CreateBrushGradientRadialEx - ProGUI Reference Manual

Syntax

Brush = CreateBrushGradientRadialEx(CenterX.d, CenterY.d, OriginOffsetX.d, OriginOffsetY.d, RadiusX.d, RadiusY.d, *gradientStops.PG_GradientStop, gradientStopCount.i)

Description

Creates a radial gradient brush that blends multiple colors outwards from an origin point within an ellipse defined by a center point and radii. Color stops defining the colors, opacities, and positions are provided via an array of `PG_GradientStop` structures.

Parameters

CenterX.d, CenterY.d
The coordinates (in DIPs relative to the drawing origin) of the center of the gradient ellipse.

OriginOffsetX.d, OriginOffsetY.d
The offset (in DIPs) of the gradient origin relative to the `CenterX`, `CenterY`. The first color stop effectively begins at this origin point.

RadiusX.d, RadiusY.d
The horizontal and vertical radii (in DIPs) of the gradient ellipse.

*gradientStops.PG_GradientStop
A pointer to the first element of an array of `PG_GradientStop` structures. Each structure defines a color, opacity, and position for a stop in the gradient.

gradientStopCount.i
The number of elements in the `*gradientStops` array.

The PG_GradientStop structure has the following fields:

Structure PG_GradientStop
  position.f ; Position along the radius (0.0 to 1.0)
  color.l ; RGB color value for this stop
  opacity.f ; Opacity for this stop (0.0 to 1.0)
EndStructure

Return Value

Returns a handle to the newly created radial gradient brush object if successful, or #Null if the brush could not be created (e.g., invalid parameters).

Remarks

The gradient transitions smoothly between the specified color stops radiating outwards from the origin. The `position` field in `PG_GradientStop` must be between 0.0 and 1.0, inclusive, and the stops should generally be ordered by position. The extend mode (BrushSetExtendMode) determines behavior outside the ellipse. The brush can be transformed. Remember to free the brush using FreeBrush().

Example

IncludeFile "ProGUI_PB.pbi"

Global MyGradient

Procedure DrawHandler(Window, EventType, *EventData.PG_EventDraw)
  DrawClear(RGB(240, 240, 240), 1)
  ; No need to set position here as coordinates are absolute for the fill area
  DrawBoxFill(0, 0, 400, 300, MyGradient)
EndProcedure

StartProGUI()

MyWindow = CreateWindow(0, 0, 400, 300, "Multi-Stop Radial Gradient")

If MyWindow
  ; Define the color stops for a target-like gradient
  Dim MyStops.PG_GradientStop(2)
  MyStops(0)\position = 0.0 : MyStops(0)\color = RGB(255, 0, 0) : MyStops(0)\opacity = 1.0 ; Red center
  MyStops(1)\position = 0.5 : MyStops(1)\color = RGB(255, 255, 255) : MyStops(1)\opacity = 1.0 ; White ring
  MyStops(2)\position = 1.0 : MyStops(2)\color = RGB(0, 0, 255) : MyStops(2)\opacity = 1.0 ; Blue edge
    
  ; Create a circular radial gradient centered at (200, 150) with radius 100
  MyGradient = CreateBrushGradientRadialEx(200, 150, 0, 0, 100, 100, @MyStops(), 3)

  If MyGradient
    
    AddEventHandler(MyWindow, #PG_Event_Draw, @DrawHandler())
    WindowShow(MyWindow, #True, #PG_Window_ScreenCentered)

    Repeat
        Event = WaitWindowEvent()
    Until Event = #PB_Event_CloseWindow

    FreeBrush(MyGradient) ; Free the brush
    
  EndIf
EndIf

StopProGUI()

Supported OS

Windows, Linux