIDER oSld VAR nVolume RANGE 0, 100 ;
      SIZE 300, 30 PIXEL OF oWnd HORIZONTAL ;
      ON CHANGE oWnd:SetText( "Volume: " + Str( nVolume, 3 ) + "%" )

   ACTIVATE WINDOW oWnd CENTERED

return nil

Selector with Tick Marks

#include "FiveWin.ch"

function Main()

   local oWnd, oSld, nOption := 3, aOpts := { "Low", "Med", "Norm", "High", "Max" }

   DEFINE WINDOW oWnd TITLE "Speed Selector" SIZE 400, 150

   @ 40, 30 SLIDER oSld VAR nOption RANGE 1, 5 ;
      SIZE 300, 30 PIXEL OF oWnd HORIZONTAL ;
      MARKS 5 EXACT ;
      ON CHANGE oWnd:SetText( "Speed: " + aOpts[ nOption ] )

   ACTIVATE WINDOW oWnd CENTERED

return nil

Notes

The slider is a self-drawn GDI control, not the Windows common trackbar. This ensures consistent appearance across Windows versions and provides the slim style option.
When MARKS nMarks is specified together with EXACT, the thumb snaps to the nearest tick mark position, providing discrete step behavior.
Slim style (lSlimStyle or the SLIM clause) renders a thinner track with a colored thumb (defaults to CLR_BLUE) for a modern appearance.
Keyboard navigation: Left/Up decrements the value, Right/Down increments it. Page Up/Page Down jump by larger steps.
The control supports both mouse dragging and click-to-position interaction. Dragging the thumb produces real-time value updates via the bChange code block.