package gradient

import "golang.org/x/exp/shiny/iconvg/internal/gradient"

Package gradient provides linear and radial gradient images.

Index ¶

• type Gradient
• func (g *Gradient) At(x, y int) color.Color
• func (g *Gradient) Bounds() image.Rectangle
• func (g *Gradient) ColorModel() color.Model
• func (g *Gradient) Init(shape Shape, spread Spread, pix2Grad f64.Aff3, stops []Stop)
• type Range
• func AppendRanges(a []Range, stops []Stop) []Range
• func MakeRange(s0, s1 Stop) Range
• type Shape
• type Spread
• func (s Spread) Clamp(x float64) float64
• type Stop

Types ¶

type Gradient ¶

type Gradient struct {
	Shape  Shape
	Spread Spread

	// Pix2Grad transforms coordinates from pixel space (the arguments to the
	// Image.At method) to gradient space. Gradient space is where a linear
	// gradient ranges from x == 0 to x == 1, and a radial gradient has center
	// (0, 0) and radius 1.
	//
	// This is an affine transform, so it can represent elliptical gradients in
	// pixel space, including non-axis-aligned ellipses.
	//
	// For a linear gradient, the bottom row is ignored.
	Pix2Grad f64.Aff3

	Ranges []Range

	// First and Last are the first and last stop's colors.
	First, Last color.RGBA64
}

Gradient is a very large image.Image (the same size as an image.Uniform) whose colors form a gradient.

func (*Gradient) At ¶

func (g *Gradient) At(x, y int) color.Color

At satisfies the image.Image interface.

func (*Gradient) Bounds ¶

func (g *Gradient) Bounds() image.Rectangle

Bounds satisfies the image.Image interface.

func (*Gradient) ColorModel ¶

func (g *Gradient) ColorModel() color.Model

ColorModel satisfies the image.Image interface.

func (*Gradient) Init ¶

func (g *Gradient) Init(shape Shape, spread Spread, pix2Grad f64.Aff3, stops []Stop)

Init initializes g to a gradient whose geometry is defined by shape and pix2Grad and whose colors are defined by spread and stops.

type Range ¶

type Range struct {
	Offset0 float64
	Offset1 float64
	Width   float64
	R0      float64
	R1      float64
	G0      float64
	G1      float64
	B0      float64
	B1      float64
	A0      float64
	A1      float64
}

Range is the range between two stops.

func AppendRanges ¶

func AppendRanges(a []Range, stops []Stop) []Range

AppendRanges appends to a the ranges defined by a's implicit final stop (if any exist) and stops.

func MakeRange ¶

func MakeRange(s0, s1 Stop) Range

MakeRange returns the range between two stops.

type Shape ¶

type Shape uint8

Shape is the gradient shape.

const (
	ShapeLinear Shape = iota
	ShapeRadial
)

type Spread ¶

type Spread uint8

Spread is the gradient spread, or how to spread a gradient past its nominal bounds (from offset being 0.0 to offset being 1.0).

const (
	// SpreadNone means that offsets outside of the [0, 1] range map to
	// transparent black.
	SpreadNone Spread = iota
	// SpreadPad means that offsets below 0 and above 1 map to the colors that
	// 0 and 1 would map to.
	SpreadPad
	// SpreadReflect means that the offset mapping is reflected start-to-end,
	// end-to-start, start-to-end, etc.
	SpreadReflect
	// SpreadRepeat means that the offset mapping is repeated start-to-end,
	// start-to-end, start-to-end, etc.
	SpreadRepeat
)

func (Spread) Clamp ¶

func (s Spread) Clamp(x float64) float64

Clamp clamps x to the range [0, 1]. If x is outside that range, it is converted to a value in that range according to s's semantics. It returns -1 if s is SpreadNone and x is outside the range [0, 1].

type Stop ¶

type Stop struct {
	Offset float64
	RGBA64 color.RGBA64
}

Stop is an offset and color.

Source Files ¶

gradient.go