TGSelector / TChooseGradient / TInk

Source: source/classes/tgselect.prg

TGSelector from TControl, TChooseGradient standalone dialog, TInk standalone

TGSelector is a gradient bar editor control that allows users to visually create and edit color gradients by adding, moving, and removing color stops ("inks") along a gradient bar. TChooseGradient provides a complete dialog wrapper around TGSelector with RGB sliders for precise color editing. TInk represents a single color stop within the gradient.

TGSelector

A TControl subclass that displays an interactive gradient bar with movable color stops.

Key DATA Members

DATA	Type	Description
`aInks`	Array	Array of TInk objects representing gradient color stops
`aGradOut`	Array	Output gradient array: `{ { nPercent, nColorStart, nColorEnd }, ... }`
`oInkOver`	Object	The TInk currently under the mouse cursor
`lChanged`	Logical	Whether the gradient has been modified
`bSelected`	Code block	Evaluated when an ink is selected
`bChanged`	Code block	Evaluated when the gradient is modified
`nMargin`	Numeric	Left/right margin in pixels (default 10)

TGSelector Methods

Method	Description
`New( nTop, nLeft, nW, nH, oWnd, aInit )`	Create the gradient selector. `aInit` is an optional initial gradient array.
`AddInk( nPct, nClr1, nClr2 )`	Add a new color stop at the given percentage with start/end colors
`InsInk( n, nPct, nClr1, nClr2 )`	Insert a color stop at position n
`SetColorInk( nClr )`	Change the color of the currently selected ink
`BuildGradientArray()`	Build the output gradient array from current ink positions. Returns `aGradOut`.
`BuildInkFromArray( aInit )`	Initialize inks from a gradient array

TChooseGradient

A complete modal dialog for editing gradients with visual feedback and RGB controls.

Method	Description
`New( aInit, bCode, bOnOK, bOnCancel )`	Open the gradient editor dialog. `aInit` is the initial gradient array. `bCode` is evaluated on change. `bOnOK`/`bOnCancel` are action blocks.

TInk

Represents a single color stop in the gradient.

DATA	Type	Description
`nPorcentClr`	Numeric	Percentage position along the gradient (0.0 to 1.0)
`nColorStart`	Numeric	Start color (left side of the stop)
`nColorEnd`	Numeric	End color (right side of the stop)
`lSelected`	Logical	Whether this ink is currently selected
`lMove`	Logical	Whether the ink can be moved (false for boundary inks)
`lFirst`	Logical	Whether this is the first (leftmost) ink in the gradient

Free Function

Function	Description
`ChooseGradient( aInit ) --> aGradOut`	Opens the gradient picker dialog and returns the resulting gradient array. This is the simplest way to use the gradient editor.

Example

#include "FiveWin.ch"

function Main()

   local aGrad

   // Initial gradient: black to white
   local aInit := { { 1, 0, nRGB( 255, 255, 255 ) } }

   // Open the gradient picker dialog
   aGrad := ChooseGradient( aInit )

   if ! Empty( aGrad )
      // Use the gradient: e.g., fill a window background
      MsgInfo( "Gradient created with " + Str( Len( aGrad ) ) + " stops" )
   endif

return nil

Notes

The ChooseGradient() function is the simplest entry point -- it opens a full dialog with RGB sliders, a color panel, and OK/Cancel buttons, then returns the resulting gradient array.
The gradient output array format is { { nPercent, nColorStart, nColorEnd }, ... }, which is directly usable by GradientFill() and other gradient drawing functions.
Right-clicking an interior ink removes it (merges its space with neighbors).
Double-clicking an ink opens the Windows color picker (ChooseColor()) to edit its color.
Inks can be dragged left/right to adjust their position in the gradient.